A large amount of heat is generated during the operation of electronic gadgets. Efficient thermal... more A large amount of heat is generated during the operation of electronic gadgets. Efficient thermal management is crucial for their safe operation and reliability. Phase change materials serve the role to maintain almost constant temperature during the phase change process by absorbing the generated heat. Therefore, the present experimental investigation is performed to single out the thermal performance of nickel foam-based heat sink embedded with RT-44HC paraffin as phase change material (PCM). Nickel foam is used for a high heat transfer area with a minimum reduction in the latent heat of a composite PCM. Results revealed that at the end of the charging process, the heat sink base temperature is reduced by 18.6% when a PCM volume fraction of 0.6 was added to the nickel foam. Furthermore, as the PCM fraction increased, the base temperature decreased further. An 11.6% additional decrease in temperature of the PCM was observed for volume fraction increment from 0.6 to 0.8. The effective thermal conductivity of the composite PCM was noticed to be enhanced by six times as that of a pristine PCM. The discharging process of the composite PCM was delayed compared with that of nickel foam without PCM. However, the sink temperature lies within the safe limits for the composite PCM. The latent heat of the composite PCM was diminished by 23% when effective thermal conductivity was enhanced. Thus, a nickel foam-PCM based heat sink is an efficient source to maintain the electronics temperature within the safe limits.
Present experimental investigation focuses on the performance analysis of metallic foam and phase... more Present experimental investigation focuses on the performance analysis of metallic foam and phase change material (PCM)based heat sink at variable heat loads. High porosity (97%) copper and nickel foams are used with PCM (RT-54HC) to enhance the surface area for the heat transfer. Experimental results reveal that metallic foam-based heat sink embedded with PCM can reduce the base temperature of the heat sink efficiently. Copper foam is recognized to be more promising when compared to nickel foam in lowering base temperature for all heat loads (8 W, 16 W and 24 W). It was found that copper foam embedded with 0.8 volume fraction of PCM reduced the base temperature by 26% as compared to that of nickel foam without PCM at 24 W. Furthermore, when the PCM fraction is increased, final temperature of the heat sink gets lessened at the end of charging process while discharging process remains almost intact. So, in this study, copper foam with 0.8 volume fraction is determined to be an optimized configuration.
International Journal of Heat and Mass Transfer, 2020
In this paper, experimental investigations are carried out to study the thermal performance of me... more In this paper, experimental investigations are carried out to study the thermal performance of metallic foams impregnated with phase change material (PCM) based heat sinks for thermal management of electronics. Herein, RT-35HC with melting point 34-36°C is chosen as PCM and copper foam1 (95% porosity), copper foam2 (97% porosity) and Iron-Nickel foam (97% porosity) are used as thermal conductivity enhancer. Various configurations of the heat sink are investigated for 5400 s each for charging and discharging processes under heat flux 0.8-2.4 kW/m 2 for PCM volume fractions 0.0, 0.6, 0.7 and 0.8. Results revealed that copper foam-based heat sink showed 5-6°C less base temperature as compared to that of Iron-Nickel foam. While investigating the effect of foam porosity, copper foam with lower porosity (95%) has shown 11% less base temperature at the end of the charging cycle. It was also noticed that the maximum thermal conductivity enhancement of PCM was found to be 34 times for 95% porosity copper foam with the latent heat reduction of 37%. Copper foam1-PCM composite posed the maximum enhancement in operation time of heat sink 7.9 times more as compared to that of the empty aluminum heat sink. Copper foam-PCM composite with 95% porosity of foam with 0.8 vol fraction of PCM is best recommended configuration for the present experimental study.
The present experimental study is performed to investigate the thermal performances of double pas... more The present experimental study is performed to investigate the thermal performances of double pass solar air heater comprising of phase change materials (PCM) contained in metallic finned tubes to have increased energy storage and heat transfer rate. Experimental results were also helpful in the evaluation of the charging and the discharging characteristics of the PCMs. The air heater is studied for three different configurations. In the first configuration, is no PCM used. In the second configuration, RT44HC having higher melting point filled in semi-circular finned tubes (SFT) on the upper pass of double pass solar air heater (DPSAH) as a thermal storage medium (TSM) is used. While the third configuration is a combination of the second configuration and RT18HC having lower melting point, filled in circular finned tubes (FT) as TSM placed in the lower pass to enhance the thermal storage capacity of solar air heater (SAH). The heater's thermal performance is evaluated for all configurations separately. It was revealed that the third configuration containing RT44HC and RT18HC in upper and lower passes respectively is the best among others for optimum heater performance.
