Liquid Cooling System Research Articles

Mini-Channel Liquid Cooling System for Improving Heat Transfer Capacity and Thermal Uniformity in Battery Packs for Electric Vehicles

Abstract Temperature is a significant factor affecting performance and safety of energy storage systems such as battery packs. How to design a reliable battery thermal management system (BTMS) is still a hot issue at present. Most of the past researches have focused on methods of reducing temperature rise. This paper mainly studies how to reduce the temperature deviation of the battery pack while ensuring heat dissipation conditions. This paper designs a mini-channel liquid cooling BTMS with a side cover to improve heat transfer capacity and thermal uniformity in battery packs. By analyzing different side cover materials, cooling water temperature, and water channel structure, the influence of different parameters on battery heat dissipation and uniformity is obtained. The main findings are: (1) the presence of the side cover can effectively reduce the maximum temperature and temperature deviation, and the material with high thermal conductivity is more likely to dissipate heat, (2) The increase of cooling water inlet temperature can improve temperature uniformity, and (3) When the cross-sectional area is fixed, as the channel depth increases, the temperature deviation gradually decreases.

Thermal Performance of Vapour Chamber in Different Tilting Configurations for Battery Liquid Cooling System

Vapour chamber is a planar heat pipe and has been widely used in the thermal management of electronic device. In this work, a grooved aluminium vapour chamber was presented with a one-through cooling plate to develop a simplified and practicable battery liquid cooling system. The impact of filling ratio and tilting configuration on the thermal performance of vapour chamber was experimentally investigated. The results showed that the thermal resistance of the vapour chamber increased gradually with the increase in filling ratio, and there was a deterioration of the heat transfer in tilting configuration. However, the vapour chamber at 20% filling ratio had a better performance at positive tilting angle configuration compared with that at negative tilting angle configuration. Moreover, the temperature distribution of the heating surface is fairly uniform with the application of the vapour chamber. Despite the temperature rise of the cooling water in the cooling plate up to 3.8ºC, the minimum temperature difference of the heating surface could be kept within 1 ºC and the minimum thermal resistance could be kept within 0.075ºC/W. The results indicate that the temperature difference of the heating surface can be suppressed through the heat and mass transport of phases inside the vapour chamber.

Performance analysis on liquid-cooled battery thermal management for electric vehicles based on machine learning

In this paper, the coupling system of liquid-cooled battery thermal management system (BTMS) and heat pump air conditioning system (HPACS) for battery electric vehicles (BEV) is designed and analyzed. The performances of liquid-cooled BTMS are concerned and analyzed from the perspective of air conditioning based experimental data. Besides, an automatic calibration model of the liquid-cooled BTMS based HPACS is established to predict cooling capacity and system coefficient of performance (COP) of the BTMS by support vector regression (SVR). To better obtain three hyper parameters (the penalty coefficient C, the RBF kernel function parameter γ, and the insensitive loss coefficient ε) of SVR model, particle swarm optimization (PSO) algorithm is introduced to optimize above three parameters. It is found that compared to SVR model, the correlation coefficient (R) of cooling capacity and system COP for the proposed PSO-SVR model in this paper is improved 2.1% and 2.8% respectively, the mean squared error (MSE) of and cooling capacity and system COP is reduced 87.8% and 82.9% respectively, which indicated that PSO-SVR model can be used as a new method to fit the complex nonlinear relationship among the system COP, cooling capacity and other influencing factors of the liquid-cooled BTMS based HPACS.

Investigation and optimization on cooling performance of a novel double helix structure for cylindrical lithium-ion batteries

Abstract Liquid cooling system was critical to keep the performance of lithium-ion battery due to its good conductivity to keep battery working in a cool environment. In this study, a novel double helix cooling structure was designed for an 18650 lithium battery. The numerical simulation was carried out to investigate the effects of the coolant mass flow rate (M), helix groove pitch (P) and flow diameter (D) on cooling performance. The design points obtained by Latin hypercube sampling were calculated numerically. Kriging approximate model method was adopted to reduce computing time. Using Non-dominated Sorting Genetic Algorithm II obtained the Pareto solution, and the multiple criteria decision making (MCDM) algorithm was used to sort the optimal solution set. The results showed that increasing mass flow rate can effectively lower the maximum temperature and temperature difference of the battery within a certain range of mass flow rate. When the mass flow rate increased to a certain value, the benefit from increasing the mass flow was limited. And the pitch and diameter would also have a tendency to the decrease of the maximum temperature or even the opposite result when they exceeded a certain value. The best cooling performance can be obtained when the mass flow rate is 1.94 × 10−3 kg/s, the pitch is 100 mm and the diameter is 0.4 mm. The novel cooling structure proposed in this study can provided a new approach for the structure design of the liquid-cooled cylindrical battery thermal management system.

