Abstract Energy storage devices have important role in the energy system as they minimize the mismatch between the supply and demand. This leads to improvement of the performance and the reliability of the systems. In thermal energy storage systems the Latent heat type thermal energy storages (LHTES) are attractive since they have high energy storage density and nearly isothermal operation at the phase transition temperature of the material usedthat is commonly known as phase change material (PCM). In this paper PCMs with solid-solid and solid-liquid phase transition are discussed. Though PCMs with solid-solid phase transition seem attractive due to their less stringent containment requirements but they are not widely used because of their low latent heat. PCMs with solid-liquid phase transition are the most studied and used latent heat storage materials. Those are discussed in details with their selection criterion, classification and applications. The steps involved in development of the energy storage systems and problems associated with PCMs are discussed in the next part of the paper. This will give better understanding of the latent heat storage systems to the reader. KeyWords: Latent heat storage (LHS), Phase change materials (PCM), Thermal conductivity, Thermal cycling.
Thermal energy storage materials and systems for solar energy applicationsSivanjaneya Reddy
How to enhance thermal conductivity for phase change materials and selection of phase change material and about systems for solar energy application has been presented
This document proposes a novel latent heat storage system for solar space heating and cooling systems using refrigerant storage. The system utilizes an absorption refrigeration cycle using a heat source such as solar energy to generate refrigerant gas. The refrigerant is condensed and stored for later use, providing improved energy storage capacity over sensible heat storage methods. When heating or cooling is needed, the stored refrigerant is evaporated to power the cycle. For heating, the absorber heat is used to heat buildings. The refrigerant storage concept provides high energy density, near-ambient storage temperatures, and low storage pressures. This system could improve the viability of solar heating and cooling if extended for combined year-round operation.
The document presents the results of an experimental analysis of a flat plate solar collector with an integrated latent heat storage unit using phase change material (PCM). Tests were conducted over 60 days from October 2016 to March 2017 in Colombia. The collector reached an average thermal efficiency of 24.11% and a maximum outlet temperature of 50°C. While the PCM provided stability to outlet temperatures during cloudiness, it was unable to supply thermal energy after sunset likely due to a short charging time where the absorber plate temperature reached the PCM melting point. Using a PCM with a lower melting point may increase charging time and improve performance.
This document discusses thermal energy storage using phase change materials (PCMs). PCMs can effectively store thermal energy during phase transitions from solid to liquid or vice versa, providing high energy storage density. Some commonly used PCMs are salt hydrates and hydrocarbons. Thermal energy stored as latent heat during phase changes can be 5-10 times more dense than thermal energy stored sensibly through temperature changes alone. The document outlines applications of PCM thermal storage in building insulation and solar energy systems.
Phase-change materials (PCMs) can be used for thermal energy storage. PCMs absorb and release large amounts of energy as they change phase from solid to liquid and back. This latent heat storage allows PCMs to store more energy per unit volume compared to sensible heat storage methods. Effective PCMs for thermal energy storage applications should have suitable melting temperatures, heat of fusion, thermal and mechanical stability over repeated phase changes, and acceptable costs. However, challenges remain regarding material compatibility, conditioning, safety, and cost-effectiveness compared to other thermal energy storage options.
With the introduction of the government’s Renewable Heat Incentive (RHI), there is an increasing interest in all the technologies associated with the scheme. This CPD gives an overview of a range of policy initiatives in Renewable Heat, an introduction to the different technologies and looks at some of the benefits and issues you need to consider when using renewable heat.
This CPD seminar covers the following topics: Introduction to REHAU, DECC Heat Strategy & Renewable Heat Incentive (RHI), Ground Source Heat Pumps, Biomass Boilers (incl. district heating), Biogas/Anaerobic Digestion, Solar Thermal & Underground Thermal Energy Storage.
This document discusses different types of energy storage systems including superconducting magnetic energy storage (SMES), thermal energy storage (TES), and their applications. SMES stores energy in a superconducting coil's magnetic field and can quickly discharge stored energy back to the electric grid. TES temporarily stores thermal energy and can balance energy supply and demand. TES includes sensible heat storage using liquids, solids, or both, and latent heat storage using phase change materials. These storage systems provide benefits like clean power generation and mitigating renewable energy fluctuations.
Thermal energy storage materials and systems for solar energy applicationsSivanjaneya Reddy
How to enhance thermal conductivity for phase change materials and selection of phase change material and about systems for solar energy application has been presented
This document proposes a novel latent heat storage system for solar space heating and cooling systems using refrigerant storage. The system utilizes an absorption refrigeration cycle using a heat source such as solar energy to generate refrigerant gas. The refrigerant is condensed and stored for later use, providing improved energy storage capacity over sensible heat storage methods. When heating or cooling is needed, the stored refrigerant is evaporated to power the cycle. For heating, the absorber heat is used to heat buildings. The refrigerant storage concept provides high energy density, near-ambient storage temperatures, and low storage pressures. This system could improve the viability of solar heating and cooling if extended for combined year-round operation.
The document presents the results of an experimental analysis of a flat plate solar collector with an integrated latent heat storage unit using phase change material (PCM). Tests were conducted over 60 days from October 2016 to March 2017 in Colombia. The collector reached an average thermal efficiency of 24.11% and a maximum outlet temperature of 50°C. While the PCM provided stability to outlet temperatures during cloudiness, it was unable to supply thermal energy after sunset likely due to a short charging time where the absorber plate temperature reached the PCM melting point. Using a PCM with a lower melting point may increase charging time and improve performance.
This document discusses thermal energy storage using phase change materials (PCMs). PCMs can effectively store thermal energy during phase transitions from solid to liquid or vice versa, providing high energy storage density. Some commonly used PCMs are salt hydrates and hydrocarbons. Thermal energy stored as latent heat during phase changes can be 5-10 times more dense than thermal energy stored sensibly through temperature changes alone. The document outlines applications of PCM thermal storage in building insulation and solar energy systems.
Phase-change materials (PCMs) can be used for thermal energy storage. PCMs absorb and release large amounts of energy as they change phase from solid to liquid and back. This latent heat storage allows PCMs to store more energy per unit volume compared to sensible heat storage methods. Effective PCMs for thermal energy storage applications should have suitable melting temperatures, heat of fusion, thermal and mechanical stability over repeated phase changes, and acceptable costs. However, challenges remain regarding material compatibility, conditioning, safety, and cost-effectiveness compared to other thermal energy storage options.
With the introduction of the government’s Renewable Heat Incentive (RHI), there is an increasing interest in all the technologies associated with the scheme. This CPD gives an overview of a range of policy initiatives in Renewable Heat, an introduction to the different technologies and looks at some of the benefits and issues you need to consider when using renewable heat.
This CPD seminar covers the following topics: Introduction to REHAU, DECC Heat Strategy & Renewable Heat Incentive (RHI), Ground Source Heat Pumps, Biomass Boilers (incl. district heating), Biogas/Anaerobic Digestion, Solar Thermal & Underground Thermal Energy Storage.
This document discusses different types of energy storage systems including superconducting magnetic energy storage (SMES), thermal energy storage (TES), and their applications. SMES stores energy in a superconducting coil's magnetic field and can quickly discharge stored energy back to the electric grid. TES temporarily stores thermal energy and can balance energy supply and demand. TES includes sensible heat storage using liquids, solids, or both, and latent heat storage using phase change materials. These storage systems provide benefits like clean power generation and mitigating renewable energy fluctuations.
This document summarizes research on integrating phase change materials (PCMs) into solar water heating systems for thermal energy storage. It reviews five studies that examined using PCMs like paraffin wax, calcium chloride hexahydrate, and sodium thiosulfate pentahydrate. The performance enhancements of PCMs include storing up to 3.45 times more energy and maintaining hot water temperatures during off-sunshine hours through latent heat release. However, flow rate affects efficiency, with lower rates providing hot water longer. Increased PCM mass also lengthens storage time but lowers charging temperatures. Overall, PCMs improve solar water heating by enabling isothermal energy storage and release.
This document summarizes a presentation given at the 4th International Conference on Advances in Energy Research held at the Indian Institute of Technology Bombay in India on October 10, 2013. The presentation discusses enhancements to a thermal storage system for domestic use through the use of phase change material (PCM). Specifically:
- An experimental investigation of a 10 liter per day capacity thermal storage system found that including PCM occupying 26% of the volume improved the thermal storage capacity by 22% compared to a system without PCM.
- The PCM used was HS-58, which has suitable thermal properties for domestic solar water heating systems.
- Temperature time data from the experiments show that the system with PCM maintained
01 thermal energy storage using ice slurryWahid Mohamed
This document discusses thermal energy storage using ice slurry. It begins with an introduction to thermal energy storage, including sensible energy storage using water and latent cool storage technologies. It defines ice slurry as a suspension of ice crystals in liquid. The document outlines the components of an ice slurry generator system, including schematics of different configurations. It notes benefits like higher energy transport density and consistently cool temperatures near the phase change point. Applications include district cooling systems, and case studies demonstrate cost savings from peak shaving and improved chiller efficiency.
Thermal energy storage systems store thermal energy and make it available at a later time for uses such as balancing energy supply and demand or shifting energy use from peak to off-peak hours. The document discusses several types of thermal energy storage including latent heat storage using phase change materials, sensible heat storage using temperature changes in materials, and thermo-chemical storage using chemical reactions. Case studies of thermal energy storage applications in solar plants, buildings, and cold chain transportation are also presented.
Sensible heat energy storage technology using low cost locally available ther...Husain Mehdi
Thermal energy storage in packed beds is increasing attention due to necessary component for efficient utilization of solar energy. A one dimensional thermal model for the behavior of a packed bed is presented for low cost thermal energy sensible heat energy storage materials (i.e. stone, glass, rocks, bricks, and granite) and air as the heat transfer fluid. This model predicts successfully during storage are presented for brick and rock in a cylindrical packed bed storage unit. Explicit expression for time variation of storage material temperature and air flowing in the system have been developed and performance parameters have been computed for five storage materials.
This document discusses phase change materials (PCMs) which can store and release large amounts of thermal energy during phase transitions between solid and liquid states. PCMs provide high energy storage density with small temperature changes. Thermal energy storage methods include sensible heat storage based on temperature change and latent heat storage using phase change. PCMs are classified as organic, inorganic, or eutectic and are selected based on properties like melting temperature and thermal stability. Applications of PCMs include construction materials, textiles, food/medical packaging, and automobiles.
