This document analyzes the technical and economic feasibility of two solar cooling systems - a solar-powered absorption cooling system (SACS) and a photovoltaic cooling system (PCS) - applied to a hotel in Cuba. Both systems were simulated considering regional weather conditions and the thermodynamic principles that govern them. The results show that both systems can reduce energy consumption and the environmental impact of HVAC systems compared to conventional electric systems. However, the economic analysis found that the PCS has a lower cooling generation cost, while the energy assessment determined the SACS has better thermal performance for the climate and conditions of the case study hotel. Equations are provided describing the thermal and electrical models used to simulate the performance of the two solar
Cascaded Thermodynamic and Environmental Analyses of Energy Generation Modali...Ozyegin University
This document summarizes a study that analyzes the energy and exergy flows of a high-performance academic building under five different operation scenarios, based on real measurements. The scenarios include: 1) the original design, 2) adding a ground-air heat exchanger, 3) installing roof-top solar PV panels, 4) using a trigeneration system instead of boilers, and 5) integrating all three alternative energy sources. Dynamic thermodynamic, economic and environmental analyses were performed for each scenario. It was determined that using a trigeneration system provided the best outcomes in terms of reduced energy demand and costs as well as improved exergy efficiency and sustainability, compared to the other scenarios. However, an integrated approach combining all
Scope of Improving Energy Utilization in Coal Based Co-Generation on Thermal ...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Photovoltaic thermal (PVT), which is the popular technology for harvesting solar energy, receive solar energy and convert it into electrical and thermal energy simultaneously. In this review, design, heat transfer, energy modelling and performance analysis of PVT systems are presented. Four types of PVT systems base on heat transfer medium; air-based PVT system, water-based PVT system, the combination of water/air-based PVT system, and nanofluid-based PVT system are presented. In addition, major finding on energy and exergy analysis of PVT systems are summarized.
Mathematikal model of calclation parabola-cylindirical solar hot water system...SubmissionResearchpa
The article analyzes a mathematical model for calculating solar parabola cylindrical hot water systems for industrial and municipal enterprises. The formulas for determining heat losses associated with radiant and convective heat exchange, as well as useful heat energy and efficiency of solar parabola-cylindrical systems for obtaining heat for industrial purposes are given. by Sulaymonov Husanboy Mannopovich 2020. Mathematikal model of calclation parabola-cylindirical solar hot water systems of industrial enterprises. International Journal on Integrated Education. 3, 9 (Sep. 2020), 33-38. DOI:https://doi.org/10.31149/ijie.v3i9.584. https://journals.researchparks.org/index.php/IJIE/article/view/584/558 https://journals.researchparks.org/index.php/IJIE/article/view/584
This thesis analyzes the performance of a steam jet ejector chiller solar cooling system installed at Hochschule Karlsruhe during the summer of 2015. Key findings include:
1) The system operated reliably on days with temperatures under 32°C and provided the desired building cooling, though average cooling capacity was lower than the chiller's nominal rating.
2) Data analysis software was developed to evaluate seasonal performance indicators like collectors' yield, utilization factor, and COP values.
3) Over the summer, 25 operative days provided a total of 3,951 kWh of useful cooling while consuming 1,226 kWh of electricity. Thermal and electrical COP were 0.36 and 3.22 respectively
This review presents various research and development, as well as design and performances of bifluid-based PVT systems. Moreover, the development of PVT system is a very promising area of research. PVT systems using in various applications, such as solar drying, solar cooling, water heating, desalination, and pool heating. With the recognition of the potentials and contributions of PV system, considerable research has been conducted to attain the most advancement which may produce reliable and sustainable PVT system. The cooling system’s design refers to the absorber design which mostly focuses on water and air-based PVT systems. An air-based system has been developed through different absorber configurations, air flow modes and single- or double-pass design. Bifluid-based PVT system is used to remove heat accumulated in a PV panel and reuses the waste heat (hot air and water) in an appropriate way. PV, thermal and PVT efficiencies of bifluid PVT systems were 6.6%-18.6%, 31%–90% and 60%-83%, respectively.
Application of energy and exergy analyses to a ci engine usig biodiesel fueljohnmyls2000
This document discusses applying energy and exergy analyses to evaluate the performance of a diesel engine fueled by biodiesel and petroleum diesel. The researchers collected experimental data from tests of a four-cylinder diesel engine operating on soybean methyl ester biodiesel and petroleum diesel. They performed first and second law analyses to determine various performance parameters, including fuel energy, thermal efficiency, heat and exhaust losses, fuel exergy, and exergetic efficiency. Their results found the energetic performance of the biodiesel was similar to petroleum diesel. Additionally, the exergetic performance parameters generally followed trends consistent with the energetic parameters.
The document summarizes an exergy and exergo-economic analysis of the Montazer Ghaem gas turbine power plant in Iran. The analysis finds that the combustion chamber has the highest exergy destruction due to the large temperature difference between the flame and operating fluid. The gas turbine's performance and efficiency are significantly affected by ambient temperature. An increase in ambient temperature decreases the net power output and exergy efficiency. The exergo-economic analysis determines that the combustion chamber also has the largest cost of exergy destruction.
Cascaded Thermodynamic and Environmental Analyses of Energy Generation Modali...Ozyegin University
This document summarizes a study that analyzes the energy and exergy flows of a high-performance academic building under five different operation scenarios, based on real measurements. The scenarios include: 1) the original design, 2) adding a ground-air heat exchanger, 3) installing roof-top solar PV panels, 4) using a trigeneration system instead of boilers, and 5) integrating all three alternative energy sources. Dynamic thermodynamic, economic and environmental analyses were performed for each scenario. It was determined that using a trigeneration system provided the best outcomes in terms of reduced energy demand and costs as well as improved exergy efficiency and sustainability, compared to the other scenarios. However, an integrated approach combining all
Scope of Improving Energy Utilization in Coal Based Co-Generation on Thermal ...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Photovoltaic thermal (PVT), which is the popular technology for harvesting solar energy, receive solar energy and convert it into electrical and thermal energy simultaneously. In this review, design, heat transfer, energy modelling and performance analysis of PVT systems are presented. Four types of PVT systems base on heat transfer medium; air-based PVT system, water-based PVT system, the combination of water/air-based PVT system, and nanofluid-based PVT system are presented. In addition, major finding on energy and exergy analysis of PVT systems are summarized.
Mathematikal model of calclation parabola-cylindirical solar hot water system...SubmissionResearchpa
The article analyzes a mathematical model for calculating solar parabola cylindrical hot water systems for industrial and municipal enterprises. The formulas for determining heat losses associated with radiant and convective heat exchange, as well as useful heat energy and efficiency of solar parabola-cylindrical systems for obtaining heat for industrial purposes are given. by Sulaymonov Husanboy Mannopovich 2020. Mathematikal model of calclation parabola-cylindirical solar hot water systems of industrial enterprises. International Journal on Integrated Education. 3, 9 (Sep. 2020), 33-38. DOI:https://doi.org/10.31149/ijie.v3i9.584. https://journals.researchparks.org/index.php/IJIE/article/view/584/558 https://journals.researchparks.org/index.php/IJIE/article/view/584
This thesis analyzes the performance of a steam jet ejector chiller solar cooling system installed at Hochschule Karlsruhe during the summer of 2015. Key findings include:
1) The system operated reliably on days with temperatures under 32°C and provided the desired building cooling, though average cooling capacity was lower than the chiller's nominal rating.
2) Data analysis software was developed to evaluate seasonal performance indicators like collectors' yield, utilization factor, and COP values.
3) Over the summer, 25 operative days provided a total of 3,951 kWh of useful cooling while consuming 1,226 kWh of electricity. Thermal and electrical COP were 0.36 and 3.22 respectively
This review presents various research and development, as well as design and performances of bifluid-based PVT systems. Moreover, the development of PVT system is a very promising area of research. PVT systems using in various applications, such as solar drying, solar cooling, water heating, desalination, and pool heating. With the recognition of the potentials and contributions of PV system, considerable research has been conducted to attain the most advancement which may produce reliable and sustainable PVT system. The cooling system’s design refers to the absorber design which mostly focuses on water and air-based PVT systems. An air-based system has been developed through different absorber configurations, air flow modes and single- or double-pass design. Bifluid-based PVT system is used to remove heat accumulated in a PV panel and reuses the waste heat (hot air and water) in an appropriate way. PV, thermal and PVT efficiencies of bifluid PVT systems were 6.6%-18.6%, 31%–90% and 60%-83%, respectively.
