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Battery thermal management system (BTMS) is essential for maintaining batteries in electric vehicles at a uniform temperature. The aim of the present work is to propose most suitable cooling for BTMS. The most significant factors in battery thermal management are operating temperature, reliability, safety, and battery life cycle. The experimental setup is designed and fabricated for that purpose. In experimental work, thermal performance parameter, i.e. variation of maximum cell temperature in battery pack with natural and forced convection, is studied and compared at three different charging rates low (1 C), moderate (2 C), and high (3 C). The numerical model for natural and forced convection battery thermal management is developed using Ansys 22.1. For the present work, the cylindrical cell Li-ion battery pack is considered and simulates the cooling effect due to natural convection and forced convection. For the various flow rate of air, the cooling effect is investigated and efficient flow velocity is obtained by a numerical model for two climatic conditions. Further, the cooling performance of the battery pack with and without fin for optimum velocity is simulated. Based on experimentation, it is seen that forced convection gives better results as compared to natural convection. The temperature drops from 60.46 °C to 43.03 °C (28.82%) at 1 C, 65.81 °C to 48.01 °C at 2 C (27.06%), and 67.05 °C to 50.4 °C (24.77%) at 3 C heat generation rate when forced convection is used for cooling purpose. In the numerical studies, charging of Li-ion cell at 1.5 C rate is studied. Using forced convection maximum temperature is reduced by 27.26% when the inlet velocity is kept 2 m s−1 when ambient is 27 °C. Using fin, battery cell maximum temperature is reduced by 39.23%, as compared with natural convection. Using fin at 27 °C atmospheric temperature, battery cell maximum temperature is reduced by 39.23%, as compared with natural convection, and when the atmospheric temperature reaches to 41 °C, the maximum temperature is reduced to 51.26 °C (12.75%). [ABSTRACT FROM AUTHOR]

Vanadium redox flow batteries are recognized as well-developed flow batteries. The flow rate and current density of the electrolyte are important control mechanisms in the operation of this type of battery, which affect its energy power. The thermal behavior and performance of this battery during charging and discharging modes are also important. As a consequence, the aim of this investigation is to deeply study the impact of different working parameters on the temperature distribution and state of charge of these batteries. To achieve these goals, a single battery thermal model is established. The effects of various operating parameters, including working temperature, molar concentration, flow rate, and current density of the electrolyte, on the thermal behavior, state of charge, and performance of this type of battery are investigated. It is observed that the temperature distribution of high flow rate (90 mL min−1) is more uniform than that of other flow rates (30 and 60 mL min−1). In the end of the discharging mode, the battery voltage performance increases with the increase in the electrolyte flow rate. The temperature distribution of high current density (80 mA cm−2) is relatively uneven, and the local heating is produced at the battery outlet. The end time in the charging and discharging modes for the case of the high current density (80 mA cm−2) is faster than other current densities (20 and 40 mA cm−2). [ABSTRACT FROM AUTHOR]

The present study aims to evaluate the feasibility of a novel dual-evaporator loop heat pipe (DE-LHP) in battery thermal management systems (BTMS). A 3S4P (3-series and 4-parallel) Li-ion battery module with a 12.6 V and 10 Ah capacity is made and tested under various C rates for different environmental conditions. The battery generates an average heat of 11.28 W@1C and 24.44 W@1.5C with 100% discharge and 43.36 W@2C with 50% discharge at an ambient temperature of 30 °C. An increase in temperature from 30 to 40 °C results in a decline in the depth of discharge. The proposed DE-LHP is evaluated using deionized water with filling volumes of 12, 16, 20, and 24 mL. The DE-LHP started working above 5 W regardless of the filling volume, and before the evaporator reached dry-out, the DE-LHP transferred heat loads of 10, 30, 35, and 55 W with filling volumes of 12, 16, 20, and 24 mL, respectively. At a heat load of 30 W, the evaporator section of the 20-mL filled LHP demonstrated a minimum thermal resistance of 0.274 KW-1, while the condenser section exhibited a minimum thermal resistance of 0.372 KW-1 at a heat load of 35 W. The DE-LHP is found to be effective in transferring heat of 35 W to keep the module temperature below 60 °C. Based on these initial findings, it is suggested that incorporating the multi-evaporator LHP-based BTMS could be a feasible and efficient solution for the thermal management of battery modules/packs for electric vehicles. [ABSTRACT FROM AUTHOR]