This document summarizes research on thermochemical materials for heat storage. It compares different heat storage systems and discusses the principle and selection of thermochemical heat storage (THSS) materials. The characteristics of SrBr2 and MgSO4 hydrates are described based on thermal analysis. Composites of these materials with activated carbon and expanded natural graphite were manufactured and tested through multiple cycles. The composites showed stable performance over cycles but challenges remain around material stability and geometry changes during cycling. Overall, the research aims to develop low-cost thermochemical materials for seasonal heat storage applications.
Development of a thermal energy storage system in a domestic environment into...Nelson García Polanco
My speech on April 27, 2015 at Energy Storage World Forum Rome, was focused on how to recover and reuse low-temperature wasted heat from kitchen appliances, and the technologies for the thermal energy storage. A full prototype of Thermal Energy Storage (TES) system was created. The TES system is based on a packed bed of macro-encapsulated phase change material (PCM). Typical household appliances were analyzed in order to evaluate the waste heat produced on the basis of the average user habits at European level.
1. Thermal energy storage (TES) technologies like phase change materials (PCMs), sorption, and thermochemical materials can store solar and renewable heat for use when needed.
2. PCMs use the heat of phase change during melting and freezing to efficiently store and release thermal energy. Organic PCMs like paraffin wax are promising due to their high storage density and melting temperatures around human comfort levels.
3. Sorption technologies use physical or chemical bonding to store heat in materials like silica gels, zeolites, or chemical reactions. A demonstration used zeolite to store nighttime heat from district heating for use during the day.
Review on nanomaterials for thermal energy storage technologiesOwolabi Afolabi
This document reviews research on nanomaterials for thermal energy storage technologies. It discusses various types of phase change materials and nanomaterials that have been investigated as possible materials for efficient thermal energy storage. Nanoadditives have been used to enhance the thermal properties of phase change materials by increasing their thermal conductivity. The document outlines different classification systems for phase change materials, nanomaterials, and nanofluids/nanocomposites developed for thermal energy storage. It also reviews various synthesis methods that have been used to prepare nanofluids and nanocomposites, including one-step direct evaporation and two-step methods.
A review on phase change materials & their applicationsiaemedu
The document is a review article on phase change materials (PCMs) and their applications. It discusses that PCMs can store large amounts of heat or cold in the form of latent heat during phase transition from solid to liquid or vice versa. This allows PCMs to store 2-3 times more energy per unit volume compared to sensible heat storage. The article then reviews different types of PCMs including organic, inorganic, and eutectic PCMs. Organic PCMs are further divided into paraffin and non-paraffin materials. Several properties of ideal PCMs for thermal energy storage applications are also outlined.
PCM Thermal Energy Storage Systems; Ashrae 2004 Conference PaperZafer Ure
The document discusses positive temperature eutectic (PCM) thermal energy storage systems. It begins by explaining the disadvantages of conventional water-ice storage systems, which require low-temperature chillers. The document then introduces positive temperature eutectic solutions, which can freeze and melt above 0°C, overcoming these disadvantages. Various PCM mixtures are presented, along with encapsulation techniques to contain them. The document argues that PCM storage enables higher evaporator temperatures and lower condenser pressures, improving energy efficiency. A variety of applications are proposed, including utilizing chilled water and refrigeration temperature ranges for charging.
A review of phase change materials (pcms) for cold energy storage applicationsTAHA RAJEH
This document summarizes a review on phase change materials (PCMs) for cold energy storage applications. It discusses how PCMs can be used for cold thermal energy storage (TES) due to their high latent heat of fusion during phase change. The document outlines different types of PCMs and criteria for selecting them, including thermophysical properties like melting temperature and heat of fusion. It provides examples of common inorganic and organic PCMs and discusses techniques to improve PCMs, such as nanostructuring and encapsulation, which can increase heat transfer and thermal conductivity. The document concludes that properly selecting PCMs based on these factors is important for efficiently designing cold storage systems.
Experimental analysis of a flat plate solar collector with integrated latent heat thermal storage
*Mauricio, Carmona1, Mario Palacio2, ArnoldMartínez3
1 Mechanical Engineering Department, Universidad del Norte, Colombia
2 Faculty of Mechanical and Industrial Engineering, Universidad PontificiaBolivariana, Colombia
3 Mechanical Engineering Department, Universidad de Córdoba, Colombia
1E mail: mycarmona@uninorte.edu.co,2E mail: mario.palaciov@upb.edu.co
A B S T R A C T
In the present paper, an experimental analysis of a solar water heating collector with an integrated latent heat storage unit is presented. With the purpose to determine the performance of a device on a lab scale, but with commercial features, a flat plate solar collector with phase change material (PCM) containers under the absorber plate was constructed and tested. PCM used was a commercial semi-refined light paraffin with a melting point of 60°C. Tests were carried out in outdoor conditions from October 2016 to March 2017 starting at 7:00 AM until the collector does not transfer heat to the water after sunset. Performance variables as water inlet temperature, outlet temperature, mass flow and solar radiation were measured in order to determine a useful heat and the collector efficiency. Furthermore, operating temperatures of the glass cover, air gap, absorber plate, and PCM containers are presented. Other external variables as ambient temperature, humidity and wind speed were measured with a weather station located next to the collector. The developed prototype reached an average thermal efficiency of 24.11% and a maximum outlet temperature of 50°C. Results indicate that the absorber plate reached the PCM melting point in few cases, this suggests that the use of a PCM with a lower melting point could be a potential strategy to increase thermal storage. A thermal analysis and conclusions of the device performance are discussed.
Phase change materials or PCMs are compounds which store and release latent heat by changing chemical bonds through a phase alteration. These materials absorb energy during the heating and release energy to the surroundings through a reverse cooling process. The integration of PCM in textiles by coating, encapsulation or any other means has grown concentration to the scientist. In this paper; characteristics, classification, working principle of PCMs and its versatile application in textiles are mainly discussed.
This document discusses using phase changing materials (PCMs) for thermal energy storage. PCMs absorb heat when melting from solid to liquid at a certain temperature range, and release heat when solidifying from liquid to solid. The author proposes storing PCMs in building walls and HVAC systems to help maintain comfortable indoor temperatures and reduce energy usage. Various PCM options are described, along with encapsulation methods to control volume changes and prevent reactivity. Techniques for increasing PCM thermal conductivity, like adding metallic fillers or fins, are also summarized. The conclusion reiterates that further PCM research and system design optimization could improve energy storage efficiency.
This document summarizes the development of an adsorption cooling system with a thermal energy storage-based evaporator for air conditioning applications. Key points include:
- The system uses zeolite 13X/CaCl2 composite adsorbent to adsorb and desorb water as the refrigerant.
- It incorporates a latent thermal energy storage system using pentadecane to reduce temperature fluctuations in the chilled water output.
- Experimental testing showed improvements over previous designs, including higher specific cooling power, lower weight, better coefficient of performance, and more stable chilled water temperatures.
- Further recommendations to optimize the system include integrating solar heating and adding nano-particles to the phase change material for improved
Innovative thermal energy storage technologies (Vincent O'Brien)campone
Vincent O'Brien of Copper Industries (Ireland) Ltd presented on innovative thermal energy storage technologies developed through collaborations with the University of Ulster. This included the MaxiPod thermal store, which can provide up to 38 kW of domestic hot water while maintaining temperature, and the HotHead stratifying cylinder, which exhibits increased stratification and solar collector efficiency. Copper Industries is commissioning an in-house test facility through a KTP project to characterize the performance of various thermal energy storage systems and integrate renewables with combi-systems more effectively.
This presentation describes how use of judiciously selected Phase Change Materials can be used effectively to store energy and make it available when needed.
In a solar thermal application, typically sunlight is available in a 6-8 hour window from 8am to 4pm. However, the usage extends much beyond that. Phase Change Materials can be used to store energy for usage as required.
This document discusses conducting materials used in dye-sensitized solar cells. It begins by providing background on solar cells and photovoltaics, and describes dye-sensitized solar cells. It then focuses on different types of conducting materials used in these cells, including conductive polymers and electrolyte systems using ionic liquids. The document concludes by discussing the promising results of using ionic liquid electrolytes to optimize the performance of dye-sensitized solar cells.
The document describes the Ocean Thermal Extractable Energy Visualization (OTEEV) project, which aims to assess the maximum practically extractable ocean thermal energy (MPEE) on a global scale. The project uses output from a high-resolution ocean model run through an energy extraction model to produce estimated net power per location. This data will be integrated into an interactive GIS tool for public visualization of the global ocean thermal energy resource. Key accomplishments to date include completing the OTEC power extraction model and validating it using ocean temperature and depth profiles. Remaining work includes incorporating full model output into the GIS tool and delivering the final report.
This document summarizes research on integrating phase change materials (PCMs) into solar water heating systems for thermal energy storage. It reviews five studies that examined using PCMs like paraffin wax, calcium chloride hexahydrate, and sodium thiosulfate pentahydrate. The performance enhancements of PCMs include storing up to 3.45 times more energy and maintaining hot water temperatures during off-sunshine hours through latent heat release. However, flow rate affects efficiency, with lower rates providing hot water longer. Increased PCM mass also lengthens storage time but lowers charging temperatures. Overall, PCMs improve solar water heating by enabling isothermal energy storage and release.
This document summarizes a presentation given at the 4th International Conference on Advances in Energy Research held at the Indian Institute of Technology Bombay in India on October 10, 2013. The presentation discusses enhancements to a thermal storage system for domestic use through the use of phase change material (PCM). Specifically:
- An experimental investigation of a 10 liter per day capacity thermal storage system found that including PCM occupying 26% of the volume improved the thermal storage capacity by 22% compared to a system without PCM.
- The PCM used was HS-58, which has suitable thermal properties for domestic solar water heating systems.
- Temperature time data from the experiments show that the system with PCM maintained
01 thermal energy storage using ice slurryWahid Mohamed
This document discusses thermal energy storage using ice slurry. It begins with an introduction to thermal energy storage, including sensible energy storage using water and latent cool storage technologies. It defines ice slurry as a suspension of ice crystals in liquid. The document outlines the components of an ice slurry generator system, including schematics of different configurations. It notes benefits like higher energy transport density and consistently cool temperatures near the phase change point. Applications include district cooling systems, and case studies demonstrate cost savings from peak shaving and improved chiller efficiency.
Thermal energy storage systems store thermal energy and make it available at a later time for uses such as balancing energy supply and demand or shifting energy use from peak to off-peak hours. The document discusses several types of thermal energy storage including latent heat storage using phase change materials, sensible heat storage using temperature changes in materials, and thermo-chemical storage using chemical reactions. Case studies of thermal energy storage applications in solar plants, buildings, and cold chain transportation are also presented.
