Liquid Cooling System Research Articles

Heat Transfer Performance of Copper Foam-Based Vapor Chamber Composite Liquid Cooling System Under Double-Sided Heating

Heat Transfer Performance of Copper Foam-Based Vapor Chamber Composite Liquid Cooling System Under Double-Sided Heating

Lithium Battery Thermal Management Based on Lightweight Stepped-Channel Liquid Cooling

Abstract This study proposes a stepped-channel liquid-cooled battery thermal management system based on lightweight. The impact of channel width, cell-to-cell lateral spacing, contact height, and contact angle on the effectiveness of the thermal control system (TCS) is investigated using numerical simulation. The weight sensitivity factor is adopted to evaluate the effect of TCS weight (mTCS) on the maximum temperature (Tmax) of battery pack. Results suggest that the channel width plays the most critical role, followed by cell-to-cell lateral spacing and contact angle, while the contact height has minimal influence. Four parameters that affect the thermal balance performance of battery pack, including the number of channels, and baffles, baffle angle, and coolant inlet velocity, are presented using orthogonal experiment. Results indicate that the number of channels and baffle angle have a significant influence on the thermal balance of battery pack, while thermal performance is largely insensitive to coolant inlet velocity and the number of baffles. Based on the analysis stated in this work, an improved design of the TCS is presented that reduces weight by 54.08% while increasing Tmax only by 2.52 K.

Comparison of the Peltier Effect Cooled Liquid Cooling System Developed for Computers Operating in Harsh Environment Conditions with the Fan Cooling System

Günümüzde kullanım alanları artan bilgisayar sistemleri çeşitli sorunları da beraberinde getirmiştir. Yüksek işlem gücü elde etmek için işlemcilerin elektronik bileşenleri daha sıkı yapılar haline getirilmektedir. Bu durumda ısının uzaklaştırılması önemli bir sorundur. Yarıiletken malzemelerin sıcaklıklarının artması daha yüksek güç tüketimlerine ve kararlı yapılarının bozulmasına sebep olmaktadır. Bilgisayar işlemcilerinin soğutulması amacıyla geliştirilen fanlı soğutma sistemleri bilgisayarın bulunduğu ortamın toz ve sıcaklık gibi çevresel şartlarından etkilenmektedir. Klimalı soğutma sistemlerinin çevreye zararlı gazlar yayması bilgisayar soğutma sistemlerinin geliştirilmesinde araştırmacıları yeni yöntemlere yönlendirmiştir. Bu çalışmada; peltier etki ile soğutulan sıvı soğutma sisteminin, fanlı soğutma sistemine göre 2511 MHz saat hızında %40, 2745 MHz saat hızında %24 oranında soğutma verimliliği sağladığı görülmüştür. Yapılan deneylerde peltier etkisi ile soğutulan sıvı soğutma sisteminin fanlı soğutma sistemine göre %32,85 oranında daha fazla güç tükettiği tespit edilmiştir.

Liquid Cooling Systems for Batteries of Electric Vertical Takeoff and Landing Aircraft

Batteries are the lynchpin of electric vertical takeoff and landing (eVTOL) aircraft, and the high discharge rates pose a critical challenge to the battery thermal management system (BTMS). This work presents a channeled liquid cooling technology-based BTMS for eVTOL aircraft. During the flight, the heat generated from the batteries is partly extracted by circulating liquid coolant within a wavy channel (WC) attached firmly to the battery cells. The heat is then transported into a plate-fin compact heat exchanger (HEX), where all the heat is dissipated into the atmosphere. We report sensitivity analyses of the HEX model to shed light on the impact of the relevant design parameters on the BTMS size, weight, and power. We also examine critical parameters of the coupled WC-HEX BTMS in a one-dimensional off-design analysis. We demonstrate that the liquid cooling system can maintain the battery operating temperature within acceptable levels with a mass of less than 20% of the battery pack mass. Battery degradation using the liquid cooling system is reduced by over three times compared to an air-cooled system for both tilt-wing and lift+cruise eVTOL aircraft.

