The Experts below are selected from a list of 55461 Experts worldwide ranked by ideXlab platform
Dimos Poulikakos - One of the best experts on this subject based on the ideXlab platform.
-
a novel method of energy efficient hotspot targeted embedded Liquid Cooling for electronics an experimental study
International Journal of Heat and Mass Transfer, 2015Co-Authors: Chander Shekhar Sharma, B. Michel, Manish K Tiwari, Thomas Brunschwiler, Gerd Schlottig, Dimos PoulikakosAbstract:Abstract The shift to multicore microprocessor architecture is likely to result in higher coolant flow requirements and thus exacerbate the problem of increasing data center energy consumption, also with respect to hotspot elimination. We present and experimentally prove a novel concept, for embedded, hotspot-targeted and energy efficient Cooling of heterogeneous chip power landscapes. The rationally distributed, embedded microstructures presented here are able to adapt the heat transfer capability to a steady but non-uniform chip power map by passively throttling the flow in low heat flux areas. For the industrially acceptable limit on pressure drop of approximately 0.4 bar, the hotspot-targeted embedded Liquid Cooling (HT-ELC) designs are evaluated against a conservatively chosen conventional embedded Liquid Cooling (C-ELC) design and existing heat sinks in the literature. For an average steady-state heat flux of 150 W/cm 2 in core areas (hotspots) and 20 W/cm 2 over the remaining chip area (background), the chip temperature variation is reduced from 10 °C under the conventional Cooling to 4 °C under the current hotspot targeted heat sink – a reduction of 57%. For heat fluxes of 300 and 24 W/cm 2 , the temperature variation is reduced by 30%. We show that the HT-ELC designs consume less than 0.3% of total chip power as pumping power to achieve this thermal performance, which the C-ELC design cannot match under all feasible levels of pumping power. Moreover, the HT-ELC designs achieve at least 70% improvement over the existing hotspot targeted heat sinks in terms of normalized chip temperature non-uniformity, without the need for any additional system level complexity, reducing reliability risks.
-
energy efficient hotspot targeted embedded Liquid Cooling of electronics
Applied Energy, 2015Co-Authors: Chander Shekhar Sharma, B. Michel, Manish K Tiwari, Severin Zimmermann, Thomas Brunschwiler, Gerd Schlottig, Dimos PoulikakosAbstract:Large data centers today already account for nearly 1.31% of total electricity consumption with Cooling responsible for roughly 33% of that energy consumption. This energy intensive Cooling problem is exacerbated by the presence of hotspots in multicore microprocessors due to excess coolant flow requirement for thermal management. Here we present a novel Liquid-Cooling concept, for targeted, energy efficient Cooling of hotspots through passively optimized microchannel structures etched into the backside of a chip (embedded Liquid Cooling or ELC architecture). We adopt an experimentally validated and computationally efficient modeling approach to predict the performance of our hotspot-targeted ELC design. The design is optimized for exemplar non-uniform chip power maps using Response Surface Methodology (RSM). For industrially acceptable limits of approximately 0.4 bar (40 kPa) on pressure drop and one percent of total chip power on pumping power, the optimized designs are computationally evaluated against a base, standard ELC design with uniform channel widths and uniform flow distribution. For an average steady-state heat flux of 150 W/cm 2
Xiaoming Fang - One of the best experts on this subject based on the ideXlab platform.
-
delayed Liquid Cooling strategy with phase change material to achieve high temperature uniformity of li ion battery under high rate discharge
Journal of Power Sources, 2020Co-Authors: Jiahao Cao, Ziye Ling, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract This work aims at achieving high temperature uniformity of large battery modules during high C-rate discharge with a low flowrate fluid. A new scheme of delayed Liquid Cooling combing phase change material (PCM) and Liquid Cooling is proposed for a Li-ion battery pack with 40 cylindrical cells. A heatsink is designed and optimized with a numerical model, then a real Cooling plate is manufactured and its performance is verified with experiment. The results show the low Cooling temperature of Liquid could increase the temperature difference of the battery pack and reduce the discharge capacity. Therefore, a high inlet water temperature should be the priority if the battery temperature is within the limit. Compared with traditionally continued Cooling, delayed Cooling system shows better performance especially under high discharge current up to 4C with a Cooling flowrate of 40 L/h. Delayed Cooling significantly reduces the temperature difference between batteries and within a battery. Furthermore, this new Cooling mode shortens the period of Liquid Cooling thereby saving the power consumption of the system. This hybrid Cooling system can be useful in the design of battery thermal management for the battery used under high-rate discharge during climbing hills or other high-power cases.