Sensible heat energy storage technology using low cost locally available ther...Husain Mehdi
Thermal energy storage in packed beds is increasing attention due to necessary component for efficient utilization of solar energy. A one dimensional thermal model for the behavior of a packed bed is presented for low cost thermal energy sensible heat energy storage materials (i.e. stone, glass, rocks, bricks, and granite) and air as the heat transfer fluid. This model predicts successfully during storage are presented for brick and rock in a cylindrical packed bed storage unit. Explicit expression for time variation of storage material temperature and air flowing in the system have been developed and performance parameters have been computed for five storage materials.
This document discusses phase change materials (PCMs) which can store and release large amounts of thermal energy during phase transitions between solid and liquid states. PCMs provide high energy storage density with small temperature changes. Thermal energy storage methods include sensible heat storage based on temperature change and latent heat storage using phase change. PCMs are classified as organic, inorganic, or eutectic and are selected based on properties like melting temperature and thermal stability. Applications of PCMs include construction materials, textiles, food/medical packaging, and automobiles.
This document summarizes research on thermochemical materials for heat storage. It compares different heat storage systems and discusses the principle and selection of thermochemical heat storage (THSS) materials. The characteristics of SrBr2 and MgSO4 hydrates are described based on thermal analysis. Composites of these materials with activated carbon and expanded natural graphite were manufactured and tested through multiple cycles. The composites showed stable performance over cycles but challenges remain around material stability and geometry changes during cycling. Overall, the research aims to develop low-cost thermochemical materials for seasonal heat storage applications.
Development of a thermal energy storage system in a domestic environment into...Nelson García Polanco
My speech on April 27, 2015 at Energy Storage World Forum Rome, was focused on how to recover and reuse low-temperature wasted heat from kitchen appliances, and the technologies for the thermal energy storage. A full prototype of Thermal Energy Storage (TES) system was created. The TES system is based on a packed bed of macro-encapsulated phase change material (PCM). Typical household appliances were analyzed in order to evaluate the waste heat produced on the basis of the average user habits at European level.
1. Thermal energy storage (TES) technologies like phase change materials (PCMs), sorption, and thermochemical materials can store solar and renewable heat for use when needed.
2. PCMs use the heat of phase change during melting and freezing to efficiently store and release thermal energy. Organic PCMs like paraffin wax are promising due to their high storage density and melting temperatures around human comfort levels.
3. Sorption technologies use physical or chemical bonding to store heat in materials like silica gels, zeolites, or chemical reactions. A demonstration used zeolite to store nighttime heat from district heating for use during the day.
Review on nanomaterials for thermal energy storage technologiesOwolabi Afolabi
This document reviews research on nanomaterials for thermal energy storage technologies. It discusses various types of phase change materials and nanomaterials that have been investigated as possible materials for efficient thermal energy storage. Nanoadditives have been used to enhance the thermal properties of phase change materials by increasing their thermal conductivity. The document outlines different classification systems for phase change materials, nanomaterials, and nanofluids/nanocomposites developed for thermal energy storage. It also reviews various synthesis methods that have been used to prepare nanofluids and nanocomposites, including one-step direct evaporation and two-step methods.
A review on phase change materials & their applicationsiaemedu
The document is a review article on phase change materials (PCMs) and their applications. It discusses that PCMs can store large amounts of heat or cold in the form of latent heat during phase transition from solid to liquid or vice versa. This allows PCMs to store 2-3 times more energy per unit volume compared to sensible heat storage. The article then reviews different types of PCMs including organic, inorganic, and eutectic PCMs. Organic PCMs are further divided into paraffin and non-paraffin materials. Several properties of ideal PCMs for thermal energy storage applications are also outlined.
PCM Thermal Energy Storage Systems; Ashrae 2004 Conference PaperZafer Ure
The document discusses positive temperature eutectic (PCM) thermal energy storage systems. It begins by explaining the disadvantages of conventional water-ice storage systems, which require low-temperature chillers. The document then introduces positive temperature eutectic solutions, which can freeze and melt above 0°C, overcoming these disadvantages. Various PCM mixtures are presented, along with encapsulation techniques to contain them. The document argues that PCM storage enables higher evaporator temperatures and lower condenser pressures, improving energy efficiency. A variety of applications are proposed, including utilizing chilled water and refrigeration temperature ranges for charging.
A review of phase change materials (pcms) for cold energy storage applicationsTAHA RAJEH
This document summarizes a review on phase change materials (PCMs) for cold energy storage applications. It discusses how PCMs can be used for cold thermal energy storage (TES) due to their high latent heat of fusion during phase change. The document outlines different types of PCMs and criteria for selecting them, including thermophysical properties like melting temperature and heat of fusion. It provides examples of common inorganic and organic PCMs and discusses techniques to improve PCMs, such as nanostructuring and encapsulation, which can increase heat transfer and thermal conductivity. The document concludes that properly selecting PCMs based on these factors is important for efficiently designing cold storage systems.
Experimental analysis of a flat plate solar collector with integrated latent heat thermal storage
*Mauricio, Carmona1, Mario Palacio2, ArnoldMartínez3
1 Mechanical Engineering Department, Universidad del Norte, Colombia
2 Faculty of Mechanical and Industrial Engineering, Universidad PontificiaBolivariana, Colombia
3 Mechanical Engineering Department, Universidad de Córdoba, Colombia
1E mail: mycarmona@uninorte.edu.co,2E mail: mario.palaciov@upb.edu.co
A B S T R A C T
In the present paper, an experimental analysis of a solar water heating collector with an integrated latent heat storage unit is presented. With the purpose to determine the performance of a device on a lab scale, but with commercial features, a flat plate solar collector with phase change material (PCM) containers under the absorber plate was constructed and tested. PCM used was a commercial semi-refined light paraffin with a melting point of 60°C. Tests were carried out in outdoor conditions from October 2016 to March 2017 starting at 7:00 AM until the collector does not transfer heat to the water after sunset. Performance variables as water inlet temperature, outlet temperature, mass flow and solar radiation were measured in order to determine a useful heat and the collector efficiency. Furthermore, operating temperatures of the glass cover, air gap, absorber plate, and PCM containers are presented. Other external variables as ambient temperature, humidity and wind speed were measured with a weather station located next to the collector. The developed prototype reached an average thermal efficiency of 24.11% and a maximum outlet temperature of 50°C. Results indicate that the absorber plate reached the PCM melting point in few cases, this suggests that the use of a PCM with a lower melting point could be a potential strategy to increase thermal storage. A thermal analysis and conclusions of the device performance are discussed.
Phase change materials or PCMs are compounds which store and release latent heat by changing chemical bonds through a phase alteration. These materials absorb energy during the heating and release energy to the surroundings through a reverse cooling process. The integration of PCM in textiles by coating, encapsulation or any other means has grown concentration to the scientist. In this paper; characteristics, classification, working principle of PCMs and its versatile application in textiles are mainly discussed.
This document discusses using phase changing materials (PCMs) for thermal energy storage. PCMs absorb heat when melting from solid to liquid at a certain temperature range, and release heat when solidifying from liquid to solid. The author proposes storing PCMs in building walls and HVAC systems to help maintain comfortable indoor temperatures and reduce energy usage. Various PCM options are described, along with encapsulation methods to control volume changes and prevent reactivity. Techniques for increasing PCM thermal conductivity, like adding metallic fillers or fins, are also summarized. The conclusion reiterates that further PCM research and system design optimization could improve energy storage efficiency.
This document summarizes the development of an adsorption cooling system with a thermal energy storage-based evaporator for air conditioning applications. Key points include:
- The system uses zeolite 13X/CaCl2 composite adsorbent to adsorb and desorb water as the refrigerant.
- It incorporates a latent thermal energy storage system using pentadecane to reduce temperature fluctuations in the chilled water output.
- Experimental testing showed improvements over previous designs, including higher specific cooling power, lower weight, better coefficient of performance, and more stable chilled water temperatures.
- Further recommendations to optimize the system include integrating solar heating and adding nano-particles to the phase change material for improved
Innovative thermal energy storage technologies (Vincent O'Brien)campone
Vincent O'Brien of Copper Industries (Ireland) Ltd presented on innovative thermal energy storage technologies developed through collaborations with the University of Ulster. This included the MaxiPod thermal store, which can provide up to 38 kW of domestic hot water while maintaining temperature, and the HotHead stratifying cylinder, which exhibits increased stratification and solar collector efficiency. Copper Industries is commissioning an in-house test facility through a KTP project to characterize the performance of various thermal energy storage systems and integrate renewables with combi-systems more effectively.
This presentation describes how use of judiciously selected Phase Change Materials can be used effectively to store energy and make it available when needed.
In a solar thermal application, typically sunlight is available in a 6-8 hour window from 8am to 4pm. However, the usage extends much beyond that. Phase Change Materials can be used to store energy for usage as required.
This document discusses conducting materials used in dye-sensitized solar cells. It begins by providing background on solar cells and photovoltaics, and describes dye-sensitized solar cells. It then focuses on different types of conducting materials used in these cells, including conductive polymers and electrolyte systems using ionic liquids. The document concludes by discussing the promising results of using ionic liquid electrolytes to optimize the performance of dye-sensitized solar cells.
The document describes the Ocean Thermal Extractable Energy Visualization (OTEEV) project, which aims to assess the maximum practically extractable ocean thermal energy (MPEE) on a global scale. The project uses output from a high-resolution ocean model run through an energy extraction model to produce estimated net power per location. This data will be integrated into an interactive GIS tool for public visualization of the global ocean thermal energy resource. Key accomplishments to date include completing the OTEC power extraction model and validating it using ocean temperature and depth profiles. Remaining work includes incorporating full model output into the GIS tool and delivering the final report.
This document discusses specific latent heat, which is the amount of heat required to change the phase of a substance without changing its temperature. It provides examples of specific latent heat values for ice and water. During phase changes like melting, boiling, and condensing, heat is absorbed or released but temperature remains constant as the heat energy goes towards breaking or forming molecular bonds rather than increasing kinetic energy. Applications where specific latent heat is important include cooling drinks with ice and using steam for cooking or heating.