The thermal management of the batteries in electrical and hybrid vehicles is a major concern for operation safety, battery life, and performance. In the current research, the temperature of the battery is tracked for 10,000 s of operation while using a Ranque–Hilsch vortex tube (RHVT) for the thermal management of the battery. An analytical model is developed and validated to study the impact of the heat generated per unit volume from the battery, the mass ratio for the cold air at the outlet to the total air at the inlet (x), entered air pressure, temperature, and mass flow rate. The peak temperature of the battery can be reduced by increasing the pressure and mass flow rate of the air at the inlet, decreasing the temperature of the air at the inlet, and using four RHVTs instead of a single RHVT. The proposed system significantly decreased the maximum temperature of the battery to 48.12 °C, compared to the battery thermal management method of using direct air, which resulted in a temperature of 75.73 °C. Furthermore, employing four RHVTs to cool the battery further reduced the maximum temperature from 48.12 to 11.23 °C, demonstrating a substantial improvement compared to utilizing a single RHVT. Utilizing the RHVT provides a good solution for the battery thermal management problem because it is cheap, small, and reduces the temperature of the air rapidly. [ABSTRACT FROM AUTHOR]

In this paper, a 60Ah lithium-ion battery thermal behavior is investigated by coupling experimental and dynamic modeling investigations to develop an accurate tridimensional predictions of battery operating temperature and heat management. The battery maximum temperature, heat generation and entropic heat coefficients were performed at different charge and discharge cycles with various state of charge (SOC) ranges and current. The results show that the developed model presents an accurate prediction in dynamic and quasi stationary regimes. Three SOC zones were identified during charge / discharge processes for which the entropic heat coefficient was endothermic or exothermic. The cycle initial state of charge impacts the battery operating temperature and heat dissipation which reduces by 13% for starting cycle with the battery discharge process. The highest battery temperature and energy amount were obtained for the battery SOC higher than 80%. Increasing the range of the battery SOC leads to increase the reversible and irreversible heat but the battery maximum temperature rise becomes stable for SOC ranging from 20 to 80%. Based on the experimental data, the new correlations were proposed for the battery maximum temperature, heat generation, entropic heat coefficients, and internal resistance for charge/discharge state. The proposed correlation estimates heat generation with high accuracy lower than 10% compared to the measurements. [ABSTRACT FROM AUTHOR]

This review of the literature explores the potentials of liquid micro-/mini-channels to reduce operating temperatures and make temperature distributions more uniform in batteries. First, a classification and an overview of the various methods of battery thermal management are presented. Then, different types of lithium-ion batteries and their advantages and disadvantages are introduced, and the components of batteries are described in detail. The studies conducted on the performance of micro-/mini-channels for cooling all types of rectangular and cylindrical batteries are reviewed, and the key finding of these studies is presented. It is shown that, in general, using counterflow configuration creates a rather uniform temperature distribution in the battery cell and keeps the maximum temperature difference below 5 ∘ C . The lowest battery maximum temperature is obtained for parallel and counterflow configurations in the straight and U-turn channels, respectively. In a parallel configuration, the peak point of the battery temperature is in the outlet area. However, in the counter-flow configuration, it occurs in the central region of the battery module. The survey of the literature further reveals that proper channel paths and flow configurations keep the battery maximum temperature within the safe range of 25 ∘ C < T max < 40 ∘ C . For such flow configurations, the pressure drop remains minimally affected. [ABSTRACT FROM AUTHOR]