Application of energy and exergy analyses to a ci engine usig biodiesel fueljohnmyls2000
This document discusses applying energy and exergy analyses to evaluate the performance of a diesel engine fueled by biodiesel and petroleum diesel. The researchers collected experimental data from tests of a four-cylinder diesel engine operating on soybean methyl ester biodiesel and petroleum diesel. They performed first and second law analyses to determine various performance parameters, including fuel energy, thermal efficiency, heat and exhaust losses, fuel exergy, and exergetic efficiency. Their results found the energetic performance of the biodiesel was similar to petroleum diesel. Additionally, the exergetic performance parameters generally followed trends consistent with the energetic parameters.
The document summarizes an exergy and exergo-economic analysis of the Montazer Ghaem gas turbine power plant in Iran. The analysis finds that the combustion chamber has the highest exergy destruction due to the large temperature difference between the flame and operating fluid. The gas turbine's performance and efficiency are significantly affected by ambient temperature. An increase in ambient temperature decreases the net power output and exergy efficiency. The exergo-economic analysis determines that the combustion chamber also has the largest cost of exergy destruction.
This document discusses steam turbine power plant design and cycles. It describes typical steam conditions between 600-1450 psig at 750-950°F for Army power plants. Back pressure turbines exhaust at 250-15 psig and condensing turbines exhaust at 1-5 inches of mercury absolute. Cogeneration plants use back pressure or controlled extraction/condensing cycles to simultaneously produce electric power and steam for heat. The document compares plant heat rates, turbine heat rates, and discusses optimizing steam power plant cycles for maximum efficiency and economy.
Energy and exergy analysis of air based photovoltaic thermal (PVT) collector:...IJECEIAES
Photovoltaic thermal (PVT) collectors convert solar radiation directly to both electrical and thermal energies. A PVT collector basiccaly combines the functions of a flat plate solar collector and those of a PV panel. This review presents thermodinamics fundamentals, descriptions, and previous works conducted on energy and exergy analysis of air based PVT collector. Studies in 2010 to 2018 of the energy and exergy analysis of air based PVT collectors are summarized. The energy and exergy efficiency of air based PVT collector ranges from 31% to 94% and 8.7% to 18%, respectively. In addition, flat plate solar collector is presented. Studies conducted on air based PVT collectors are reviewed.
Financial Evaluation of Solar Powered Absorption Cooling System for Computer ...IRJET Journal
This document evaluates the financial feasibility of a solar powered absorption cooling system for a computer laboratory in Bharatpur, India. It finds that:
1. The system is technically feasible, achieving a solar fraction of 0.52-0.75 depending on the collector area. However,
2. Financially, the system is currently not feasible due to the high initial costs of absorption chillers and solar collectors. It provides only marginal annual savings, resulting in very high payback periods of 67-83 years.
3. A sensitivity analysis found that with reduced total investment costs (e.g. due to technology improvements) and increased electricity prices in the future, the payback period could decrease significantly
Experimental and Modeling Dynamic Study of the Indirect Solar Water Heater: A...IJAAS Team
The document presents an experimental and theoretical study of an indirect solar water heater system in Rabat, Morocco. A theoretical dynamic multi-node model is proposed and validated experimentally. The system includes a 1.91 m2 flat plate collector and 300 L storage tank that heats water solely with solar energy. Experimental data was collected over sunny and cloudy days and showed good agreement with the model, with average deviations of 2-5% for water temperature and 4-9% for useful energy. The thermal efficiency was also determined experimentally and theoretically, agreeing well with industry standards.
Generating, Cataloging and Applying Energy Efficiency Performance StandardsMark Miller, P.E.
This document introduces a new energy benchmarking method called Pathian Analysis. It explains that Pathian Analysis more accurately compares energy consumption habits by evaluating energy usage over very small time periods (e.g. 15 minutes) when weather can be treated as constant, rather than normalizing for weather. Pathian Analysis generates precise benchmark curves called Pathian Curves that show energy usage at specific weather conditions, allowing accurate peer comparison. The document provides an example comparing Pathian Curves to traditional benchmarking methods to demonstrate Pathian Analysis' higher accuracy.
A novel cogeneration system based on SOFC and air source heat pump with heat ...Giulio Vialetto
The system proposed is based on SOFC combined with an air source heat pump (ASHP): exhausted gases of SOFC are mixed with inlet air of heat pump to increase efficiency in particular when evaporator may freeze.
The document summarizes a student's proposed work on analyzing a natural draught cross-flow cooling tower using computational fluid dynamics (CFD). The student aims to take different air entering angles and check the cooling effect of those angles. It provides background on cooling towers and how they work. It also reviews previous literature on cooling tower analysis and performance, limitations of existing methods, and the use of CFD to model cooling towers. The student proposes taking readings from a thermal power plant and using those readings in CFD software to analyze cooling effectiveness at different air entrance angles.
This document summarizes a research article that developed a simulation application to optimize the position and number of solar collectors in an array to maximize annual energy gain and thermal efficiency. The article describes analyzing a solar collector array system in Macedonia with collectors at different tilts, orientations, and hydraulic connections. It developed a simulation program using the INSEL programming language to perform parametric runs and optimization. Two scenarios were compared: changing the tilt of southeast oriented collectors from 35 to 25 degrees, and retaining the existing 35 degree tilt but adding more collectors. Scenario 1 resulted in over 13% more annual energy gain, while Scenario 2 had 2% higher thermal efficiency.
Solar air heater (SAH), which is the most essential component of solar drying systems, receive solar energy and convert it into thermal energy. This review presents descriptions and previous works conducted on performances analysis of SAHs. Exergoenviroeconomic, exergoenvironmental, environmental, and exergy analyses are also presented. In addition, results on the performances of SAHs are summarized. The exergy and energy efficiencies of SAHs at laboratorium testing range from 8% to 61% and from 30% to 79%, respectively.
Innovative cogeneration system for residential purposeGiulio Vialetto
This system was presented ad the Global Conference on Global Warning 2015 in Athens. The system is made by a SOFC system and a ground source heat pump (GSHP).
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.
Modeling and simulation of thermoelectric device used as a heat pump and an e...Bourhan Tashtoush
This document summarizes a research article that models and simulates a thermoelectric device that can operate as both a heat pump and electric generator under Mediterranean climate conditions. It presents performance curves for the device in both modes and estimates potential energy savings and payback period for using it in homes, schools, and offices in the Mediterranean region. The device utilizes solar energy through an evacuated tube collector to generate electricity when not needed for heating or cooling. The study investigates how device performance is affected by solar radiation, ambient conditions, and device parameters for both operating modes.
This document proposes a hybrid PID-cascade control system for HVAC systems to improve control performance. It models the heat exchanger and air conditioning space components of an HVAC system. It then designs a hybrid PID-cascade controller that combines traditional PID control with an internal cascade loop. Simulations show the hybrid controller has faster response, better setpoint tracking and disturbance rejection compared to traditional PID, compensator and Ziegler-Nichols tuned PID controllers. The cascade control inner loop improves response speed and precision, while the outer PID loop enhances stability and disturbance rejection for the HVAC system.
Innovative cogeneration system for residential purpose combined with eletrica...Giulio Vialetto
An innovative cogeneration system based on SOFC, ground source heat pump (GSHP) and a Stirling engine is proposed for residential purpose combined with electrical mobility.
The document summarizes research on the suitability of heat exchangers for use as solar receivers in solar thermal power applications. It discusses two main solar collector technologies - point focusing and line focusing collectors - and the receiver design requirements for each. It then outlines the methodology used, which includes designing and fabricating a shell and helical tube heat exchanger, modeling a porous disc line receiver with CFD, simulating different configurations and working fluids, and determining parameters for maximum efficiency. Literature on existing receiver models is reviewed and key findings are summarized. Experimental work involving a shell and helical tube receiver with nanofluid is described and optimization of parameters is discussed. Results from CFD analysis of the porous disc receiver showing heat transfer and fluid
This document discusses a computational fluid dynamics (CFD) analysis of a shell and tube heat exchanger with different baffle inclinations. The study aims to determine the optimal baffle inclination angle and mass flow rate. It analyzes heat transfer characteristics for baffle inclinations of 0, 10 and 20 degrees. The results indicate that a helical baffle configuration forces fluid rotation, increasing heat transfer rates and coefficients more than a segmental baffle design. Overall, the CFD simulation allows determination of outlet temperatures, pressure drops, and optimal design parameters for improved heat exchanger performance.
