Cell Temperature Uniformity Research Articles

Analysis of ultra-high concentration solar cells integrated with a confined microjet impingement cooling

The high solar concentration levels result in an intense influx of energy onto the concentrated triple-junction solar cell, leading to elevated temperatures that can degrade the cell’s performance and overall lifespan. This necessitates the development of innovative and efficient cooling strategies to mitigate temperature-induced losses and ensure optimal energy conversion. This study introduces an innovative micro jet impingement cooling system designed for ultrahigh concentrated solar cells, addressing the critical challenge of temperature management under high solar concentration levels. Furthermore, structural modifications were proposed, including reducing ceramic layer thickness to decrease the thermal resistance and using thermal interface materials to improve the cell temperature uniformity. A three-dimensional computational fluid dynamics model was developed to evaluate the proposed system’s performance and compare it with the traditional jet impingement heat sink. The model was verified and validated using empirical data in the literature. In addition, the Response Surface Method was employed to provide a comprehensive understanding of the system’s behavior under various weather conditions and cooling fluid effects. The results showed that concentration ratio and direct normal irradiance significantly affect the system’s performance. Moreover, the new cooling system maintains temperatures below the recommended operating temperature. Finally, the environmental assessment indicated substantial energy payback time reductions at 20,000 Suns, which is significantly lower than at 1000 Suns. The CO2 emissions analysis shows a marked potential for emissions mitigation, particularly at higher CRs and longer sunshine hours. These insights offer a comprehensive overview of ultrahigh concentrated solar cell thermal system performance, highlighting its efficiency and environmental sustainability in solar energy applications.

Numerical optimization study on the thermal management of planar sodium nickel chloride battery module

A numerical study is conducted to build up a thermal management strategy for a battery module consisting of stacked planar sodium metal chloride (Na-MCl2) unit cells at the intermediate temperature of 180 °C. Because the sodium metal chloride battery for an energy storage system operates for a long cycle period and maintains a high temperature, a different approach is required considering uniform temperature distribution and efficiency compared with lithium-ion battery. This study starts with a lumped analytical model for preliminary investigation and moves on to a computational fluid dynamics (CFD) analysis for a more sophisticated optimization. In this study, the 2 × 4 and 3 × 3 arrangements of cylinders, each of which represents a 10-cell stack, are considered. From the lumped model in the preliminary design, the insulation thickness and initial approach values of the detailed design are determined by predicting the temperature and heat generation throughout the entire operating cycle of the module. In the detailed CFD analysis, passive thermal management through natural convection has a limitation of cell temperature uniformity. To achieve a uniform cell temperature distribution, case studies are conducted with active fans inside the module. The optimal operating points are proposed based on the overlaid response surface. Finally, for the operating points in this study, the module efficiencies are compared considering the cell failure mode. The efficiencies of optimized module are increased to 26.9 % for 2 × 4 and 21.2 % for 3 × 3 arrangements.

Experimental studies of reciprocating liquid immersion cooling for 18650 lithium-ion battery under fast charging conditions

In this study, the reciprocating liquid immersion cooling has been proposed and tested for cooling the cylindrical lithium-ion battery (LIB) under fast charging conditions. First, the temperature responses of LIB under fast charging conditions with liquid immersion cooling and natural convection are compared. Experimental results show that the reciprocating liquid immersion cooling possesses better heat dissipation performance than natural convection, not only can precisely control the cell temperature to around 50 °C during fast charging, but also can improve the cell temperature uniformity. Meanwhile, the reciprocating system enables rapid cooling of the battery during the resting process, which consequently achieves asymmetric control of high-temperature charging and room temperature discharging. Then, the effects of different charging rates and different charging protocols are explored, and the high-speed photography is used to observe and record the liquid-gas phase transition phenomenon under three different charging rates. Finally, the temperature response and energy consumption analysis of LIB in the fast-charging process with three different assembly schemes are investigated. This study provides preliminary proof for the advantage of applying liquid immersion cooling for LIB under fast charging.