A large amount of storage may cause large-scale fire or explosion accidents due to the potential fire risk of lithium-ion batteries, which poses a great threat to the safety of personnel and property. In this study, the fire model of an individual cell is established according to the experimental data and the relevant parameters of thermal runaway simulation of large capacity battery are determined. The battery pack model is established according to the real setting of a warehouse. The fire characteristics of the battery pack spreading around in the warehouse environment are studied. The results show that the fire of lithium-ion batteries is preferentially diffused to the upper battery pack in the warehouse environment, and spread to the upper battery pack 19 s after the initial battery thermal runaway. The fire propagation of the horizontal battery pack is greatly affected by the distance. The farther the battery string is from the thermal runaway battery, the later the fire propagation battery string occurs. Furthermore, the role and effect of battery pack spacing, fire warning and automatic sprinkler system in fire are provided, so as to carry out better research on the storage safety of lithium-ion battery warehouses. [ABSTRACT FROM AUTHOR]

The dynamic response characteristic is an important performance indicator of the proton exchange membrane fuel cell (PEMFC), which has a great influence on the durability and reliability. The cooling capacity is an important factor that affects the stability of the PEMFC output after the change. This research proposes to apply the micro-heat pipe array (MHPA) to the thermal management of PEMFC. A novel MHPA-PEMFC stack is designed, and four cases involving comparative dynamic response experiments are studied. The results show that compared with the traditional air-cooled PEMFC, the MHPA-PEMFC significantly reduces the maximum step voltage, dynamic internal resistance and step temperature, shortens the temperature response time and improves the internal temperature uniformity. In the case where the output current stepped up from 10 to 30 A, the maximum step voltage and the maximum dynamic impedance of MHPA-PEMFC are lower than those of PEMFC by 0.449 V and 0.037 Ω, respectively. The maximum step temperature has been reduced by 4.44 °C, and the temperature response time has been reduced by 180 s. The research results provide a basis for using MHPA in PEMFC thermal management applications. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries should continuously be operated at the optimum temperature range 15 ∼ 40 ∘ C for the best performance. Surface temperature monitoring is critical for the safe and efficient operation of the battery. In this study, initially, the electrical parameters of the battery are determined by applying a second-order equivalent circuit model. This model then is integrated with a thermal model based on the temperature dependent behavior of the electrical parameters and the heat generated. The input parameters to the electro-thermal model include the current, the ambient fluid temperature and the output parameters include the terminal voltage, state of charge, cell core temperature and cell surface temperature. In this research, the entropic coefficient and battery thermal parameters have been taken into consideration concurrently, which will lead to both saving plenty of time and cost compared to other methods. The accuracy of the suggested analytical approach for estimating the surface temperature and the amount of heat generation is validated with the pulse-rest tests of an 18,650 cylindrical lithium-ion battery with a nominal capacity of 2600 mAh at three different ambient temperatures and three charge/discharge current rates. The comparison of results indicate that the maximum error of the proposed algorithm is about 0.6 K under a wide range of test conditions. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries have high energy density, excellent life cycle, and low self-discharge characteristics, but their performance is sensitive to temperature. In particular, the performance of lithium-ion batteries is degraded, and the internal resistance increased may prevent the battery from operating such as charged or discharged at subzero temperatures. Therefore, the study of thermal stability of lithium-ion batteries at low temperatures is as important as the battery thermal safety problem at high temperatures. In this paper, an analysis of preheating methods for battery packs designed for aircraft engine startup in low-temperature environments is conducted. The battery pack was designed by the design constraints that assumed ambient of −32 °C. The preheating is carried out using external heating for operation of the battery pack in low-temperature environments. Sixteen resistance heaters are installed inside the battery pack, which consists of 112 cylindrical lithium-ion cells. In addition, for effective heating of cylindrical battery cells, the battery cells are inserted inside the aluminum square battery tray, and the resistance heaters are attached sides of the battery tray for heating it. The thermal analysis when the designed preheating method was applied was carried out to review thermal distributions such as temperature uniformity of batteries according to heating. The heating volume of the resistance heater and the modification of the aluminum tray was considered, and the modified design method provided additional cell temperature homogeneity within the battery pack, resulting in thermal management strategy to use the battery pack in low temperatures. [ABSTRACT FROM AUTHOR]