-
Liquid Cooling with phase change materials for cylindrical li ion batteries an experimental and numerical study
Energy, 2020Co-Authors: Jiahao Cao, Ziye Ling, Xiaoming Fang, Mingyun Luo, Zhengguo ZhangAbstract:Abstract In this study, we design a hybrid thermal management system that combines Liquid Cooling and phase change materials (PCMs) for a battery pack of 20 Li-ion cylindrical cells. This system integrates a cold plate through which water flows into a PCM matrix composed of expanded graphite/RT44HC composites. The study aims at exploring factors that influence the temperature rise and the temperature uniformity of batteries. Experiments have been conducted to study the effect of water inlet temperature and flowrate, as well as the PCM content in a battery. The results show that the best control strategy would be to limit the water temperature less than 40 °C and as close to the ambient temperature. The high water flowrate reduces Tmax and ΔTplanar slightly but can significantly increase ΔTaxial and power consumption; therefore, a low flowrate is preferred. Composite PCMs with a high mass fraction of RT44HC perform better, especially under high discharge current up to 2.9C. A numerical model has also been proposed for the hybrid thermal management system to visualise temperature distribution and heat transfer routines and for system optimisation.
-
Experimental and simulative investigations on a phase change material nano-emulsion-based Liquid Cooling thermal management system for a lithium-ion battery pack
Energy, 2020Co-Authors: Fangxian Wang, Ziye Ling, Zhengguo Zhang, Jiahao Cao, Xiaoming FangAbstract:Abstract Thermal management systems (TMSs) are indispensable for practical applications of lithium-ion battery packs. In this study, phase change material (PCM) nano-emulsions with enhanced energy storage capacity, excellent dispersion stability, low viscosity and good thermal reliability were employed as coolants for high-performance Liquid Cooling thermal management systems (LCTMSs) for the first time. The maximum temperature (Tmax) and maximum temperature difference ( Δ Tmax) in a 5S4P battery pack were measured to evaluate the thermal management performance of these coolants. When a 10 wt% OP28E nano-emulsion was used at a flow rate of 200 mL min−1, Tmax and Δ Tmax were 1.1 °C and 0.8 °C, respectively, lower than those based on water, at a discharge rate of 2C. The increase in OP28E mass fraction of the nano-emulsion led to a gradual decrease in Tmax and Δ Tmax at identical discharge rates. Simulation studies were also conducted and validated by comparing with the experimental results. It was revealed that, Tmax and Δ Tmax decreased with increasing flow rate of the coolants, and the thermal management performance of the 10 wt% OP28E nano-emulsion was always better than that of water. This work sheds light on improving the performance of LCTMSs by using PCM nano-emulsions.
-
Compact Liquid Cooling strategy with phase change materials for Li-ion batteries optimized using response surface methodology
Applied Energy, 2018Co-Authors: Ziye Ling, Wenbo Zhang, Zhengguo Zhang, Xiaoming FangAbstract:Abstract The hybrid system that integrates active Cooling into phase change materials (PCMs)/expanded graphite (EG) shows great prospects for power battery thermal management. But because of the heavy weight, the system need to be optimized with a balance of the Cooling capacity contributed by the active and passive Cooling. This study develops an optimization method based on the response surface methodology (RSM) and a numerical heat transfer model to minimize the weight and volume of such a battery thermal management system. With the PCM thermo-physical property models incorporated, the method can optimize the PCM composition along with the active Cooling structure – taking the contributions of both the active and passive Cooling into account. We minimize the PCM mass of the system with this method, and analyze the effects of the PCM composition, the battery module layouts and the active Cooling configuration on the thermal management performance. Then we present an optimal design for this hybrid thermal management system, which helps save the PCM mass by up to 94.1% and the volume by up to 55.6%. The thermal management performance of the design is verified with an experiment. The results show the maximum battery temperature in a 20-battery module during the 1.5C discharge is limited to 37.0 °C while the maximum temperature difference is limited to be smaller than 3 °C. Compared with the conventional Liquid Cooling system, the hybrid system is not only highly efficient, but lightweight, with simple structure and flexible to the batteries with arbitrary shapes.
Zhengguo Zhang - One of the best experts on this subject based on the ideXlab platform.