Design and simulation of locally enhanced microchannel heat sink for diode partially pumped slab laser

With the power level of diode-pumped solid-state laser (DPSSL) rising continuously, its thermal effect has become the main problem limiting the laser performance. In this paper, based on the heat distribution of diode partially end-pumped slab (Innoslab) laser, a shunt rectangular microchannel heat sink with locally enhanced heat dissipation is designed. Firstly, multi-stage parallel short channels are designed in the heat concentration area to enhance the solid-liquid heat exchange in this area, and the effects of structure and working conditions on its heat dissipation performance are investigated. Secondly, the copper layer is introduced into the end face of the low thermal conductivity crystal to form a high thermal conductivity path, which alleviates the heat accumulation inside the crystal. Under a certain condition, compared with the traditional liquid-cooled plate system, the maximum temperature of the laser crystal is reduced from 169.62 to 118.18 °C, the pressure drop is reduced by 66.75%, and the total mass of the system is reduced to 4.87% of the original system, which effectively improves the practical performance of the device.

A compact and optimized liquid-cooled thermal management system for high power lithium-ion capacitors

Designing a proper thermal management system (TMS) is indispensable to the energy storage systems (ESS) of electric vehicles for reliability and safety. The high heat transfer rate and low power consumption of liquid cooling systems made them a perfect candidate amongst various TMS. Nonetheless, the compactness of the liquid cooling TMS has paid less attention in the literature, which plays a vital role in the specific energy of ESSs. In this study, a liquid-based TMS is designed for a prismatic high-power lithium-ion capacitor (LiC). The proposed TMS integrates a LiC cell surrounded by two cooling plates through which coolant fluid flows into serpentine channels. This study aims to explore factors that affect the temperature contour and uniformity of the battery. Experimental tests have been conducted to investigate the effect of inlet coolant temperature and inlet coolant flow rate. As the gap filler eliminates the air gap barrier between the cell and cooling plates, the impact of the selected thermal interface material (TIM) is also studied. Besides, the number of arcs of the channels in the coolant path and the channel diameter is investigated in the optimization section. The experimental results revealed that the monitored temperature in three cases of natural convection, forced convection, and liquid-based TMS was recorded as 55.7 °C, 44.8 °C, and 32.6 °C, respectively. The optimization results proved that by increasing the inlet coolant temperature from 23 °C to 30 °C, the temperature sensed by the thermocouple increases by 11.5%. Also, by increasing the inlet flow rate from 100 mL/min to 200 mL/min, the temperature declines from 32.6 °C to 31.5 °C; hence, to avoid higher power consumption and pressure drop, the main flow rate of 100 mL/min is preferred.

A Review on Development of Liquid Cooling System for Central Processing Unit (CPU)

Electronic devices are becoming more efficient while getting a smaller size and compact design thus increase heat generation significantly. High heat generation from high technology electronic devices are needed to be cool down or control its temperature to prevent overheating problems. Due to the high cooling performance of liquid cooling, the electronic cooling system is shifting from an air-cooling system to a liquid cooling system. In the past few decades, numerous methods proposed by researchers for the central process unit (CPU) cooling using the liquid system either active cooling or passive cooling system. Other than physical configuration such as heat sink design, different configurations of working fluids are widely been studied by most of the researchers. Different working fluids have different heat transfer performance. Furthermore, a recent study has come out more interesting finding using nanofluid which can enhance heat transfer performance of liquid cooling. Nanofluid is a working fluid that has nanoparticles disperse in the base fluid which can increase the thermal properties of the based fluid. In this paper, comprehensive literature on the type of working fluid used in the respective system and methods of liquid cooling system for CPU including its cooling performance. Furthermore, this review paper discussed the different configuration of the liquid block and also the working fluid that had been used in the CPU cooling system.