Iris Publishers- Journal of Engineering Sciences | Performance and Design Opt...IrisPublishers
The aim of this work is to optimize the design and performance of solar powered γ Stirling engine based on genetic algorithm (GA). A second-order mathematical model which includes thermal losses coupled with genetic algorithm GA has been developed and used to find the best values for different design variables. The physical geometry of the γ Stirling engine has been used as an objective variable in the genetic algorithm GA to determine the optimal parameters. The design geometry of the heat exchanger was considered to be the objective variable. The heater slots height, heater effective length, cooler slots height, cooler effective length, re-generator foil unrolled length and re-generator effective length are assumed to be the objective variables. Also, three different types of working fluids have been used in the model simulation to investigate the effect of the different working fluid on the engine performance. The comparison between the results obtained from the simulation by using the original parameters and the results from the optimized parameters when the engine was powered by solar energy; the higher temperature was 923 K applied to the working fluid when the air, helium, and hydrogen were used as working fluid. The engine power increases from 140.58 watts to 228.54 watts, and it is enhanced by approximately 50%, when the heating temperature is 923 K and the air is used as working fluid. The result showed that the working temperature is one of the most important parameters; because the output power increases by increasing of the hot side temperature.
This document summarizes Giulio Vialetto's Ph.D. research on improving energy efficiency in industrial facilities through innovative energy systems and data analysis methods. The research analyzed systems combining solid oxide fuel cells with heat pumps for advanced heat recovery and reversible solid oxide cell systems for combined heat, power, and hydrogen production. Cluster analysis of energy demand data was also studied to better design energy systems and identify opportunities to reduce mismatch between demand and supply. Case studies found primary energy savings of 2-6.5% were possible depending on the production levels and improvements implemented.
This document presents a comparative study of the thermodynamic and economic performance of three organic Rankine cycle (ORC) configurations - a basic ORC, a regenerative ORC (RORC), and a two-stage evaporation ORC (TSEORC) - for geothermal electricity production in developed and developing countries. The study optimizes operating parameters of the cycles using different methods and evaluates economic performance based on levelized cost of electricity, return on investment, and payback period for 20 countries with geothermal resources. The results show that a TSEORC with working fluid R123 has the highest return on investment and shortest payback period for Australia, while basic ORC with R134a and R
Form jurnal international 5814 24797-1-pbSttind Padang
This document summarizes an economic analysis of a hybrid power generation system combining biomass gasification, a solid oxide fuel cell (SOFC), and a gas turbine with a total capacity of 1.7 MW. The authors conduct a cost analysis of the various components including the SOFC system, heat recovery steam generator (HRSG), and auxiliary elements. They then evaluate the economic performance of the system based on energy prices in Europe, the US, and Iran to determine the most economically justifiable location. The results show Europe has the highest internal rate of return of 15.5% and shortest payback period of 6.7 years, making it the most economically viable region for this system based on current prices and economic conditions.
Paper bags are not always more environmentally friendly than plastic bags as commonly believed. Sustainability strategist Leyla Acaroglu argues that opting for paper over plastic is an oversimplification, and that we need to rethink environmental folklore and assumptions. She calls for moving past myths to develop systems and products that are truly better for the planet.
Leyla Acaroglu is the founder and director of Eco Innovators Pty Ltd. She will be giving a talk called "Paper Beats Plastic" on August 1st from 2-7pm at the KLCC venue. In her talk, Leyla will break through common environmental folklore and myths in order to reveal the true impacts of everyday products and materials when considering their full lifecycles. Her goal is to educate people and companies to think more holistically about sustainability.
This document discusses steam turbine power plant design and cycles. It describes typical steam conditions between 600-1450 psig at 750-950°F for Army power plants. Back pressure turbines exhaust at 250-15 psig and condensing turbines exhaust at 1-5 inches of mercury absolute. Cogeneration plants use back pressure or controlled extraction/condensing cycles to simultaneously produce electric power and steam for heat. The document compares plant heat rates, turbine heat rates, and discusses optimizing steam power plant cycles for maximum efficiency and economy.
Energy and exergy analysis of air based photovoltaic thermal (PVT) collector:...IJECEIAES
Photovoltaic thermal (PVT) collectors convert solar radiation directly to both electrical and thermal energies. A PVT collector basiccaly combines the functions of a flat plate solar collector and those of a PV panel. This review presents thermodinamics fundamentals, descriptions, and previous works conducted on energy and exergy analysis of air based PVT collector. Studies in 2010 to 2018 of the energy and exergy analysis of air based PVT collectors are summarized. The energy and exergy efficiency of air based PVT collector ranges from 31% to 94% and 8.7% to 18%, respectively. In addition, flat plate solar collector is presented. Studies conducted on air based PVT collectors are reviewed.
Financial Evaluation of Solar Powered Absorption Cooling System for Computer ...IRJET Journal
This document evaluates the financial feasibility of a solar powered absorption cooling system for a computer laboratory in Bharatpur, India. It finds that:
1. The system is technically feasible, achieving a solar fraction of 0.52-0.75 depending on the collector area. However,
2. Financially, the system is currently not feasible due to the high initial costs of absorption chillers and solar collectors. It provides only marginal annual savings, resulting in very high payback periods of 67-83 years.
3. A sensitivity analysis found that with reduced total investment costs (e.g. due to technology improvements) and increased electricity prices in the future, the payback period could decrease significantly
Experimental and Modeling Dynamic Study of the Indirect Solar Water Heater: A...IJAAS Team
The document presents an experimental and theoretical study of an indirect solar water heater system in Rabat, Morocco. A theoretical dynamic multi-node model is proposed and validated experimentally. The system includes a 1.91 m2 flat plate collector and 300 L storage tank that heats water solely with solar energy. Experimental data was collected over sunny and cloudy days and showed good agreement with the model, with average deviations of 2-5% for water temperature and 4-9% for useful energy. The thermal efficiency was also determined experimentally and theoretically, agreeing well with industry standards.
Generating, Cataloging and Applying Energy Efficiency Performance StandardsMark Miller, P.E.
This document introduces a new energy benchmarking method called Pathian Analysis. It explains that Pathian Analysis more accurately compares energy consumption habits by evaluating energy usage over very small time periods (e.g. 15 minutes) when weather can be treated as constant, rather than normalizing for weather. Pathian Analysis generates precise benchmark curves called Pathian Curves that show energy usage at specific weather conditions, allowing accurate peer comparison. The document provides an example comparing Pathian Curves to traditional benchmarking methods to demonstrate Pathian Analysis' higher accuracy.
A novel cogeneration system based on SOFC and air source heat pump with heat ...Giulio Vialetto
The system proposed is based on SOFC combined with an air source heat pump (ASHP): exhausted gases of SOFC are mixed with inlet air of heat pump to increase efficiency in particular when evaporator may freeze.
The document summarizes a student's proposed work on analyzing a natural draught cross-flow cooling tower using computational fluid dynamics (CFD). The student aims to take different air entering angles and check the cooling effect of those angles. It provides background on cooling towers and how they work. It also reviews previous literature on cooling tower analysis and performance, limitations of existing methods, and the use of CFD to model cooling towers. The student proposes taking readings from a thermal power plant and using those readings in CFD software to analyze cooling effectiveness at different air entrance angles.
This document summarizes a research article that developed a simulation application to optimize the position and number of solar collectors in an array to maximize annual energy gain and thermal efficiency. The article describes analyzing a solar collector array system in Macedonia with collectors at different tilts, orientations, and hydraulic connections. It developed a simulation program using the INSEL programming language to perform parametric runs and optimization. Two scenarios were compared: changing the tilt of southeast oriented collectors from 35 to 25 degrees, and retaining the existing 35 degree tilt but adding more collectors. Scenario 1 resulted in over 13% more annual energy gain, while Scenario 2 had 2% higher thermal efficiency.
Solar air heater (SAH), which is the most essential component of solar drying systems, receive solar energy and convert it into thermal energy. This review presents descriptions and previous works conducted on performances analysis of SAHs. Exergoenviroeconomic, exergoenvironmental, environmental, and exergy analyses are also presented. In addition, results on the performances of SAHs are summarized. The exergy and energy efficiencies of SAHs at laboratorium testing range from 8% to 61% and from 30% to 79%, respectively.
Innovative cogeneration system for residential purposeGiulio Vialetto
This system was presented ad the Global Conference on Global Warning 2015 in Athens. The system is made by a SOFC system and a ground source heat pump (GSHP).
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.