Overcharge is a common case of battery thermal abuse, which can accelerate the aging of battery and cause the attenuation of battery capacity. In extreme conditions, overcharge can generate a large amount of heat, leading to battery failure and thermal runaway. Therefore, it is necessary to take measures to improve the safety during the overcharge process. In this paper, phase change materials (PCMs) are used to mitigate the temperature of overcharged lithium-ion batteries (LIBs), which proves that PCMs can effectively reduce the battery surface temperature as well as the probability of thermal runaway. In order to identify the appropriate PCM on the thermal management of overcharged LIBs, PCMs with phase change temperatures (PCTs) of 37°C, 43°C, 58°C are used in the tests. The results show that the PCM-37 exhibits the best performance. In addition, different degrees of overcharge also bring different effects to the battery, while the applications of PCMs can well mitigate the sharp increase in temperature. The findings demonstrate the feasibility of PCMs on improving the thermal safety of overcharging LIBs and further provide guidance on the development of more efficient battery thermal management systems (BTMSs) where the overcharge usually occurs. [ABSTRACT FROM AUTHOR]

Oscillating heat pipes (OHPs) are applicable in different energy systems such as solar collectors, desalinations and fuel cells as thermal mediums or thermal management devices. Thermal resistance of OHPs is affected by different elements including the architecture of OHP, filling ratio, heat load and operating fluid. Depending on the operating temperature range, appropriate working fluid is used. Acetone is one of the fluids that is applicable for the OHPs working in low or medium temperatures. Performance modeling of OHPs can be conducted by employing numerical simulation and data-driven methods. Utilizing powerful data-driven methods can be preferred in terms of time consumption and computational cost. In the present article, two types of artificial neural network, multilayer perceptron (MLP) and group method of data handling (GMDH), are utilized for thermal resistance modeling of OHPs filled with acetone under various working conditions. To find the models with the highest possible accuracy, different architectures are considered in this work. Models' outputs revealed that the thermal resistance of the aforementioned OHPs can be reliably predicted by using the abovementioned methods. R-squared of the models proposed by using MLP and GMDH are 0.989 and 0.965, respectively. Values of mean squared errors for the mentioned methods are around 0.0045 and 0.0144, respectively. [ABSTRACT FROM AUTHOR]

Hybrid nanofluid is a new revolutionized cooling liquid with improved thermo-physical properties as compared to conventional coolant. This paper presents the feasibility of hybrid Al2O3–SiO2 nanofluids as an advanced coolant for PEM fuel cell application in terms of thermal–electrical–hydraulic thermo-physical properties. Nine mixture ratios of Al2O3–SiO2 were used in this experiment, ranging from 10:90 to 90:10 mixture ratios. The result demonstrated that both thermal conductivity and electrical conductivity decreased as the percentage of Al2O3 was increased in the mixture. In contrast, the dynamic viscosity property increased as the Al2O3 percentage ratio was increased. In summary, property enhancement ratio (PER) of thermo-hydraulic (PERt/v) and thermo-electrical (PERt/e) was established. Both PERt/v and PERt/e analyses favor 10:90 ratio of Al2O3–SiO2 hybrid as the most feasible ratio for the implementation in PEMFC. This is due to the dominant effect of thermal over viscosity and electrical conductivity. [ABSTRACT FROM AUTHOR]