Solar Or Waste Heat Absorption Cooling System
DRAMATIC INCREASE OF AIR CONDITIONING SINCE THE EARLY 80’S
• COST OF ENERGY
• ISSUES RELATED TO ENVIRONMENTAL POLLUTION
DUE TO ENERGY PRODUCTION
DUE TO THE USE OF CFC’S AND HCFC’S
• MATCHES DEMAND WITH SOURCE AVAILABILITY
• CRUCIAL FOR IMPROVING LIFE STANDARDS IN DEVELOPING COUNTRIES
The document describes the principles and operation of a vapour absorption refrigeration system. It discusses how the absorption system differs from a vapour compression system by replacing the compressor with an absorber, generator, and pump. The absorption cycle uses two fluids, a refrigerant like ammonia or water, and an absorbent like lithium bromide or water. Heat is added in the generator to desorb the refrigerant from the absorbent, and the vapors are then condensed and expanded to provide cooling before being reabsorbed to repeat the cycle. Advantages include only needing a pump and ability to handle large cooling loads, while disadvantages are lower efficiency and longer response time than vapor compression systems.
This document summarizes different techniques for solar cooling, including absorption cooling, desiccant cooling, and adsorption cooling. It provides details on the underlying physics and thermodynamic cycles involved. Absorption cooling uses lithium bromide or water/ammonia as working fluids. Adsorption cooling uses a solid adsorbent material to remove vapor from a gas in a reversible process, cycling between heating/pressurization and cooling/depressurization phases. While solar cooling technologies show potential, the document concludes they still require further technological development, performance data from real installations, and subsidies to improve market penetration and achieve significant energy savings compared to conventional cooling.
The document provides an overview of different types of energy, including chemical, electrical, thermal, electromagnetic, mechanical, and nuclear energy. It also discusses renewable and non-renewable energy sources such as oil, coal, natural gas, uranium, biomass, hydroelectric, solar, eolic, geothermal, and tidal energy. The future of energy and ways to save energy are also briefly covered.
This document discusses solar ponds and their applications. It begins with an introduction to solar ponds, explaining that they are bodies of water that collect and store solar energy through restricting convection currents. It then describes the different types of solar ponds, including non-convecting and convecting, and provides examples. Applications of solar ponds discussed include process heating, desalination, and refrigeration. Advantages are their low cost and ability to use diffuse radiation. The document concludes that solar ponds can replace fossil fuels for thermal energy applications.
This document discusses various concepts related to heat, including:
[1] Heat capacity and specific heat capacity, which refer to the amount of heat required to change the temperature of a substance. Specific heat capacity is a material's heat capacity per unit mass.
[2] Latent heat of fusion and vaporization, which is the heat absorbed or released during phase changes between solid, liquid, and gas with no change in temperature.
[3] Methods for determining specific heat capacity experimentally, including the mixture method of transferring heat between substances and the electrical method of applying heat from an electrical source.
This document summarizes solar space heating and cooling systems. It describes passive solar systems that use design features like windows and heat-absorbing materials to collect solar energy. Active systems have collectors that absorb solar radiation and fans/pumps to transfer heat. Passive systems are less complex but active systems allow retrofitting. Solar space cooling uses absorption chillers, where a refrigerant absorbs heat and is pumped to a generator before re-vaporizing to provide cooling. Heat is provided by solar collectors in the form of hot water.
This document discusses solar ponds, which are large bodies of saltwater that efficiently collect and store solar energy. Solar ponds work by creating layers of saltwater with different salt concentrations, allowing the sun's heat to be trapped without convection. There are two main types: non-convecting salt gradient ponds and convecting shallow ponds. Salt gradient ponds can reach temperatures as high as 93°C and extract heat via pumps. Solar ponds have advantages like being renewable, low maintenance, and able to provide thermal energy for various applications. The largest solar pond built was in Israel and generated 5MW of electricity.
Solar energy is an abundant renewable source that can be collected and stored using solar ponds. A solar pond consists of three layers - an upper fresh water layer, a middle non-convective gradient layer, and a lower dense salt water layer that stores heat. The salinity gradient in the pond prevents convection and traps solar heat in the bottom layer. Solar ponds have applications in industries like salt production, aquaculture, dairy, and desalination by providing process heat and refrigeration using the stored solar energy.
1. Solar refrigeration has applications in both developing and developed countries for vaccine storage, food preservation, and air conditioning. Previous research on photovoltaic and solar thermal refrigeration systems is reviewed.
2. Research is underway at Warwick University on carbon-ammonia refrigerators driven by steam heat from a thermosyphon heat pipe sourced by solar energy or biomass. A new area of interest is using desiccant wheel technology for solar powered air conditioning.
3. The basic principles of solar absorption refrigeration are described and past experience is assessed. Solar absorption refrigeration shows potential but current systems are still costly.
Air conditioning works by altering the temperature and humidity of air to more comfortable levels. There are two main types: window units which fit in windows, and split systems which separate the hot and cold components.
Window units contain a compressor, expansion valve, hot and cold coils, fans, and controls. Split systems separate the cold indoor coil from the hot outdoor condensing unit. When powered, the compressor increases the pressure and temperature of the working fluid which then cools as it passes through the condenser.
Solar air conditioning uses solar power through hybrid systems that combine photovoltaics and batteries, or absorption chillers that cool air through evaporation and solar-powered fans. While more environmentally friendly than conventional AC
Solar refrigeration uses solar energy to power refrigeration systems for food and medicine preservation and comfort cooling. There are three main types of solar refrigeration: photovoltaic operated vapor compression, solar mechanical vapor compression using a Rankine cycle, and absorption refrigeration. Absorption refrigeration replaces the compressor with a thermal compression system using ammonia as the working fluid and a generator powered by solar collectors to desorb the ammonia, providing refrigeration without large mechanical energy inputs. While solar refrigeration has benefits of being environmentally friendly and not relying on power grids, its high initial costs and low coefficient of performance currently limit widespread adoption.
SOLAR POWER VAPOUR ABSORPTION REFRIGERATION SYSTEMaj12345ay
USE OF SOLAR POWER IN REFRIGERATION SYSTEM
The power incident from the sun to the earth has very much amount of energy that the present consumption rate of all the commercial and general uses. We utilize only 0.1% of total incident sun energy on the surface of earth. Thus solar energy can fulfill our present as well as future needs of energy. That is a reason it called renewable sources of energy. It is also environmental clean source of energy and available at whole part of world where people live. Using of solar energy in the field of refrigeration and air conditioning system it become very economical.
In our project we provide solar heat in generator for heating purpose of vapor compression refrigeration system.
For past few decades, energy has played a prominent role in the development of technology and economy. Energy has now become inevitable factor for production as well. The objective of this project is to develop an environment friendly vapour absorption system. Vapour absorption system uses heat energy, instead of mechanical energy as in vapour compression system, in order to change the condition of refrigerant required for the operation of the cycle. R 717(NH3) and water are used as working fluids in this system. The basic idea of this project is derived from the solar heating panel to obtain heat energy, instead of using any conventional source of heat energy. In this project various observations are done by varying operating conditions related to heat source, condenser, absorber and evaporator temperatures. The drawback of this system is that, it remains idle in the cloudy weather conditions.
COMPONENTS USED IN SOLAR POWERED AQUA-AMMONIA VAPOUR ABSORPTION SYSTEM
• ABSORBER
• PUMP
• HEAT EXCHANGER
• GENERATOR
• SOLAR PANEL
• CONDENSER
• EXPANSION VALVE
• EVAPORATOR
• DC BATTERY
• FAN
1) The document discusses solar air conditioning as an alternative to traditional air conditioning that uses fossil fuels.
2) Traditional air conditioning has high electricity consumption from fossil fuels, contributing to greenhouse gas emissions and global warming.
3) Solar air conditioning aims to reduce dependence on fossil fuels and provide an environmentally friendly cooling solution by using the sun's heat for thermal compression instead of mechanical compression.
The document describes solar ponds, which are large shallow bodies of water arranged to have reversed temperature gradients compared to normal ponds. Solar ponds consist of three layers - an upper convective zone, a non-convecting zone, and a lower convective zone. The salinity and temperature increase with depth in the non-convecting zone, inhibiting convection and providing insulation. Heat is stored in the lower convecting zone at temperatures 40-50°C above ambient. Solar ponds can be used for electric power generation, desalination, and space or water heating.
IRJET- A Review on Utilization of Phase Change Material in Solar Water Heatin...IRJET Journal
This document reviews the use of phase change materials (PCMs) in solar water heating systems. It discusses how PCMs can provide thermal energy storage to improve system efficiency by storing solar energy for use when sunlight is unavailable. The document examines different types of PCMs used, including paraffin and sodium acetate trihydrate. It also explores applications of PCMs in building walls, roofs, and windows to stabilize indoor temperatures. The review finds that solar water heaters equipped with PCMs can provide hot water at night, improving on conventional systems only able to heat water during the day.
This document provides a review of thermal energy storage, with a focus on phase change materials (PCMs). It begins by discussing different types of thermal energy storage, including sensible heat, latent heat, and thermochemical storage. Latent heat storage using PCMs is identified as particularly promising due to its high energy storage density. The document then reviews literature on various PCMs and composites that have been studied, including their properties. Challenges with PCMs like poor thermal conductivity and leakage are mentioned. The review identifies needs for more accurate material property data and improved thermal energy storage test rigs. It concludes by discussing research gaps and directions for future work, such as material durability testing and developing low-cost
Enhancement of Latent Heat Thermal Energy Storage using Embedded Heat PipeIRJET Journal
This document discusses using heat pipes to enhance latent heat thermal energy storage. Heat pipes can increase heat transfer rates in latent heat thermal energy storage systems by reducing thermal resistance in phase change materials. The document presents an experiment that validates using heat pipes in latent heat thermal energy storage to lower thermal resistance. It also models a large-scale latent heat thermal energy storage system with gravity-assisted heat pipes and conducts a cost analysis. The results show that including heat pipes can increase phase change material melting rates by around 60% compared to configurations without heat pipes.
Fabrication of new ceramics nanocomposites for solar energy storage and releasejournalBEEI
The carbides nanostructures have huge applications in renewable energy fields such as the saving of solar energy and release which attributed to the good their properties (thermal, electrical, mechanical, optical and chemical). So, in this paper, the solar energy storage and release of carbides nanoparticles/water for building heating and cooling applications have been investigated with different concentrations of metals carbides nanoparticles (tantalum carbide-silicon carbide). The results showed that the melting and solidification times for thermal energy storage and release decrease with an increase (TaC-SiC) nanoparticles concentrations. From the obtained results, the TaC/SiC nanostructures/ water nano-system are considered as promising materials for solar energy storage and release with high efficiency and high gain (more than 50% compare with the water). Also, the TaC/SiC may be used for heating and cooling fields with good performance and high gain.
