Temperature Distribution Of Battery Research Articles

A novel hybrid liquid-cooled battery thermal management system for electric vehicles in highway fuel-economy condition

A hybrid liquid cooling system that contains both direct and indirect liquid cooling methods is numerically investigated to enhance the thermal efficiency of a 21700-format lithium-ion battery pack during the discharge operation. One of the most significant challenges that liquid-based direct cooling systems face is the filling of the heat capacity of the coolant during the cooling process, hindering the effective dissipation of heat generated from batteries. This paper aims to introduce a battery thermal management system to address this issue. In the present study, the influences of immersion and flow cooling methods using HFE-7100 and water (as working fluids), inflow velocities of cooling channel and tubes, parallel and counter flow, battery cell space, and highway fuel-economy test on the temperature distribution of batteries were studied comprehensively. Results highlight that immersion cooling with water outperforms due to the lower thermal conductivity of HFE-7100. In addition, Flow cooling significantly reduces the battery pack's highest temperature and non-uniformity compared to immersion. According to the numerical results, using cooling tubes as an indirect cooling system integrated with the direct flow cooling method can remarkably improve the thermal efficiency of the battery pack. Moreover, results exhibited that counterflow between cooling tubes/channels can keep the highest temperature and temperature variance of Li-ion battery package below 32.15 °C and 3.04 °C, respectively. Varying battery cell spaces shows that a 14 mm space reduces the battery package's highest temperature by 1.54 °C compared to a 10 mm space. Finally, highway fuel-economy condition is applied to the simulations of this study, illustrating the effect of an innovative hybrid battery thermal management system for a 21700-type Li-ion battery pack.

Locality Preserving Projections-Based Spatiotemporal Modeling of the Temperature Distribution of Lithium-Ion Batteries

The temperature distribution is one of the key factors affecting the safety, capacity fade, and optimal use of lithium-ion batteries (LIBs). However, it is a challenging task to develop an accurate approximation model for estimating this distribution, owing to the inherent nature of thermal processes, including time/space coupling, infinite dimensions, and strong nonlinearity. Therefore, this paper proposes a novel locality preserving projections (LPP)-based spatiotemporal modeling method to address this problem. First, an orthogonal enhanced LPP (OELPP) method is proposed for time/space decoupling. With this novel reduction dimension technique, the spatiotemporal temperature variables are separated into spatial basis functions (SBFs) and low-dimensional time variables. Then, to handle the temporal nonlinearity, a broad learning system with kernel-based manifold features (BLS-KMF) is designed to construct a dynamic temporal model. To improve the modeling performance, the kernel trick and the intrinsic manifold information are introduced to the proposed BLS-KMF to learn the mapped features. Finally, with the time/space synthesis, the battery temperature distribution can be reconstructed. Experimental results on a 32 Ah ternary lithium-ion battery illustrate the superior performance and effectiveness of the proposed method.

Inlet setting strategy via machine learning algorithm for thermal management of container-type battery energy-storage systems (BESS)

This research enhances the safety and efficiency of the container-type battery energy storage systems (BESS) through the utilization of machine learning algorithms. The decision tree algorithm and support vector machine (SVM) are employed to clarify the influence of cooling air on temperature distribution and predict the safety of battery modules. The results indicate that the flow rate of cooling air has significant impact on both the maximum temperature and temperature difference of the batteries, while the inlet temperature only affects the maximum temperature. Additionally, the distributed inlet setting strategy is introduced for the container-type BESS. The strategy effectively reduces the temperature of the target battery by 8.6 % and decreases the highest temperature in the BESS by 3.2 % without creating new hotspots. Comparing with the uniform inlet setting strategy, this strategy reduces the power consumption by 40 %, providing great efficiency for cost consideration. In conclusion, this research clarifies the relationship between the conditions of cooling air and the temperature distribution of batteries using the machine learning algorithms, and introduces the distributed inlet setting strategy to prevent thermal runaway in the BESS with less power consumption.

