Electric Vehicle Thermal Management Research Articles

Experimental and numerical thermal analysis of a lithium-ion battery module based on a novel liquid cooling plate embedded with phase change material

In this paper, the thermal behavior of a battery module based on a novel liquid cooling plate (LCP) is experimentally and numerically studied. The cooling plate is embedded with phase change material (PCM), and it is named a hybrid LCP as it provides a combination of active (liquid) and passive (PCM) cooling methods for battery with a modular design. The cooling performance of the proposed thermal management system is investigated for three cases, including low currents with pure passive cooling, medium currents with triggered liquid cooling, and high currents with constant liquid cooling. Additionally, the potential of the PCM in preventing the switched-off module from a fast temperature drop in cold environments is examined. The thermal performance of the hybrid LCP is numerically compared with a conventional aluminum LCP of the same dimension. The results indicate that pure passive cooling is able to keep the module temperature in the desired range at low currents. The hybrid LCP reduces the energy consumption of the pump by around 40% during the triggered liquid cooling. The cold temperature investigations show that the hybrid LCP is able to keep the module 5.5 °C higher than a module with aluminum LCP after 1.5 h in a cold environment of 0 °C, that can reduce the energy needed for warming the batteries up. Based on the results of this research, the proposed hybrid LCP could be a promising solution for utilizing PCMs in combination with liquid cooling for battery thermal management in electric vehicles.

Design and analysis of electric vehicle thermal management system based on refrigerant-direct cooling and heating batteries

A thermal management system (TMS) based on R134a refrigerant is proposed, which not only meet the thermal requirements of cabin, but also refrigerant-directly cool and heat battery. Compared with the traditional electric vehicle (EV) TMSs, an electronic expansion valve (EXV) is equipped after the battery cooling/heating plate in the refrigerant branch circuit. The mainly working modes of the TMS and their control methods are described in detail. The paper applies mathematical one-dimension simulation method to analyze the feasibility of mainly working modes, including battery preheating mode, mixed heating mode, low-temperature mixed heating mode. The results show that the TMS is completely feasible to balance the heat distribution between cabin and battery by controlling the EXVs opening. In the battery pre-heating mode, the relationship between refrigerant state of cooling/heating plate outlet and the battery temperature uniformity is analyzed, and a control strategy to improve the battery temperature uniformity is proposed. In low temperature environment, when the TMS switches from cabin heating mode to mixed heating mode, the cabin air temperature will drop sharply. This is because the battery temperature is too low, that pressure of TMS is too low to maintain the heating demand of the cabin.

Investigation on the performance enhancement of electric vehicle thermal management system utilizing floating loop with finite heat exchanger size

This study suggests an electric vehicle heat pump and thermal management system employing a floating loop. The floating loop manages the thermal state of power electronics and electric motors by utilizing the liquid refrigerant at the condenser outlet. This loop recovers the waste heat generated by power electronics and electric motors in winter and enhances the cooling performance in summer through the superior cooling performance of evaporative heat transfer. Configurations of heat pump and thermal management system are presented with operating schematic in summer and winter. To verify the performance of the suggested system, the heat pump and thermal management system model is established based on experimentally validated heat pump component models and electric device models. Heat exchangers are reallocated within a finite volume to investigate the effect of thermal load shift from the coolant to the refrigerant. The result shows that the heat pump system utilizing a floating loop with the largest refrigerant heat exchanger can save power consumptions in winter up to 27.7% and 5.8% in summer while maintaining the thermal state of electric devices within the appropriate range.

Solidification Thermal Behavior of Fin Heat Exchanger with Phase Change Material for Electric Vehicle Thermal Management

Solidification Thermal Behavior of Fin Heat Exchanger with Phase Change Material for Electric Vehicle Thermal Management

An experimental investigation on the evaporation and condensation heat transfer of air-cooled multi-port flat heat pipes