A Review of Cooling Technologies in Lithium-Ion Power Battery Thermal Management Systems for New Energy Vehicles

The power battery is an important component of new energy vehicles, and thermal safety is the key issue in its development. During charging and discharging, how to enhance the rapid and uniform heat dissipation of power batteries has become a hotspot. This paper briefly introduces the heat generation mechanism and models, and emphatically summarizes the main principle, research focuses, and development trends of cooling technologies in the thermal management of power batteries in new energy vehicles in the past few years. Currently, the commonly used models for battery heat generation are the electrochemical-thermal model and the electrical-thermal model. Scholars have conducted more research based on multidimensional electrochemical-thermal/electrical-thermal models because taking the actual characteristics of the battery into account can provide a more comprehensive and systematic description. Among various cooling technologies, the air-cooling system boasts the most economical manufacturing costs and a compact, reliable structure. The heat transfer coefficient of the liquid-cooling system is very high, while the temperature remains uniform in the PCMs cooling system during the material phase transition process. Against the background of increasing energy density in future batteries, immersion liquid phase change cooling technology has great development prospects, but it needs to overcome limitations such as high cost and heavy weight. Therefore, the current lithium-ion battery thermal management technology that combines multiple cooling systems is the main development direction. Suitable cooling methods can be selected and combined based on the advantages and disadvantages of different cooling technologies to meet the thermal management needs of different users.

Thermal Performance Analysis of Liquid Cooling System in Lithium-ion Battery

Electric vehicles (EV) have been rapidly developing and are becoming increasingly popular due to its zero emission, low operating cost and noise free. However, there are some factors that limit the development of electric vehicles, such as the thermal performance, cost, lifetime and safety of the battery. To address this difficulty integration of liquid cooling system is the promising solution. The battery cooling technologies like air cooling system, liquid cooling system, direct refrigerant cooling system, phase change material (PCM) cooling system are used in e-vehicle. In this research, the main goal is to better understand how to improve the consistent temperature distribution in battery packs. The study provides general strategies to reduce thermal unevenness or achieve almost no differences in temperature within lithium-ion battery modules. These modules are cooled using channelled liquid flow, where a liquid circulates through channels designed for thermal management. To demonstrate the effectiveness of the proposed strategies, the research numerically analyzes two cases: one with multiple short channels and another with orderly magnified contact areas. Two of the methods demonstrate significant improvement in the overall thermal uniformity of the battery pack.(a) Shortening flow paths with multiple serpentine channels, and (b) enhancing contact areas between batteries and serpentine channels along the flow path in the stream wise direction, both show considerable promise in improving pack thermal uniformity.The study investigates the thermal effects of varying liquid flow rates in a computational fluid dynamics model for an 71 18,650 battery pack discharged at 5C. A three-dimensional model is built in ANSYS and the mesh is generated using Fluent Meshing. The maximum temperature differences observed across the battery module during a 5C discharge are 2.2 K for one strategy and 0.7 K for the other. This information highlights the effectiveness of the second strategy in achieving lower temperature variations, indicating better thermal uniformity during the discharge process compared to the first strategy.

A new design of cooling plate for liquid-cooled battery thermal management system with variable heat transfer path

Liquid-cooled battery thermal management system (BTMS) is of great significance to improve the safety and efficiency of electric vehicles. However, the temperature gradient of the coolant along the flow direction has been an obstacle to improve the thermal uniformity of the cell. In this study, a BTMS design based on variable heat transfer path (VHTP) was developed and applied to prismatic cells. Compared with the reference liquid cooling plate, the variable heat transfer path design changes the heat transfer path between the coolant channel and the battery surface by setting a reasonable groove, thereby changing the basic feature that the battery surface temperature rises monotonously along the flow direction. The geometric parameters of the trench are optimized. The results show that grooves with d1 = 0, d2 = 26 mm, d3 = 57 mm, and d4 = 0 are the best VHTP designs to improve thermal uniformity. The optimized VHTP cooling plate reduces the temperature difference across the battery surface by 22.7 % to 25.4 % for different discharge rates and cooling fluid mass flow rates, while slightly improving the maximum temperature on the battery surface, compared to the reference cooling plate.