Experimental and simulation study of liquid coolant battery thermal management system for electric vehicles: A review

Lithium-ion batteries are among the most commonly used batteries to produce power for electric vehicles, which leads to the higher needs for battery thermal management system (BTMS). There are many key concerning points for the users of these batteries, which include reliability, safety, life cycle, and the operating temperature of the batteries. It is known through review that water is the best coolant for batteries, in which the maximum temperature was 43.3°C while the temperature of the coolant was 30°C during the discharge rate of battery pack at 4 C. An effective cooling system is necessary in prolonging the battery life, which controls the temperature difference between the batteries and the peak temperature of the battery. This review paper aims to summarize the recent published papers on battery liquid-cooling systems, which include: battery pack design, liquid-cooling system classification, and coolant performance. Furthermore, this study discusses other factors related to the recent studies, such as the properties and applications of different liquid coolants (oil and water) under the classification of liquid-cooling system and the difference between passive and active, indirect and direct, and external and internal cooling systems are discussed. Moreover, this paper investigates the effect of temperature on the performance of battery in three aspects: low, high, and differential temperatures. Moreover, the study provides a systematic review of liquid-based systems for direct and indirect contact modes.

Liquid Cooling System and Air Cooling System in Data Center: A Comparison

Liquid Cooling System and Air Cooling System in Data Center: A Comparison

Microporous Layer Design for High Performing Open-Cathode Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) are a key sustainable energy source which can cater for energy demands ranging from miniature power requirements to portable, automotive and various stationary power applications. PEMFCs deliver electricity by means of undergoing electrochemical reactions and produce water and heat as by-products. At high current densities, flooding and overheating can cause local hot spots leading to degradation and failure of the membrane electrode assembly (MEA) during long term operations [1]. Hence, hygrothermal management is normally ensured by means of liquid cooling of the bipolar plates. However, this traditional design incurs extra cost of balance-of-plant (BOP) components and enhances the overall size of the system. Using ambient air as oxidant as well as coolant with an ‘open-cathode’ design can drastically reduce the system size and weight, however the performance of such a system is limited by overheating and drying of the MEA.The objective of the present work is to develop a suitable microporous layer (MPL) design for efficient cell performance of an open-cathode PEMFC system operating at hot ambient air conditions. A pre-validated comprehensive, 3D computational fuel cell model [2] is used to study the mass, momentum and heat balance inside the system along with water transport and current distribution in various components of the system. The gas diffusion layer (GDL) comprised of a bi-layer macroporous substrate and MPL structure is one of the key components of the overall system design and plays a significant role in water transport inside the cells [3]. Whereas in conventional liquid-cooled systems, the presence of a hydrophobic MPL can facilitate wicking of liquid water out of the MEA to prevent oversaturation and flooding [4], ‘open-cathode’ fuel cells are more likely to experience drying than flooding and may therefore benefit from alternate MPL designs. As shown in Figure 1, thinner MPLs (30 μm) with higher porosity (60%) are found to result in elevated open-cathode cell performance as a result of optimum water retention and O2 diffusion across the MPL. The increment in performance is found to be broadly visible at higher current densities, where mass transport effects are more dominant. The MPL effective diffusivity which is a function of its porosity along with the MPL thickness are also found to be important for the overall thermal and water balance of the MEA. The optimum RH and temperature levels achieved in the MEA are further found to negate the overheating and drying effects obtained in earlier system designs.AcknowledgmentsThis work was supported by the funding provided by Simon Fraser University and Indian Oil R&D Centre under the SFU-IOCL joint PhD program in clean energy.

Experiment investigation on a novel composite silica gel plate coupled with liquid-cooling system for square battery thermal management

Battery thermal management (BTM) technology has been widely utilized in pure/hybrid electric vehicles. In this study, a novel and effective hybrid cooling system including composite silica gel plate (CSGP) coupled with cooling tubes has been designed for battery module. Combining the excellent cooling effect of copper tubes and CSGP with low contact thermal resistance between each other, the coupling of CSGP and copper tubes is a feasible and effective method with more suitable temperature and smaller temperature difference. For comparison, the natural cooling module and the forced air convection module (CSGP-FC) based CSGP have also been designed. The experiment results revealed that the natural cooling module was hardly to satisfy the requirements of temperature in practical application. Meanwhile, although the CSGP-FC could enhance the heat dissipation at a certain degree, it was still not enough to control the temperature of the module below 45 °C after ten cycling tests. Compared with natural cooling module and CSGP-FC, the CSGP coupled with copper tubes can absorb the heat quickly and transfer it through the water flowing in the copper tubes efficiently, which can control the maximum temperature (Tmax) and make it have a decreasing tendency in ten charge and discharge cycles. The liquid cooling module (CSGP-LC) with 0.8 m/s water flowing rate can control the Tmax below 42.7℃ and temperature difference (ΔT) within 2.7 ℃ at 4C discharge rate. In addition, the energy consumption of the CSGP-LC was half of the CSGP-FC. It should be noted that the expanded graphite (EG) and copper foam added into silica gel (SG) can transfer the heat generating by batteries to copper tubes timely and promptly owing to high thermal conductivity, giving rise to a superior thermal management effect for battery module, especially at high discharge rate. Thus, it can be concluded that this designed cooling approach can provide a new insight for optimizing structure of liquid cooling technology and greatly promote the development of BMS systems.

