International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
This document discusses heat exchangers and includes the following key points:
- It describes different types of heat exchangers including concentric-tube, cross-flow, shell-and-tube, and compact heat exchangers.
- It discusses the overall heat transfer coefficient and factors that influence it such as convection, conduction, fins, and fouling.
- It introduces the log mean temperature difference (LMTD) method for calculating heat transfer in heat exchangers and how LMTD is evaluated for different flow configurations.
- It provides an example problem demonstrating how to determine the overall heat transfer coefficient and heat transfer rate for a heat recovery device.
Definition and Requirements
Types of Heat Exchangers
The Overall Heat Transfer Coefficient
The Convection Heat Transfer Coefficients—Forced Convection
Heat Exchanger Analysis
Heat Exchanger Design and Performance Analysis
The document summarizes an experiment to determine heat transfer coefficients in a cross-flow plate heat exchanger under both continuous and batch operations. For continuous operation, the heat transfer rate and coefficient increased with increasing cold water flow rate. The heat transfer coefficient was highest at around 5 gallons per minute. For batch operation, the heat transfer coefficient was determined to be 7490 ± 300 W/m2K using linear regression modeling, which was higher than continuous operation. Heat losses to the environment likely contributed to the lower coefficient in continuous operation compared to batch.
This document provides a project report on a tri duct heat exchanger. It includes an introduction to heat transfer and functions of heat exchangers. It describes the construction and flow arrangements of a tri duct heat exchanger. The theory section discusses overall resistance to heat transfer, which includes resistance from the hot and cold fluid films and the metal wall. Dimensionless parameters like Nusselt, Reynolds and Prandtl numbers are also introduced.
Shell and tube heat exchangers transfer heat between two fluids, where one fluid flows through tubes inside a shell and the other flows over the tubes through the shell. They work by exploiting the temperature difference between the two fluids using conduction and convection to transfer heat from one to the other. Common types include straight tube and U-tube exchangers. Baffles inside the shell help direct flow, hold tubes in position, and prevent vibration. Applications include cooling engine fluids, swimming pool water, and in nuclear power plant reactors.
Thermodynamic Cycles for Power Generation—Brief Review
Real Steam Power Plants—General Considerations
Steam-Turbine Internal Efficiency and Expansion Lines
Closed Feed water Heaters (Surface Heaters)
The Steam Turbine
Turbine-Cycle Heat Balance and Heat and Mass Balance Diagrams
Steam-Turbine Power Plant System Performance Analysis Considerations
Second-Law Analysis of Steam-Turbine Power Plants
Gas-Turbine Power Plant Systems
Combined-Cycle Power Plant Systems
This design project aims to propose a plate type heat exchanger that can meet given heat duty and find the number of plates required. Plate type heat exchanger uses metal plates to transfer heat between two fluids. Starting point of this design is to define given properties
Introduction to Air Distribution Systems, Fluid Mechanics—A Brief Review, Air Duct Sizing—Special Design Considerations, Minor Head Loss in a Run of Pipe or Duct , Minor Losses in the Design of Air Duct Systems—Equal Friction Method, Fans—Brief Overview and Selection Procedures
This document discusses heat exchangers and includes the following key points:
- It describes different types of heat exchangers including concentric-tube, cross-flow, shell-and-tube, and compact heat exchangers.
- It discusses the overall heat transfer coefficient and factors that influence it such as convection, conduction, fins, and fouling.
- It introduces the log mean temperature difference (LMTD) method for calculating heat transfer in heat exchangers and how LMTD is evaluated for different flow configurations.
- It provides an example problem demonstrating how to determine the overall heat transfer coefficient and heat transfer rate for a heat recovery device.
Definition and Requirements
Types of Heat Exchangers
The Overall Heat Transfer Coefficient
The Convection Heat Transfer Coefficients—Forced Convection
Heat Exchanger Analysis
Heat Exchanger Design and Performance Analysis
The document summarizes an experiment to determine heat transfer coefficients in a cross-flow plate heat exchanger under both continuous and batch operations. For continuous operation, the heat transfer rate and coefficient increased with increasing cold water flow rate. The heat transfer coefficient was highest at around 5 gallons per minute. For batch operation, the heat transfer coefficient was determined to be 7490 ± 300 W/m2K using linear regression modeling, which was higher than continuous operation. Heat losses to the environment likely contributed to the lower coefficient in continuous operation compared to batch.
This document provides a project report on a tri duct heat exchanger. It includes an introduction to heat transfer and functions of heat exchangers. It describes the construction and flow arrangements of a tri duct heat exchanger. The theory section discusses overall resistance to heat transfer, which includes resistance from the hot and cold fluid films and the metal wall. Dimensionless parameters like Nusselt, Reynolds and Prandtl numbers are also introduced.
Shell and tube heat exchangers transfer heat between two fluids, where one fluid flows through tubes inside a shell and the other flows over the tubes through the shell. They work by exploiting the temperature difference between the two fluids using conduction and convection to transfer heat from one to the other. Common types include straight tube and U-tube exchangers. Baffles inside the shell help direct flow, hold tubes in position, and prevent vibration. Applications include cooling engine fluids, swimming pool water, and in nuclear power plant reactors.
Thermodynamic Cycles for Power Generation—Brief Review
Real Steam Power Plants—General Considerations
Steam-Turbine Internal Efficiency and Expansion Lines
Closed Feed water Heaters (Surface Heaters)
The Steam Turbine
Turbine-Cycle Heat Balance and Heat and Mass Balance Diagrams
Steam-Turbine Power Plant System Performance Analysis Considerations
Second-Law Analysis of Steam-Turbine Power Plants
Gas-Turbine Power Plant Systems
Combined-Cycle Power Plant Systems
This design project aims to propose a plate type heat exchanger that can meet given heat duty and find the number of plates required. Plate type heat exchanger uses metal plates to transfer heat between two fluids. Starting point of this design is to define given properties
Introduction to Air Distribution Systems, Fluid Mechanics—A Brief Review, Air Duct Sizing—Special Design Considerations, Minor Head Loss in a Run of Pipe or Duct , Minor Losses in the Design of Air Duct Systems—Equal Friction Method, Fans—Brief Overview and Selection Procedures
Parallel flow heat exchanger is analysed with CFD tool. A comparative study of the analytical and experimental data is carried out to better understand the temperature profile, surface heat flux and heat transfer co-efficient parameters of the heat exchanger
The document discusses compact heat exchangers, including their definition as having a heat transfer area density greater than 700 m2/m3. It describes several types of compact heat exchangers like plate and frame, brazed plate, welded plate, spiral, plate fin, and printed circuit heat exchangers. Advantages are listed as improved energy efficiency, smaller size, lower cost and improved safety. Limitations include fouling susceptibility and limited design choices for high pressures. Care must be taken to prevent fouling and corrosion in compact heat exchangers.