Numerical Simulation of Immersed Liquid Cooling System for Lithium-Ion Battery Thermal Management System of New Energy Vehicles

Power batteries generate a large amount of heat during the charging and discharging processes, which seriously affects the operation safety and service life. An efficient cooling system is crucial for the batteries. This paper numerically simulated a power battery pack composed of 8 lithium-ion cells immersed in the coolant AmpCool AC-110 to study the effects of different coolants, different discharge rates, different coolant mass flow rates, different inlet temperatures and different inlet and outlet settings on the maximum temperature, the maximum temperature difference, the pressure drop, and the required pump power in the battery pack. Among the five coolants studied, W-E in water-based fluids has the best cooling effect, but because of high electric conductivity, it requires special considerations to avoid electric leakage. Increasing the mass flow rate of the coolant can significantly decrease Tmax and ΔTmax, but when the mass flow rate is already high, the decrease is limited and not obvious. Both Δp and the required pump power increase as the mass flow rate increases, and the required pump power increases faster. The inlet temperature will affect the physical properties of the coolant, and choosing the appropriate inlet temperature can not only decrease ΔTmax, but also decrease Δp and the required pump power in the battery pack. The range of 25~27 °C of the coolant AC-110 inlet temperature is recommended. For different inlet and outlet settings, the two-inlet two-outlet setting used in Case 7 has the best cooling effect, and the results indicate uniform distribution is very important to decrease temperature.

Electric-controlled pressure relief valve for enhanced safety in liquid-cooled lithium-ion battery packs

The liquid-cooled battery energy storage system (LCBESS) has gained significant attention due to its superior thermal management capacity. However, liquid-cooled battery pack (LCBP) usually has a high sealing level above IP65, which can trap flammable and explosive gases from battery thermal runaway and cause explosions. This poses serious safety risks and challenges for LCBESS. In this study, we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure relief valve (PRV) on the LCBP had a delayed response and low-pressure relief efficiency. A realistic 20-foot model of an energy storage cabin was constructed using the Flacs finite element simulation software. Comparative studies were conducted to evaluate the pressure relief efficiency and the influence on neighboring battery packs in case of internal explosions, considering different sizes and installation positions of the PRV. Here, a newly developed electric-controlled PRV integrated with battery fault detection is introduced, capable of starting within 50 ms of the battery safety valve opening. Furthermore, the PRV was integrated with the battery management system and changed the battery charging and discharging strategy after the PRV was opened. Experimental tests confirmed the efficacy of this method in preventing explosions. This paper addresses the safety concerns associated with LCBPs and proposes an effective solution for explosion relief.

Experimental Investigation of Thermal Runaway Propagation in a Lithium-Ion Battery Pack: Effects of State of Charge and Coolant Flow Rate

Lithium-ion batteries (LIBs) are widely used as power sources for electric vehicles due to their various advantages, including high energy density and low self-discharge rate. However, the safety challenges associated with LIB thermal runaway (TR) still need to be addressed. In the present study, the effects of the battery SOC value and coolant flow rate on the TR behavior in a LIB pack are comprehensively investigated. The battery pack consists of 10 18650-type LIBs applied with the serpentine channel liquid-cooling thermal management system (TMS). The TR tests for various SOC values (50%, 75% and 100%) and coolant flow rates (0 L/h, 32 L/h, 64 L/h and 96 L/h) are analyzed. The retarding effect of the TMS on TR propagation is found to be correlated with both the coolant flow rate and the battery SOC value, and a larger coolant flow rate and lower SOC generally result in fewer TR batteries. Furthermore, the TR propagation rate, evaluated by the time interval of TR occurrence between the adjacent batteries, increases with the battery SOC. The battery pack with 100% SOC shows more rapid TR propagation, which can be completed in just a few seconds, in contrast to several minutes for 50% and 75% SOC cases. In addition, the impact of the battery SOC and coolant flow rate on the maximum temperature of the TR battery is also examined, and no determined association is observed between them. However, it is found that the upstream batteries (closer to the external heater) show a slightly higher maximum temperature than the downstream ones, indicating a weak association between the TR battery maximum temperature and the external heating duration or the battery temperature at which the TR starts to take place.