Experimental Study on Phase Change Material based Thermal Energy Storage SystemIRJET Journal
1) The document describes an experimental study on using phase change materials (PCMs) like calcium chloride hexahydrate and sodium carbonate decahydrate to store thermal energy.
2) The experiment involved charging two PCMs by flowing hot water through a copper tube containing the PCMs, and discharging by flowing cold water, measuring temperatures over time.
3) The results showed that increasing the flow rate of the heat transfer fluid during charging and discharging increased the heat storage and release capacity of both PCMs.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Seminar Report - Phase Change Material (PCM).pdfShahidTavar
A Seminar Report On “Phase Change Material (PCM)” submitted By Shahid Tavar.
Phase Change Material (PCMs) is a material which absorbs or releases the maximum heat during its state change due to change in temperature. It uses chemical bonds to store and releases the heat. The thermal energy transfer occurs when a material changes from a solid to a liquid or from a liquid to a solid. This is called a change in state or phase. Ice changes phase when heated at 0°C and is converted to water. Ice is an excellent phase change material.
This seminar contains the introduction of Phase Change Material, it’s need, properties, working, types, various applications in energy saving, selection criterion of phase change material, its advantages and effect of operating temperature on selection of PCM.
Phase Change Materials (PCMs) are theoretically able to change state at constant temperature and therefore store large quantities of energy. Seminar also focuses the Energy Conservation by using Solar Energy with Phase Change Material.
IRJET- Performance Analysis of PCM based Thermal Energy Storage System Co...IRJET Journal
This document discusses a study that analyzed the performance of a thermal energy storage system containing nanoparticles. The study aimed to improve the thermal conductivity of a phase change material (PCM) by dispersing nickel oxide nanoparticles within it. Experiments were conducted with pure PCM and PCM mixed with nanoparticles. The results showed that adding nanoparticles enhanced heat transfer by increasing the thermal conductivity of the PCM. Parameters like nanoparticle volume concentration and heat transfer fluid flow rate were also tested to determine their effects. The findings indicate nanoparticles can help address the typically low thermal conductivity of PCMs and thus improve the rates of heat storage and release in thermal energy storage systems.
IRJET- Performance Analysis of PCM based Thermal Energy Storage System Contai...IRJET Journal
This document discusses a study that analyzed the performance of a thermal energy storage system containing nanoparticles. The study aimed to improve the thermal conductivity of a phase change material (PCM) by dispersing nickel oxide nanoparticles within it. Experiments were conducted with pure PCM and PCM mixed with nanoparticles. The results showed that adding nanoparticles enhanced heat transfer by increasing the thermal conductivity of the PCM. Parameters like nanoparticle volume concentration and heat transfer fluid flow rate were also tested to determine their effects. The findings indicate nanoparticles can help address the typically low thermal conductivity of PCMs and thus improve the rates of heat storage and release in thermal energy storage systems.
Waste Heat Recovery and Sustainable EnergyYOGESH AHIRE
The document discusses waste heat storage systems for waste heat recovery applications. It identifies the need for energy storage to address mismatches between energy supply and demand from intermittent heat sources. It describes various types of thermal energy storage systems including sensible heat, latent heat, and thermochemical storage. It outlines several factors to consider when selecting a waste heat storage system, such as the required temperature range, storage duration, and storage/delivery power. Thermal performance metrics like storage efficiency and exergy efficiency are also discussed.
An Assessment of Phase Change Materials for Domestic ApplicatonsEditorIJAERD
Thermal Energy storage has been the significant area of research over the last many decades. Various methods
and materials are developed for storing heat energy. Yet a main obstacle to modern methods is its lack of thermal mass.
Phase change materials are one of the optimized alternate to various energy storing methods and materials. They have
high energy storage capacity. In any case, despite the fact that the data is quantitatively tremendous, it is moreover
spread generally in the writing, and hard to discover. This report contrasts on the properties of phase change materials
and also reveals their significant applications. Furthermore, the discussion includes main benefits and drawbacks of
phase change materials over the different renewable energy sources. It also carries various types of PCMs and
performance analysis of PCMs for selecting the best required PCM for the purpose of heating and cooling of building.
IRJET- Evaluations of Multi Walled Carbon Nanotubes-Paraffin Wax Compositions...IRJET Journal
This document discusses using multi-walled carbon nanotubes (MWCNTs) mixed with paraffin wax as a phase change material (PCM) for thermal energy storage. MWCNTs are added to paraffin wax in concentrations up to 3 wt%. Testing shows the MWCNT-paraffin wax composites have up to a 20% increase in charging efficiency compared to pure paraffin wax. A tube-in-shell heat exchanger design is used, with the PCM-MWCNT composite in the outer shell and water flowing through the inner tube for heat transfer. The addition of MWCNTs improves the thermal conductivity of the PCM and increases how much thermal energy it can store
To study the behaviour of nanorefrigerant in vapour compression cycle a revieweSAT Journals
Abstract Nanofluid is an advanced kind of fluid, which contain nanometer sized (10-9 m) solid particles that are known as nanoparticles. Nanoparticles enhance the property of normal fluid. In past five years, nanorefrigerant has become the input for large number of experimental and vapour compression systems because of shortage of energy and environmental considerations. The conventional refrigerants have major role in global warming and depletion of the ozone layer. Therefore, there is need to improve the performance of vapour compression refrigeartion system with the help of using suitable refrigerant. Nearly all the works carried out in relation with nanofluids in vapour compression is regarding their applications in systems like domestic refrigerators and industrial purposes etc. The present paper investigate the performance of the nanorefrigerant in vapour compression cycle and the challenges of using nanorefrigerants in vapour compression cycle. Keywords: Nanofluids, nanoparticles, nanometer, nanorefrigerants, vapour compression, ecofriendly, domestic refrigerator
Transient thermal analysis of phase change material based heat sinkseSAT Journals
This document summarizes a numerical study on transient thermal analysis of phase change material (PCM) based heat sinks. The study considers different configurations of finned heat sinks with and without PCM. The configurations include a finned heat sink without PCM, a finned heat sink fully filled with PCM, and a finned heat sink half-filled with PCM towards the fin tip side. Unsteady analyses are performed to analyze the transient thermal behavior. The results provide insight into heat transfer characteristics and melting/solidification of PCM in different heat sink designs.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IRJET- Nano Enhanced Phase Change Material for Thermal Energy Storage App...IRJET Journal
This document discusses using nano-enhanced phase change materials (PCMs) for thermal energy storage. Specifically, it analyzes adding alumina nanoparticles to paraffin wax to increase its thermal conductivity and storage capacity. The results show that a composite of paraffin wax and alumina nanoparticles has improved thermal storage performance compared to paraffin wax alone in a shell and tube heat exchanger. Adding nanoparticles is an effective way to enhance the thermal properties and performance of PCMs for thermal energy storage applications.
A Review On Thermal Energy Storage For Concentrating Solar Power PlantsSophia Diaz
The document reviews thermal energy storage technologies for concentrating solar power plants. It discusses several thermal energy storage systems including two-tank direct, two-tank indirect, and single tank thermocline systems. It also examines different types of thermal storage materials including sensible heat materials like molten salts, latent heat phase change materials, and chemical heat storage. Thermal energy storage can help overcome the intermittency of solar energy and reduce the levelized cost of energy for concentrating solar power plants.
REVIEW OF THERMAL ENERGY STORAGE SYSTEMS AND THEIR APPLICATIONSijiert bestjournal
Nowadays,the worldwide worry about a global climat e change pushes to develop new energetic strategies. And more,after the recent energetic cr isis due to the increase of oil price,or the gas crisis arisen between Russia and Ukraine This paper reviews the Thermal energy storage systems which have the potential for increasing the effecti ve use of thermal energy equipment and for facilitating large-scale switching. They are normal ly useful for correcting the mismatch between the supply and demand of energy. There are different me thods in thermal storage systems.
IRJET-Nano Enhanced Phase Change Material Paraffin Wax with Ti02 for Thermal ...IRJET Journal
This document discusses using titanium dioxide nanoparticles to enhance the thermal properties of paraffin wax for thermal energy storage applications. Specifically:
- Paraffin wax is commonly used as a phase change material (PCM) for thermal energy storage due to its favorable properties. However, it has low thermal conductivity which limits its effectiveness.
- Adding titanium dioxide nanoparticles to the paraffin wax improves its thermal conductivity. Experimental analysis showed the nano-enhanced PCM had improved thermal storage capacity compared to plain paraffin wax in a heat exchanger.
- The nanoparticles increase the effective thermal conductivity of the paraffin wax PCM without negatively impacting its other desirable properties like melting point and heat of fusion. This
IRJET- Selection of Phase Change Material using Shenon Entropy and Vikor ...IRJET Journal
This document discusses the selection of phase change materials (PCMs) for latent heat thermal energy storage using multi-criteria decision making methods. It presents the properties of several potential PCM candidates and evaluates them using the Vikor and entropy methods. First, the normalized decision matrix of PCM properties is calculated. Then, Shannon's entropy is used to determine the weights of each property criterion. Finally, the Vikor method is applied to rank the PCM alternatives based on their closeness to the ideal solution. The top performing PCM identified is a combination of PEG6000, polyurethlene and graphene.
Similar to Review on latent heat storage and problems associated with phase change materials (20)
Mechanical properties of hybrid fiber reinforced concrete for pavementseSAT Journals
Abstract
The effect of addition of mono fibers and hybrid fibers on the mechanical properties of concrete mixture is studied in the present
investigation. Steel fibers of 1% and polypropylene fibers 0.036% were added individually to the concrete mixture as mono fibers and
then they were added together to form a hybrid fiber reinforced concrete. Mechanical properties such as compressive, split tensile and
flexural strength were determined. The results show that hybrid fibers improve the compressive strength marginally as compared to
mono fibers. Whereas, hybridization improves split tensile strength and flexural strength noticeably.
Keywords:-Hybridization, mono fibers, steel fiber, polypropylene fiber, Improvement in mechanical properties.