Modeling and simulation of thermoelectric device used as a heat pump and an e...Bourhan Tashtoush
This document summarizes a research article that models and simulates a thermoelectric device that can operate as both a heat pump and electric generator under Mediterranean climate conditions. It presents performance curves for the device in both modes and estimates potential energy savings and payback period for using it in homes, schools, and offices in the Mediterranean region. The device utilizes solar energy through an evacuated tube collector to generate electricity when not needed for heating or cooling. The study investigates how device performance is affected by solar radiation, ambient conditions, and device parameters for both operating modes.
This document proposes a hybrid PID-cascade control system for HVAC systems to improve control performance. It models the heat exchanger and air conditioning space components of an HVAC system. It then designs a hybrid PID-cascade controller that combines traditional PID control with an internal cascade loop. Simulations show the hybrid controller has faster response, better setpoint tracking and disturbance rejection compared to traditional PID, compensator and Ziegler-Nichols tuned PID controllers. The cascade control inner loop improves response speed and precision, while the outer PID loop enhances stability and disturbance rejection for the HVAC system.
Innovative cogeneration system for residential purpose combined with eletrica...Giulio Vialetto
An innovative cogeneration system based on SOFC, ground source heat pump (GSHP) and a Stirling engine is proposed for residential purpose combined with electrical mobility.
The document summarizes research on the suitability of heat exchangers for use as solar receivers in solar thermal power applications. It discusses two main solar collector technologies - point focusing and line focusing collectors - and the receiver design requirements for each. It then outlines the methodology used, which includes designing and fabricating a shell and helical tube heat exchanger, modeling a porous disc line receiver with CFD, simulating different configurations and working fluids, and determining parameters for maximum efficiency. Literature on existing receiver models is reviewed and key findings are summarized. Experimental work involving a shell and helical tube receiver with nanofluid is described and optimization of parameters is discussed. Results from CFD analysis of the porous disc receiver showing heat transfer and fluid
This document discusses a computational fluid dynamics (CFD) analysis of a shell and tube heat exchanger with different baffle inclinations. The study aims to determine the optimal baffle inclination angle and mass flow rate. It analyzes heat transfer characteristics for baffle inclinations of 0, 10 and 20 degrees. The results indicate that a helical baffle configuration forces fluid rotation, increasing heat transfer rates and coefficients more than a segmental baffle design. Overall, the CFD simulation allows determination of outlet temperatures, pressure drops, and optimal design parameters for improved heat exchanger performance.
Iris Publishers- Journal of Engineering Sciences | Performance and Design Opt...IrisPublishers
The aim of this work is to optimize the design and performance of solar powered γ Stirling engine based on genetic algorithm (GA). A second-order mathematical model which includes thermal losses coupled with genetic algorithm GA has been developed and used to find the best values for different design variables. The physical geometry of the γ Stirling engine has been used as an objective variable in the genetic algorithm GA to determine the optimal parameters. The design geometry of the heat exchanger was considered to be the objective variable. The heater slots height, heater effective length, cooler slots height, cooler effective length, re-generator foil unrolled length and re-generator effective length are assumed to be the objective variables. Also, three different types of working fluids have been used in the model simulation to investigate the effect of the different working fluid on the engine performance. The comparison between the results obtained from the simulation by using the original parameters and the results from the optimized parameters when the engine was powered by solar energy; the higher temperature was 923 K applied to the working fluid when the air, helium, and hydrogen were used as working fluid. The engine power increases from 140.58 watts to 228.54 watts, and it is enhanced by approximately 50%, when the heating temperature is 923 K and the air is used as working fluid. The result showed that the working temperature is one of the most important parameters; because the output power increases by increasing of the hot side temperature.
This document summarizes Giulio Vialetto's Ph.D. research on improving energy efficiency in industrial facilities through innovative energy systems and data analysis methods. The research analyzed systems combining solid oxide fuel cells with heat pumps for advanced heat recovery and reversible solid oxide cell systems for combined heat, power, and hydrogen production. Cluster analysis of energy demand data was also studied to better design energy systems and identify opportunities to reduce mismatch between demand and supply. Case studies found primary energy savings of 2-6.5% were possible depending on the production levels and improvements implemented.
This document presents a comparative study of the thermodynamic and economic performance of three organic Rankine cycle (ORC) configurations - a basic ORC, a regenerative ORC (RORC), and a two-stage evaporation ORC (TSEORC) - for geothermal electricity production in developed and developing countries. The study optimizes operating parameters of the cycles using different methods and evaluates economic performance based on levelized cost of electricity, return on investment, and payback period for 20 countries with geothermal resources. The results show that a TSEORC with working fluid R123 has the highest return on investment and shortest payback period for Australia, while basic ORC with R134a and R
Form jurnal international 5814 24797-1-pbSttind Padang
This document summarizes an economic analysis of a hybrid power generation system combining biomass gasification, a solid oxide fuel cell (SOFC), and a gas turbine with a total capacity of 1.7 MW. The authors conduct a cost analysis of the various components including the SOFC system, heat recovery steam generator (HRSG), and auxiliary elements. They then evaluate the economic performance of the system based on energy prices in Europe, the US, and Iran to determine the most economically justifiable location. The results show Europe has the highest internal rate of return of 15.5% and shortest payback period of 6.7 years, making it the most economically viable region for this system based on current prices and economic conditions.
Paper bags are not always more environmentally friendly than plastic bags as commonly believed. Sustainability strategist Leyla Acaroglu argues that opting for paper over plastic is an oversimplification, and that we need to rethink environmental folklore and assumptions. She calls for moving past myths to develop systems and products that are truly better for the planet.
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This document analyzes the front cover, contents page, and double page spread of a magazine.
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The document discusses a social studies class taught by Vicki Vives at Escola Casa Nostra. It mentions Carla Tortós-Sala from the 4th year of secondary school education. Key places discussed include Florence, Rome, and figures such as Michelangelo. Details are provided about baths, pleats, musculature, faces, knees, and a raised right hand gesture. Tables of law are also mentioned.
This document reviews photovoltaic-thermal (PV-T) systems for combined cooling, heating and power applications in buildings. It summarizes previous reviews on PV-T collectors and systems, which have mainly focused on stand-alone PV-T collectors or solar cooling applications. This review provides an overview of PV-T collector technologies and discusses PV-T-based systems for solar combined cooling, heating and power for buildings. It compares these systems with conventional solar heating and cooling technologies, reviews the heating and cooling technology market, and identifies challenges and opportunities to improve the cost-competitiveness of PV-T systems.
This document describes the design of a solar absorption chiller for an air conditioning laboratory in India. It begins with an introduction to solar cooling systems and their advantages over traditional cooling methods. It then provides details on the laboratory space that requires cooling, including its dimensions, materials, and heat-generating equipment. Next, it outlines the methodology for designing the solar absorption chiller, which includes calculating the cooling load, selecting an appropriate solar cooling technology, and optimizing the system design. The document concludes by providing theoretical results for the cooling system, such as the monthly cooling load requirement and cost analysis. The overall goal is to utilize solar energy and reduce emissions from air conditioning the laboratory.
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.
This document presents a comparative economic feasibility study of photovoltaic (PV) heat pump systems for space heating and cooling of two livestock farms in Spain. It analyzes two technical solutions: a grid-connected self-consumption (SC) configuration and an autonomous (AU) configuration using thermal energy storage and a diesel generator backup. Both systems were sized to meet the farms' heating and cooling needs. The economic analysis evaluates the profitability, levelized cost of energy, and savings compared to a grid-only system over a 25-year period. Results show that both PV-HP systems are economically feasible, with the autonomous system offering higher profits from electricity bill savings but the self-consumption system having lower overall energy costs due to
A solar PV array system is comprised of the following components - solar cells, panel modules, and an array system. Thus, overall optimal design of a solar PV system involves the optimal design of the components at three levels - solar cell, panel module, and array. In the present work, a comparison between different optimization methods is applied to design optimization of single channel Photovoltaic (SCPVT) system. The purpose of these methodologies is to obtain optimum values of the design parameters of SCPVT system, such that the overall economic profit is maximized throughout the PV system lifetime operational period which is not directly calculated in our work rather energy efficiency is calculated . Out of many design parameters available for this system, in the present work only few parameters are taken. The optimal design parameters chosen here are length of channel, depth of channel, velocity of fluid in the cell, and temperature of the cell. The objective function of the proposed optimization algorithm which is Gravitational Search Algorithm (GSA) implemented for design optimization of the system is the energy efficiency, which has to be maximized.
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.