An experimental investigation was conducted to evaluate the evaporation as well as condensation heat transfer of air-cooled multi-port flat heat pipes (AMFHPs), designed for extreme working conditions of power battery thermal management in electric vehicles. The experimentally obtained evaporation as well as condensation heat transfer coefficients (HTCs) under various working conditions were compared and analyzed. It was found that, both the orders of the intensity of heat transfer mode in the liquid pool and the condensation Nuc were R134a > ammonia > acetone. The orders of the evaporation HTCs referring to ammonia and R134a AMFHPs with different filling ratios (FRs) were 50 > 30 > 100 > 70 and 30 > 50 > 70 > 100%, while those of Nuc were 50 > 30 > 70 > 100 and 30–50–70 > 100%, respectively. In most cases, evaporation HTC increased with the rise of heating power as well as the decrease of cooling air velocity, while the condensation Nuc decreased with the increasing in the heating power as well as the air velocity slightly. The measured evaporation HTCs were compared with some predictive correlations of pool boiling and pool boiling-thin film evaporation expressions for the evaporator section at different FRs, and the condensation HTCs were also evaluated by several available filmwise condensation models. Results showed that Cooper correlation for pool boiling revealed quite a good agreement with measured results for the AMFHPs of 100% R134a, 70% ammonia and 100% ammonia, and Rohsenow correlation predicted the condensation HTCs of R134a AMFHPs with FR<100% accurately. However, for ammonia, the prediction of the evaporation HTCs in the case of FR < 70% was difficult, and Nusselt theory significantly overestimated the condensation HTCs of all the ammonia samples.

Experimental study on the performance of vehicle integrated thermal management system for pure electric vehicles

The thermal management of electric vehicles is mainly to regulate the temperatures of battery, motor, electric control, and crew cabin, so as to ensure that they are working at the most appropriate temperature. The integrated thermal management system, which stands at the perspective of the vehicle system, coordinates and controls the heat dissipating capacity of the vehicle. In this paper, a novel vehicle integrated thermal system, consisting of the Li-ion battery packs circuit, the electric motor and power electronics cooling circuit, as well as the air conditioning circuit, etc., is proposed to obtain the integrated optimization of the vehicle system. The results, expressed through thermal parameters, discharging and charging parameters of the battery system, are initially evaluated utilizing theoretical analysis and numerical model of the vehicle system and then experimentally analyzed with the arrangement of a 1:1 scale laboratory test bench. The collections of results demonstrate the excellent design and performance of the proposed integrated thermal management system in satisfying the real-time operating conditions under general temperature requirements. These experimental investigations are expected to afford a practical insight into the design and optimization of thermal management systems in electric vehicles.

A Method of Developing Quantile Convolutional Neural Networks for Electric Vehicle Battery Temperature Prediction Trained on Cross-Domain Data

The energy consumption caused by battery thermal management of electric vehicles can be reduced using predictive control. A predictive controller needs a prediction model of the battery temperature, for example for different battery cooling and heating thresholds. In the proposed method, cross-domain data from simulation, vehicle fleet and weather stations were analyzed and processed as training data for a Convolutional Neural Network (CNN). The CNN took data from previous road segments and predictions for following road segments as input and predicted the change in battery temperature as quantile sequences over a prediction horizon. Properties of the collected cross-domain data sets were analyzed and considered during preprocessing, before 150 models were trained, of which the best performing model was further analyzed. Point-forecast metrics and quantile-related metrics were used for model comparison and evaluation. For example, the median prediction achieved a mean absolute error (MAE) of 0.27 &#x2218;C and the true values were below the median prediction in 47% of the test data. Possible improvements of the method such as increasing data size, using more complex architectures as well as optimizing the horizon sizes were discussed. In conclusion, the method was able to well predict battery temperatures for different battery cooling thresholds.

Life Cycle Climate Performance Evaluation of Electric Vehicle Thermal Management System Under Chinese Climate and Driving Condition

Life Cycle Climate Performance Evaluation of Electric Vehicle Thermal Management System Under Chinese Climate and Driving Condition

Comparative analysis of battery electric vehicle thermal management systems under long-range drive cycles