The document discusses heat exchangers and fouling factors. It describes how fouling decreases heat transfer over time by creating additional thermal resistance. Fouling depends on operating conditions like temperature and fluid velocities. The types of fouling include precipitation of solids, corrosion, chemicals, and biological growth. The document also summarizes methods for analyzing heat exchangers and factors to consider when selecting a heat exchanger, such as heat transfer rate, size, cost, pumping power requirements, and materials.
An experimental study of heat transfer in a corrugated plate heat exchangerIAEME Publication
1. The document discusses an experimental study of heat transfer in a corrugated plate heat exchanger. Experiments were conducted to analyze heat transfer characteristics for different flow arrangements of hot and cold fluids through the heat exchanger.
2. The effectiveness and exergy loss of the heat exchanger were calculated for parallel and counter flow arrangements. The average effectiveness was found to be 48% higher and exergy loss 33% lower in the counter flow arrangement compared to the parallel flow arrangement.
3. Maximum heat transfer was observed at the highest hot fluid inlet temperature of 70°C, being 5% greater in the parallel flow arrangement. However, the non-dimensional exergy loss and log mean temperature difference were both lower in the
The document summarizes a study of the vortex tube using computational fluid dynamics (CFD) modeling. It discusses the basic workings of the Ranque-Hilsch vortex tube, which uses compressed gas to produce hot and cold air streams without moving parts. The study uses ANSYS Fluent software to build a 3D CFD model of the vortex tube and simulate the temperature separation phenomenon using the k-epsilon turbulence model. The model is meshed and boundary conditions are applied to analyze factors like temperature distribution, energy transfer, and heat dissipation within the vortex tube.
This document appears to be a project report on the thermal design of an evaporative condenser. It includes an abstract that summarizes calculating the design parameters of an evaporative condenser for a refrigeration unit at a dairy plant. It then discusses the refrigeration system arrangement at the plant site, calculations performed to determine the condenser design, and results and conclusions. The report was submitted by 4 students for their Bachelor's degree in partial fulfillment of project requirements.
What is heat exchanger & its Functions
Types of Heat Exchangers
Compact Heat Exchangers
Part of Fin Plate Heat Exchangers
Advantages & Disadvantages of Fin Plate Exchangers
Materials & Manufacturing
Overall Heat transfer Coefficient & Fouling Factor
LMTD Method
Effectiveness - NTU Method
CFD ANALYSIS OF DOUBLE PIPE HEAT EXCHANGEREzhil Raj s
This document summarizes a CFD analysis of a double pipe heat exchanger. It describes the geometry of the heat exchanger with an inner copper tube and outer aluminum tube. It also discusses the meshing and boundary conditions used in the CFD model. The results show that counter-current flow has a more uniform temperature distribution and higher heat transfer rate compared to parallel flow. The conclusion is that counter-current flow is more effective for heat transfer in a double pipe heat exchanger.
The vortex tube is a device that separates a gas flow into hot and cold exits without moving parts. High pressure gas enters tangentially through nozzles, creating a swirling vortex. There are two types - uniform and counter flow - which differ in exit placement. In operation, the gas separates into inner and outer layers with different temperatures due to centrifugal forces. The inner layer exits cold and the outer layer exits hot. Vortex tubes provide simple cooling with no refrigerants but have low efficiency. Potential applications include industries needing simultaneous hot and cold air.
This document discusses different types of modern heat exchangers, including shell and tube, plate, spiral, plate and shell, plate fin, and microchannel heat exchangers. It describes the basic components and functions of shell and tube heat exchangers. It also outlines key advantages and disadvantages of different heat exchanger types, such as their operating pressures and temperatures, efficiency, size, maintenance requirements, and materials. The document emphasizes that heat exchanger design must optimize minimizing pressure drop, maximizing thermal performance, and minimizing entropy generation.
Parametric study of the performance of heat pipe – a review 2IAEME Publication
The document reviews the parametric study of heat pipe performance. It discusses how heat pipes transfer heat using both thermal conductivity and phase change. The key factors that affect heat pipe performance are identified as working fluid, wick structure, tilt angle, heat input, and applications. Limitations to heat transport in heat pipes are the capillary, viscous, sonic, entrainment, and boiling limitations. The effect of the wick structure on heat pipe performance is also examined.
AN EXPERIMENTAL STUDY OF EXERGY IN A CORRUGATED PLATE HEAT EXCHANGERIAEME Publication
In the present work an attempt has been made to investigate the performance of a 3 channel 1-1 pass, corrugated plate heat exchanger. The plates had sinusoidal wavy surfaces with corrugation angle of 450. Hot water at different inlet temperature ranging from 400C to 600C was made to flow in the central channel to get cooled by water in the outer channels.
K10888 ramratan malav (refrigeration & air conditioning)9672269693
The document summarizes a major assignment presentation on CFD analysis of a vortex tube for refrigeration and air conditioning. It includes an introduction to vortex tubes and their working principle, objectives of analyzing flow parameters and temperature separation, a literature review of previous studies, modeling of a vortex tube with specific dimensions, results and discussion of temperature, pressure, and velocity distributions, applications of vortex tubes, advantages, and conclusions. The presentation aims to optimize design parameters like aspect ratio, number of inlets, and pressures to improve temperature separation performance.
The document discusses the principle and operation of pulse tube refrigeration. It begins with an introduction to pulse tube refrigerators and their history. It then describes the basic components of a pulse tube refrigerator, including the pulse tube, regenerator, pressure wave generator, and heat exchangers. The document explains how compression and expansion of the working gas, typically helium, leads to cooling at one end of the pulse tube. It also briefly discusses modifications like the orifice pulse tube refrigerator. Applications include military, environmental, transportation and energy uses.