Implementation of the characteristic equation method in quasi-dynamic.pdfAlvaro Ochoa
This document presents a mathematical model for simulating the quasi-dynamic behavior of an absorption chiller that uses a lithium nitrate/ammonia working fluid pair. The model is based on the characteristic equation method and solves mass and energy balance equations using the first law of thermodynamics. It models the major system components as single thermal components that exchange heat between external water circuits and internal refrigerant/solution circuits. Validation against experimental data showed good agreement, with relative errors below 5%. A sensitivity analysis then examined the chiller's dynamic response to variations in operating temperatures.
Novel technique for maximizing the thermal efficiency of a hybrid pveSAT Journals
Abstract In this paper a comparison between numerical model and experimental work results for a fixed Photovoltaic/ Thermal (PV/T) hybrid system is presented. The simulation in this work is based on a numerical model in solving the equations and determining the Photovoltaic (PV) cells thermal characteristics using both MATLAB and COMSOL Multiphysics. COMSOL is simulating the electromagnetic waves produced by the Sun through solving Maxwell's equations in three dimensions using Finite Elements Methods (FEM) and the sun irradiance is assumed to be Gaussian distribution across the twelve mourning hours. Beside that an experimental work is presented depending on the results conjured from the theoretical experience used in Comsol Multiphysics. A Pulse Width Modulator (PWM) is used to control the solenoid valve operation. In addition to the above a thermal analysis for the fixed PV modules and the piping water is presented where the output water temperatures, rate of heat transfer, overall heat transfer coefficient and thermal efficiency are calculated. As a result, a significant enhancement in the total thermal efficiency is observed with acceptable increase in the output water temperature. Keywords: Cooling systems; DAQ; Hybrid; COMSOL MULTIPHYSICS; MATLAB; Solid work; Lab view.
This document discusses optimizing the size of thermal storage tanks for solar domestic hot water systems. It first provides background on how domestic hot water consumption varies and the need for storage. It then describes an experimental solar plant and transient simulation model that was developed and validated. The simulation model is used to determine optimal storage tank sizing criteria for solar domestic hot water plants under daily transient conditions throughout a year. Comparison of simulation results to an existing regulation shows differences and can help establish better sizing guidelines.
Photovoltaic (PV) cell from solar energy is one of the most widely adopted renewable energy source and commercially available system that can be used in various applications. More appealing application of PV arrays used in thermoelectric (TE) device was it can convert solar thermal energy from temperature difference into electric energy to act as power generators. In this study, a theoretical model is developed by using conducting steady state energy analysis of a PVT-TE air collector. The matrix inversion method is used to obtain energy balance equation. The effect of various parameters also investigated. The mass flow rate of range 0.01 kg/s to 0.05 kg/s and solar intensity of 400 W/m2, 600 W/m2 and 800 W/m2 was used to obtain outlet temperature, To in the range about 28.9oC to 43.7oC and PV temperature, Tp about 35.3oC to 60oC.
This document summarizes a study on using computational fluid dynamics (CFD) to model and analyze the heat transfer performance of ceramic heat exchangers with different duct cross-sectional shapes (rectangular, elliptical, cylindrical). CFD was used to calculate parameters like temperature distribution, velocity distribution, heat transfer rate, and effectiveness. The predicted heat transfer rate from CFD analysis was found to be 15% higher than theoretical calculations. Analysis showed that cylindrical ducts had the highest effectiveness at 62%, followed by elliptical at 55% and rectangular at 52%. The document also provides background on the need to improve energy efficiency and reduce emissions, and discusses objectives, assumptions, and modeling steps of the CFD analysis.
international research journal of engineering and technology 3 nov.pdfnareshkotra
The International Journal of Mechanical Engineering Research and Technology is an international online journal in English published Quarterly offers a fast publication schedule whilst maintaining a proper peer review and the use of recommended electronic formats for an article delivery expedites the process of All submitted research articles are subjected to an immediate rapid screening by the editors consultation with the Editorial Board or others working in the field as assure that they are likely to be the level of interest and importance of appropriate for the journal.
This document summarizes a study on using computational fluid dynamics (CFD) to model and analyze the heat transfer performance of ceramic heat exchangers with different duct cross-sectional shapes (rectangular, elliptical, cylindrical). CFD was used to calculate parameters like temperature distribution, velocity distribution, heat transfer rate, and effectiveness. The predicted heat transfer rate from CFD analysis was found to be 15% higher than theoretical calculations. Analysis showed that cylindrical ducts had the highest effectiveness at 62%, followed by elliptical at 55% and rectangular at 52%. The document also provides background on the need to improve energy efficiency and reduce emissions, and discusses objectives, assumptions, and methodology of the CFD modeling and analysis.
The International Journal of Mechanical Engineering Research and Technology is an international online journal in English published Quarterly offers a fast publication schedule whilst maintaining rigorous peer review the use of recommended electronic formats for article delivery expedites the process All submitted research articles are subjected to immediate rapid screening by the editors consultation with the Editorial Board or others working in the field as appropriate to ensure they are likely to be the level of interest and importance appropriate for the journal.
This document discusses control strategies used to compensate for beam-induced heat loads in the Large Hadron Collider's (LHC) cryogenic systems in real-time. The LHC beam deposits significant heat in beam screens through synchrotron radiation, image currents, and electron clouds. Several control strategies were developed, including feed-forward compensation that forecasts beam-induced heat loads to preemptively adjust cryogenic systems. These strategies were modeled and simulated before successful deployment in 2015, allowing the LHC to operate at full energy while maintaining stable beam screen temperatures despite dynamic heat loads.
DIRECT EXPANSION GROUND SOURCE HEAT PUMPS FOR HEATING AND COOLINGIJSIT Editor
This article is an introduction to the energy problem and the possible saving that can be achieved
through improving building performance and the use of ground energy sources. The relevance and
importance of the study is discussed in the paper, which, also, highlights the objectives of the study, and the
scope of the theme. This study discusses some of the current activity in the GSHPs field. The basic system and
several variations for buildings are presented along with examples of systems in operation. Finally, the GCHP
is presented as an alternative that is able to counter much of the criticism leveled by the natural gas industry
toward conventional heat pumps. Several advantages and disadvantages are listed. Operating and installation
costs are briefly discussed.
Design and Performance Analysis of Solar Powered Absorption Cooling System fo...IRJET Journal
- The document discusses the design and performance analysis of a solar powered absorption cooling system for a computer lab located in Bharatpur, India.
- The peak cooling load of the computer lab is calculated to be 34.94 kW, so a 10TR vapor absorption cooling system is adopted.
- Simulations are carried out using the TRANSOL program to analyze the performance of the solar cooling system using different solar collector types and areas. Parameters like solar fraction, primary energy savings, and electrical COP are evaluated.
- It is concluded that the solar thermal cooling system can achieve good solar fractions between 0.52-0.75 and primary energy savings up to 52% for the considered location and collector areas.
Absorption Refrigeration Systems Based on Ammonia asRefrigerant Using Differe...Alvaro Ochoa
This document reviews absorption refrigeration systems that use ammonia as the refrigerant and different absorbents such as water, lithium nitrate, and lithium nitrate plus water. It discusses the state-of-the-art of these systems, describing their development over the years based on relevant studies in six categories: thermodynamic properties, residential/industrial applications, evaluation studies, heat and mass transfer processes, activation by solar energy, and prototype systems. The review aims to fill a gap in consistently studying design requirements for absorption chillers and their working fluids and processes.
Review of magnetic refrigeration system as alternative to conventional refrig...Naji Abdullah
The refrigeration system is one of the most important systems in industry.
Developers are constantly seeking for how to avoid the damage to the environment. Magnetic
refrigeration is an emerging, environment-friendly technology based on a magnetic solid that
acts as a refrigerant by magneto-caloric effect (MCE). In the case of ferromagnetic materials,
MCE warms as the magnetic moments of the atom are aligned by the application of a magnetic
field. There are two types of magnetic phase changes that may occur at the Curie point: first
order magnetic transition (FOMT) and second order magnetic transition (SOMT). The
reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative cycle),
where the magnetic material matrix works both as a refrigerating medium and as a heat
regenerating medium, while the fluid flowing in the porous matrix works as a heat transfer
medium. Regeneration can be accomplished by blowing a heat transfer fluid in a reciprocating
fashion through the regenerator made of magnetocaloric material that is alternately magnetized
and demagnetized. Many magnetic refrigeration prototypes with different designs and software
models have been built in different parts of the world. In this paper, the authors try to shed
light on the magnetic refrigeration and show its effectiveness compared with conventional
refrigeration methods.