-
delayed Liquid Cooling strategy with phase change material to achieve high temperature uniformity of li ion battery under high rate discharge
Journal of Power Sources, 2020Co-Authors: Jiahao Cao, Ziye Ling, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract This work aims at achieving high temperature uniformity of large battery modules during high C-rate discharge with a low flowrate fluid. A new scheme of delayed Liquid Cooling combing phase change material (PCM) and Liquid Cooling is proposed for a Li-ion battery pack with 40 cylindrical cells. A heatsink is designed and optimized with a numerical model, then a real Cooling plate is manufactured and its performance is verified with experiment. The results show the low Cooling temperature of Liquid could increase the temperature difference of the battery pack and reduce the discharge capacity. Therefore, a high inlet water temperature should be the priority if the battery temperature is within the limit. Compared with traditionally continued Cooling, delayed Cooling system shows better performance especially under high discharge current up to 4C with a Cooling flowrate of 40 L/h. Delayed Cooling significantly reduces the temperature difference between batteries and within a battery. Furthermore, this new Cooling mode shortens the period of Liquid Cooling thereby saving the power consumption of the system. This hybrid Cooling system can be useful in the design of battery thermal management for the battery used under high-rate discharge during climbing hills or other high-power cases.
-
Liquid Cooling with phase change materials for cylindrical li ion batteries an experimental and numerical study
Energy, 2020Co-Authors: Jiahao Cao, Ziye Ling, Xiaoming Fang, Mingyun Luo, Zhengguo ZhangAbstract:Abstract In this study, we design a hybrid thermal management system that combines Liquid Cooling and phase change materials (PCMs) for a battery pack of 20 Li-ion cylindrical cells. This system integrates a cold plate through which water flows into a PCM matrix composed of expanded graphite/RT44HC composites. The study aims at exploring factors that influence the temperature rise and the temperature uniformity of batteries. Experiments have been conducted to study the effect of water inlet temperature and flowrate, as well as the PCM content in a battery. The results show that the best control strategy would be to limit the water temperature less than 40 °C and as close to the ambient temperature. The high water flowrate reduces Tmax and ΔTplanar slightly but can significantly increase ΔTaxial and power consumption; therefore, a low flowrate is preferred. Composite PCMs with a high mass fraction of RT44HC perform better, especially under high discharge current up to 2.9C. A numerical model has also been proposed for the hybrid thermal management system to visualise temperature distribution and heat transfer routines and for system optimisation.
-
Experimental and simulative investigations on a phase change material nano-emulsion-based Liquid Cooling thermal management system for a lithium-ion battery pack
Energy, 2020Co-Authors: Fangxian Wang, Ziye Ling, Zhengguo Zhang, Jiahao Cao, Xiaoming FangAbstract:Abstract Thermal management systems (TMSs) are indispensable for practical applications of lithium-ion battery packs. In this study, phase change material (PCM) nano-emulsions with enhanced energy storage capacity, excellent dispersion stability, low viscosity and good thermal reliability were employed as coolants for high-performance Liquid Cooling thermal management systems (LCTMSs) for the first time. The maximum temperature (Tmax) and maximum temperature difference ( Δ Tmax) in a 5S4P battery pack were measured to evaluate the thermal management performance of these coolants. When a 10 wt% OP28E nano-emulsion was used at a flow rate of 200 mL min−1, Tmax and Δ Tmax were 1.1 °C and 0.8 °C, respectively, lower than those based on water, at a discharge rate of 2C. The increase in OP28E mass fraction of the nano-emulsion led to a gradual decrease in Tmax and Δ Tmax at identical discharge rates. Simulation studies were also conducted and validated by comparing with the experimental results. It was revealed that, Tmax and Δ Tmax decreased with increasing flow rate of the coolants, and the thermal management performance of the 10 wt% OP28E nano-emulsion was always better than that of water. This work sheds light on improving the performance of LCTMSs by using PCM nano-emulsions.
-
Compact Liquid Cooling strategy with phase change materials for Li-ion batteries optimized using response surface methodology
Applied Energy, 2018Co-Authors: Ziye Ling, Wenbo Zhang, Zhengguo Zhang, Xiaoming FangAbstract:Abstract The hybrid system that integrates active Cooling into phase change materials (PCMs)/expanded graphite (EG) shows great prospects for power battery thermal management. But because of the heavy weight, the system need to be optimized with a balance of the Cooling capacity contributed by the active and passive Cooling. This study develops an optimization method based on the response surface methodology (RSM) and a numerical heat transfer model to minimize the weight and volume of such a battery thermal management system. With the PCM thermo-physical property models incorporated, the method can optimize the PCM composition along with the active Cooling structure – taking the contributions of both the active and passive Cooling into account. We minimize the PCM mass of the system with this method, and analyze the effects of the PCM composition, the battery module layouts and the active Cooling configuration on the thermal management performance. Then we present an optimal design for this hybrid thermal management system, which helps save the PCM mass by up to 94.1% and the volume by up to 55.6%. The thermal management performance of the design is verified with an experiment. The results show the maximum battery temperature in a 20-battery module during the 1.5C discharge is limited to 37.0 °C while the maximum temperature difference is limited to be smaller than 3 °C. Compared with the conventional Liquid Cooling system, the hybrid system is not only highly efficient, but lightweight, with simple structure and flexible to the batteries with arbitrary shapes.