1. Heat exchanger pressure drop analysis is important because pumping power required is directly related to pressure drop and pressure drop affects heat transfer, operation, size, and cost.
2. Major contributions to pressure drop include friction in the core and distribution devices, with core pressure drop dominated by friction, momentum effects, and entrance/exit effects.
3. Core pressure drop is analyzed using assumptions of steady, isothermal flow and accounting for friction, momentum effects, and entrance/exit contractions based on flow geometry and properties.
Design and analysis of plate heat exchanger with co2 and r134a as working fIAEME Publication
This document describes the design and analysis of a plate heat exchanger using CO2 and R134a as working fluids. The authors modeled the plate heat exchanger in Solidworks and analyzed it using computational fluid dynamics in ANSYS. They calculated the heat transfer coefficients, Nusselt number, Reynolds number, and overall heat transfer coefficient. The results from the CFD analysis matched closely with the theoretical calculations. The analysis showed a low pressure drop and the optimal design achieved a small temperature difference between the inlet and outlet of both fluids.
Analysis of forced draft cooling tower performance using ansys fluent softwareeSAT Journals
Abstract In this project the cooling tower performance has been analyzed by varying air inlet parameters with different air inlet angles and by attaching a nozzle in air inlet. The cooling tower analyzed here is used specifically for small scale industries, which is forced draft counter-flow cooling tower with single module capacities from 10 to 100 cooling tons. In this project 50 tons cooling capacity model has been taken as reference model. The analysis has been done using computational fluid dynamics (CFD) ANSYS 14.5 software. The cooling tower models have been modeled using SOLIDWORKS 2013 software and they have been meshed using ICEM CFD 14.5 software. The meshed models have been analyzed using FLUENT software. The air inlet angles varied in horizontal direction, vertical direction and by combining both horizontal and vertical inclination. A convergent nozzle has been modeled and assembled to the inlet pipe. The temperature contours of the cooling tower models have been taken from the analysis. Based on the outlet cold water temperature, the improved effectiveness of the cooling tower model has been obtained.
Keywords: Forced draft cooling tower, Air inlet parameter, Convergent nozzle, Cooling ton capacity, Counter flow cooling tower, Ansys 14.5, Solidworks 2013, ICEM CFD 14.5, Effectiveness of cooling tower.
This document discusses the advantages of considering compact heat exchangers like plate-and-frame exchangers early in the process design stage. Plate-and-frame exchangers can be significantly smaller than traditional shell-and-tube exchangers while meeting the same heat transfer needs. Specifying design requirements without considering the characteristics of different exchanger types can lead to oversized and more expensive designs. Charts are provided to help estimate the required area of plate-and-frame exchangers for preliminary sizing.
This document discusses heat exchangers and their analysis. It begins by listing the objectives of classifying heat exchangers, determining heat transfer coefficients, and analyzing heat exchangers using effectiveness-NTU and LMTD methods. Several types of heat exchangers are then described, including compact, shell-and-tube, regenerative, plate-frame, and condensers/boilers. Methods for determining overall heat transfer coefficient and fouling factors are provided. The document concludes by explaining the LMTD and effectiveness-NTU methods for analyzing heat exchangers.
This document discusses the optimization of parallel condensing in a steam power plant. It begins with background on steam power cycles and condensers, then discusses design criteria for water-cooled and air-cooled condensers. It presents the design procedure for a water-cooled condenser in 10 steps. Graphs analyze operating parameters like turbine exhaust pressure, air velocity, and transverse pitch. It concludes that a parallel condensing system utilizing both water-cooled and air-cooled condensers can reduce capital costs and improve performance compared to solely air-cooled systems, with the optimal mixture depending on water availability.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
Parallel flow heat exchanger is analysed with CFD tool. A comparative study of the analytical and experimental data is carried out to better understand the temperature profile, surface heat flux and heat transfer co-efficient parameters of the heat exchanger
The document discusses compact heat exchangers, including their definition as having a heat transfer area density greater than 700 m2/m3. It describes several types of compact heat exchangers like plate and frame, brazed plate, welded plate, spiral, plate fin, and printed circuit heat exchangers. Advantages are listed as improved energy efficiency, smaller size, lower cost and improved safety. Limitations include fouling susceptibility and limited design choices for high pressures. Care must be taken to prevent fouling and corrosion in compact heat exchangers.
The document discusses heat exchangers and fouling factors. It describes how fouling decreases heat transfer over time by creating additional thermal resistance. Fouling depends on operating conditions like temperature and fluid velocities. The types of fouling include precipitation of solids, corrosion, chemicals, and biological growth. The document also summarizes methods for analyzing heat exchangers and factors to consider when selecting a heat exchanger, such as heat transfer rate, size, cost, pumping power requirements, and materials.
An experimental study of heat transfer in a corrugated plate heat exchangerIAEME Publication
1. The document discusses an experimental study of heat transfer in a corrugated plate heat exchanger. Experiments were conducted to analyze heat transfer characteristics for different flow arrangements of hot and cold fluids through the heat exchanger.
2. The effectiveness and exergy loss of the heat exchanger were calculated for parallel and counter flow arrangements. The average effectiveness was found to be 48% higher and exergy loss 33% lower in the counter flow arrangement compared to the parallel flow arrangement.
3. Maximum heat transfer was observed at the highest hot fluid inlet temperature of 70°C, being 5% greater in the parallel flow arrangement. However, the non-dimensional exergy loss and log mean temperature difference were both lower in the
The document summarizes a study of the vortex tube using computational fluid dynamics (CFD) modeling. It discusses the basic workings of the Ranque-Hilsch vortex tube, which uses compressed gas to produce hot and cold air streams without moving parts. The study uses ANSYS Fluent software to build a 3D CFD model of the vortex tube and simulate the temperature separation phenomenon using the k-epsilon turbulence model. The model is meshed and boundary conditions are applied to analyze factors like temperature distribution, energy transfer, and heat dissipation within the vortex tube.