Performance Analysis of the Liquid Cooling System for Lithium-Ion Batteries According to Cooling Plate Parameters

In this study, the effects of battery thermal management (BTM), pumping power, and heat transfer rate were compared and analyzed under different operating conditions and cooling configurations for the liquid cooling plate of a lithium-ion battery. The results elucidated that when the flow rate in the cooling plate increased from 2 to 6 L/min, the average temperature of the battery module decreased from 53.8 to 50.7 °C, but the pumping power increased from 0.036 to 0.808 W. In addition, an increase in the width of the cooling channel and number of channels resulted in a decrease in the average temperature of the battery module and a reduction in the pumping power. The most influential variable for the temperature control of the battery was an increase in the flow rate. In addition, according to the results of the orthogonal analysis, an increase in the number of cooling plate channels resulted in the best cooling performance and reduced pumping power. Based on this, a cooling plate with six channels was applied to both the top and bottom parts, and the top and bottom cooling showed sufficient cooling performance in maintaining the average temperature of the battery module below 45 °C.

Design and performance evaluation of a firefighting protective suit with an incorporated liquid-cooled system

A liquid-cooled garment with active cooling function can make up for deficiency of the human thermoregulatory system and passive thermal insulation of the firefighting protective suit. Fabrics treated at different inlet temperatures and pipeline intervals were applied in multilayered liquid-cooled fabric assemblies (LCFAs). The heat absorbed by the skin and the second-degree burn time were evaluated by the stored energy test under low heat radiation. Results indicated that the thermal protective performance of the LCFAs was significantly improved, with the second-degree burn time increasing more than 50% on average. There was a strong negative correlation between the thermal protective performance and cooling effect under different pipeline intervals, while the negative correlation was weak for different inlet temperatures. The results gained from this study may provide valuable insight for design of the inlet temperature and pipeline interval of a liquid-cooled system in the firefighting protective suit.

Numerical study on thermal performance of cold plates with leaf type channels for lithium-ion batteries

PurposeThe purpose of this study is to design a new type of cold plate to improve the thermal performance of liquid-cooled thermal management system of lithium-ion batteries.Design/methodology/approachA cold plate with leaf type channels is proposed to enhance the cooling performance. Effects of the leaf type channel parameters (i.e. channel angle 20°, 40°, 60°, 80°; coolant mass flow rate 0.25 × 10–3, 0.50 × 10–3, 0.75 × 10–3, 1.00 × 10–3, 1.25 × 10–3 kg·s−1; channel number 1, 3, 5, 7) on the performance are numerically investigated by using a 3D mathematical model.FindingsCompared to the traditional I type channels, the leaf type channels have better cooling performance. It is found that the battery temperature variation and channel pressure drop are decreased with decreasing channel angle and increasing channel number. In addition, the cooling performance can be improved by increasing the coolant mass flow rate.Practical implicationsThis study can provide guidance for the development of novel effective cold plates.Originality/valueThe design of cold plates with leaf type channels can be used in liquid-cooled thermal management system to reduce the battery temperature difference.

Modeling and analysis of liquid-cooling thermal management of an in-house developed 100 kW/500 kWh energy storage container consisting of lithium-ion batteries retired from electric vehicles

As electric vehicles (EVs) are gradually becoming the mainstream in the transportation sector, the number of lithium-ion batteries (LIBs) retired from EVs grows continuously. Repurposing retired EV LIBs into energy storage systems (ESS) for electricity grid is an effective way to utilize them. However, the potential safety hazard of retired EV LIBs in echelon utilization poses to become a major concern nowadays. In this work is considered an in-house developed 100 kW/500 kWh ESS containing different types of retired EV LIBs. A self-developed thermal safety management system (TSMS), which can evaluate the cooling demand and safety state of batteries in real-time, is equipped with the energy storage container; a liquid-cooling battery thermal management system (BTMS) is utilized for the thermal management of the batteries. To study the performance of the BTMS, the temperature variation and temperature difference of the LIBs in the process of charging and discharging are experimentally and numerically analyzed. With a self-developed full-scale thermal-fluidic model, the temperature and temperature inconsistency of the 100 kW/500 kWh ESS under different coolant flow rates and different ambient temperatures are simulated. The experimental results corroborate the effectiveness of the liquid cooling BTMS; the maximum temperature rise of the batteries during the discharging and charging processes is less than 3 °C and 5 °C, respectively, and the maximum temperature difference between the batteries is always less than 2 °C. The simulation results show that the liquid cooling system can significantly reduce the peak temperature and temperature inconsistency in the ESS; the ambient temperature and coolant flow rate of the liquid cooling system are found to have important influence on the ESS thermal behavior. The developed ESS prototype and the full-scale thermal-fluidic model are combined to construct a research platform for future thermal safety study on the echelon utilization of retired EV LIBs.