Chander Shekhar Sharma - One of the best experts on this subject based on the ideXlab platform.
-
a novel method of energy efficient hotspot targeted embedded Liquid Cooling for electronics an experimental study
International Journal of Heat and Mass Transfer, 2015Co-Authors: Chander Shekhar Sharma, B. Michel, Manish K Tiwari, Thomas Brunschwiler, Gerd Schlottig, Dimos PoulikakosAbstract:Abstract The shift to multicore microprocessor architecture is likely to result in higher coolant flow requirements and thus exacerbate the problem of increasing data center energy consumption, also with respect to hotspot elimination. We present and experimentally prove a novel concept, for embedded, hotspot-targeted and energy efficient Cooling of heterogeneous chip power landscapes. The rationally distributed, embedded microstructures presented here are able to adapt the heat transfer capability to a steady but non-uniform chip power map by passively throttling the flow in low heat flux areas. For the industrially acceptable limit on pressure drop of approximately 0.4 bar, the hotspot-targeted embedded Liquid Cooling (HT-ELC) designs are evaluated against a conservatively chosen conventional embedded Liquid Cooling (C-ELC) design and existing heat sinks in the literature. For an average steady-state heat flux of 150 W/cm 2 in core areas (hotspots) and 20 W/cm 2 over the remaining chip area (background), the chip temperature variation is reduced from 10 °C under the conventional Cooling to 4 °C under the current hotspot targeted heat sink – a reduction of 57%. For heat fluxes of 300 and 24 W/cm 2 , the temperature variation is reduced by 30%. We show that the HT-ELC designs consume less than 0.3% of total chip power as pumping power to achieve this thermal performance, which the C-ELC design cannot match under all feasible levels of pumping power. Moreover, the HT-ELC designs achieve at least 70% improvement over the existing hotspot targeted heat sinks in terms of normalized chip temperature non-uniformity, without the need for any additional system level complexity, reducing reliability risks.
-
energy efficient hotspot targeted embedded Liquid Cooling of electronics
Applied Energy, 2015Co-Authors: Chander Shekhar Sharma, B. Michel, Manish K Tiwari, Severin Zimmermann, Thomas Brunschwiler, Gerd Schlottig, Dimos PoulikakosAbstract:Large data centers today already account for nearly 1.31% of total electricity consumption with Cooling responsible for roughly 33% of that energy consumption. This energy intensive Cooling problem is exacerbated by the presence of hotspots in multicore microprocessors due to excess coolant flow requirement for thermal management. Here we present a novel Liquid-Cooling concept, for targeted, energy efficient Cooling of hotspots through passively optimized microchannel structures etched into the backside of a chip (embedded Liquid Cooling or ELC architecture). We adopt an experimentally validated and computationally efficient modeling approach to predict the performance of our hotspot-targeted ELC design. The design is optimized for exemplar non-uniform chip power maps using Response Surface Methodology (RSM). For industrially acceptable limits of approximately 0.4 bar (40 kPa) on pressure drop and one percent of total chip power on pumping power, the optimized designs are computationally evaluated against a base, standard ELC design with uniform channel widths and uniform flow distribution. For an average steady-state heat flux of 150 W/cm 2
Ziye Ling - One of the best experts on this subject based on the ideXlab platform.
-
delayed Liquid Cooling strategy with phase change material to achieve high temperature uniformity of li ion battery under high rate discharge
Journal of Power Sources, 2020Co-Authors: Jiahao Cao, Ziye Ling, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract This work aims at achieving high temperature uniformity of large battery modules during high C-rate discharge with a low flowrate fluid. A new scheme of delayed Liquid Cooling combing phase change material (PCM) and Liquid Cooling is proposed for a Li-ion battery pack with 40 cylindrical cells. A heatsink is designed and optimized with a numerical model, then a real Cooling plate is manufactured and its performance is verified with experiment. The results show the low Cooling temperature of Liquid could increase the temperature difference of the battery pack and reduce the discharge capacity. Therefore, a high inlet water temperature should be the priority if the battery temperature is within the limit. Compared with traditionally continued Cooling, delayed Cooling system shows better performance especially under high discharge current up to 4C with a Cooling flowrate of 40 L/h. Delayed Cooling significantly reduces the temperature difference between batteries and within a battery. Furthermore, this new Cooling mode shortens the period of Liquid Cooling thereby saving the power consumption of the system. This hybrid Cooling system can be useful in the design of battery thermal management for the battery used under high-rate discharge during climbing hills or other high-power cases.