Steady and transient sensitivity investigations on a passive battery thermal management system coupling with phase change materials and heat pipes: Full numerical modeling and orthogonal tests

For safety reasons, the temperature distribution of the battery pack should be kept within a reasonable range. Therefore, in the present research, a passive battery thermal management system (BTMS) coupling with phase change material (PCM) and heat pipes (HP) was proposed. Full CFD (Computational Fluid Dynamics) models validated well by the experimental results were adopted for this research. Firstly, the sensitivity of parameters such as PCM type, PCM thickness and ambient temperature on the thermal performance of BTMS was obtained by orthogonal tests. Numerical results show that the greatest influence on the maximum temperature is the ambient temperature. In the variance analysis showed that the PCM thickness has a significant effect on decay the battery temperature difference. Furthermore, operational range and variance analysis confirmed the optimal BTMS, i.e., with PCM3 thickness of 3 mm and ambient temperature of 30 °C. Subsequently, transient modeling and analysis of the battery discharge process were carried out. Unsteady results showed that the maximum temperature of the battery was reduced from 68.90 °C to 43.19 °C, and simultaneously, the maximum temperature difference dropped from 16.58 °C to 3.66 °C. In the process of battery discharge, PCM was properly adjusted regarding of its thickness; whereas, its melting temperature should be kept approaching to the ambient temperature, which was beneficial to the operational safety of the battery. In addition, temperature distribution of the battery has a linear relationship to the ambient temperature; when every 5 °C increase was observed in ambient temperature, the maximum temperature of the battery was boosted by 2.3 °C and the temperature difference was reduced by 1.2 °C, separately. Present research, straightforwardly maintaining the temperature distribution of the power battery in a safe and efficient range, could be significant for improving energy utilization and reducing extra energy consumption of the power battery, simultaneously.

A numerical study of battery thermal management system with square spiral ring-shaped liquid cooling plate

The battery thermal management system is critical to the operating safety of power batteries. To alleviate the temperature gradient effect caused by the high local temperature of the battery, a centrally dispersed square-spiral-ring (SSR) mini-channel liquid cooling plate is designed for power batteries in this study. Through the simplification of the battery model, this liquid cooling plate battery thermal management system is investigated numerically. The effects of the number of SSR channel laps, channel width, channel bend radius and inlet mass flow rate on the temperature characteristics of the battery and coolant pressure drop are investigated. The results indicate that increasing the SSR channel laps and narrowing the channel width have a beneficial role in improving the battery and liquid cooling plate temperature distribution. The maximum battery temperature can be significantly dropped and the uniformity of battery temperature distribution can be considerably improved by enhancing the inlet mass flow rate. Moreover, additional branch channels could further improve the uniformity of the temperature distribution and the gradient effect of the battery. The maximum temperature decreases to 33.63 °C and the maximum temperature difference reduces to 6.45 °C during the 2C discharge process at a temperature of 25 °C. Furthermore, the SSR liquid cooling plate with a 5 mm-wide branch channel enables lower maximum battery temperatures and better temperature uniformity with lower pump power consumption than the existing serpentine plate. All these results and evidence provide an option for the development of novel mini-channel liquid cooling plates for battery thermal management.

Non-uniform heat generation model of pouch lithium-ion battery based on regional heat generation rate

The non-uniform distribution of temperature seriously affects the cycle performance, cycle life and safety of the pouch lithium-ion batteries. In this paper, a dynamic non-uniform heat generation model is developed to the high complexity and low precision of the modeling and characterization of dynamic non-uniform thermal characteristics of the pouch battery. Firstly, the regional heat generation rate of different regions is estimated by the particle swarm optimization based on the cell surface temperature to build a non-uniform heat generation model. Then, the battery's temperature distribution characteristics and heat generation distribution characteristics under the effect of ambient temperature, state of charge and discharge rate are analyzed. Furthermore, combined with the three-dimensional heat transfer equation, a three-dimensional heat model with non-uniform a heat source is modeled by COMSOL, the dynamic non-uniform temperature distribution of the battery is simulated at different ambient temperatures and discharge rates, and then the local temperature at any location of the battery is obtained. Finally, the simulated value of the local temperature is compared with the experimental value, and the average error under constant current discharge condition is less than 1 °C, and the relative error under dynamic current condition is less than 3 %. The result shows that the model can accurately estimate pouch lithium-ion batteries' dynamic non-uniform heat generation distribution under different working conditions.