A thermal‐optimal design of lithium‐ion battery for the container storage system

AbstractIn this paper, the permitted temperature value of the battery cell and DC‐DC converter is proposed. The flow and temperature field of the lithium‐ion batteries is obtained by the computational fluid dynamic method. Thus, the package structure of the battery pack is optimized based on four influencing factors. The results indicate that (1) setting a new inlet on the wall, I can improve ventilation and the inlet is better located below the waist of the battery pack. (2) Air inlet location close to the fan is easy to generate short air circuit, which leads to DC‐DC converter in poor condition of heat dissipation. (3) Adjusting the size of the air inlet mainly affects the temperature distribution of the cells but has little effect on the temperature of the DC‐DC converter. (4) Regulating the gap size can enhance the cell temperature uniformity. (5) The optimized battery pack structure is obtained, where the maximum cell surface temperature is 297.51 K, and the maximum surface temperature of the DC‐DC converter is 339.93 K. The above results provide an approach to exploring the optimal design method of lithium‐ion batteries for the container storage system with better thermal performance.

Numerical study on the air-cooled thermal management of Lithium-ion battery pack for electrical vehicles

A Lithium-ion battery is one of the most common batteries being widely used as the power source in Electric Vehicle (EV) due to its high energy density, power density, long life span and environment friendly. Due to the high power requirement of EV, thousands of cylindrical Lithium-ion battery cells are typically connected in parallel and/or series forming a battery pack. This significantly generates enormous heat through the internal resistance effect and exothermic reactions inside the battery during the charge or discharge process. If the fetal heat cannot be dissipated sufficiently, the battery cells may encounter capacity fade, thermal runaway and instability issues. Thus, efficient thermal management of the Lithium-ion battery pack is essential to restrain high temperature and non-uniformity of temperature in the battery pack. This issue remains a challenge, although much research has been conducted on this topic. In this work, the air cooling thermal management system is numerically investigated due to lower manufacturing cost, simple layout requirements and higher reliability of the system. A transient three-dimensional heat transfer model of the cylindrical Lithium-ion battery pack is developed to study the effect of the inlet velocity, discharge rate and cell arrangement structure on the cooling performance. The proposed system is designed to minimize the maximum cell temperature and the cell temperature uniformity. The simulated results can be further applied as a reference in designing the structures of the battery pack and planning the cooling strategies.

Heat pipe based battery thermal management: Evaluating the potential of two novel battery pack integrations

Lithium-ion batteries are widely used in high power applications and, with more industries focusing on the electrification of their processes, the need for an effective battery thermal management system is growing. The use of a thermal management system serves multiple purposes such as safeguarding the battery from catastrophic thermal runaway and increasing the lifespan of the battery pack. In the present paper, the thermal management of a sixteen-cell battery module, by two different configurations of a heat pipe based thermal management system, is investigated experimentally. In the first configuration, the module is fixed on top of a single horizontal ‘heat mat’. The second configuration consists of the module sandwiched between two vertical heat mats. The comparison of the cooling performances of these two configurations showed their ability to efficiently absorb the heat generated by the cells and maintain their temperatures close to the ideal operating range. During representative cycles of operation, the maximum cell temperature was kept below 28.5 °C and 24.5 °C for the horizontal and vertical heat mat configurations respectively. The cell temperature uniformity across the module stays in a +/-1 °C range, which will reduce cell voltage imbalance, loss of useable capacity and non-uniform ageing. The maximum temperature difference across the height of the cells was 6 °C for the horizontal configuration and 2 °C for the vertical one. The second part of this paper compares the heat removed in both configurations when loaded with a quasi-steady-state heat generation. The third study uses a faster (6C) charge rate during a representative cycle and shows that the maximum temperature stays below 30 °C and 28 °C for the horizontal and vertical configurations respectively.