This document appears to be a project report on the thermal design of an evaporative condenser. It includes an abstract that summarizes calculating the design parameters of an evaporative condenser for a refrigeration unit at a dairy plant. It then discusses the refrigeration system arrangement at the plant site, calculations performed to determine the condenser design, and results and conclusions. The report was submitted by 4 students for their Bachelor's degree in partial fulfillment of project requirements.
What is heat exchanger & its Functions
Types of Heat Exchangers
Compact Heat Exchangers
Part of Fin Plate Heat Exchangers
Advantages & Disadvantages of Fin Plate Exchangers
Materials & Manufacturing
Overall Heat transfer Coefficient & Fouling Factor
LMTD Method
Effectiveness - NTU Method
CFD ANALYSIS OF DOUBLE PIPE HEAT EXCHANGEREzhil Raj s
This document summarizes a CFD analysis of a double pipe heat exchanger. It describes the geometry of the heat exchanger with an inner copper tube and outer aluminum tube. It also discusses the meshing and boundary conditions used in the CFD model. The results show that counter-current flow has a more uniform temperature distribution and higher heat transfer rate compared to parallel flow. The conclusion is that counter-current flow is more effective for heat transfer in a double pipe heat exchanger.
The vortex tube is a device that separates a gas flow into hot and cold exits without moving parts. High pressure gas enters tangentially through nozzles, creating a swirling vortex. There are two types - uniform and counter flow - which differ in exit placement. In operation, the gas separates into inner and outer layers with different temperatures due to centrifugal forces. The inner layer exits cold and the outer layer exits hot. Vortex tubes provide simple cooling with no refrigerants but have low efficiency. Potential applications include industries needing simultaneous hot and cold air.
This document discusses different types of modern heat exchangers, including shell and tube, plate, spiral, plate and shell, plate fin, and microchannel heat exchangers. It describes the basic components and functions of shell and tube heat exchangers. It also outlines key advantages and disadvantages of different heat exchanger types, such as their operating pressures and temperatures, efficiency, size, maintenance requirements, and materials. The document emphasizes that heat exchanger design must optimize minimizing pressure drop, maximizing thermal performance, and minimizing entropy generation.
Parametric study of the performance of heat pipe – a review 2IAEME Publication
The document reviews the parametric study of heat pipe performance. It discusses how heat pipes transfer heat using both thermal conductivity and phase change. The key factors that affect heat pipe performance are identified as working fluid, wick structure, tilt angle, heat input, and applications. Limitations to heat transport in heat pipes are the capillary, viscous, sonic, entrainment, and boiling limitations. The effect of the wick structure on heat pipe performance is also examined.
AN EXPERIMENTAL STUDY OF EXERGY IN A CORRUGATED PLATE HEAT EXCHANGERIAEME Publication
In the present work an attempt has been made to investigate the performance of a 3 channel 1-1 pass, corrugated plate heat exchanger. The plates had sinusoidal wavy surfaces with corrugation angle of 450. Hot water at different inlet temperature ranging from 400C to 600C was made to flow in the central channel to get cooled by water in the outer channels.
K10888 ramratan malav (refrigeration & air conditioning)9672269693
The document summarizes a major assignment presentation on CFD analysis of a vortex tube for refrigeration and air conditioning. It includes an introduction to vortex tubes and their working principle, objectives of analyzing flow parameters and temperature separation, a literature review of previous studies, modeling of a vortex tube with specific dimensions, results and discussion of temperature, pressure, and velocity distributions, applications of vortex tubes, advantages, and conclusions. The presentation aims to optimize design parameters like aspect ratio, number of inlets, and pressures to improve temperature separation performance.
The document discusses the principle and operation of pulse tube refrigeration. It begins with an introduction to pulse tube refrigerators and their history. It then describes the basic components of a pulse tube refrigerator, including the pulse tube, regenerator, pressure wave generator, and heat exchangers. The document explains how compression and expansion of the working gas, typically helium, leads to cooling at one end of the pulse tube. It also briefly discusses modifications like the orifice pulse tube refrigerator. Applications include military, environmental, transportation and energy uses.
1. Heat exchanger pressure drop analysis is important because pumping power required is directly related to pressure drop and pressure drop affects heat transfer, operation, size, and cost.
2. Major contributions to pressure drop include friction in the core and distribution devices, with core pressure drop dominated by friction, momentum effects, and entrance/exit effects.
3. Core pressure drop is analyzed using assumptions of steady, isothermal flow and accounting for friction, momentum effects, and entrance/exit contractions based on flow geometry and properties.
Design and analysis of plate heat exchanger with co2 and r134a as working fIAEME Publication
This document describes the design and analysis of a plate heat exchanger using CO2 and R134a as working fluids. The authors modeled the plate heat exchanger in Solidworks and analyzed it using computational fluid dynamics in ANSYS. They calculated the heat transfer coefficients, Nusselt number, Reynolds number, and overall heat transfer coefficient. The results from the CFD analysis matched closely with the theoretical calculations. The analysis showed a low pressure drop and the optimal design achieved a small temperature difference between the inlet and outlet of both fluids.
Analysis of forced draft cooling tower performance using ansys fluent softwareeSAT Journals
Abstract In this project the cooling tower performance has been analyzed by varying air inlet parameters with different air inlet angles and by attaching a nozzle in air inlet. The cooling tower analyzed here is used specifically for small scale industries, which is forced draft counter-flow cooling tower with single module capacities from 10 to 100 cooling tons. In this project 50 tons cooling capacity model has been taken as reference model. The analysis has been done using computational fluid dynamics (CFD) ANSYS 14.5 software. The cooling tower models have been modeled using SOLIDWORKS 2013 software and they have been meshed using ICEM CFD 14.5 software. The meshed models have been analyzed using FLUENT software. The air inlet angles varied in horizontal direction, vertical direction and by combining both horizontal and vertical inclination. A convergent nozzle has been modeled and assembled to the inlet pipe. The temperature contours of the cooling tower models have been taken from the analysis. Based on the outlet cold water temperature, the improved effectiveness of the cooling tower model has been obtained.
Keywords: Forced draft cooling tower, Air inlet parameter, Convergent nozzle, Cooling ton capacity, Counter flow cooling tower, Ansys 14.5, Solidworks 2013, ICEM CFD 14.5, Effectiveness of cooling tower.