Phase change material (PCM) is promising media for thermal energy storage owing to its extensive ... more Phase change material (PCM) is promising media for thermal energy storage owing to its extensive value of latent heat (140-970 KJ/Kg). However, thermal conductivity of PCMs is too low which obstructs energy storage and retrieval rate. In recent days, thermally enhanced PCMs are considered promising materials for efficient heat transfer in many applications. This article designates the review on improved thermal properties and heat transfer of PCMs by using porous materials. Enhanced heat transfer of PCMs can be achieved using extended surfaces (triangular, conical, square, and rectangular fins), heat pipes, and addition of highly conductive nanoparticles (e.g. Cu, Al 2 O 3 , Au, SiC, SiO 2 and TiO 2). Major focus of this article is to study the enhanced heat transfer of PCMs through metallic (copper, nickel, and aluminum) and carbon based (carbon, graphite and expanded graphite) porous materials/foams. Effects of porosity and pore density on heat transfer, thermal conductivity, specific heat, latent heat and charging/discharging time are critically reviewed. Porous materials/foams are reported to be efficient for heat transfer/thermal conductivity enhancement by 3-500 times. Furthermore, correlations to find the effective thermal conductivity of PCM/foam are reported. Important applications of PCM/foam reported by different researchers are also discussed in this paper. Finally, conclusions and recommendations are presented to highlight the research gap in this area.
Owing to enormously high surface area and high thermal conductivity, copper foam based heat sinks... more Owing to enormously high surface area and high thermal conductivity, copper foam based heat sinks for electronic cooling are investigated in this paper. Copper foam1 with porosity 0.95 and pore density 15 pores per inch and copper foam2 with 0.97 porosity and pore density 35 pores per inch are used to investigate the performance of heat sinks filled with phase change material (PCM). Various configurations of heat sink with PCM volume fractions 0.0, 0.6, 0.7 and 0.8 are investigated under heat load of 8-24 W to figure out the optimum performance of the heat sink. Experimental results revealed that base temperature of the heat sink is reduced as the volume fraction of PCM is increased. Anyhow, discharging process is not affected significantly. Furthermore, copper foam1 (0.95 porosity) exhibited better heat transfer both in charging and discharging as compared to that of copper foam2 (0.97 porosity). Maximum temperature reduction of 9.81% was found for copper foam1/PCM at 8 W and PCM volume fraction of 0.8 when it is compared with copper foam2/PCM composite. For the same porosity, maximum reduction in base temperature was observed for 0.8 volume fraction of PCM at 16 W heat input. Finally, it is concluded that copper foam1/PCM composite impregnated with 0.8 volume fraction is an optimized configuration of heat sink.
Copper foam (with porosity 97% and pore density 35 pores per inch) based heat sink without phase ... more Copper foam (with porosity 97% and pore density 35 pores per inch) based heat sink without phase change material (PCM) and copper foam/PCM composites heat sinks are investigated to observe the behavior of operational time of heat sinks with respect to specific temperature both for charging and discharging. Paraffin wax, RT-35HC, RT-44HC and RT-54HC are used as PCM. Investigations are performed at heat flux of 0.8-2.4 KW/m 2 with a gap of 0.4 KW/m 2 uniformly distributed. PCM volume fractions of 0.68 and 0.83 are used in composites. Results indicated that at the end of 90 min charging, maximum temperature reduction of 25% is noted for RT-35HC/Copper foam at 0.8 KW/m 2 for PCM volume fraction 0.83. Afterwards, RT-44HC/Copper foam reveals maximum temperature reduction of 24% for 1.6 KW/m 2. RT-35HC/Copper foam is least efficient at 2.4 KW/m 2 which reduces the base temperature only by 5-7%. Maximum enhancement ratio in operation time is noticed as 8 and 7.7 for RT-35HC/Copper foam and RT-44HC/Copper foam respectively at set point temperature (SPT) of 40 °C and 60 °C for respective composites.