Material management in construction – a case studyeSAT Journals
Abstract
The objective of the present study is to understand about all the problems occurring in the company because of improper application
of material management. In construction project operation, often there is a project cost variance in terms of the material, equipments,
manpower, subcontractor, overhead cost, and general condition. Material is the main component in construction projects. Therefore,
if the material management is not properly managed it will create a project cost variance. Project cost can be controlled by taking
corrective actions towards the cost variance. Therefore a methodology is used to diagnose and evaluate the procurement process
involved in material management and launch a continuous improvement was developed and applied. A thorough study was carried
out along with study of cases, surveys and interviews to professionals involved in this area. As a result, a methodology for diagnosis
and improvement was proposed and tested in selected projects. The results obtained show that the main problem of procurement is
related to schedule delays and lack of specified quality for the project. To prevent this situation it is often necessary to dedicate
important resources like money, personnel, time, etc. To monitor and control the process. A great potential for improvement was
detected if state of the art technologies such as, electronic mail, electronic data interchange (EDI), and analysis were applied to the
procurement process. These helped to eliminate the root causes for many types of problems that were detected.
Managing drought short term strategies in semi arid regions a case studyeSAT Journals
Abstract
Drought management needs multidisciplinary action. Interdisciplinary efforts among the experts in various fields of the droughts
prone areas are helpful to achieve tangible and permanent solution for this recurring problem. The Gulbarga district having the total
area around 16, 240 sq.km, and accounts 8.45 per cent of the Karnataka state area. The district has been situated with latitude 17º 19'
60" North and longitude of 76 º 49' 60" east. The district is situated entirely on the Deccan plateau positioned at a height of 300 to
750 m above MSL. Sub-tropical, semi-arid type is one among the drought prone districts of Karnataka State. The drought
management is very important for a district like Gulbarga. In this paper various short term strategies are discussed to mitigate the
drought condition in the district.
Keywords: Drought, South-West monsoon, Semi-Arid, Rainfall, Strategies etc.
Life cycle cost analysis of overlay for an urban road in bangaloreeSAT Journals
Abstract
Pavements are subjected to severe condition of stresses and weathering effects from the day they are constructed and opened to traffic
mainly due to its fatigue behavior and environmental effects. Therefore, pavement rehabilitation is one of the most important
components of entire road systems. This paper highlights the design of concrete pavement with added mono fibers like polypropylene,
steel and hybrid fibres for a widened portion of existing concrete pavement and various overlay alternatives for an existing
bituminous pavement in an urban road in Bangalore. Along with this, Life cycle cost analyses at these sections are done by Net
Present Value (NPV) method to identify the most feasible option. The results show that though the initial cost of construction of
concrete overlay is high, over a period of time it prove to be better than the bituminous overlay considering the whole life cycle cost.
The economic analysis also indicates that, out of the three fibre options, hybrid reinforced concrete would be economical without
compromising the performance of the pavement.
Keywords: - Fatigue, Life cycle cost analysis, Net Present Value method, Overlay, Rehabilitation
Laboratory studies of dense bituminous mixes ii with reclaimed asphalt materialseSAT Journals
Abstract
The issue of growing demand on our nation’s roadways over that past couple of decades, decreasing budgetary funds, and the need to
provide a safe, efficient, and cost effective roadway system has led to a dramatic increase in the need to rehabilitate our existing
pavements and the issue of building sustainable road infrastructure in India. With these emergency of the mentioned needs and this
are today’s burning issue and has become the purpose of the study.
In the present study, the samples of existing bituminous layer materials were collected from NH-48(Devahalli to Hassan) site.The
mixtures were designed by Marshall Method as per Asphalt institute (MS-II) at 20% and 30% Reclaimed Asphalt Pavement (RAP).
RAP material was blended with virgin aggregate such that all specimens tested for the, Dense Bituminous Macadam-II (DBM-II)
gradation as per Ministry of Roads, Transport, and Highways (MoRT&H) and cost analysis were carried out to know the economics.
Laboratory results and analysis showed the use of recycled materials showed significant variability in Marshall Stability, and the
variability increased with the increase in RAP content. The saving can be realized from utilization of recycled materials as per the
methodology, the reduction in the total cost is 19%, 30%, comparing with the virgin mixes.
Keywords: Reclaimed Asphalt Pavement, Marshall Stability, MS-II, Dense Bituminous Macadam-II
Laboratory investigation of expansive soil stabilized with natural inorganic ...eSAT Journals
This document summarizes a study on stabilizing expansive black cotton soil with the natural inorganic stabilizer RBI-81. Laboratory tests were conducted to evaluate the effect of RBI-81 on the soil's engineering properties. The tests showed that with 2% RBI-81 and 28 days of curing, the unconfined compressive strength increased by around 250% and the CBR value improved by approximately 400% compared to the untreated soil. Overall, the study found that RBI-81 effectively improved the strength properties of the black cotton soil and its suitability as a soil stabilizer was supported.
Influence of reinforcement on the behavior of hollow concrete block masonry p...eSAT Journals
Abstract
Reinforced masonry was developed to exploit the strength potential of masonry and to solve its lack of tensile strength. Experimental
and analytical studies have been carried out to investigate the effect of reinforcement on the behavior of hollow concrete block
masonry prisms under compression and to predict ultimate failure compressive strength. In the numerical program, three dimensional
non-linear finite elements (FE) model based on the micro-modeling approach is developed for both unreinforced and reinforced
masonry prisms using ANSYS (14.5). The proposed FE model uses multi-linear stress-strain relationships to model the non-linear
behavior of hollow concrete block, mortar, and grout. Willam-Warnke’s five parameter failure theory has been adopted to model the
failure of masonry materials. The comparison of the numerical and experimental results indicates that the FE models can successfully
capture the highly nonlinear behavior of the physical specimens and accurately predict their strength and failure mechanisms.
Keywords: Structural masonry, Hollow concrete block prism, grout, Compression failure, Finite element method,
Numerical modeling.
Influence of compaction energy on soil stabilized with chemical stabilizereSAT Journals
This document summarizes a study on the influence of compaction energy on soil stabilized with a chemical stabilizer. Laboratory tests were conducted on locally available loamy soil treated with a patented polymer liquid stabilizer and compacted at four different energy levels. The study found that increasing the compaction effort increased the density of both untreated and treated soil, but the rate of increase was lower for stabilized soil. Treating the soil with the stabilizer improved its unconfined compressive strength and resilient modulus, and reduced accumulated plastic strain, with these properties further improved by higher compaction efforts. The stabilized soil exhibited strength and performance benefits compared to the untreated soil.
Geographical information system (gis) for water resources managementeSAT Journals
This document describes a hydrological framework developed in the form of a Hydrologic Information System (HIS) to meet the information needs of various government departments related to water management in a state. The HIS consists of a hydrological database coupled with tools for collecting and analyzing spatial and non-spatial water resources data. It also incorporates a hydrological model to indirectly assess water balance components over space and time. A web-based GIS portal was created to allow users to access and visualize the hydrological data, as well as outputs from the SWAT hydrological model. The framework is intended to facilitate integrated water resources planning and management across different administrative levels.
Forest type mapping of bidar forest division, karnataka using geoinformatics ...eSAT Journals
Abstract
The study demonstrate the potentiality of satellite remote sensing technique for the generation of baseline information on forest types
including tree plantation details in Bidar forest division, Karnataka covering an area of 5814.60Sq.Kms. The Total Area of Bidar
forest division is 5814Sq.Kms analysis of the satellite data in the study area reveals that about 84% of the total area is Covered by
crop land, 1.778% of the area is covered by dry deciduous forest, 1.38 % of mixed plantation, which is very threatening to the
environmental stability of the forest, future plantation site has been mapped. With the use of latest Geo-informatics technology proper
and exact condition of the trees can be observed and necessary precautions can be taken for future plantation works in an appropriate
manner
Keywords:-RS, GIS, GPS, Forest Type, Tree Plantation
Factors influencing compressive strength of geopolymer concreteeSAT Journals
Abstract
To study effects of several factors on the properties of fly ash based geopolymer concrete on the compressive strength and also the
cost comparison with the normal concrete. The test variables were molarities of sodium hydroxide(NaOH) 8M,14M and 16M, ratio of
NaOH to sodium silicate (Na2SiO3) 1, 1.5, 2 and 2.5, alkaline liquid to fly ash ratio 0.35 and 0.40 and replacement of water in
Na2SiO3 solution by 10%, 20% and 30% were used in the present study. The test results indicated that the highest compressive
strength 54 MPa was observed for 16M of NaOH, ratio of NaOH to Na2SiO3 2.5 and alkaline liquid to fly ash ratio of 0.35. Lowest
compressive strength of 27 MPa was observed for 8M of NaOH, ratio of NaOH to Na2SiO3 is 1 and alkaline liquid to fly ash ratio of
0.40. Alkaline liquid to fly ash ratio of 0.35, water replacement of 10% and 30% for 8 and 16 molarity of NaOH and has resulted in
compressive strength of 36 MPa and 20 MPa respectively. Superplasticiser dosage of 2 % by weight of fly ash has given higher
strength in all cases.
Keywords: compressive strength, alkaline liquid, fly ash
Experimental investigation on circular hollow steel columns in filled with li...eSAT Journals
Abstract
Composite Circular hollow Steel tubes with and without GFRP infill for three different grades of Light weight concrete are tested for
ultimate load capacity and axial shortening , under Cyclic loading. Steel tubes are compared for different lengths, cross sections and
thickness. Specimens were tested separately after adopting Taguchi’s L9 (Latin Squares) Orthogonal array in order to save the initial
experimental cost on number of specimens and experimental duration. Analysis was carried out using ANN (Artificial Neural
Network) technique with the assistance of Mini Tab- a statistical soft tool. Comparison for predicted, experimental & ANN output is
obtained from linear regression plots. From this research study, it can be concluded that *Cross sectional area of steel tube has most
significant effect on ultimate load carrying capacity, *as length of steel tube increased- load carrying capacity decreased & *ANN
modeling predicted acceptable results. Thus ANN tool can be utilized for predicting ultimate load carrying capacity for composite
columns.
Keywords: Light weight concrete, GFRP, Artificial Neural Network, Linear Regression, Back propagation, orthogonal
Array, Latin Squares
Experimental behavior of circular hsscfrc filled steel tubular columns under ...eSAT Journals
This document summarizes an experimental study that tested circular concrete-filled steel tube columns with varying parameters. 45 specimens were tested with different fiber percentages (0-2%), tube diameter-to-wall-thickness ratios (D/t from 15-25), and length-to-diameter (L/d) ratios (from 2.97-7.04). The results found that columns filled with fiber-reinforced concrete exhibited higher stiffness, equal ductility, and enhanced energy absorption compared to those filled with plain concrete. The load carrying capacity increased with fiber content up to 1.5% but not at 2.0%. The analytical predictions of failure load closely matched the experimental values.