This document discusses the advantages of considering compact heat exchangers like plate-and-frame exchangers early in the process design stage. Plate-and-frame exchangers can be significantly smaller than traditional shell-and-tube exchangers while meeting the same heat transfer needs. Specifying design requirements without considering the characteristics of different exchanger types can lead to oversized and more expensive designs. Charts are provided to help estimate the required area of plate-and-frame exchangers for preliminary sizing.
This document discusses heat exchangers and their analysis. It begins by listing the objectives of classifying heat exchangers, determining heat transfer coefficients, and analyzing heat exchangers using effectiveness-NTU and LMTD methods. Several types of heat exchangers are then described, including compact, shell-and-tube, regenerative, plate-frame, and condensers/boilers. Methods for determining overall heat transfer coefficient and fouling factors are provided. The document concludes by explaining the LMTD and effectiveness-NTU methods for analyzing heat exchangers.
This document discusses the optimization of parallel condensing in a steam power plant. It begins with background on steam power cycles and condensers, then discusses design criteria for water-cooled and air-cooled condensers. It presents the design procedure for a water-cooled condenser in 10 steps. Graphs analyze operating parameters like turbine exhaust pressure, air velocity, and transverse pitch. It concludes that a parallel condensing system utilizing both water-cooled and air-cooled condensers can reduce capital costs and improve performance compared to solely air-cooled systems, with the optimal mixture depending on water availability.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
Este documento presenta un catálogo de herramientas dividido en tres secciones: herramientas de jardinería, herramientas de floristería y ropa de trabajo. En la sección de herramientas de jardinería describe tijeras para cortar setos, rastrillos, azadas y carretillas. La sección de herramientas de floristería incluye elementos como pelarosas, esponjas, cinta adhesiva y kenzan. Finalmente, la ropa de trabajo menciona botas, monos, guantes y cascos de protección
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
This document contains 12 quotes from various Twitter users on topics related to inbound marketing. The quotes discuss the importance of employee culture, how consumers research purchases using different channels and mobile devices, the short attention spans of online consumers, the need for sales to embrace inbound marketing, and how mobile should be a priority in all marketing efforts. The quotes are attributed to people active in discussing inbound marketing on Twitter.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
El documento presenta la idea de un proyecto empresarial para crear una tienda de ropa online para hombres bajo una marca propia. Explica que un negocio exitoso requiere de una idea diferenciada y que un e-commerce es una tienda en Internet sin presencia física que tiene bajos costos de inicio y operación. La idea propuesta es vender ropa masculina de una marca propia con características distintivas que le permitan destacar en el mercado.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
Unified client management session from Microsoft partner boot campOlav Tvedt
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This paper addresses the numerical simulation of
helically coiled closed loop pulsating heat pipe which is carried
in ANSYS Fluent. The values of thermal resistance for
constant heat fluxes vs. transient heat fluxes are analyzed.
Phase change visualization after the end of simulation is
carried out to observe the phenomenon in liquid at its
saturation temperature and pressure. Finally, helical heat
pipes are found to have thermal resistance less by 2.7K/W,
0.56 K/W, and 0.227 K/W for 8W, 40W and 80W heat inputs
than circular pipes. Helical heat pipes are found more efficient
than circular heat pipes.
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Heat Transfer Enhancement of Shell and Tube Heat Exchanger Using Conical Tapes.IJERA Editor
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International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
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the paper aim is to presenting the heat transfer analysis of refrigerant flow in an evaporator
tube is done. The main objective of this paper is to find the length of the evaporator tube for a pre-defined
refrigerant inlet state such that the refrigerant at the tube outlet is superheated. The problem involves
refrigerant flowing inside a straight, horizontal copper tube over which water is in cross flow. Inlet
condition of the both fluids and evaporator tube detail except its length are specified. here pressure and
enthalpy at discrete points along the tube are calculated by using two-phase frictional pressure drop model.
Predicted values were compared using another different pressure drop model. A computer-code using
Turbo C has been developed for performing the entire calculation
IRJET- An Experimental Study of Pool Boiling Heat Transfer Enhancement in...IRJET Journal
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Heat exchangers transfer heat from one fluid to another. Common types include condensers, evaporators, boilers and radiators. Heat exchangers can be classified based on their flow arrangements, which include parallel flow, counterflow and multipass configurations. Counterflow arrangements provide more uniform heat transfer and allow greater heat recovery compared to parallel flow. Multipass designs increase surface area and heat transfer by having the fluid pass through the tubes multiple times in different flow directions.
This document discusses different types of heat exchangers used in food processing. It begins by defining heat exchangers and their purpose in food processing applications such as heating, cooling, and heat exchange between food streams. The main types discussed include plate heat exchangers, scraped surface heat exchangers, double pipe heat exchangers, multiple pass heat exchangers, and tubular heat exchangers. Key differences between types include direct contact vs non-contact heat transfer and flow configurations like co-current vs counter-current. Advantages and uses of each type are also summarized.
This document summarizes a research paper on the thermal performance of air conditioners using nanofluids compared to base fluids. Key points:
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This document discusses the design of a heat exchanger to raise the temperature of air from 25°C to 400°C using combustion gas at 1800°C. It includes the problem statement, assumptions, relevant equations, and calculations to determine the required tube length. The key steps are: (1) determining mass flow rates and properties of air and combustion gas, (2) calculating heat transfer coefficients on the tube and shell sides, and (3) using effectiveness-NTU method to calculate the required tube length based on the heat transfer rates and coefficients. The goal is to evaluate if the heat exchanger dimensions provide high efficiency and could be applied to real systems.
Ijri te-03-011 performance testing of vortex tubes with variable parametersIjripublishers Ijri
Conventional refrigeration system is a type of refrigeration systems which are costly; noisy, harmful gases released from a machine based on application of this type of system and it is required more maintenance. So, we need to go for unconventional refrigeration systems like vortex tube refrigeration system, which produce less vibrations and which require less maintenance and which are noiseless. It is required for our mechanical engineers to look for enhancing the performance of such vortex tubes. So as a part of my project work, I have chosen various sizes of vortex tubes and test their performances for finding out optimum performance. We will be testing the performance of vortex tubes with different ‘l/d’ ratios and different cold fractions, with different pressures and different nozzle sizes.