Experimental study on top liquid-cooling thermal management system based on Z-shaped micro heat pipe array

The traditional bottom liquid-cooling thermal management system (TMS) has poor cooling performance and is prone to causing significant temperature difference in the lithium-ion battery (LIB) module. In order to solve the above problems, this study takes the Z-shaped micro heat pipe array (MHPA) as the core heat transfer element and establishes a top liquid-cooling (TLC) TMS based on Z-shaped MHPA. The thermal management performance of the TLC TMS based on Z-shaped MHPA is analyzed by comparing it with the traditional bottom liquid-cooling TMS. Results show that under the conditions of 40 °C ambient temperature and 25 °C cold water inlet temperature, the bottom liquid-cooling TMS can no longer meet the thermal management requirements of the module at a 2C charge–discharge rate. In comparison, the TLC TMS based on Z-shaped MHPA can ensure the module's maximum temperature below 55 °C, and the battery and module level's temperature difference can be controlled below 4 °C under 3C charge–discharge rate. The TLC TMS based on Z-shaped MHPA can not only effectively delay the battery's temperature rise under high charge–discharge rate, but also significantly reduce the temperature difference; its thermal management performance is significantly better than the bottom liquid-cooling TMS.

Optimization of the Effect of Distance Between Fins (DBF) on Average Heatsink Temperature (AHT) in Liquid Cooling Systems of Computers by Finite Volume Analysis

Teknolojinin ilerlemesiyle birlikte hemen her alanda kullanılan bilgisayarların yüksek performansta uzun süre çalışması oldukça önem arz etmektedir. Bilgisayar sistemlerinde performansı en çok etkileyen birimlerden biri olan merkezi işlem biriminin çalışma sıcaklığı performansına doğrudan etki etmektedir. Artan soğutma ihtiyaçlarına geleneksel hava soğutma sistemlerinin cevap verememesinden dolayı sıvı soğutma tabanlı sistemler endüstride yaygınlaşmaktadır. Gelişen simülasyon yazılımları, tasarlanan ürünün prototipini üretmeden sanal ortamda testlerini zamandan ve prototip maliyetlerinden tasarruf ederek gerçekleştirme olanağı sunmaktadır. Bu çalışma kapsamında merkezi işlem birimlerinin soğutulması için kullanılan sıvı soğutma sistemlerinin bir bileşeni olan mikrofinin sanal ortamda hesaplamalı akışkanlar dinamiği (HAD) yöntemi kullanılarak akış simülasyonları gerçekleştirilmiştir. Bu simülasyonlar gerçekleştirilirken mikrofinin ısıtma performansını doğrudan etkileyen finler arası mesafe (FAM: 0.1, 0.2, 0.3 mm) parametresi referans alınmıştır. Gerçekleştirilen sonlu hacimler analizi sonucunda ortalama mikrofin sıcaklığı (OMS) incelenmiştir. Akış simülasyonları sonucunda FAM’ın artmasıyla birlikte OMS’nin de arttığı gözlemlenmiştir.

Bionic liquid cooling plate thermal management system based on flow resistance-thermal resistance model

Since the computational fluid dynamics (CFD) method is cumbersome and computationally intensive in optimizing the battery thermal management system (BTMS), a comprehensive computational method of total thermal resistance and pressure loss of liquid-cooled battery thermal management system with coupled flow resistance model (FRM) and thermal resistance model (TRM) was proposed, so that the total thermal resistance (TTR) and pressure drop (ΔP) of liquid-cooled battery thermal management system under various operating conditions can be calculated concisely and quickly, and then the optimization of the structural parameters of liquid-cooled plates can be achieved quickly. First, the reliability of the CFD simulation was verified by liquid-cooled plate (LCP) experiments, and the reliability of the flow resistance-thermal resistance model was further verified by CFD simulation results. Then, the sensitivity of different mass flow rate and liquid cooling channel structure parameters were analyzed. The results showed that the thermal performance and system energy consumption of the cold plate were mainly influenced by the coolant mass flow rate (m) and the channel structure factors such as the bifurcation channel angle (α), channel width (b), channel height (h), and distance between bifurcation channels (d1, d4) of the cold plate. Finally, the Neighborhood Cultivation Genetic Algorithm (NCGA) was used to optimize the total thermal resistance (TTR) and pressure drop (ΔP) of the liquid-cooled plate with the above six parameters as design variables and the total thermal resistance (TTR) and pressure drop (ΔP) as objective functions. Compared to the model before optimization, the total thermal resistance (TTR) and pressure drop (ΔP) of the optimized cold plate were reduced by 0.2409 K/W and 8.7371 Pa, respectively.