Optimal-Sensing-Based Recursive Estimation for Temperature Distribution of Pouch-Type Batteries

Real-time monitoring of the battery temperature distribution is essential in developing advanced thermal management systems. This work proposes a recursive temperature field estimation methodology for pouch-type batteries under optimal deployment of limited sensing. First, we utilize the time/space (T/S) spectral expansion to mathematically derive a physics-based dynamic model considering uncertainty from the complex thermal process. Then we find the optimal sensor placement through the observability degree of the system quantified by the attenuation rate of estimation error (AREE). Finally, we perform model-based temperature field estimation, whose performance is boosted by favorable measurements from layout-optimized sensors. Experimental studies indicate the validity of the proposed method.

Numerical research on lithium-ion battery thermal management utilizing a novel cobweb-like channel cooling plate exchanger

As a key component of a pure electric vehicle, the battery in an overheated state will have a direct impact on battery life and vehicle safety. To promote battery heat dissipation, a novel cobweb-like type (C-type) channel cooling plate with asymmetric inlet and outlet is designed. The C-type channel cooling plate is numerically simulated in two coolant flow directions (Ifd and IIfd), using the computational fluid dynamics software STAR-CCM+, and compared to the conventional serpentine type (S-type) channel. Meanwhile, the effects of three structural parameters (channel diameter, spacing, and cooling plate thickness) on maximum temperature and temperature difference of the C-type cooling plate, and pressure drop are investigated. Based on this, the C-type channel is optimized by orthogonal test. The results show that the C-type with IIfd coolant flow direction has a better heat dissipation effect on the battery module than the C-type with Ifd and S-type under the same conditions, and the maximum temperature and temperature difference are respectively reduced by 0.2% and 17.8%, while the pressure drop is increased by 17.3%. In addition, increasing channel diameter can obtain good battery temperature distribution and smaller pressure drop, while the increase of cooling plate thickness and channel spacing has a greater effect on the battery temperature difference compared to the change of maximum temperature. Finally, the results of the orthogonal tests show that the cooling effect is best when the diameter of the cobweb-like channel cooling plate is 7 mm, the thickness of the cooling plate is 12 mm, and the channel spacing is 16 mm, and the maximum temperature and temperature difference are reduced by 0.7% and 6.8%, respectively, and the pressure drop is reduced by 37.6% compared to the initial cobweb-like channel scheme. This offers a fresh perspective on cooling plate channel design in liquid-cooled battery thermal management.

Variable duty cycle heating strategy based online two-dimensional model for self-heating lithium-ion battery

It is a challenge to online obtain the time-varying temperature distribution of self-heating lithium-ion battery (SHLB), which results in a lack of theoretical basis for heating strategies to optimize heating time and temperature distribution uniformity. To reveal the evolution of temperature distribution and improve the temperature distribution uniformity of SHLB during heating, a variable duty cycle heating strategy with online two-dimensional model is proposed. Distributed thermal equivalent circuit model coupled with electrical model can obtain the two-dimensional temperature distribution of battery in real-time. The results show that the maximum temperature gap between the proposed model and the finite element model (FEM) is only 1.2 °C, while 90 % of the calculation time is saved. The proposed model can calculate the temperature distribution almost as accurately as FEM under different conditions. Based on the proposed model, heating currents of different values and duty cycles are applied to investigate their effects on the temperature distribution evolution of SHLB. Finally, we propose a variable duty cycle heating strategy that can automatically switch the duty cycle of the heating current according to the heating uniformity requirements in order to consider both heating time and the temperature distribution uniformity. The results show that compared with constant duty cycle heating, the variable duty cycle heating strategy can reduce the temperature difference by 35 % and limit the temperature difference to the pre-set boundary. The proposed strategy and method have considerable potential for use as improved temperature uniformity in battery management system.