1) The document presents an experimental study of heat transfer through a uniformly heated vertical tube air heater.
2) The study investigates the effect of tube length, diameter, and heat flux on heat transfer and buoyancy induced airflow.
3) It was found that the heat transfer coefficient increases with increasing heat flux but decreases with increasing tube diameter and length, while air outlet temperature increases with tube length and heat flux but decreases with diameter.
This document provides an overview of heat pipes and their applications in electronics cooling. It discusses the basic components and operation of heat pipes including the evaporator, condenser, wick and working fluid. The key advantages of heat pipes are their high thermal conductivity and ability to transport heat efficiently. Limitations include the capillary and boiling limits. Different types of heat pipes are described along with considerations for choosing materials and designing heat pipes for specific applications like electronics cooling.
This document discusses heat exchangers, specifically double pipe and shell and tube heat exchangers. It defines heat exchangers as devices used to transfer heat between fluids or between fluids and solids. It then describes the basic construction and working principles of double pipe heat exchangers, including their applications in areas like aircraft and commercial uses. The document also briefly introduces shell and tube heat exchangers.
A REPORT ON HEAT TRANSFER OPTIMIZATION OFSHELL AND TUBE HEAT EXCHANGER USING ...IRJET Journal
The document presents a study on optimizing heat transfer in a shell and tube heat exchanger using different fluids through computational fluid dynamics (CFD) analysis. A shell and tube heat exchanger model was created in CATIA software and CFD analysis was performed in Solidworks Flow Simulation. Water and two types of nanofluids (SiO2 and Al2O3 nanoparticles mixed with water) were analyzed as fluids flowing through the heat exchanger tubes at varying velocities from 0.2 m/s to 1 m/s. The results found that increasing fluid velocity improved heat transfer effectiveness and overall heat transfer while decreasing friction factor. Heat transfer performance was highest for the nanofluids compared to water alone.
This document presents an experimental study of heat transfer enhancement in a pipe-in-pipe helical coil heat exchanger. Experiments were conducted with two different inner coil diameters (6mm and 8mm) under varying mass flow rates in the inner coil and annulus. The overall heat transfer coefficient and inner Nusselt number were found to increase with increasing mass flow rates. Counter-flow configuration resulted in higher heat transfer rates than parallel flow due to the larger log mean temperature difference, though overall heat transfer coefficients were similar between the two flow arrangements. Experimental results for inner Nusselt number agreed with established correlations in parallel flow but were higher in counter-flow.
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International Journal of Engineering and Science Invention (IJESI)
1. International Journal of Engineering Science Invention
ISSN (Online): 2319 – 6734, ISSN (Print): 2319 – 6726
www.ijesi.org Volume 2 Issue 9ǁ September 2013 ǁ PP.18-22
Thermal Performance of Closed Loop Pulsating Heat Pipe Using
Different Working Fluid: A Review
Prajwal D. Chawane1, Sujay A. Basunathe2 , Shweta D. Borekar3
1,2,3,
B.E.Student, Dept. of Mechanical Engg., Prof. Ram Meghe Institute of Technology and Research, Badnera,
ABSTRACT: Heat pipe is very efficient device for dissipating heat from the device. But new technology
introduces which is nothing but Pulsating Heat Pipe. Thermodynamic characteristic of PHP is been highlighted
in this paper. Three thermo dynamical boundary condition should be met to make PHP work properly which
includes internal tube diameter, the applied heat flux and amount of the working fluid in the system. Number of
turns of the device and thermo physical properties of the working fluid also plays vital role in determining
thermal behavior apart from this fluid.Unsolved issues regarding PHP with various working fluid and
application are discussed.
KEYWORDS: pulsating heat pipe
I.
INTRODUCTION
Akachi proposed and patented Pulsating or Loop type Heat Pipein 1990s [1]. It is a member of wickless heat
pipes the oscillation of working fluid and phase change phenomina in capillary tube is basic principle. To make
liquid and vapour plugs to exist diameter of tube must be small. It can work at higher heat fluxes. It has
excellent feature like high thermal performance, rapid response to high heat load, simple design and low costSo
PHP has been considered as one of the promising technology regarding electric cooling, cell cryopreservation,
the spacecraft thermal control system, etc.A Pulsating heat pipe consists of meandering tube of capillary
dimensions with many U-turns, as see in figure 1[2]. In contrast to a conventional heat pipe, there is no
additional capillary structure inside the tube. There are three ways to arrange the tube- Open Loop System,
Closed Loop System, and Closed Loop System with additional flow control check valves As the name suggest,
in close loop structure, the tube is joined end to end. The tube is evacuated and then filled partially with working
fluid, which distributes itself naturally in the form of liquid vapor plugs and slugs inside the capillary tube. One
end of this tube receives heat, transferring it to the other end by pulsating action of the liquid vapors/ bubble
slug system. There may exist an optional adiabatic zone in between evaporator and condenser.
Figure1. Schematic of a pulsating heat pipe and its design variations [2]
The PHP is first evacuated and then partially filled with the working fluid. Effects from surface tension
cause the formation of liquid slugs interspersed with vapor bubbles. When one end of the bundle of turns of the
undulating capillary tube is subjected to high temperature, the working fluid inside evaporates and increases the
vapor pressure, which causes the bubbles in the evaporator zone to grow. This pushes the liquid column toward
the low temperature end (condenser). The condensation at the low temperature end will further increase the
pressure difference between the two ends. Because of the interconnection of the tubes, motion of liquid slugs
and vapor bubbles at one section of the tube toward the condenser also leads to the motion of slugs and bubbles
www.ijesi.org
18 | Page
2. Thermal Performance Of Closed Loop…
in the next section toward the high temperature end (evaporator). This works as the restoring force. The interplay between the driving force and the restoring force leads to oscillation of the vapor bubble and liquid slugs in
the axial direction. The frequency and the amplitude of the oscillation are expected to be dependent on the shear
flow and mass fraction of the liquid in the tube
II. PRINCIPLES OF OPERATION
1.
Thermodynamic Principles
Heat addition and rejection and the growth and extinction of vapor bubbles drive the flow in a PHP.