Influence of certain experimental factors and methods of data processing on the correctness of the resultant kinetics is considered on the basis of dynamic model of differential scanning calorimeter, DSC. Firstly, essential effect of sample temperature deviation from linearity or from constant outer temperature due to heat accumulation in the sample on reaction proceeding is discussed. Disregard of this effect may and will be one of the reasons of obtaining the inadequate kinetics. The method for calculation of sample temperature deviation (reconstructing sample temperature) is proposed. Secondly, influence of a DSC curve distortion due to thermal inertia of the cell on the results of kinetic analysis is considered. The method for correction of this distortion (data deconvolution) is presented which can be safely used for processing of data of kinetic experiments. Special attention is paid to the importance of data deconvolution when the kinetic experiment is carried out under isoperibolic conditions. Finally, the combined effect of temperature deviation and inertia-induced distortions is considered. It should be emphasized that the matters considered are especially important when energetic materials are tested due to big heat release and rate of heat generation. At first, all the matters are discussed on the basis of simulated data. This allows elimination of various uncertainties of real experiment and influence of unknown kinetic model and gives vivid illustration of the subject. Then, the effects are demonstrated on the basis of real experimental data. Both the model-free and model-based kinetics evaluation methods were used. The simple method is proposed which allows vivid cross-verification of both these types of kinetics. [ABSTRACT FROM AUTHOR]

This paper presents a unique thermal control strategy to improve the ageing of the battery and to maintain the internal temperature of the battery within the optimum limit of 20 °C–40 °C for electric vehicle (EV) applications. The hybrid EV system encompasses photovoltaic (PV) module, high power density device supercapacitor (SC) and high energy density Li-ion battery (LIB) as an energy storage element. The vehicle dynamics encounter frequent voltage fluctuations in the direct current (DC) bus, which ultimately reduces the lifecycle of the battery and also the heat is generated inside the battery when it is connected in parallel to the DC bus. The frequent charging/discharging of LIB is controlled by the unique thermal control strategy of the hybrid EV system. The DC bus voltage is controlled by the SC bi-directional converter (BDC) where, the battery BDC delivers the essential constant current from the main source (PV) to the DC bus. This unique thermal control strategy supports the distribution of power from the PV/LIB/SC hybrid source system to the EV and also improves the battery life cycle. Due to constant charging/discharging of battery the thermal runaway (TR) problem such as leak, smoke, gas venting, rapid disassembly, flames etc., can be eliminated. Decoupling of load power and battery power comprises the growth in the battery lifecycle and to maintain the optimum internal temperature of the LIB by conditional flow of current through hybrid thermal management system (HTMS). To certify the thermal control strategy and to estimate the performance of HTMS, a simulation of a hybrid source system with vehicle dynamics is performed in MATLAB/Simulink. Numerical analysis of the LIB during constant charging/discharging is performed using ANSYS fluent software to validate the temperature effect of HTMS. [ABSTRACT FROM AUTHOR]

The utilization of porous media and its effects on thermal management of internally cooled lithium-ion battery with the aid of porous media has been investigated. Two different configurations of the porous zone have been studied through three-dimensional transient thermal analysis of prismatic lithium-ion battery with liquid electrolyte as a coolant. At first, both configurations of the porous zone were investigated in pursuit of detecting the optimum configuration. Afterward, the effects of various materials, porosities and pores sizes were explored on the standard deviation of the temperature field and maximum temperature inside the battery in the optimum porous zone configuration. In the end, the utilization of the response surface method due to the parametric study and discover the most crucial parameters in battery performance was scrutinized. Compared to the non-inclined porous, the inclined porous zone case decreases the standard deviation of the temperature field significantly. Using the inclined porous zone also indicates that decreasing porosity results in the enhancement of both maximum temperature and standard deviation of the temperature about 20.75%. Hence, the increment of pore size results in decreasing maximum temperature inside the battery, while it could help the standard deviation of the temperature to be improved by about 24.88%. [ABSTRACT FROM AUTHOR]