A large amount of heat is generated during the operation of electronic gadgets. Efficient thermal... more A large amount of heat is generated during the operation of electronic gadgets. Efficient thermal management is crucial for their safe operation and reliability. Phase change materials serve the role to maintain almost constant temperature during the phase change process by absorbing the generated heat. Therefore, the present experimental investigation is performed to single out the thermal performance of nickel foam-based heat sink embedded with RT-44HC paraffin as phase change material (PCM). Nickel foam is used for a high heat transfer area with a minimum reduction in the latent heat of a composite PCM. Results revealed that at the end of the charging process, the heat sink base temperature is reduced by 18.6% when a PCM volume fraction of 0.6 was added to the nickel foam. Furthermore, as the PCM fraction increased, the base temperature decreased further. An 11.6% additional decrease in temperature of the PCM was observed for volume fraction increment from 0.6 to 0.8. The effective thermal conductivity of the composite PCM was noticed to be enhanced by six times as that of a pristine PCM. The discharging process of the composite PCM was delayed compared with that of nickel foam without PCM. However, the sink temperature lies within the safe limits for the composite PCM. The latent heat of the composite PCM was diminished by 23% when effective thermal conductivity was enhanced. Thus, a nickel foam-PCM based heat sink is an efficient source to maintain the electronics temperature within the safe limits.
Present experimental investigation focuses on the performance analysis of metallic foam and phase... more Present experimental investigation focuses on the performance analysis of metallic foam and phase change material (PCM)based heat sink at variable heat loads. High porosity (97%) copper and nickel foams are used with PCM (RT-54HC) to enhance the surface area for the heat transfer. Experimental results reveal that metallic foam-based heat sink embedded with PCM can reduce the base temperature of the heat sink efficiently. Copper foam is recognized to be more promising when compared to nickel foam in lowering base temperature for all heat loads (8 W, 16 W and 24 W). It was found that copper foam embedded with 0.8 volume fraction of PCM reduced the base temperature by 26% as compared to that of nickel foam without PCM at 24 W. Furthermore, when the PCM fraction is increased, final temperature of the heat sink gets lessened at the end of charging process while discharging process remains almost intact. So, in this study, copper foam with 0.8 volume fraction is determined to be an optimized configuration.
International Journal of Heat and Mass Transfer, 2020
In this paper, experimental investigations are carried out to study the thermal performance of me... more In this paper, experimental investigations are carried out to study the thermal performance of metallic foams impregnated with phase change material (PCM) based heat sinks for thermal management of electronics. Herein, RT-35HC with melting point 34-36°C is chosen as PCM and copper foam1 (95% porosity), copper foam2 (97% porosity) and Iron-Nickel foam (97% porosity) are used as thermal conductivity enhancer. Various configurations of the heat sink are investigated for 5400 s each for charging and discharging processes under heat flux 0.8-2.4 kW/m 2 for PCM volume fractions 0.0, 0.6, 0.7 and 0.8. Results revealed that copper foam-based heat sink showed 5-6°C less base temperature as compared to that of Iron-Nickel foam. While investigating the effect of foam porosity, copper foam with lower porosity (95%) has shown 11% less base temperature at the end of the charging cycle. It was also noticed that the maximum thermal conductivity enhancement of PCM was found to be 34 times for 95% porosity copper foam with the latent heat reduction of 37%. Copper foam1-PCM composite posed the maximum enhancement in operation time of heat sink 7.9 times more as compared to that of the empty aluminum heat sink. Copper foam-PCM composite with 95% porosity of foam with 0.8 vol fraction of PCM is best recommended configuration for the present experimental study.
The present experimental study is performed to investigate the thermal performances of double pas... more The present experimental study is performed to investigate the thermal performances of double pass solar air heater comprising of phase change materials (PCM) contained in metallic finned tubes to have increased energy storage and heat transfer rate. Experimental results were also helpful in the evaluation of the charging and the discharging characteristics of the PCMs. The air heater is studied for three different configurations. In the first configuration, is no PCM used. In the second configuration, RT44HC having higher melting point filled in semi-circular finned tubes (SFT) on the upper pass of double pass solar air heater (DPSAH) as a thermal storage medium (TSM) is used. While the third configuration is a combination of the second configuration and RT18HC having lower melting point, filled in circular finned tubes (FT) as TSM placed in the lower pass to enhance the thermal storage capacity of solar air heater (SAH). The heater's thermal performance is evaluated for all configurations separately. It was revealed that the third configuration containing RT44HC and RT18HC in upper and lower passes respectively is the best among others for optimum heater performance.