This document provides an overview of solar air conditioning technologies and best practice examples from several European countries. It describes two main types of solar cooling systems: chilled water systems and open cycle desiccant cooling systems. Chilled water systems use absorption or adsorption chillers to produce chilled water for air conditioning, while open cycle systems directly condition the supply air. The document outlines the technologies used in small and medium sized solar cooling applications and provides examples of installed systems in Austria, France, Germany, Greece, Italy, Portugal, and Spain.
Similar to Feasibility evaluation of two solar cooling systems applied to a cuban (20)
Feasibility evaluation of two solar cooling systems applied to a cuban
1. Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –35 –
Feasibility evaluation of two solar cooling systems applied to a cuban
hotel. Comparative analysis
Evaluacion de factibilidad del uso dos sistemas climatización solar
aplicado a un hotel cubano. Análisis comparativo
Yamile -Diaz Torres José Pedro -Monteagudo Yanes
Yarelis-Valdivia Nodal Yudit-Miranda Torres
Recibido: junio de 2015
Aprobado: septiembre de 2015
ABSTRACT/RESUMEN
The article presents an analysis of technical and economic feasibility of using two configurations of solar
cooling in a Cuban hotel. HVAC hybrid schemes are: a cooler of ice water vapor compression (chiller)
interconnected in parallel with a smaller capacity chiller, first with a solar-powered absorption cooling system
(SACS), and then with a photovoltaic cooling system(PSC). Both were simulated taking into account the
weather conditions in the region, thermodynamic calculation methodologies and principles that govern these
technologies. The results show that the use of these alternatives contributes to reducing energy consumption
and the environmental impact of heating, ventilation and air conditioning systems (HVAC). Economic analysis
highlights that PCS is more favorable than the SACS taking into account the cooling cost generation (CCG)
but energy assessment indicates that SACS has higher thermal performance for the case study to which it is
applied.
Keys words: chiller; feasibility analysis; photovoltaic cooling system; solar-powered absorption cooling system.
El artículo presenta un análisis de factibilidad técnica y económica de uso de dos configuraciones de
climatización solar en un hotel cubano. Los esquemas de climatización híbridas son: una enfriadora de agua
helada de compresión de vapor (chiller) interconectada en paralelo con una enfriadora de absorción asistida
con energía solar térmica (SACS, siglas en inglés), y posteriormente con un chiller asistido por un sistema
solar fotovoltaico (PSC, siglas en ingles). Ambos fueron simulados teniendo en cuenta las condiciones
meteorológicas de la región, metodologías de cálculo y principios termodinámicos que gobiernan estos
sistemas. Los resultados muestran que el uso de estas alternativas contribuye a la reducción del consumo
energético y el impacto ambiental de los sistemas calefacción, ventilación y aire acondicionado (HVAC, siglas
en inglés). El análisis económico resalta que PCS es más favorable que el SACS, teniendo en cuenta el costo
de generación de frío (CCG, siglas en inglés) pero la evaluación energética indica que este último posee
mayores prestaciones térmicas para el caso de estudio al cual se le aplica.
Palabras clave: chiller; análisis de factibilidad; sistema de climatización solar fotovoltaica; sistema de
climatización solar por absorción.
INTRODUCTION
Solar energy could supply all the present and the future energy needs of the world on continuing basis. This
makes it one of the most promising of the unconventional energy source [1].
The use of solar energy in applications such as refrigeration has become an attractive solution in view of the
energetic sustainability. In this scenario where it is evident the increased use of fossil fuels for air conditioning
of buildings, solar cooling technology seems to be a promising alternative to conventional electrical driven
APLICACIONES INDUSTRIALES
2. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –36 –
units. The main advantage of solar cooling systems is the coincidence in time between cooling demand from
the building and energy supply in the form of solar irradiance. This implies the reduction of primary energy
consumption and the decrease of global warning impact of HVAC systems. Absorption refrigeration systems
are not yet competitive to mechanical compression ones. For that reason, research and development activities
are necessary in order to reduce the cost of using solar assisted air conditioning in buildings.
Solar cooling literature is rich in papers that assess, develop and optimize a wide variety of solar thermal
cooling options, particularly absorption cooling systems. Mokhtar et al. proposed a methodology for assessing
solar cooling technologies based on the performance of each solar cooling technology as a system taking into
account cost and performance parameters in addition to important boundary conditions of weather and cooling
demand [2]. Results showed that large-scale cooling plant options are the most economical. On a smaller
scale, Fresnel concentrators and thin film photovoltaic (PV) cells are the most economically viable. In terms of
overall efficiency however multicrystalline PV cells with vapor compression chillers were the most efficient
option of all. Solar resource availability is a major factor in determining the most suitable solar cooling
technology for a certain location.
Otanicar et al. analyzed a variety of solar cooling schemes and revealed some keys details regarding the
choice of the system taking into account economically and environmentally aspects: For solar electric cooling
system, the cost is highly dependent on the system coefficient of performance (COP) when photovoltaic (PV)
prices remain at the current levels but when prices are lowered the impact of COP on cost diminishes [3]. For
solar thermal cooling, the cost of solar collection is much lower as a percentage of the overall cost, but the
cost of the refrigeration system represents a larger percentage of the total cost. Additionally, the paper reveals
that the costs for solar thermal cooling are not projected to decrease as much as PV cooling over the next 20
years due to the relatively stable cost of collection and storage. The tourism sector is one of the main industries
in Cuba, also high consumer of electricity, where it is known that 60 % of electricity consumption is due to
HVAC equipment. In the country using solar cooling technologies discussed above are not recorded. In this
scenario the real potential of these systems are not known taking into account the climatic conditions of the
region. The objective of this research is to investigate the thermal performance of the operation of the two
schemes solar cooling, a SACS and a PSC system using mathematical models to predict the savings in energy
and reduction in CO2 emissions. In order to verify the systems’ overall performance, the proposed
methodologies is implemented for a hotel facility and the developed model in this study presents a
comprehensive analysis that suits Cuba climate and an economic assessment based on the commercialized
system components which are commonly existed. The last step was the comparison of both systems in order
to find a better solution to apply a hybrid scheme for a cooling production.
General description of the thermal cooling system without any backup
The SACS consists basically of thermal collectors, a hot water storage tank, lithium bromide solution
(LiBr)/water simple effect absorption chiller and a cooling tower which is shown schematically in figure 1. The
systems include domestic hot water (DHW) production.
Fig. 1. General scheme of a solar-powered single-effect absorption cooling system [4]
The operation of the system described above generates demand and energy charges which can be assessed
using the basic energy balance equations presented by the mathematical models used by Ghait and Abussita
with key assumptions that govern this technology: [5]
3. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –37 –
The system is assumed to be under-steady state conditions.
All phases are in thermal and mechanical equilibrium.
The water temperature in the tank is uniform.
Shading of collector absorber plate is negligible
Assuming negligible heat losses in piping between collector and the tank
Assuming negligible losses between the storage tank and the generator.
The useful energy, Qu collected by the thermal collectors can be determined by the equation (1), describe by
Duffie and Beckman,[6].
)1()()],(*)([* kWTaiTcUGFAQu LRC
Where G, (W/m2
) is the incident solar radiation intensity; Ac (m2
) the area of collectors, τ is the transmissivity
coefficient of the glass cover; α is the absorptance of receiver’splate surface; FR is the heat removal factor; Tc,i
(K)is the inlet fluid temperature; Ta,(K)is the ambient temperature; and UL,(W/m2
/K).is the overall heat transfer
coefficients. The useful energy it’s given also by the first thermodynamics law, equation (2).
)2()()( ,, kWTTCpmQu icoc
Where ṁ, (kg/s) is the mass flow rate of collectors and Tc,o, (K)is the outlet fluid temperature. Combining Eqs.
(1)–(2), the water outlet temperature of the collectors can be expressed as equation 3:
)3()(
)],(*)([*
,. KT
Cpm
TaiTcUGFA
T ic
LRC
oc
Equation (3), can be used to estimate the collector area required to provide hot water at specified flow rate
and temperature.
Storage tank
The energy balance of the storage tank temperature can express by equation (4):
)4()()( ,, gLtptspwS QTaTsAsUQ
dt
dTs
CmCm
Where Cpw,s,(kJ/kgK); ṁs, (kg/s) and Ts(K)are the specific heat of water, mass flow rate and temperature of
water in the storage tank respectively. Cp,t and ṁt are the specific heat and the mass of the empty tank,
respectively. UL(W/m2
/K) is the overall heat loss coefficient of the tank and As (m2
) is the area of the storage
tank. Qg, (kW) is the energy received by the generator in the absorption chiller[7].Assuming negligible heat
losses in piping between collector and the tank by guarantee good thermal insulation implies that Q=Qu.