Structure design and effect analysis on refrigerant cooling enhancement of battery thermal management system for electric vehicles

A liquid-cooled battery thermal management system, consisting of a refrigerant flow through a cold plate, allows the battery to recharge cycles at aggressive rates and temperatures. Based on the validated fluid-solid coupling model, the design and evaluation of the refrigerant-based thermal management structure, and the analysis and control of characteristic parameters under different conditions are explored in this paper. A thermal management structure, involving the tube side and cross-section of the cold plate, reaches a compromise between heat exchange quantity, required power consumption, mass, volume. For the controllable parameters, results show that the refrigerant mass flux has an optimal solution for thermal management, yet the evaporation temperature is the limit of system stability and control. Based on the refrigerant properties, a cascade-change strategy with priority is proposed to consider both temperature drop and temperature uniformity of the battery. Besides, although the refrigerant-based thermal management structure cannot prevent the thermal abused of a single cell, it can suppress the thermal runaway propagation from one to adjacent cells.

A GPU Spatial Processing System for CHIME

We present an overview of the Graphics Processing Unit (GPU)-based spatial processing system created for the Canadian Hydrogen Intensity Mapping Experiment (CHIME). The design employs AMD S9300x2 GPUs and readily available commercial hardware in its processing nodes to provide a cost- and power-efficient processing substrate. These nodes are supported by a liquid-cooling system which allows continuous operation with modest power consumption and in all but the most adverse conditions. Capable of continuously correlating 2048 receiver-polarizations across 400[Formula: see text]MHz of bandwidth, the CHIME X-engine constitutes the most powerful radio correlator currently in existence. It receives 6.6[Formula: see text]Tb/s of channelized data from CHIME’s FPGA-based F-engine, and the primary correlation task requires [Formula: see text] complex multiply-and-accumulate operations per second. The same system also provides formed-beam data products to commensal FRB and Pulsar experiments; it constitutes a general spatial-processing system of unprecedented scale and capability, with correspondingly great challenges in computation, data transport, heat dissipation, and interference shielding.

Attachment of Liquid Cooling System and Air Pre Heater in Two Wheeler

Attachment of Liquid Cooling System and Air Pre Heater in Two Wheeler

Heat Dissipation Analysis on the Liquid Cooling System Coupled with a Flat Heat Pipe of a Lithium-Ion Battery.

The liquid-cooled thermal management system based on a flat heat pipe has a good thermal management effect on a single battery pack, and this article further applies it to a power battery system to verify the thermal management effect. The effects of different discharge rates, different coolant flow rates, and different coolant inlet temperatures on the temperature distribution uniformity of the power battery system were analyzed, and the effectiveness of the flat heat pipe in improving the thermal equilibrium performance of the liquid-cooled thermal management system was verified.

Research on battery liquid-cooled system based on the parallel connection of cold plates

The performance of a power battery is greatly affected by temperature. This paper optimized the power battery liquid-cooled system and put forward the way of adding fins to the liquid-cooled plate to improve the cooling efficiency of the thermal management system. In this paper, a liquid-cooled battery system model was established, and the thermal balance performance of the parallel liquid-cooled system was studied through numerical analysis. The results show that the parallel liquid-cooled system with an optimized shunt could maintain the maximum temperature of the battery system below 44.31 °C, and the temperature difference of the battery system could maintain at 3 °C, which could meet the temperature requirements of the power battery system.

Cooling capacity of a novel modular liquid-cooled battery thermal management system for cylindrical lithium ion batteries

Effective battery thermal management system (BTMS) is significant for electric vehicle to maintain the properties and life-time of the battery packs. As an effective cooling method, liquid cooling appears in many publications, but the study of cooling performance based on practical modular structure is relatively scarce. This paper has proposed a novel modular liquid-cooled system for batteries and carried out the numerical simulation and experiment to study the effect of coolant flow rate and cooling mode (Serial cooling and parallel cooling) on the thermal behavior of the battery module. The results show that increasing the coolant flow rate can significantly lower the maximum temperature and improve the temperature uniformity of the battery module in a certain flow range; when the flow rate increases to a certain value, increasing the cooling water flow rate has no obvious effect on improving cooling effect. Compared with serial cooling, parallel cooling can evidently promote the temperature uniformity of the battery module. Furthermore, the designed flow direction layout III can control Tmax to 35.74 °C with ΔT as 4.17 °C. The modular structure can be suitable for industrial batch production and group the batteries flexibly to meet the actual demand. The present study can provide a new approach for the modular design of liquid-cooled battery thermal management system.