Phase change material (PCM) is promising media for thermal energy storage owing to its extensive ... more Phase change material (PCM) is promising media for thermal energy storage owing to its extensive value of latent heat (140-970 KJ/Kg). However, thermal conductivity of PCMs is too low which obstructs energy storage and retrieval rate. In recent days, thermally enhanced PCMs are considered promising materials for efficient heat transfer in many applications. This article designates the review on improved thermal properties and heat transfer of PCMs by using porous materials. Enhanced heat transfer of PCMs can be achieved using extended surfaces (triangular, conical, square, and rectangular fins), heat pipes, and addition of highly conductive nanoparticles (e.g. Cu, Al 2 O 3 , Au, SiC, SiO 2 and TiO 2). Major focus of this article is to study the enhanced heat transfer of PCMs through metallic (copper, nickel, and aluminum) and carbon based (carbon, graphite and expanded graphite) porous materials/foams. Effects of porosity and pore density on heat transfer, thermal conductivity, specific heat, latent heat and charging/discharging time are critically reviewed. Porous materials/foams are reported to be efficient for heat transfer/thermal conductivity enhancement by 3-500 times. Furthermore, correlations to find the effective thermal conductivity of PCM/foam are reported. Important applications of PCM/foam reported by different researchers are also discussed in this paper. Finally, conclusions and recommendations are presented to highlight the research gap in this area.
Owing to enormously high surface area and high thermal conductivity, copper foam based heat sinks... more Owing to enormously high surface area and high thermal conductivity, copper foam based heat sinks for electronic cooling are investigated in this paper. Copper foam1 with porosity 0.95 and pore density 15 pores per inch and copper foam2 with 0.97 porosity and pore density 35 pores per inch are used to investigate the performance of heat sinks filled with phase change material (PCM). Various configurations of heat sink with PCM volume fractions 0.0, 0.6, 0.7 and 0.8 are investigated under heat load of 8-24 W to figure out the optimum performance of the heat sink. Experimental results revealed that base temperature of the heat sink is reduced as the volume fraction of PCM is increased. Anyhow, discharging process is not affected significantly. Furthermore, copper foam1 (0.95 porosity) exhibited better heat transfer both in charging and discharging as compared to that of copper foam2 (0.97 porosity). Maximum temperature reduction of 9.81% was found for copper foam1/PCM at 8 W and PCM volume fraction of 0.8 when it is compared with copper foam2/PCM composite. For the same porosity, maximum reduction in base temperature was observed for 0.8 volume fraction of PCM at 16 W heat input. Finally, it is concluded that copper foam1/PCM composite impregnated with 0.8 volume fraction is an optimized configuration of heat sink.
Copper foam (with porosity 97% and pore density 35 pores per inch) based heat sink without phase ... more Copper foam (with porosity 97% and pore density 35 pores per inch) based heat sink without phase change material (PCM) and copper foam/PCM composites heat sinks are investigated to observe the behavior of operational time of heat sinks with respect to specific temperature both for charging and discharging. Paraffin wax, RT-35HC, RT-44HC and RT-54HC are used as PCM. Investigations are performed at heat flux of 0.8-2.4 KW/m 2 with a gap of 0.4 KW/m 2 uniformly distributed. PCM volume fractions of 0.68 and 0.83 are used in composites. Results indicated that at the end of 90 min charging, maximum temperature reduction of 25% is noted for RT-35HC/Copper foam at 0.8 KW/m 2 for PCM volume fraction 0.83. Afterwards, RT-44HC/Copper foam reveals maximum temperature reduction of 24% for 1.6 KW/m 2. RT-35HC/Copper foam is least efficient at 2.4 KW/m 2 which reduces the base temperature only by 5-7%. Maximum enhancement ratio in operation time is noticed as 8 and 7.7 for RT-35HC/Copper foam and RT-44HC/Copper foam respectively at set point temperature (SPT) of 40 °C and 60 °C for respective composites.
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