An evaluation of surface temperature distribution under different charging and discharging modes of the lithium-ion phosphate battery using Thermal Imaging

This study aims to determine the thermal behavior of lithium-ion phosphate (LiFePO4) 20Ah battery by Thermal imaging. This study focuses on day/night charging and discharging to the battery's temperature distribution. The thermal gradient of battery, LiFePO4 powered bike at different speeds 30kmph, 40kmph, 50kmph both load and without load condition. The spatial distribution of LiFePO4 cells was not stable during the discharging process. No significant temperature rise was recorded at the end of the discharge. During the range test at 30kmph, 40kmph, and 50kmph, the maximum surface temperature reached 47.90℃, 44.20℃, and 46.70 ℃, respectively. The battery's front view was most of the highest surface temperature region. The result shows thermal imaging is an effective tool to predict the temperature behavior of batteries and provide a better thermal management system in battery development

Simulation study of a cylindrical battery module

Currently, batteries are widely used in the new energy industry, but battery heating is inevitable, and in order to increase the heat dissipation arrangement, it not only occupies the limited vehicle volume but also increases the body weight. Considering that the battery module is a part of the electric vehicle structure, the long cylindrical lithium battery module structure is proposed in order to reduce the weight of the vehicle body and increase the driving range of the vehicle. The larger the surface area of the battery module, the better the heat dissipation capability compared to the heat dissipation capability of a conventional battery module. The battery temperature distribution in the liquid-cooled model is obtained by simulating the temperature distribution of the battery module in the vehicle at the maximum discharge rate and the maximum charge rate. Reflects the trend and connection of battery temperature and temperature difference for the design of battery modules.

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.

Parameters of liquid cooling thermal management system effect on the Li-ion battery temperature distribution

In order to investigated the influence on the liquid cooling system cooling effect by changing the structural parameters, single Li-ion battery heat generation model is conducted, and used in following simulation. Subsequently, sixteen models are designed by orthogonal array, and the results are obtained by extremum difference analysis, which can quantify the influence degree, identify major and minor factors, and find the relatively optimum combination. Finally, different channel entrance lay-out is adopted to investigated. With a series of work, the effective of single battery heat generation model is proved by the discharge experiment. The coolant velocity has most evident influence on the Li-ion battery temperature rise, rectangular channel aspect ratio is second one, and the heat conducting plate thickness has the smallest influence. Similarly, for Li-ion battery temperature difference, the effect of heat conducting plate thickness and rectangular channel aspect ratio as the same, both are secondary factor, and coolant velocity is main factor. With different channel entrance lay-out, both the maximum temperatures denote a same upward trend, and better balance temperature distribution is obtained by adopt Case C system which with alternating arrange channel entrance lay-out.

Thermal simulation and prediction of high-energy LiNi0.8Co0.15Al0.05O2//Si-C pouch battery during rapid discharging

Accurate thermal simulation of lithium-ion batteries is of great significance for evaluating and predicting the battery performance to avoid safety hazards. In this paper, research focused on the effects of current rates and ambient temperature on the thermal behavior of high-energy LiNi0.8Co0.15Al0.05O2//Si-C pouch battery is presented. The heat generation rate as a function of discharge rate is calculated by the means of electrochemical calorimetric study. Then by using the finite element analysis method, a three-dimensional model is developed to predict the battery temperature distribution at different discharge rates (0.33, 1.0, 3.0, and 5.0 C). The results reveal a minimum temperature difference of less than 1 °C between simulations and experiments even at 5.0 C rate. Notably, the increased rate leads to an enlarged temperature gradient field of battery, where the maximum battery temperature appears at its geometric center, then it gradually decreases from the center to edges in an annular gradient radiation manner. Accordingly, the simulation results provide a comprehensive evaluation and prediction for the thermal behavior of high-energy battery, which are well consistent with the experimental measurements.

Effect of non-conjugate and conjugate condition on heat transfer from battery pack

Li-ion battery packs provide high energy density but with a concern of thermal management. Hence cooling mechanism is necessary to have a good life and reliability on the battery system. The main objective of this article is to investigate the effect of conjugate and non-conjugate boundary conditions on battery pack heat transfer characteristics. In conjugate conditions, coolant flow is considered with heat flux continuity at the battery and fluid interface. In non-conjugate condition, just convection condition is adopted. The finite volume method is adopted for the numerical analysis, and a code is written for computations of the governing equations. Effects of different parameters like heat generation, conductivity ratio, coolants, and Biot number on temperature distribution in the battery pack are analyzed. The maximum temperature contours are located near the top end of the battery, whereas at the bottom end, the battery's temperature is low. Such high and low-temperature regions in the battery pack create uneven thermal stresses, resulting in battery failure. To have better performance results for the battery system, one should maintain the proper balance of thermal conductivity between the solid and fluid domains. From comparative analysis it is found that the non-conjugate condition gives the temperature distribution in battery to be of symmetrical nature and more uniform. Practically, this is not true which is confirmed by the realistic conjugate condition where the high temperature zones are closer to the trailing edge of the battery pack. Liquid metals and nanofluids provide a much safer operating temperature of the pack where the maximum temperature is well below the critical temperature. The application of conjugate condition for battery thermal analysis leads to be have an insight of the hotspot zones accurately which are operated using conventional fluids mentioned in this work.

