Maximum Temperature Of Battery Pack Research Articles

Experimental investigation of change in performance parameters on cooling of lithium‐ion battery pack using nanofluids

AbstractElectric vehicles surged into the automobile industry due to increasing emissions and future extinction of fossil fuels which resulted due to their unforeseen utilization all over the globe. Battery is important components for manufacturing of electric vehicles (EVs). Currently lithium‐ion (Li‐ion) cells are the most advanced and efficient cell technology developed till date. These cells work well within an operating temperature range of 15° C to 35°C. Thus, many battery cooling techniques were developed such as air, liquid, phase change material (PCM) and heat pipe based cooling system. Liquid cooling was found to be the most efficient, adoptable and convenient system used in EVs. The current paper focuses on development of an active indirect liquid cooling system using nanofluids as coolant. Different performance parameters such as mass flow rate, nanoparticle concentration and maximum temperature of battery pack were varied and simulation results were validated using experimental results. The results concluded that nanofluids show improved and enhanced cooling as in comparison with other coolants such as water and ethylene glycol. Al2O3‐water nanofluid is the most preferable to use in EVs as coolants due to its efficient cooling, low cost and environmental friendly nature. On increasing the mass flow rate of the coolants, flowing into the cooling tube increases the cooling performance and reduces the temperature of battery pack within the battery operating zone. The cooling performance using nanofluids increased by 40% as in comparison with water and ethylene glycol as coolants when tested experimentally.

Prediction on thermal performance of refrigerant-based battery thermal management system for a HEV battery pack

The thermal performance of refrigerant-based battery thermal management system (BTMS) for a real HEV battery pack in both the cooling and heating conditions is numerically and experimentally investigated in this paper. The heat generation model of battery cells and the numerical methodology for predicting the cooling performance of refrigerant-based cooling system are validated by experiments and the predicted results are consistent with experimental data. The effects of discharging C-rate, mass flow rate, initial temperature and vapor quality of refrigerant on thermal performance of battery pack are analyzed in detail. The thermal performance of refrigerant-based BTMS at a real driving cycle is also examined. The results indicate that the discharging C-rate has a significant impact on thermal performance of battery pack due to the distinctive heat transfer behaviors of battery pack at different discharging C-rates. Increasing mass flow rate of refrigerant is contributed to descend the maximum temperature and improve temperature uniformity of battery pack. Decreasing initial temperature of refrigerant is beneficial to reducing the maximum temperature of battery pack but is disadvantageous to temperature uniformity. The effect of vapor quality on thermal performance of battery pack is limited. The cooling performance of refrigerant satisfies the requirement of BTMS at the real driving cycle. The optimum heating power of the battery pack at heating condition ranges from 400 W to 460 W.

Thermal performance of lithium-ion battery thermal management system based on nanofluid

As the power source of EVs (Electric Vehicles), lithium-ion power batteries have severe requirements for the temperature of the working environment, which makes BTMS (Battery Thermal Management System) very important. A liquid cooling BTMS for 18,650 lithium-ion batteries is established. In order to improve the thermal performance, nanofluids with high thermal conductivity are introduced as coolants, and various kinds of nanofluids are compared with water in terms of their cooling effects on batteries. The best performing is Cu water-based nanofluid, which decreases by 12.6% relative to water in terms of maximum temperature difference of the battery pack, and by 1.066 K in terms of maximum temperature. Then, the influence of various parameters of nanofluids on the thermal performance of BTMS has been studied. The results show that the maximum temperature difference and maximum temperature of the battery pack decrease with the increase of volume fraction and flow velocity of nanofluids, but the pressure drop increases accordingly. The decrease of nanofluid temperature can reduce the maximum temperature of battery pack by 10 K, and the effect is remarkable. But in the same way, it also destroyed the temperature uniformity of the battery pack, and the maximum temperature difference once reached 8.333 K. The influence of cooling channel structure parameters on the thermal performance of BTMS has also been studied. Under the same condition of nanofluid flow velocity, the increase in contact angle at the folded back of the cooling channel can improve space utilization, but will reduce the minimum temperature of the battery pack and disrupt the temperature uniformity.

Liquid-cooled structure design and heat dissipation characteristics analysis of cross-flow channels for lithium batteries

A detailed three-dimensional thermal model is developed to examine the thermal behaviour of a lithium-ion battery. This model is a cross-flow liquid cooling model, which can make the heat dissipation of lithium-ion battery pack achieve higher safety. Two kinds of fluids are used for cooling, and the polynomial fitting function is used as the heat source term of lithium battery pack. The battery temperature distribution under the conditions of different Reynolds numbers, different numbers of micro-channel and different micro-channel radii are studied for this model. The simulation results show that the maximum battery temperature is 295.84 K, the minimum battery temperature is 293.14 K, and the maximum temperature difference of the battery pack is 2.7 K. The maximum temperature and temperature difference of the battery under the model are in line with the reasonable operating temperature range of lithium-ion battery pack. The maximum temperature of battery pack decreases with the increase of Reynolds number, but the effect of Reynolds number on heat dissipation of lithium-ion battery pack has a critical value. As the number of micro-channels increases, the maximum temperature of the battery string decreases. However, when the number of micro-channels increases to a certain value, the maximum temperature of the battery pack decreases slowly. The maximum temperature of the battery pack does not decrease monotonically as the radius of the micro-channel increases. Orthogonal analysis results show that the Reynolds number has the greatest influence on the cooling effect of the model, followed by the size of the micro-channel radius, and the number of micro-channels has the least influence. The optimized liquid cooling model can effectively reduce the maximum temperature of lithium-ion battery in theory, and the maximum temperature of lithium-ion battery decreases by 26.24 K in comparison with that of single battery at 2C discharge rate. The reliability of the cross-flow channel model is proved by numerical analysis, and it is also proved that the cross-flow channel has an equilibrium point between the perturbation gain and the flow retarding effect. The heat dissipation effect of lithium- ion battery pack is correlated with the number and radius of micro-channels, but not a single positive correlation. Reasonably increasing the number and size of micro-channels can effectively enhance the heat dissipation effect of battery pack.

Experimental and numerical study of employing Potassium poly acrylate hydrogel for thermal management of 500 Wh cylindrical LiFePO4 battery pack

One of the main challenges of employing lithium-ion batteries specially in large-scale applications is overheating due to the heat generation. In this work, the effect of using Potassium Polyacrylate, a superabsorbent hydrogel, on decrease in the maximum temperature inside a 500 Wh industrial pack consisting of 38,120 cells is studied. Experiments are performed for 1C and 2C discharge current rates. Due to experimental limitations, results for discharging battery pack at 3C rate are obtained by numerical simulation. Heat source term in simulation part of work is obtained based on the experimental data for different discharge rates. It was found that inserting hydrogel inside the battery pack leads to 3.9 °C, 7.5 °C and 10.9 °C decreases in the maximum temperature for 1C, 2C and 3C discharge rates, respectively. In addition, results revealed that the decreases in the temperature of the battery pack is considerably influenced by full filling of hydrogel at points near the edges. Moreover, the effect of distance variation between cells on the temperature distribution of the battery pack is numerically studied. The results demonstrated a significant advantage to employ hydrogel for controlling battery pack temperature compared to increasing distance between cells. Finally, to compare the effect of different parameters on the maximum temperature of battery pack, the sensitivity analysis was performed. Results showed that cell density and specific heat capacity play significant role on the pack thermal behavior.