An Overview of Thermal and Mechanical Design, Control, and Testing of the World's Most Powerful and Fastest Supercomputer

Abstract A new era of computing has begun with the development of high-performance computing (HPC), artificial intelligence (AI), machine learning (ML), and cognitive systems. Dramatic increases in the power density of the electronic components have led to the design and architecture of efficient thermal management technologies on these systems. IBM designed and delivered in 2018 the most powerful and fastest supercomputers of the world known as Summit and Sierra having 200 petaflops peak computing performance through LINPACK benchmarks. These systems which are called as IBM POWER AC922 are both air and liquid cooled, where water is employed in liquid-cooled systems to cool the high-power electronic components including IBM POWER9 processors and NVIDIA graphics processing units (GPUs). In this paper, we highlight the overview of the thermal and mechanical design strategies applied to these systems. Testing and experimental analysis with comparison to computational modeling is provided. Thermal control strategies are investigated for the optimization of overall system efficiency. In air cooled systems, we discuss the fan and heat sink designs, as well as the preheating effect on the PCIe section. In liquid-cooled systems, which have a unique cold plate design cooling the processors and the GPUs with water, we examine the water flow path design for the central processing units (CPUs), the GPUs, and the thermal performance of the cold plate. An overview of the cooling assemblies such as TIMs and air baffles in these systems is discussed. Unit and rack manifolds and rear door heat exchanger (RDHx) are investigated. Water flow and pressure distribution at the node and rack-level are provided.

Two-phase liquid-immersion data center cooling system: Experimental performance and thermoeconomic analysis

• System-scale performance assessment is done for a two-phase immersion cooling system. • The best COP and PUE trends are found at the highest server power rate. • Exergy efficiency varies between 8.0 and 18.9% at various operation loads. • Exergy costs are found 3.25 times as higher than the energy costs. The liquid-cooling data center (DC) systems have been becoming important for the rapidly developing high-performance processors since the traditional air-cooled DC systems cannot efficiently manage them due to high heat dissipation rates. Two-phase liquid-immersion cooling is one of the promising direct liquid-cooled DC systems, but its system-scale thermal management performance has not been investigated in detail yet. This study performs the system-scale thermal management of a two-phase liquid-immersion cooling DC system under six different real-time and dynamic operation loads in the range of 3.43-9.17 kW to see the thermodynamic and thermoeconomic performances. The system includes the DC server tank, circulation pump, and dry tower. Results show that the best coefficient of performance ( COP ) and power usage effectiveness ( PUE ) values are seen at the highest operation load with 6.67 and 1.15 while the minimum COP and the highest PUE are seen at the lowest operation load with 2.5 and 1.4, respectively. In the component-based assessments, the dry tower is found as the most dominant component according to the exergy destruction ratio analysis, energy costing, and carbon-related costs. The exergy efficiency varies between 8.0% and 18.9% for different operation loads, and the operating temperatures have a crucial impact on the exergetic performances. The thermoeconomic analysis deduces that the levelized product cost is roundly 1.14 S$ · h -1 which means the exergy-related terms (e.g. destruction and loss) increase the costing trends 3.25 times as high compared to the traditional energy-based economic calculations.

Operation Optimization of Liquid Cooling Systems in Data Centers by the Heat Current Method and Artificial Neural Network

Liquid cooling systems in data centers have been attracting more attentions due to its better cooling capability and less energy consumption. In order to propose an effective optimization method for the operation of indirect liquid cooling systems, this paper first constructs an experiment platform and applies the heat current method to build the global heat transfer constraints of the whole system. Particularly, the thermal conductance of each heat exchanger under different working conditions is predicted by the Artificial Neural Networks (ANN) trained by the historical data. On this basis, combining the heat transfer and fluid flow constraints together with the Lagrange multiplier method builds the optimization model with the objective of minimum pumping power consumption (PPC), solving which by the solution strategy designed obtains the optimal frequencies of the variable frequency pumps (VFPs). Operating with the optimal and other feasible operating conditions validates the optimization model. Meanwhile, the experiments with variable heat loads and flow resistances provide some guidelines for the optimal system operation. For instance, to address heat load increase of a branch, it needs to increase the frequencies of the VFPs, not only the corresponding hot loop but also the whole cold loop.