-
Liquid Cooling with phase change materials for cylindrical li ion batteries an experimental and numerical study
Energy, 2020Co-Authors: Jiahao Cao, Ziye Ling, Xiaoming Fang, Mingyun Luo, Zhengguo ZhangAbstract:Abstract In this study, we design a hybrid thermal management system that combines Liquid Cooling and phase change materials (PCMs) for a battery pack of 20 Li-ion cylindrical cells. This system integrates a cold plate through which water flows into a PCM matrix composed of expanded graphite/RT44HC composites. The study aims at exploring factors that influence the temperature rise and the temperature uniformity of batteries. Experiments have been conducted to study the effect of water inlet temperature and flowrate, as well as the PCM content in a battery. The results show that the best control strategy would be to limit the water temperature less than 40 °C and as close to the ambient temperature. The high water flowrate reduces Tmax and ΔTplanar slightly but can significantly increase ΔTaxial and power consumption; therefore, a low flowrate is preferred. Composite PCMs with a high mass fraction of RT44HC perform better, especially under high discharge current up to 2.9C. A numerical model has also been proposed for the hybrid thermal management system to visualise temperature distribution and heat transfer routines and for system optimisation.
-
Experimental and simulative investigations on a phase change material nano-emulsion-based Liquid Cooling thermal management system for a lithium-ion battery pack
Energy, 2020Co-Authors: Fangxian Wang, Ziye Ling, Zhengguo Zhang, Jiahao Cao, Xiaoming FangAbstract:Abstract Thermal management systems (TMSs) are indispensable for practical applications of lithium-ion battery packs. In this study, phase change material (PCM) nano-emulsions with enhanced energy storage capacity, excellent dispersion stability, low viscosity and good thermal reliability were employed as coolants for high-performance Liquid Cooling thermal management systems (LCTMSs) for the first time. The maximum temperature (Tmax) and maximum temperature difference ( Δ Tmax) in a 5S4P battery pack were measured to evaluate the thermal management performance of these coolants. When a 10 wt% OP28E nano-emulsion was used at a flow rate of 200 mL min−1, Tmax and Δ Tmax were 1.1 °C and 0.8 °C, respectively, lower than those based on water, at a discharge rate of 2C. The increase in OP28E mass fraction of the nano-emulsion led to a gradual decrease in Tmax and Δ Tmax at identical discharge rates. Simulation studies were also conducted and validated by comparing with the experimental results. It was revealed that, Tmax and Δ Tmax decreased with increasing flow rate of the coolants, and the thermal management performance of the 10 wt% OP28E nano-emulsion was always better than that of water. This work sheds light on improving the performance of LCTMSs by using PCM nano-emulsions.
-
Compact Liquid Cooling strategy with phase change materials for Li-ion batteries optimized using response surface methodology
Applied Energy, 2018Co-Authors: Ziye Ling, Wenbo Zhang, Zhengguo Zhang, Xiaoming FangAbstract:Abstract The hybrid system that integrates active Cooling into phase change materials (PCMs)/expanded graphite (EG) shows great prospects for power battery thermal management. But because of the heavy weight, the system need to be optimized with a balance of the Cooling capacity contributed by the active and passive Cooling. This study develops an optimization method based on the response surface methodology (RSM) and a numerical heat transfer model to minimize the weight and volume of such a battery thermal management system. With the PCM thermo-physical property models incorporated, the method can optimize the PCM composition along with the active Cooling structure – taking the contributions of both the active and passive Cooling into account. We minimize the PCM mass of the system with this method, and analyze the effects of the PCM composition, the battery module layouts and the active Cooling configuration on the thermal management performance. Then we present an optimal design for this hybrid thermal management system, which helps save the PCM mass by up to 94.1% and the volume by up to 55.6%. The thermal management performance of the design is verified with an experiment. The results show the maximum battery temperature in a 20-battery module during the 1.5C discharge is limited to 37.0 °C while the maximum temperature difference is limited to be smaller than 3 °C. Compared with the conventional Liquid Cooling system, the hybrid system is not only highly efficient, but lightweight, with simple structure and flexible to the batteries with arbitrary shapes.