Multi-objective design optimization of battery thermal management system for electric vehicles

• Genetic programming shows reliable surrogate modelling. • Properties of liquid-based battery thermal management system are analyzed. • Cooling plate design and inlet coolant velocity are the main factors affect the temperature uniformity and pressure drop. • The pressure drop has been significantly optimized with the proposed optimization framework. Lithium batteries are commonly used as the primary power storage unit for electric vehicles, and their performance is sensitive to temperature. Thus, the battery thermal management system is crucially needed to allow the EVs to work safely and efficiently. This paper mainly focuses on the performance analysis and design optimization of the battery thermal management system with a U-shaped cooling channel. A Computational fluid dynamics model of a battery thermal management system is built to study the battery temperature distribution and pressure distribution. Through the establishment of the genetic programming model, sensitivity analysis and parameter interaction analysis are carried out to analyze the influence of cooling plate thickness, cooling plate wall thickness, inlet coolant temperature and flow velocity on the comprehensive performance of the battery thermal management system. A new surrogate-assisted multi-objective optimization scheme is proposed by introducing an integrated AI system that includes a surrogate battery model built with genetic programming (GP) and a design optimizer driven by the second-generation non-dominated sorting genetic algorithm (NSGA-II). Results show that the inlet coolant temperature has the most significant influence on the rise of battery temperature (59.87%) but has no influence on the pressure drop. The structural parameters of the cooling plate and the velocity of the inlet coolant have apparent effects on the uniformity of the battery temperature distribution and the pressure drop. The battery thermal management system achieves an ideal comprehensive performance when the thickness of the cooling plate is 4.50 mm, the thickness of the cooling plate wall is 1.49 mm, the inlet coolant temperature is 298.15 K, and the inlet coolant velocity is 0.29 m/s. Under such optimized parameter settings, the max temperature rise of the battery reduces from 7.72 K to 7.69 K, the standard deviation of the temperature distribution 2.54 K (a drop of 0.02 K), and the pressure drop decrease from 1022.1 Pa to 436.43 Pa (decrease by 57.3%). Such results have guiding significance for the design of the battery thermal management system with a U-shaped channel and the application of genetic programming in system performance analysis and optimization.

TSSR algorithm based battery space optimization on thermal management system

ABSTRACT In recent years, the Li-ion batteries have received substantial consideration for the use of electrical vehicles and mobile electronics because of its excellent life span and high specific energy. It is necessary to connect the battery cells in series or parallel to obtain the essential power. In such cases, certain safety issues namely heat dissipation and rise in temperature must be taken into consideration. The excess temperature in Li-ion batteries affects the working performances to a very large extend. To address such issues, this paper proposes a TSSR based battery thermal management system using ANSYS FLUENT to obtain optimal battery spacing. The tunicate swarm as well as the search and rescue optimization algorithms are combined together to form a tunicate swarm search and rescue (TSSR) algorithm. Here, the battery spacing is optimized by employing TSSR optimization algorithm thereby minimizing the rate of heat transfer in the battery packs independent of specific heat capacity. The CFD model is employed since it plays a significant role in the simulation of battery temperature distribution to examine the battery thermal management system (BTMS). Finally, 10 different test functions are applied to the proposed TSSR algorithm to demonstrate its efficiency and applicability. The performance evaluation and the comparative analysis are carried out and the results reveal that the proposed approach provides optimal battery spacing thus the cooling performances of the battery packs are enhanced.