Losses between the generator circuit and the storage tank are negligible; the amount of heat which is
demanded for driving the refrigeration cycle is obtained by the following equation (5).
)5()()( ,, kWTTCmQ ogigpgg
Where ṁgis the mass flow rate of water, Tg,i and Tg,o, (K) are the water inlet and outlet temperature of the
generator, respectively. The amount of heat Qs (kW), stored in a tank for a working day, when the water tank
reaches its maximum temperature, can be expressed by the equation (6)
)6()()( ,max,, kWTTCMQ ifsspwss
Ts,max (K) is the water temperature at storage tank. Tf,I is the inlet water temperature entering the tank. At night
it is vital to assume that storage tank is cleaned properly for DHW application when air conditioning system is
switched off.
Absorption chiller
4. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –38 –
For the absorption chiller, the COP can be expressed as equation (7), where Qc(kW) is the amount of cooling
energy generated by the chiller’s compressor.
)7(
G
C
Q
Q
COP
Overall thermal model
By substituting equations 4 and 1 into equation7integrating the heat transfer processes associated with the
solar collector, storage tank, and absorption chiller obtaining the cooling load concerning the systems can be
given by equation (8):
)8()()()],(*)([* ,,
assL
s
tptspwsLRCC TTAU
dt
dT
CMCMTaiTcUGFACOPQ
This mathematical model allows a wide range of cooling load, Qc, (kW) varying the system design parameters
such as the collecting area, mass flow, as well as choosing the appropriate optical parameters according solar
technology, to meet the thermal demand chiller Qg(kW). The performance of solar cooling system (COPs) can
be given by equation (9).It´s finding by the COP multiplied by η, solar array efficiency[8]:
)9(*COPCOPs
General description of the photovoltaic cooling system without storage
The system is similar to the conventional system HVAC but the energy demand is covered by the electricity
obtained by PV modules and if required from the public grid. A PCS without storage typically consists by four
basic components: photovoltaic modules, an inverter circuit and a vapor compression AC unit which is shown
schematically in figure. 2.
Fig. 2 Schematic of a stand-alone PV system [3]
Electrical power generation PV array
For the PV cooling system described above, the prediction of PV module performance in terms of electrical
power output in the field, is modeled by the expressions presented by Skoplaki and Payvos. The power output
of PV array can be calculated from the equation (10) [9].
)10()(251*max,max WTc
G
G
PP
Tref
T
refpv
Where Pmax,ref, (W) is the nominal electrical power of photovoltaic generator at under standards conditions
(STC), GT(W/ m2
) is a solar radiation on tilted plane module GTref, is a solar radiation at STC, equal 1000 W/
m2
, γ (o
C-1
)is the temperature factor for powerequal to -0.045 for crystalline silicon modules. Tc, (o
C) is the cell
temperature, is calculated using the equation (11), presented Evans [10].
)11()(800/)20( CGNOCTTambTc o
T
The operation cell temperature NOCT employed in equation 11, it is common to use it as an indicator of module
temperature. It is an important parameter in module characterization since it is a reference of how the module
5. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –39 –
will work when operating in real conditions. Furthermore, in PV system design and simulation programs, many
calculations are based on the determination of module temperature from ambient temperature and NOCT.
Tamb (oC) is the environmental temperature. The traditional linear expression for the PV electrical efficiency is
given by equation (12), presented in [11].
)12()(1 TrefTcTrefc
In which ηref is the module’s electrical efficiency at the reference temperature Tref equal 25 o
C, at solar radiation
flux of 1000 W/m2
.
Feasibility analysis
Final total investment costs determine annual capital cost and therefore have a strong influence in the
economic and financial values such as payback and cost of primary energy. The payback period is defined as
the period of time (i.e. no. of years) required for the return of investment and can be expressed mathematically
by equation (13)
Paybackperiod = difference in capital cost/ annual operating cost savings (13)
Various author ranked the solar cooling technologies according to the cooling generation cost (CGC),
expressed in equation 14 [2,12]. CGC takes into account the capital cost of the solar field, the cooling
equipment, the thermal storage, the land and the problems of supply–demand mismatch and how performance
of the system changes with conditions. It also includes the costs of annual maintenance throughout the life
time of the plant embedded in the finance parameter α.
$
$
( ) (14)
Specific annual payments
M Capex Oyear kW
CGC
FLH kWhh
Number of full load hours per year
year
Where Capex is the capital cost [$/kWh cooling capacity], α is the ratio between the capital investment and the
annual fixed payments, M is the annual maintenance cost [% of Capex per year], ΣO is the annual operation
cost [$/kW cooling capacity], FLH is the usable cooling yield expressed as the number of full load hours per
year [h/year].
The economic assumptions are:
Maintenance is assumed to be constant throughout the life time of the plant (25 year), it is normally provided
in the contract as a percentage of Capex. Values between 0,5 % and 3 % of Capex are reported in the literature
for the solar field and the cooling equipment
Operational cost are mainly dominated by the cost of electricity needed to run the chilled water pump, cooling
tower, condenser water pump, and air handling unit (AHU).Since we assume that this demand is met by extra
PV cells which price is included in Capex, operational costs are assumed to be zero.
The number of full load hour is the total amount of cooling generated by each technology in kWh, normalized
by the total chillers’ capacity in kW. This number is the same for all cooling technologies. Assumed that all
technologies should satisfy a solar fraction of 75% of the cooling load.
Meteorological data
The global radiation and ambient temperature is shown in figure 3a. Integrating a total available solar energy
of 6 967MJ is obtained, corresponding to 6,54 kWh/(m2
day). For winter day, figure 3b. The total available
energy of 4 653.44 MJ is obtained, corresponding 5.04 kWh/(m2
day). Both examples are good agreement whit
historical data for Cuba.
6. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –40 –
(a) (b)
Fig. 3. Solar irradiance on a flat plate oriented South and tilted 30o
, and ambient temperature.
a) Summer day b) winter day
Measurements daters for figure 3, were taken outside the building of the meteorological center of Cienfuegos
Cuba.
RESULTS AND DISCUSSION
Case study 1: solar-powered absorption cooling system. Energy performance
The building considered in the study is a hotel with 149 rooms available for tourism. The main building has a
capacity of one hundred thirty six rooms (136),a block of thirteen (13) cabins located in the pool area. The
HVAC systems of the hotel are two water chillers model, CHAWT-1402-AT-BP-RC-100 C1-VT, with a cooling
capacity: 404 kW each, 115 Tons of refrigeration (TR) chilled water flow GW-70 m3 / h. Temperature Input /
output: 11/6 ° C. The available roof area is 1500 m2
for the installation of solar collectors
This installation is considered as a transit hotel, so during daylight hours from 10:00 am to 4:00 pm a maximum
of 50 TR it´s only need to satisfy their air conditioning needs on the ¨areas nobles¨ circuit that it’s compound
of offices, store and administrations departments. To cover the same mixed air conditioning scheme, which
incorporates a solar absorption air conditioning to existing conventional HVAC systems is proposed.
For the SACS system, the key elements are: solar collector array: 180 (468 m2
) Flat plane collector EURO-20
AR. The absorption chiller: COGENIE LT-5 with a capacity of 176 kW and COP equal to 0.69. The Hot water
is driven to the generator side at temperature of 85o
C. This SACS was analyzed under the following operating
system: At 08:30 am when the sunshine on the roof reaches about 200-250 W/m2
, the primary circuit pump is
switched on and circulate water in a closed circuit, made by the solar field and heat storage tank, gradually
raising the temperature of the fluid until it´s reaches 80o
C. Then hot water is driven to the generator circuit.
The system doesn’t use auxiliary heating system. The main requirement is that the absorption chiller should
be operational at 10:00 am at 60% of its cooling capacity. The system operates until 16:00 hours (minimum
requirement, could be more, depending on environmental conditions), when comes into operation the
conventional system, because the thermal load in the hotel increases. When it’s not needed to heat or cool
the water or is sent through a heat exchanger for DHW, raising water it to its operating temperature of 60o
C.
The heat delivered to the absorption chiller can be calculated by integrating the product of the flow rate through
the chiller with the temperature drop across the generator. The flow rate through the chiller is constant. The
operation of the chiller is summarized in figure 4a), for a typical summer day and a typical winter day it´s show
in figure 4b). In the figure plot shows inlet/outlet temperature of chilled water (CHW), hot water (HW) – left axis,
and the coefficient of performance of the chiller (COP)-right axis.