Even though the exact features of the thermodynamic cycle are still unknown, Groll and Khandekar [3]
described it in general.
2.
Fluid Dynamic Principles
Fluid flow in a capillary tube consists of liquid slugs and vapor plugs moving in unison. The slugs and
plugs initially distribute themselves in the partially filled tube. The liquid slugs are able to completely bridge the
tube because surface tension forces overcome gravitational forces. There is a meniscus region on either end of
each slug caused by surface tension at the solid/liquid/vapor interface. The slugs are separated by plugs of the
working fluid in the vapor phase. The vapor plug is surrounded by a thin liquid film trailing from the slug.
3.
Heat Transfer Principles
As the liquid slugs oscillate, they enter the evaporator section of the PHP. Sensible heat is transferred
to the slug as its temperature increases, and when the slug moves back to the condenser end of the PHP, it gives
up its heat. Latent heat transfer generates the pressure differential that drives the oscillating flow. The phase
change heat transfer takes place in the thin liquid film between the tube wall and a vapor plug and in the
meniscus region between the plug and slug, which requires complex analysis.
III. INFLUENCE PARAMETERS AFFECTING PHP PERFORMANCE
Looking into the available literature, it can be seen that six major thermo-mechanical parameters have emerged
as the primary design parameters affecting the PHP system dynamics. These include [4]:
a. Internal diameter of the PHP tube,
b. Input heat flux to the device,
c. Volumetric filling ratio of the working fluid,
d. Total number of turns,
e. Device orientation with respect to gravity, and
f. Working fluid thermo-physical properties.
Other conditions which influence the operation are:
a. Use of flow direction control check valves,
b. Tube cross sectional shape,
c. Tube material and fluid combination, and
d. Rigidity of the tube material, etc.
Apart from these variables, the performance is also strongly linked with the flow patterns existing inside the
device (which in turn depends on the complex combination of other design parameters). Various flow patterns
other than capillary slug flow, e.g. bubbly flow, developing or semi-annular flow and fully developed annular
flow (in case of CLPHPs) have also been reported which have a significant effect on the thermal performance of
the device.
1.
Tube Diameter
The internal tube diameter is one of the parameters which essentially define a PHP. The physical
behavior adheres to the „pulsating‟ mode only under a certain range of diameters. The critical Bond number (or
Eötvös) criterion gives the tentative design rule for the diameter. The theoretical maximum inner diameter of
capillary tube can be calculated as)
If D < Dcri, surface tension forces dominate and stable liquid plugs are formed. However, if D > Dcri, the
surface tension is reduced and the working fluid will stratify by gravity and oscillations will cease. The OHP
may operate as an interconnected array of two-phase thermosyphons.
www.ijesi.org
19 | Page
3. Thermal Performance Of Closed Loop…
2.
Applied Heat Flux.
The applied heat flux affects the following
1.1 Internal bubble dynamics, sizes and agglomeration/breaking patterns,
1.2 Level of perturbations and flow instabilities, and
1.3 Flow pattern transition from capillary slug flow to semi-annular and annular.
PHPs are inherently suitable for high heat flux operation. Since the input heat provides the pumping
power, below a certain level, no oscillations commence. In case of CLPHPs, a Unidirectional circulating flow
has been observed at high heat fluxes. In addition, the flow also gets transformed from oscillating slug flow to
annular flow. Once a flow direction is established, alternating tubes sections become hot and cold (hot fluid
flows from evaporator in one tube and cold fluid from the condenser flows in the adjacent tube). Further
increase of heat flux will lead to some dry out mechanism(s) induced by thermo-hydrodynamic limitations.
These have not been clearly identified and studied so far.
3.
Working Fluids
A First consideration in the selection of a suitable working fluid is the operating vapor temperature
range. Within the approximate temperature band, (50 to 150 o C) several possible working fluids may exist. A
variety of characteristics must be examined in order to determine the most acceptable of these fluids for the
application considered. The prime requirement are: compatibility with heat pipe material, thermal stability,
wettability, reasonable vapor pressure, high latent heat and thermal conductivity, low liquid and vapor
viscosities, and acceptable freezing point.For most commercial electronics cooling applications, the
thermodynamic attributes of water makes it better than any other fluids for the pulsating heat pipes. Its high
latent heat spreads more heat with less fluid flow. This result in low pressure drops and high power throughout.
Its high thermal conductivity minimizes the temperature difference associated with conduction through the two
phase flow in the PHP. Water is also a safe substance.Although water high surface tension allows a it to
generate a large capillary force and allow the heat pipe to operate in any orientation. It may have adverse effect
on the operation of PHP in other words, the high surface tension may cause additional frictional and hinder the
two phase flow oscillation in the PHP. Methanol with lower surface tension (about 1/3rd of water) is a good
substitute particularly if the heat pipe is used for sub 0C application [5].
4.
Total Number Of Turns
The number of turns increases the level of perturbations inside the device. If the number of turns is less
than a critical value, then there is a possibility of a stop-over phenomenon to occur. In such a condition, all the
evaporator U-sections has a vapor bubble and the rest of the PHP has liquid. This condition essentially leads to a
dry out and small perturbations cannot amplify to make the system operate self-sustained.
IV. DESIRABLE PROPERTIES OF WORKING FLUID
The experience gained so far by earlier studies suggests that the working fluid employed for pulsating
heat pipes should have the following properties:
· High value of (dP/dT)sat: ensuring that a small change in evaporator temperature generates a large change
in corresponding Psat inside the generated bubble which aids in the bubble pumping action of the device.
The same is true in reverse manner in the condenser
.
Low dynamic viscosity: This generates lower shear stress.
· Low latent heat: should be desirable, aiding quick bubble generation and collapse, given the fact that
sensible heat is the predominant heat transfer mode.
· High specific heat: is desirable complimenting the low latent heat requirement; although there are no specific
studies which explicitly suggest the effect of specific heat of the liquid on the thermal performance. It is to
be noted that if a flow regime change from slug to annular takes place, the respective roles of latent and
sensible heat transport mechanism may considerably change, as explained earlier. This aspect requires
further investigation.
· Low surface tension: This, in conjunction with dynamic contact angle hysteresis may create additional
pressure drop.