Evaluation of punching shear in flat slabseSAT Journals
Abstract
Flat-slab construction has been widely used in construction today because of many advantages that it offers. The basic philosophy in
the design of flat slab is to consider only gravity forces; this method ignores the effect of punching shear due to unbalanced moments
at the slab column junction which is critical. An attempt has been made to generate generalized design sheets which accounts both
punching shear due to gravity loads and unbalanced moments for cases (a) interior column; (b) edge column (bending perpendicular
to shorter edge); (c) edge column (bending parallel to shorter edge); (d) corner column. These design sheets are prepared as per
codal provisions of IS 456-2000. These design sheets will be helpful in calculating the shear reinforcement to be provided at the
critical section which is ignored in many design offices. Apart from its usefulness in evaluating punching shear and the necessary
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Review on latent heat storage and problems associated with phase change materials
1. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 10 | Oct -2015, Available @ http://www.ijret.org 176
REVIEW ON LATENT HEAT STORAGE AND PROBLEMS
ASSOCIATED WITH PHASE CHANGE MATERIALS.
Kavendra A. Thakare1
, A. G. Bhave2
1
Student, M.E. Mechanical (Energy Engineering), K. J. SomaiyaCollege of Engineering, Vidyavihar,
Mumbai-400077, India.
2
Senior Professor, Department ofMechanical engineering, K. J. SomaiyaCollege of Engineering, Vidyavihar,
Mumbai-400077, India.
Abstract
Energy storage devices have important role in the energy system as they minimize the mismatch between the supply and demand.
This leads to improvement of the performance and the reliability of the systems. In thermal energy storage systems the Latent heat
type thermal energy storages (LHTES) are attractive since they have high energy storage density and nearly isothermal operation
at the phase transition temperature of the material usedthat is commonly known as phase change material (PCM). In this paper
PCMs with solid-solid and solid-liquid phase transition are discussed. Though PCMs with solid-solid phase transition seem
attractive due to their less stringent containment requirements but they are not widely used because of their low latent heat. PCMs
with solid-liquid phase transition are the most studied and used latent heat storage materials. Those are discussed in details with
their selection criterion, classification and applications. The steps involved in development of the energy storage systems and
problems associated with PCMs are discussed in the next part of the paper. This will give better understanding of the latent heat
storage systems to the reader.
KeyWords: Latent heat storage (LHS), Phase change materials (PCM), Thermal conductivity, Thermal cycling.
--------------------------------------------------------------------***----------------------------------------------------------------------
1. INTRODUCTION
In energy systems, energy storages have crucial role to play
as to ensure the supply on demand, to improve the
performance and reliability and to conserve energy
[1,2].There are various types of energy storages viz. (i)
Mechanical Energy Storage e.g. flywheel etc., (ii) Electrical
Energy storage e.g. battery etc. and (iii) Thermal Energy
Storage e.g. sensible heat, latent heat and thermochemical
storages.
In Sensible heat storages,thermal energy is stored on an
account of temperature difference. Quantity of thermal
energy storage depends upon, temperature gradient, specific
heat capacity of medium and amount of storage material
used,
𝑄 = 𝑚𝐶𝑝∆𝑇 = 𝑚𝐶𝑝(𝑇𝑓 − 𝑇𝑖)
e.g. water, pebble bed, thermic oils etc.
In Latent heat storages (LHS), thermal energy is stored on
the account of heat absorbed or released during phase
changeof the storage material.The storage capacity of the
LHS with solid to liquid phase change is given as,
𝑄 = 𝑚[𝐶𝑝𝑠 𝑇 𝑚 − 𝑇𝑖 + 𝑎 𝑚 𝐻𝐿 + 𝐶𝑝𝑙 𝑇𝑓 − 𝑇 𝑚 ]
e.g. Paraffins, salt hydrates etc.
In Thermochemical storage, thermal energy is stored in the
form of the heat of the reaction of the completely reversible
chemical reaction. The amount of heat stored depends upon
amount of storage material, the endothermic heat of reaction
and the extent of reaction.
𝑄 = 𝑚𝑓𝑟 𝐻 𝑅
e.g. CH4 + H2O ↔ CO + 3H2, etc.
1.1latent Heat Storage
Latent heat storages are the thermal energy storages in
which storage material undergoes change of phase and
thermal energy is stored in the form of the latent heat of
phase change of the corresponding material. Principle of
latent heat storageis as shown in Fig-1.
Fig-1: Principle of latent heat storage.
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The material used in latent heat storage is called as Phase
Change Material (PCM) since it undergoes change ofphase.
Latent heat storages have some advantages over sensible
heat storages. i.e.
High storage density,
Roughly isothermal operation near phase change
temperature of the PCM.
The Fig-2 gives the comparison between sensible and latent
type heat storages [3].
Fig-2: Comparison of Sensible and Latent heat storages.
The possible combinations of change of phase may be of
solid-solid, solid-liquid, solid-gas and liquid-gas or vice-
versa. Amongst them solid-gas and liquid-gas have high
latent heat of phase change but have containment problems
because of their high volume changes. This makes them
non-suitable for practical implementation in thermal
storages.
In Solid-solid phase transitions, heat is stored in the material
as its crystal structure changes from one to other [4-6].
In Solid-liquid phase transitions, the volume changes are
comparatively low (around 10%). This type of PCMs are
widely studied and used.
Following Table-1 gives comparison between Solid-solid
and Solid-liquid PCMs.
Table-1: Comparison of Solid-solid and Solid-liquid PCMs.
Solid-solid Solid-liquid
Heat stored due to Change in crystal
structure
Change in
Phase
Volume changes Very small Small
Storage density Comparatively low Higher
Containment Less stringent More stringent
Encapsulation Not needed Needed
Design flexibility Greater Moderate
Cost High Comparatively
low
Availability Not easily available Easily
available
Some examples of solid-solid PCMs from available
literature are listed in Table-2 [5, 6].
Table-2: List ofSolid-solid type PCMs.
PCM
Phase
transition
temperature
(°C)
Latent
heat
(kJ/kg.K)
Neopentyl Glycol (NPG) 43 130
Crosslinked Polyethylene 110 – 115 125 – 146
Cross linked HDPE 125 – 146 167 – 201
38.2% NPG / 61.8% PE 170 147
Pentaerithrytol (PE) 180 303
1.2 Desirable Properties Of Phase Change
Materials
Selection criterion for the PCM is given below [1,7].
Phase change temperature of the PCM must be suitable
for required thermal application.
PCM should possess high heat of fusion per unit
weight and volume, so that small amount of material
can hold large magnitudes of thermal energy.
High specific heat enables the PCM to store more
sensible heat.
PCM should have high thermal conductivity in both
the phases which enables storing and extraction of
thermal energy from the storage with less temperature
gradient.
PCM should have high density, so that the container
required for storage would be small and of low cost.
PCM should possess low vapor pressure; this gives
mechanical stability to PCM containers.
Volume change during phase transition should be low,
so that simple container and heat exchanger can be
used.
PCM should completely melt, i.e., congruent melting,
so that segregation can be avoided and homogeneous
solid and liquid phases can be obtained.
PCM should show little or no super-cooling with high
rate of crystal growth; this enables melting and
solidification to occur at same temperature.
PCM operation should be reliable without any
degradation for long time.
PCM should possess completely reversible melting and
solidification cycle.
PCM should be chemically stable and non-poisonous.
PCM should not corrode the container and heat
exchanger materials.
PCM should be non-hazardous and inflammable.
PCM should be inexpensive, easily available and long
lasting.
As no single PCM satisfies the all criterion stated
above, so PCM with more suitable properties should be
selected.
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Volume: 04 Issue: 10 | Oct -2015, Available @ http://www.ijret.org 178
2. CLASSIFICATION OF SOLID-LIQUID
PHASE CHANGE MATERIALS
Solid-liquid PCMs are classified into three categories named
Organic compounds, Inorganic compounds and Eutectics.
Detail classification is given in the Fig-3 [1,4].
Fig-3: Types of Solid-Liquid Phase Change Materials.
2.1 Organic Compounds
These are organic materials and further sub-categorised as
paraffins and non-paraffins.
(a) Paraffins:
These are mostly straight chain alkanes.Their melting point
and latent heat increase with increase in chain length.
Advantages: Availability in large temperature range.
Congruent melting and good nucleating properties.
Reliable and predictable behavior.
Safe and non- corrosive.
Economic.
Disadvantages: Low thermal conductivity.
Non compatibility with plastic containers.
Moderately flammable.
(b) Non-paraffins:
These are most numerous PCMs with varied properties.Most
of them are esters, fatty acids, alcohols and glycols with
high heat of fusion.
Advantages: High heat of fusion, Inflammable.
Disadvantages: Low thermal conductivity, low flashpoint.
Instability at higher temperature.
High cost.
2.2 Inorganic Compound
Inorganic PCMs are further categorized as salt hydrates and
metallics.These PCMs do not show appreciable super-
cooling and show favorable thermal cycling.
(a) Salt hydrates:
These are nothing but the alloys of inorganic salt and water,
in which crystalline solids are formed.Solid-liquid phase
transition of salt hydrates is the process of hydration and
dehydration.
Advantages: High latent heat of fusion per unit volume.
Relatively high thermal conductivity.
Small volume changes on melting.
Inexpensive.
Disadvantages: Phase separation, poor nucleation properties
and incongruent melting.
(b)Metallics:
These are the low melting metals and metal eutectics.
Advantages: High thermal conductivity.
High heat of fusion per unit volume.
Low vapour pressure.
Disadvantages: Higher weight.
2.3 Eutectics
Eutectic is a mixture of two or more components with
minimum melting point called as eutectic point, in which
each component melts and freezes congruently forming
mixture of crystals of components. Eutectics aresub-divided
into organic-organic, inorganic-inorganic andorganic-
inorganic types.
Fig-4shows chart of comparison of different types of PCM.
Fig-4:Comparison of all types of PCM.
Table-3 gives list of PCMs from each category[1,5,6].
4. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 10 | Oct -2015, Available @ http://www.ijret.org 179
Table-3: List of Phase change materials.
Type Material M.P.