In a typical summer day the chiller begins operating at 10:00 am, when 39 800 l of water at the set point of 88o
C have
been accumulated. Operation continues for over 6 hours, during this period of time a 7 592.39 MJ of hot water from
the tank is supplied to the chiller. Return chilled water from the cold air handlers enters the chiller and is cooled
approximately 4.5-6.7o
C in standards conditions, the chilled water flow rate is constant. A total chilled water production
of 3 977.9 MJ, corresponding to an average chiller COP of 0.53 is obtained, slightly lower than the value that can be
calculated using the manufacturer´s technical literature. The instantaneous COP plotted oscillates between 0.45 and
0.75, the low values corresponding to peaks in the heat delivered at the generator circuit.
7. Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –41 –
(a)
(b)
Fig 4. Performance of the absorption chiller as function of time in a) summer day; b) winter day
In a typical winter day, figure 4b) the chiller begins operating at 11:00 am, and the operation continues for over
5 hours, the total heat energy delivered is 3 110.39 MJ and the total chilled water production of 5 000.39 MJ.
The instantaneous COP oscillates between 0.5 -0.8, corresponding to an average COP of 0.62 a better
performance than in summer day. In resume for a whole year the SACS supplies the cooling requirements of
the hotel during 6 hours. The overall system predict 300 303 kWh of cooling per year.
Case study 2: Photovoltaic cooling system. Energy performance
The proposed system was implemented for same facilities. The cooling demand of the building could be
covered during 11:00 am until 4:00 pm by a chiller CHAMT-601 with 159 kW cooling capacities. For this case
it’s needed a photovoltaic solar arrays of 454 PV modules JAP6 60-245/3BB750 m2
for produce enough energy
to cover the demand from 10:00 am to 4:00 pm, and 5 inverters SMA TRIPOWER 17 000 TL. Figure 5, show
the theoretical electric power and electrical efficiency of the PV array evaluated by using equation.10 and
equation. 12
(a) (b)
Fig. 5 Theoretical electrical power (AC) delivered by PV array and electrical efficiency performance
(a) summer day (b) winter day
8. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –42 –
In the case of summer conditions, the chiller CHAMT-60 requires 54,70 kW of compressor input power to
deliver 159.20 kW of unit capacity. These working conditions are reached from 9:30 a.m. until 5:00 pm. The
energy delivered by the photovoltaic array is obtained by integrating the area under the curve shown in the
previous figure. It´s predicts that this system delivers a total of 619 kWh per day during a typical summer day
and 428 kWh in one typical winter day. This will also allow delivering to the local grid a total of 288 kWh and
154 kWh, respectively. The PCS system supplies the cooling requirements of the hotel during 6 hours. The
overall system predict 235 356 kWh of cooling per year.
Feasibility comparison of both systems
The cost of a solar cooling installation is a direct function of the design of the entire system, the weather
conditions of the region and the choice of technology constantly developing by changing the relationship
between the surface of solar panels and air conditioning load or volume storage. In the paper the investment
costs are the sums of all the component of each system. The cost of the main components is calculated by
multiplying the size of each component by specific cost shown in table 1. No funding subsidies are included.
Table 1. Cost and parameters considered in the calculations [17]
Cost/parameter Unit
Specific cost, compression chiller 310 €/kW
Specific cost absorption chiller 700 €/kW
Cooling tower 150 €/kW
PV module 0.82 €/W peak
Solar collector FPC 280 €/m2
Heat Storage Unit 800 €/m3
Inverter 4 819 €/u
Control cost 5 000 €
Planning cost 10 % on inv. cost
Yearly maintenance cost of solar system 1 % on inv. cost
Yearly maintenance cost of other components 1,5 % on inv. cost
Electricity cost-energy 0,20€/kWh
Expected lifetime of solar system 20 Years
Lifetime of compression system 8 Years
Lifetime of other components 15 Years
CO2 emission rate (electricity) 0,91 Kg CO2/kWh
Compared to conventional HVAC equipment, these systems are expensive. According to several case studies
analyzed, the investment costs of both technologies in a high percentage exceed operational costs as shown
in figure 6.It seems an increase of 40 % of SACS regarding the PCS. Due to the complexity of the scheme
SACS system some components like additional pumps, cooling towers, thermal collectors, storage tanks and
relevant controllers are pricey.
Fig 6. Economic comparison between SACS and PCS
9. Feasibility Evaluation of Two Solar Cooling Systems Applied to a Cuban Hotel. Comparative Analysis
Y. Diaz Torres, Y. Valdivia Nodal, J. P. Monteagudo Yanes and Y. Miranda Torres
Ingeniería Energética, 2016:XXXVII(1):35-44, Enero/Abril, ISSN 1815-5901 –43 –
Considering the energy performance of both schemes plus the costs of these facilities apply the expression
14 obtained the CGC of SACS and PCS are 13,7 ¢/kWh and 0,10. ¢/kWh respectively. The result also showed
that SACS has slightly longer payback period compared to PCS estimated to be 10 years and 6 years in that
order. For the SACS systems the savings means 232.7 Tons CO2reductions of carbon emissions, equivalent
also to remove 42 cars out of roads or savings 541,11 barrels of crude oil. For the PCS systems, included the
energy delivered to the local grid. Estimated saving represents 307,4 Tons CO2 the reduction of carbon
emissions, removing 56 cars out of roads and savings 714 barrels of crude oil.
CONCLUSION
In this paper, the energy and environmental performance of a SACS system and PSC system were evaluated
and both technologies were compared, considering mathematical models that describe these systems. In
summary, the outcomes of this paper are outlined below:
SACS system predicts 300 303 kWh/year cooling. On a typical summer day the system could work a little more
than 7 hours, when solar field will reach peak temperatures between 95o
C and 100o
C. The instantaneous COP
oscillates between 0,45 and 0,75 and the low values will correspond to peaks in the heat delivered at the
generator circuit. On a typical winter day, the COP will improve oscillates between 0,5-0,8; but the
meteorological conditions will allow the system to work an average of 5 hours. This configurations offer the
advantage of the availability of hot water for HWD.
PCS system predicts 235 356 kWh/year cooling. The energy delivered by the photovoltaic array will be
619 kWh on a typical summer day and 428 kWh in one typical winter day. This will also permit delivering to
the local grid a total of 288 kWh and 154 kWh respectively, the system could work an average of 6 hours. The
COPs range from 0.4-0.6, low values it´s caused by low efficiency performance of PV array.
Economic results show that the photovoltaic cooling system is favorable in comparison with the SACS. An
exhaustive sensitive analysis show a strong influence of initial investment cost on the payback and in the CGC.
But energetic comparison indicates that SACS has more thermal applications.
RECOMMENDATIONS
It’s convenient the study of the use of solar photovoltaic–thermal (PVT) collectors. It’s a promising
technology that was receiving wide attention. Cooling of the PV modules by the heat transfer fluid flowing
through the PVT collector then leads to an increase in the overall energy collection and conversion
efficiencies of the system. Also with this collector is obtained thermal energy for hot water applications.
A reduction of this cost is necessary to increase the feasibility of solar driven cooling systems. Further
comprehensive, prompt research and development activities are necessary in Cuba in order to promote
this kind of air conditioning hybrid system schemes.
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AUTHORS
Yamile Díaz Torres
Eng in Mechanical Engineering in 2004, the Bs. Eng in Industrial engineering in 2011, and the MS degree in
Energy Efficiency in 2013, a professor at the Centre for Studies of Energy and Environment (CEEMA) of the
Cienfuegos University and a PhD student.
e-mail: ydtorres@ucf.edu.cu.
Yarelis Valdivia Nodal
Eng in Mechanical Engineering in 2006, and the MS degree in Energy Efficiency in 2008, a professor at the
Centre for Studies of Energy and Environment (CEEMA) of the Cienfuegos University. And a PhD student
e-mail: yvaldivia@ucf.edu.cu.
José Pedro Monteagudo Yanes
Eng in Mechanical engineer in 1975 and PhD in technical sciences at the Instituto Superior Politécnico "José
À. Echeverría" Havana, in 1997. He works at the Centre for Studies of Energy and Environment (CEEMA) of
the Cienfuegos University as lecturer and consultant work for teaching, postgraduate and research.
e-mail jpmyanes@ucf.edu.cu
Yudit Miranda Torres
She received the BS degree in the teaching of English language from the Cienfuegos University and the MSc.
Degree in English in 2004. A professor at the Cienfuegos University and a PhD student.
e-mail: ymiranda@ucf.edu.cu