The above noted property trends are based on the available knowledge so far and are subject to change as
more studies reveal the thermo-mechanical physics. In addition, quite often instead of individual thermo
physical properties, groups of properties affect complex real systems like PHPs result in low pressure drops
and high power throughout. Its high thermal conductivity minimizes the temperature difference associated
with conduction through the two phase flow in the PHP. Water is also a safe substance.
Although water high surface tension allows a it to generate a large capillary force and allow the heat pipe
to operate in any orientation. It may have adverse effect on the operation of PHP in other words, t
he
high surface tension may cause additional frictional and hinder the two phase flow oscillation in the PHP.
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4. Thermal Performance Of Closed Loop…
Methanol with lower surface tension (about 1/3rd of water) is a good substitute particularly if the heat pipe is
used for sub 0C application [5].
V. EFFECT OF WORKING FLUIDS
Kaya and Ku [7] have compared the LHP performance by using three different working fluids:
ammonia, water and acetone. The model results are shown in Figure 2. It can be seen that the PHP operating
limits are different for each working fluid. The water and acetone PHPs are limited by the absolute vapour
pressure at low power levels: the absolute vapour pressure represents the maximum pressure that is available to
overcome the total system pressure drops, even when the theoretical capillary pressure head is higher than the
total pressure drops. A low pressure corresponding to a fluid temperature near the freezing point severely limits
the PHP operation. While ammonia exhibits many desirable heat transfer characteristics, its freezing point is too
high to prevent freezing in the condenser line during a safe mode on a satellite platform.
Fig. 2. Effect of the working fluid on the LHP operating temperature (Kaya and Ku [7]).
S.Khandekar et.al. [8] [2002] were conducted Experiments on a PHP made of copper capillary tube
of 2-mm inner diameter. Three different working fluids viz. water, ethanol and R-123 were employed. The PHP
was tested in vertical (bottom heat mode) and horizontal orientation. The results strongly demonstrate the effect
of input heat flux and volumetric filling ratio of the working fluid on the thermal performance of the
device.Wide range of experimental studies of pulsating heat pipes is thereby providing vital information on the
parameter dependency of their thermal performance by P.Charoensawan et.al. [9] [2003]. The influence
characterization has been done for the variation of internal diameter, number of turns, working fluid and
inclination angle of the device. CLPHPs are made of copper tubes of internal diameters 2.0 and 1.0 mm, heated
by constant temperature water bath and cooled by constant temperature water–ethylene glycol mixture. The
number of turns in the evaporator is varied from 5 to 23. The working fluids employed are water, ethanol and R123. The results indicate water filled devices showed higher performance as compared to R-123 and ethanol in
vertical orientation for the 2.0 mm devices. In contrast R-123 and ethanol showed comparable performance in
case of1.0 mm devices with water showing very poor results. This is seen in Fig.5
Fig. 5. Effect of working fluid on the thermal performance [9].
P. Meena et.al. [10] [2009]. A set of CLOHP/CV was made of copper tubes in combination of
following dimension: 1.77 mm inside diameter: 10 turn: 5, 10 and 15 cm equal lengths for evaporator, adiabatic
and condenser sections. The working fluid was filled in the tube at the filling ratio of 50%. The evaporator
section was given heat by heater while the condenser section was cooled by volume water in a cold bath. The
results obtained, as follows. When working fluids change from R123 to Ethanol and water the critical heat flux
decreased.
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5. Thermal Performance Of Closed Loop…
VII. UNSOLVED ISSUES RELATED TO WORKING FLUIDS
1.
2.
At different situations, different pure working fluids have their advantages. But till now, mixtures used as
working fluids in PHP have not been thoroughly investigated. The non-azeotropic mixtures, which have the
characteristics of phase transition with temperature floating, can make heat source and working fluids
match well in temperature [11].
The optimum quantity of working fluid needed depends on various parameters and is still an area of
research [9].
VIII. CONCLUSION
PHPs are highly attractive heat transfer elements, which due to their simple design, cost effectiveness
and excellent thermal performance may find wide applications. Since their invention in the early nineties, so far
they have found market niches in electronics equipment cooling. The work compiled here significantly increases
the understanding of the phenomena and effect of working fluids that govern the thermal performance of
pulsating heat pipes. Many unsolved issues related to working fluids still exist, but continued exploration should
be able to overcome these challenges.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
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parametric experimental investigations”. Applied Thermal Engineering, Vol. 23, pp. 2009–2020.
Groll, M., and Khandekar, S., Pulsating Heat Pipes: Progress and
Prospects, Proc. International Conference on Energy and the
Environment, Shanghai, China, 2003, vol. 1, pp. 723–730.
P. Charoensawan, S. Rittidech (2004) “Closed And Open Looped Pulsating Heat Pipes”. 13th international heat pipe conference,
shanghai, china.
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society conference on thermal phenomenon 2004.
Stéphane Launay, Valérie Sartre, Jocelyn Bonjour (2007): “Parametric analysis of loop heat pipe operation: a literature review”
International Journal of Thermal Sciences 46 (2007) 621–636
T. Kaya, J. Ku, A parametric study of performance characteristics of loop heat pipes, in: International Conference On
Environmental Systems, Denver, July 1999 (SAE paper 1999-01-2006), 7 pp.
S. Khandekar, Nicolas Dollinger, and Manfred Groll “Understanding operational regimes of closed loop pulsating heat pipes: an
experimental study”. Applied Thermal Engineering 23 (2003) 707–719.
P. Charoensawan, S. Khandekar, Manfred Groll, and Pradit Terdtoon “Closed loop pulsating heat pipes Part A: parametric
experimental investigations”. Applied Thermal Engineering 23 (2003) 2009–2020.
P. Meena, S. Rittidech and P. Tammasaeng “Effect of Evaporator Section Lengths and Working Fluids on Operational Limit of
Closed Loop Oscillating Heat Pipes with Check Valves (CLOHP/CV)” American Journal of Applied Sciences 6 (1): 133-136, 2009.
S. Khandekar and M. Groll “Pulsating Heat Pipes: Attractive Entrants in the Family of Closed Passive Two-Phase System”. Journal
of Energy, Heat And Mass Transfer, Vol. 26, pp.99-115, march-december2004.
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