In the open and closed space environments, the influence of spacing on battery pack thermal runaway propagation is studied. The mechanism of thermal runaway propagation for the lithium-ion battery pack is analyzed. The experimental results show that when the state of charge (SOC) of the battery is 100%, and the spacing is greater than 2 mm in the horizontal direction and 8 mm in the vertical arrangement, battery pack thermal runaway propagation hardly occurs in an open environment. In a closed environment, there is less chance of uncontrolled heat transmission in batteries when the rate of increase in the battery temperature is less than 0.66 °C s−1. When the horizontal spacing is more than 4 mm or the vertical spacing of the battery is more than 8 mm in a closed environment, thermal runaway propagation cannot occur in the batteries. The research results provide some reference for the arrangement of lithium-ion battery packs in transportation and storage. [ABSTRACT FROM AUTHOR]

In this paper, the fire behaviors of 60 Ah LiFePO4/graphite batteries with no safety valve are evaluated using an in situ calorimeter. The batteries experience a stable combustion stage with a small-scale flame rather than immediate jet fire after ignition and the special combustion process is analyzed and discussed in detail. It takes 201 s from ignition to thermal runaway for fully charged battery under an incident heat flux of 11.1 kW m−2. Such a time interval is beneficial for a possible early warning of the battery thermal runaway. Several characteristic parameters, including the ignition time, surface temperature, mass loss, heat release rate (HRR), and flame size are systematically determined. The peak HRR can be as high as 82.3 kW and the maximum average flame height for batteries under an incident heat flux of 11.1 kW m−2 reaches 634.6 mm. The influence of different state of charge (SOC) and incident heat flux are also investigated. The results show that the fully charged batteries exposed to high external heat flux are more vulnerable to have thermal runaway. [ABSTRACT FROM AUTHOR]

The temperature coefficient is an important parameter for the thermo-electrochemical cells. It is divided into either the isothermal coefficient or thermal one. In view of the fact that there are some vague understandings to the temperature coefficients of a cell and its electrode, this paper used the Peltier heats on the interface between electrode and electrolyte to define the isothermal coefficient and thermal coefficient. The distinction between both of them is that the former is that the change in entropy of the standard hydrogen electrode with temperature is not taken into account, and the latter does. Logically, the isothermal coefficient is a special case of the thermal coefficient, and the latter seems to be a greater doctrinal point, with more practical significance. A type of isothermal single-fluid cell has been developed for more accurate measuring the temperature coefficient. This method can replace the early double-fluid cell in which the various polarizations caused by the temperature effect, liquid junction potential, etc., are hard to be avoided, resulting in the poor reproducibility. The definition and measuring method of the temperature coefficients in this paper are not only strict in theory but also makes operable. An experiment has been made on measure of the Peltier heats of the cupric sulfate/copper system at different concentrations, obtaining their thermal coefficients and isothermal coefficients more accurately. [ABSTRACT FROM AUTHOR]

This work presents experimental analysis on the local heat flux distribution for a prismatic lithium-ion battery at various charge/discharge rates. Experimental setup for a large prismatic lithium-ion battery thermal testing is developed, and experimental investigations of the thermal dissipation of lithium-ion battery are conducted under various charge/discharge rates to provide more information on battery heat generation. The aim of the present study is to evaluate the heat generated by the electrochemical reaction inside a lithium-ion cell during numerous charging/discharging cycles until reaching steady state. In this paper, the distribution of temperature is presented for a prismatic Li-ion battery at different operating conditions. The results show that a higher battery temperature is obtained at the beginning of the charge cycle and the lower temperature is reached at the end of charge cycle and the beginning of discharge cycle. Furthermore, it is observed that the increase in charge/discharge current rate increases the battery temperature, the generated heat flux and the part of the irreversible heat compared to the reversible heat. It can be observed that at C-rate of 3C irreversible heat reaches 80% of the total generated heat. [ABSTRACT FROM AUTHOR]