A novel designed manifold ultrathin micro pin-fin channel for thermal management of high-concentrator photovoltaic system

To meet the requirements of cooling challenges of high concentrator photovoltaic (HCPV), a novel manifold ultrathin micro pin-fin heat sink (MUMPFHS) cooling technique is developed in this study. A comprehensive three-dimensional simulation model is established to investigate the thermal, energy and exergy performance of 10 × 10 mm2 HCPV cells cooling with MUMPFHS, using Star CCM+ with the help of user defined field functions. Compared with the previously proposed designs of the HCPV cooling schemes using jet impingement, hybrid jet impingement/microchannel and stepwise varying width microchannel, the present one shows great advantages of both uniform solar cell temperature and high cooling performance under a high solar concentration of 1000 suns. At inlet flow rate of 3 kg/h and temperature of 25 °C, the solar cell temperature can be reduced to 51 °C, with a small temperature non-uniformity of 3.4 °C. As the inlet flow rate increases, the average cell temperature and its non-uniformity further decrease, resulting in a higher electrical efficiency. However, the inlet coolant temperature has little impact on the cell temperature uniformity, allowing maximizing the inlet temperature to improve the thermal exergy efficiency under the recommended temperature range. In addition, five different designs of inlet/outlet plenums are proposed and integrated on the MUMPFHS, which could achieve a uniform flow distribution in each manifold channel. Thermal and exergy analysis confirms that taking the plenums into consideration increases the friction power which can be compensated by the improvement of electrical power due to the decrease of solar cell temperature. The present simulation results indicate that our designed MUMPFHS could increase the feasibility of using HCPV under higher solar concentration with safe operation.

Numerical study on cooling of prismatic lithium-ion battery module

This paper depicts about the cooling system of prismatic batteries as these batteries are space efficient for electric vehicles. Although these batteries are well known for their high heat dissipation while charging and discharging the thermal management of the battery should be in such a way that these batteries need a cooling environment to reduce the heat. In this paper, a three-dimensional CFD study is presented for cell-to-cell heat generation in the battery module. The battery module is comprised of uniformly spaced three prismatic Li-ion cells. Large spacing is assumed for safer removal of cell reaction gases in modules. The cell heat generation is computed based on the thermal model. The battery module experiences a higher temperature on the upstream side as the fluid passes across each row of cells and absorb the battery heat. Throughout the discharging process, maximum battery temperature and cell temperature uniformity are found much lower than permissible range applicable for safe operation of Li-ion module. The maximum battery temperature at discrete hot location is observed up to 34 °C, 45 °C and 60 °C respectively at 900 s, 1800 s and 3600 s. The maximum rate of heat dissipation is observed from battery 2 and its value varies from 2.83 W to 17.86 W respectively at battery discharging duration of 300 s and 3600 s. The maximum cell temperature non-uniformity in a battery module is observed 0.019 °C to 0.99 °C respectively at 300 s and 3600 s. The effect of interspacing of the batteries as well as inline and staggered arrangement within the module is needed to be analyzed in detail for efficient cooling system.

Three-dimensional CFD study on heat dissipation in cylindrical lithium-ion battery module

This paper depicts about the cooling system of battery module. The battery module comprised of 12 cylindrical 18,650 type batteries. In this paper, a three-dimensional CFD study is presented for cell-to-cell heat generation in the battery module. Large spacing is assumed for safer removal of cell reaction gases in modules. The cell heat generation is computed based on the thermal model. The battery module experiences a higher temperature on the upstream side as the fluid passes across each row of cells and absorb the battery heat. Throughout the discharging process, maximum battery temperature and cell temperature uniformity are found much lower than permissible range applicable for safe operation of Li-ion module. With the supplied air conditions and inlet design, the maximum battery temperature reached at the end of its use is lower than 35 °C. The maximum cell temperature non-uniformity in a battery module is observed 4.43 °C. The results are also presented in total heat dissipated from battery module.