(°C)
Latent
heat of
fusion
(kJ/kg)
Paraffins (Carbon atom no.
in alkane) -14
5.5 228
15 10 205
16 16.7 237.1
17 21.7 213
18 28 244
19 32 222
Non-paraffins Bees wax 61.8 177
Alpha napthol 96 163
Quinone 115 117
Acetanilide 118.9 222
Succinic
anhydride
119 204
Benzoic acid 121.7 142.8
Stilbene 124 167
Benzamide 127.2 169.4
Phenacetin 137 136.7
Alpha glucose 141 174
Fatty acids Acetic acid 16.7 184
Polyethylene
glycol 600
20-25 146
Lauric acid 49 178
Myristic acid 58 199
Stearic acid 69 202.5
Acetamide 81 241
Salt hydrates Al(NO3)2.9H2O 72 155
Ba(OH)2.8H2O 78 265
Mg(NO3)2.6H2O 89.9 167
KAl(SO4)2.12H2O 91 184
LiCl.H2O 99 212
MgCl2.6H2O 117 167
NaC2H3O2.3H2O 137 172
Metallics Gallium 30 80.1
Cerrolow eutectic 58 90.9
Bi-Cd-In eutectic 61 25
Bi-Pb-In eutectic 70 29
Bi-In eutectic 72 25
Eutectic Tryethylolethane
67.5% + Urea 32.5% 29.8 218
Mg(NO3)2.6H2O 50%
+ MgCl2.6H2O 50% 59.1 144
Mg(NO3)2.6H2O 53%
+ Al(NO3)2.9H2O 47% 61 148
Napthalene 67.1% +
Benzoic acid 32.9% 67 123.4
LiNO3 27% +
NH4NO3 68% +
NH4Cl 5%
81.6 108
3. LATENT HEAT STORAGE SYSTEMS
3.1 Design Of Latent Heat Storage Systems
Design of storage system involves three steps [8]:
1. Selection of suitable storage material i.e. PCM.
2. Design of containment for storage material.
3. Heat exchanger for charging and discharging.
Steps involved in development of latent heat thermal storage
systems are categorized in three parts as
1. Selection of PCM and optimization of its properties.
2. Designing of heat exchanger for charging and
discharging.
3. Performance evaluation on technical and economic
aspects.
Then the system is optimized for commercialization.
Therefore it important to analyse the system numerically
and experimentally [1,9]. These steps are shown
schematically in Fig-5.
Fig-5:Steps involved in development of latent heat thermal
storage systems.
3.2 Applications Of LHTES
There are numerous applications of latent heat storages in
various fields. Some of them are stated below [10,11].
Thermal storage of solar energy
Passive storage in bioclimatic building/architecture
Cooling: use of off-peak rates and reduction of
installed power, ice-bank.
Heating and sanitary hot water: using off-peak rate and
adapting unloading curves.
Safety: temperature maintenance in rooms with
computers or electrical appliances.
Thermal protection of food: transport, hotel trade, ice-
cream, etc.
Food agroindustry, wine, milk products (absorbing
5. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 10 | Oct -2015, Available @ http://www.ijret.org 180
peaks in demand), greenhouse.
Thermal protection of electronic devices (integrated in
the appliance)
Medical applications: transport of blood, operating
tables, hot–cold therapies.
Cooling of engines (electric and combustion).
Thermal comfort in vehicles.
Softening of exothermic temperature peaks in chemical
reactions.
Spacecraft thermal systems
Solar power plant, etc.
Cristopia (France), TEAP Energy (Australia), Rubitherm
GmbH (Germany), EPS Ltd. (UK), PCM Thermal solutions
(USA), Climator (Sweden) and Mitsubhishi Chemicals
(Japan) etc. are the PCM manufacturer companies around
the world [11].
Also PlusICEproduct range like TubeICE, FlatICE, BallICE,
Eutectic plates and Pouches from Phase Change Material
Products Ltd., UK [12], are available and being used in
various applications mentioned above.
4. PROBLEMS ASSOCIATED WITH PCMS
Various problems are encountered during operation of
thermal energy storages. These problems are listed
below.Many researchers exploited these problems and given
their recommendations to minimize or eliminate the same.
4.1 Phase Separation.
This kind of problem is observed in the inorganic PCMs i.e.
salt hydrates. It occurs due to incongruent melting and
density difference of inorganic salt and water.
Remedies[1,7]over this are (i) Mechanical stirring, (ii)
Encapsulation of PCM to reduce phase separation, (iii)
Addition of thickening or gelling agent to suspend heavy
phase in the solution, (iv) Extra-water Principle to avoid
supersaturation of the solution, (v) Modification of chemical
composition of system to make incongruent material
congruent.
Fig-6: Thickened salt hydrate [7].
4.2 Super-Cooling Or Sub-Cooling
The difference between melting and solidification
temperature of PCM is known as degree of super-cooling or
sub-cooling. This generally occurs due to poor nucleation
rate in the PCM. Because of super-cooling heat is
discharged at the lower temperature than fusion temperature.
This hampers the heat transfer rate and amount of heat
retrieved. Sometimes super-cooling may result in no latent
heat release.To avoid these circumstances the nucleation
properties of the PCM should be increased by adding
nucleating agents.List of some nucleating agents is given in
Table-4 [6].
Table-4: List of nucleating agents.
Nucleating agent Size (μm)
Borox (20 x 50 – 200 x 250)
Carbon (1.5 – 6.7)
TiO2 (2-200)
Copper (1.5 – 2.5)
Aluminium (8.5 - 20)
Na2SO4 -
Fig-7 shows effect of supercooling (subcooling) on latent
heat retrieval from LHS.
Fig-7: Effect of sub-cooling on heat storage. Left: with little
sub-cooling and nucleation, right:severe sub-cooling without
nucleation.
4.3 Low Thermal Conductivity
The major problem faced in latent heat storage systems is
the slow heat transfer rate or response rate. This is mainly
due to low thermal conductivity of the available PCMs.
Thermal conductivity of the PCMs can be improved by
adding high thermally conductive nanoparticles or adding
fins or mesh of conductive and compatible material. Though
this improves overall thermal conductivity of the storage
medium but this adds cost and weight penalties resulting in
less thermal storage density.
The experiments to improve the thermal conductivity
showed the better performance of the system. Also these
provides mechanical strength to the storage medium as well
as to the system. Fig-8 shows experimental investigations of
various fin geometries used [13].
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Volume: 04 Issue: 10 | Oct -2015, Available @ http://www.ijret.org 181
Fig-8: Various fin geometries used in LTES.
Also to improve thermal conductivity and mechanical
stability, PCM can be combined with other material like
graphite or metal foam to form a composite material.
Fig-9: PCM composites: Left-(a) Pure paraffin (b) Paraffin
/EG composite; Centre- Metal foam; Right: Metal foam
embedded in wax [7] [14].
Recently to counteract the problem of low thermal
conductivity, heat pipe heat exchangers were used in the
LTES systems. Use of heat pipes shows better flexibility to
the storage system. Fig-10 shows use of heat pipes in the
heat transfer enhancement between HTF and PCM [15].
Fig-10: Heat transfer enhancement using heat pipes.
4.4 Thermal Stability
In order to achieve efficient heat transfer without
degradation, to avoid leakage of the PCM and to avoid
contact of PCM with external unsuitable environment,
PCMs are encapsulated. Encapsulations are classified on
account of their sizes into macro-encapsulation and micro-
encapsulation. Micro-encapsulation results in increase in
heat transfer area in same volume and also increase in
thermal cycling of the PCM [7].
Fig-11: Macro-encapsulation (left) and micro-encapsulation
(right).
4.5 Corrosion
Compatibility is most important aspect while designing
LHTES. If material is not compatible with the container,
then it will result in corrosion of the container also in some
changes of PCM properties. The final result is poor
performance of the system. It also results in waste of cost
and effort invested. Thus before designing LHTES the
compatibility of the PCM and containment material should
be checked.
Fig-12: Corrosion: Left- Copper surface after 50 days
contact with melt of sodium thiosulphate 5-hydrate; Right:
SEM phorograph of AlMg3 after 80 days contact with melt
of sodium hydrogen phosphate 12-hydrate.
5 . APPLICATION OF PCM INCONCENTRATING
SOLAR POWER
Important application LHS is in concentrating solar power
(CSP) plants [4, 15]. Fig-13 shows schematic diagram of
CSP plant withmolten salt -two tank thermal energy storage
system with conventionalheat transfer fluid (HTF). During
sunshine hours the surplus heat is stored in the TES by
circulating high temperature HTF through the HTF to PCM
heat exchanger. The HTF which is at 393 °C transfers heat
to the cold PCM (292 °C) from cold storage tank, then hot
PCM at 385 °C is stored in the hot storage tank. During
peak demand hours or night when stored energy is
neededthen direction of flow of HTF inHTF to PCM heat
exchanger is reversed. During this heat is transferred to the
HTF from hot PCM. Then high temperature HTF generates
steam to run the power plant. The number of hours the TES
can supply the energy depends on operating temperature
range of system, amount of molten salt, thermal properties
7. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 10 | Oct -2015, Available @ http://www.ijret.org 182
of molten salt and the energy requirement to fulfill the
demand. By this way using PCM (molten salt) the offset of
supply and demand is minimised.
Fig-13:Schematic diagram of Concentrated Solar Power
plant using parabolic through concentrators.
6. CONCLUSIONS
Solid-solid PCMs are good alternatives to solid-liquid
PCMssince they do not have leakage problems, require less
stringentcontainments and have better design flexibility.
Solid-liquid PCMs are most studied and used PCMs. They
are better options due to theirfavourable properties.
Solutions and recommendations to the problems associated
with PCMs give better insight in latent heat storage systems
and will also help in the development of the new latent heat
storage systems.
Nomenclature
Q Amount of heat (kJ).
M Mass (kg).
Cp Specific heat of material (kJ/kg.°C).
Cps Specific heat of solid phase (kJ/kg.°C).
Cpl Specific heat of liquid phase (kJ/kg.°C).
ΔT Temperature gradient (°C).
Ti Initial temperature (°C).
Tm Melting temperature (°C).
Tf Final temperature (°C).
am Fraction melted.
fr Fraction reacted.
HL Latent heat of fusion (kJ/kg).
HR Endothermic heat of reaction (kJ/kg).
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BIOGRAPHIES
Kavendra A. Thakarereceived the B. Tech.
degree in Marine Engineering from
Maharashtra Academy of Naval Education
and Training, Pune in 2010. He is now
pursuing M.E. in Energy Engineering from
K. J. Somaiya College of Engineering,
Mumbai University. Email-ID:
kaven.thakare@gmail.com
Dr. A.G. Bhavereceived the degree of
Docteur-Ingenieur in
ThermiqueIndustrielle, in the area of solar
thermal energy, from Universite Paris XII
in 1985. He has worked in the renewable
energy area since, and is working as a
professor in the Mechanical Engineering Department of K.
J. Somaiya College of Engineering, Mumbai since 2009.
Email-ID: agbhave@gmail.com