Performance simulation of a heat pipe and refrigerant-based lithium-ion battery thermal management system coupled with electric vehicle air-conditioning

• A study is conducted on a novel heat pipe and refrigerant-based BTMS. • System performance is evaluated in temperature distribution, energy, and exergy. • Effect of different preset temperatures of the battery module is analyzed. • The performance optimization direction of the BTMS is pointed out. A battery thermal management system (BTMS) is crucial to ensure the safety and efficiency of electric vehicles (EVs). With the increase of battery energy density and the development of fast charging technology, a more compact and controllable BTMS is imperative for EVs to alleviate the thermal issues. In this study, a novel heat pipe and refrigerant-based BTMS coupled with an air-conditioning system is proposed for a battery module. The battery temperature distribution, energy efficiency, and exergy efficiency of the BTMS are numerically investigated under different ambient temperatures and battery heat generation rates. Besides, the effect of different preset temperatures of the battery module on the performance of the BTMS is explored. The results indicate that the maximum temperature of the battery module can be controlled at the preset temperatures (25 °C, 30 °C, and 35 °C), and the temperature difference among battery cells can be well guaranteed within 3 °C. Besides, increasing the preset temperature can improve the energy efficiency and exergy efficiency of the BTMS. When the preset temperature is increased from 25 °C to 30 °C and 35 °C, the average coefficient of performance increased by 16.95% and 38.41%, respectively; and the average exergy efficiency of the BTMS increased by 2.63% and 5.07%, respectively. Further, reducing the superheat at the outlet of the refrigerant pipelines and using a more efficient compressor are recommended to improve the performance of the BTMS. This paper aims to provide insights to the design and optimization of the BTMS in EVs.

Effect analysis on heat dissipation performance enhancement of a lithium-ion-battery pack with heat pipe for central and southern regions in China

A heat pipe (HP) heat dissipation model of a lithium-ion-battery pack is established for the climate in the central and southern regions in China, and the heat transfer effects of various fins with different spacing and thickness are investigated. According to the change of heat dissipation, inlet and outlet pressure difference and average heat transfer coefficient with fin spacing and thickness, the relatively optimal heat dissipation fin structure parameters are determined, and the battery temperature distribution and temperature change under different discharge rates of the battery pack in a high temperature environment, and the characteristics of the HP heat dissipation battery thermal management system(BTMS) are analyzed and the effects of HP-based BTMS on battery startup heating in low temperature are evaluated. The results show that the optimal parameters are that the fin spacing is 5 mm, the thickness is 2 mm, the air flow velocity varies from 4 to 16 m/s, and the average heat transfer coefficient is 7.6–11.9 W/(m·K). The battery pack using the HP can reach the proper temperature of 288.15 K in 682s, 615s, and 375 s at 1C, 2C, and 4C discharge rates respectively.

Nusselt number analysis from a battery pack cooled by different fluids and multiple back-propagation modelling using feed-forward networks

In this article, analysis of average Nusselt number (Nuavg), which indicates the heat removal from the battery pack cooled by flowing fluid is carried out considering coupled heat transfer condition at the pack and coolant interface. Five categories of coolant, mainly gases, common oils, thermal oils, nanofluids, and liquid metals, are selected. In each coolant category, five fluids (having different Prandtl number Pr) are selected and passed over the Li-ion battery pack. The analysis is made for different conductivity ratio (Cr), heat generation term (Qgen), Reynolds number (Re), and Pr. Pr varying in the range 0.0208–511.5 (25 coolants) and Cr for each category of coolant having its own upper and lower limit are used to analyze the heat removed from the battery pack. Using single feed-forward network and integrating two feed-forward networks having multi-layers with back-propagation is employed for artificial neural network (ANN) modelling. In this modelling, the concept of the main network and space network is devised for multiple back propagation (MBP). The numerical analysis revealed that the temperature distribution in battery and fluid is greatly affected by increasing Cr. The maximum temperature located close to the upper edge of battery is found to get reduced significantly with the increase of Cr, but upto a certain limit above which reduction is marginal. The analysis carried out reveals that Cr and Qgen have no role in improving Nuavg while Pr and Re vary it significantly in each step. Moreover, Nuavg is found to increase with Re continuously irrespective of any Cr and Qgen. While, for oils with an increase in Pr and Re, Nuavg was found to reduce significantly. Nanofluids are found to be more effective in improving heat transfer from the battery pack when cooled by flowing nano-coolants over it. The MBP networks proposed are successfully trained, and hence they can be used for prediction of Nuavg.