Thermal management of concentrator photovoltaic systems using microchannel heat sink with nanofluids

A new cooling method for concentrator photovoltaic system is proposed using wide microchannel heat sink with nanofluids. A comprehensive three-dimensional model is developed. The model couples the two-phase (Eulerian-Eulerian) multiphase model for the conjugate heat transfer of nanofluid flow in a wide microchannel heat sink with the thermal model of the concentrator photovoltaic systems. The model is numerically simulated and validated with the available experimental and numerical data. The influences of nanoparticle types, volume fractions, and coolant flow Reynolds number on the solar cell performance parameters are investigated. Results indicate that using SiC-water nanofluids attains lower cell temperature compared with Al2O3-water nanofluids. The increase of nanoparticles volume fraction ratio remarkably reduces the solar cell temperature and enhances the cell temperature uniformity and electrical efficiency. Furthermore, increasing the flow Reynolds number to a specific value significantly enhances the net electrical power. Further increase of the Reynolds number results in a significant reduction in the cell net gained power. By using 4% SiC-water nanofluid, the reduction in maximum local solar cell temperature is ranged between 8 °C and 3 °C compared with pure water with changing the flow Reynolds number from 12.5 to 250 at solar concentration ratio of 20.

Sodium Metal Halide Battery Thermal Design for Improved Reliability

Cell temperature uniformity inside most batteries is important, because temperature variation leads to cell resistance variation and thus cell voltage variation during discharge–charge cycling. Voltage variation among the cells leads to accelerated degradation of the overall battery. Goal of this work was to improve cell temperature uniformity of the General Electric DurathonTM E620 battery module (600 V class, 20 kWh, 280 °C nominal temperature), which uses the sodium metal halide chemistry and convection air cooling. Computation fluid dynamics (CFD) study and bench-top testing were used to evaluate multiple battery design options. The optimized battery design was prototyped and tested, which demonstrated 3.5× increase in cooling power and 30% reduction in cell temperature difference during discharge–charge cycling. Cell temperature difference during battery float was reduced 50%. The hardware design changes were implemented into production batteries, which showed 450% improvement in reliability performance during discharge–charge cycling.

Outdoor test of a hybrid jet impingement/micro-channel cooling device for densely packed concentrated photovoltaic cells

Densely packed concentrated photovoltaic (CPV) receivers require efficient active cooling in order to maintain the photovoltaic cells within their nominal operating temperature range. The cooling device must have low thermal resistance coefficients and also provide good cell temperature uniformity in order to maximize the efficiency and the reliability of the whole system. A hybrid jet impingement/microchannel cooling device designed for CPV receivers is experimentally tested under real sun in outdoor conditions. The measurements include the irradiation profile at the outlet of the secondary optics and the temperature distribution of the receiver. The experimental results show that the thermal resistance coefficient and the temperature uniformity provided by the cooling device met the requirements for CPV receivers. This work also emphasizes that the internal geometry of the cooling device must be tailored, at the design stage, to the irradiation profile provided by the optics, which is generally nonperfectly uniform in CPV systems based on densely packed receivers. The impact of the solar concentration ratio and flow rate on the electrical output of the receiver is also assessed.

Performance assessment of thermal management systems for electric and hybrid electric vehicles

Thermal management systems (TMS) are one of the key components of electric and hybrid electric vehicles to achieve high vehicle efficiency and performance under all operating conditions. Current improvements in electric battery technology allow vehicles to have relatively long ranges, fast acceleration, and long life while keeping low-maintenance costs and considerably lower emissions. However, the vehicle performance is significantly affected by the battery operating conditions. Moreover, the cell life cycle, safety, and possibility of thermal runaway significantly depend on peak temperature rise and temperature uniformity of the battery. Therefore, various TMSs are created to keep batteries within ideal operating ranges. In this article, three different TMS systems—passive cabin cooling (via air), active moderate liquid circulation (via refrigerant), and active liquid circulation (via refrigerant and coolant)—are analyzed and compared with electric and hybrid electric vehicles. A second law analysis is used to examine the areas of low exergy efficiency in each system and minimize the entropy generation based on the system configuration. Moreover, TMS systems are compared on the basis of battery temperature increase and temperature uniformity. Various parametric studies are conducted to compare the TMS in different ambient and operating conditions. On the basis of the analysis, the active liquid circulation (via refrigerant and coolant) is determined to have the lowest battery temperature increase (3.9 °C in 30 min) and most cell temperature uniformity (2.5 °C median) as well as the lowest entropy generation rate (0.0121 W/K) among the compared systems. Copyright © 2012 John Wiley & Sons, Ltd.