Experimental investigation of a data-centre cooling system using a new single-phase immersion/liquid technique

This paper presents an experimental investigation conducted on a new single-phase immersion/liquid-cooling technique developed at the OVHcloud laboratory, combining a direct-to-chip water-cooling system with passive single-immersion cooling technology. The experimental setup tested the impact of three dielectric fluids (S5X, SmartCoolant and ThermaSafe R), the effect of the water circuit configuration, and the server power/profile. Results suggest that the system cooling demand depends on the fluid's viscosity. As the viscosity increased from 4.6 to 9.8 mPa s, the cooling performance decreased by approximately 6%. Moreover, all the IT server profiles were validated at various water inlet temperatures and flow rates. The energy performance of the proposed technique and the liquid-cooling system previously used by OVHcloud was compared at a 600 kW data centre (DC). The proposed technique showed a reduction in the DC electrical power consumption by at least 20.7% compared to the liquid-cooling system. Finally, the cooling performance of the air- and liquid-cooled systems and the proposed solution was compared computationally at the server level. When using the proposed solution, the energy consumed per server was reduced by at least 20% compared with the air-cooling system and 7% compared with liquid-cooling system.

Numerical-experimental method to devise a liquid-cooling test system for lithium-ion battery packs

The liquid-cooling system (LCS) of lithium-ion battery (LIB) pack is crucial in prolonging battery lifespan and improving electric vehicle (EV) reliability. This study purposes to control the battery pack's thermal distribution within a desirable level per a new-designed LCS. Both the special experimental platform and LCS model coupled with EV dynamic model are established to pinpoint the optimal matching parameters of components and the system's operational control-strategies. The results show that the deviation between experiment and simulation is within 3.0 % under conventional conditions. Higher flowrate and lower inlet temperature lead to lower battery temperature, while delaying the cooling intervention could reduce power consumption of 20 % around. The multi-objective optimization is conducted to further slash power consumption at 2750 W, and battery temperature at 30.83 °C during normal 1C discharge, by using response surface method combined with genetic algorithm II. Moreover, the present optimization also demonstrates a well-balanced solution between the battery temperature and power consumption under drive cycle. Combined with experiment and simulation, this work is valuable for one to design an excellent LCS for LIB packs of EV.

Optimization design and numerical study on thermal performance of a novel diamond-type channel cold plate

Heat dissipation capacity is of great importance object for the battery thermal management system (BTMS). To obtain a simple and efficient liquid cooling method for rectangular lithium-ion battery, three types of diamond channel (line, inner arc and outer arc) cold plate were established. Firstly, the temperature rise of line diamond microchannel cold plate under basic conditions were simulated. Then, an experimental device for measuring the surface temperatures of cold plate was designed, and the numerical simulation results were verified. The results showed that the errors between the avenge temperature (Tavg) of experiment and simulation were between 0.66% and 2.1%, and the inner arc diamond-type channel cold plate had better cooling effectiveness. Then the effects of the connection form of the intermediate channel, structural parameters and the layout of the inlet and outlet on the cooling performance of the cold plate were discussed. The pressure drop (ΔP) and Tavg of the best results reach 5.33Pa and 36.52 °C respectively. Compared with the initial condition, ΔP was decreased by 32.81Pa (86.03%) and Tavg was decreased by 0.69 °C (1.9%). The above research results depict that the new diamond-shaped cold plate proposed in this paper could greatly enhance the cooling performance of the liquid-cooling system.