Due to increasing regulation on emissions and shifting consumer preferences, the wide adoption of battery electric vehicles (BEV) hinges on research and development of technologies that can extend system range. This can be accomplished either by increasing the battery size or via more efficient operation of the electrical and thermal systems. This study endeavours to accomplish the latter through comparative investigation of BEV integrated thermal management system (ITMS) performance across a range of ambient conditions (-20 °C to 40 °C), cabin setpoints (18 °C to 24 °C), and six different ITMS architectures. A dynamic ITMS modelling framework for a long-range electric vehicle is established with comprehensive sub models for the operation of the drive train, power electronics, battery, vapor compression cycle components, and cabin conditioning in a comprehensive transient thermal system modelling environment. A baseline thermal management system is studied using this modelling framework, as well as four common thermal management systems found in literature. This study is novel for its combination of comprehensive BEV characterization, broad parametric analysis, and the long range BEV that is studied. Additionally, a novel low-temperature waste heat recovery (LT WHR) system is proposed and has shown achieve up to a 15% range increase at low temperatures compared to the baseline system, through the reduction of the necessary cabin ventilation loading. While this system shows performance improvements, the regular WHR system offers the greatest benefit, a 13.5% increase in cold climate range, for long-range BEV drive cycles in terms of system range and transient response without the need for additional thermal system equipment.

Loop Heat Pipes for Thermal Management of Electric Vehicles

Abstract The present paper investigates the potential of loop heat pipe (LHP), with respect to technological merits and application niche, in automotive thermal management. Broadly, LHP design and applicability for hot spot cooling in electronics (local dissipation), and for heat transport over longer distances (remote dissipation) has been proposed and discussed in detail. The basic module in these applications includes loop heat pipe with different shapes and sizing factors. Two types of LHP designs have being tested and results discussed. The miniature version, with 10 mm thick and flat disk evaporator, for cooling electronic control unit (ECU) with 70 W chipset while keeping source temperature below 100 °C limit was evaluated. Two larger versions with cylindrical evaporator, 25 mm diameter and 150 mm length, and heat transfer distances of 250 mm and 1000 mm, respectively, were tested for power electronics and battery cooling, with more than 500 W transport capabilities in gravity field. In conclusions, loop heat pipes will provide an energy efficient passive thermal control solution for next-generation low emission automotive, particularly for electric vehicles (EVs), which have high-level electrifications and more definitive cooling requirements.

A REVIEW OF THE EXERGY ANALYSIS OF THERMAL MANAGEMENT SYSTEMS IN ELECTRIC VEHICLES

Exergy analysis is an advanced and a fair method of performance evaluation compared to the traditional energy analysis. In this article, a review of the exergy analysis studies carried out in the field of thermal management of electric vehicles is conducted. Studies conducted on battery, electric motor, cabin and electronics have been considered. It is noted that most of the work is done on battery thermal management. The nature of the work, methods used, parameters varied and parameters evaluated are listed. It can be found that the amount of work carried out in this field is very much limited. Hence, the scope of future work is more and is described in the conclusions.&#x0D;

A novel electric vehicle thermal management system based on cooling and heating of batteries by refrigerant

A refrigerant-based thermal management system (TMS) for electric vehicles (EVs) is proposed and analyzed, aiming to tackle the conflict between the cabin thermal comfort and the battery thermal safety, and to realize the battery heating or cooling directly by the refrigerant without supplementary devices. Compared with the traditional EV TMSs, an electronic expansion valve (EEV) is equipped after the battery cooling/heating device in the refrigerant branch circuit. The performance of the proposed new TMS is investigated by mathematical simulations in conditions of the standardized New European Driving Cycles (NEDC) and different climates. The simulation results indicate that both the temperatures of the cabin air and the battery pack can be well controlled by the proposed TMS. In the cabin-and-battery mixed cooling mode for summer, the cooling temperatures for the cabin and the battery can be adjusted independently, and the cabin air can be cooled to the target temperature effectively as well as the battery thermal safety is guaranteed. In the cabin-and-battery mixed heating mode for winter, the high temperature refrigerant flows through the battery cooling plate and heats the batteries with the latent heat of condensation, and the battery preheating can be completed within 15 min and 9 min in the condition of 0 °C and 7 °C ambient temperature, respectively. Besides the thermal behaviors of the cabin and the battery, the controls of the compressor and the valves are also investigated to verify the practical feasibility of the proposed TMS.

1D-3D Online Coupled Transient Analysis for Powertrain-Control Integrated Thermal Management in an Electric Vehicle

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Thermal management in electric vehicles (EVs) has attracted more attention due to its increasing significance, and computer aided engineering (CAE) plays an important role in its development. A 1D-3D online coupling approach is proposed to completely characterize transient thermal performance of an electric vehicle on a high performance computer (HPC) platform. The 1D thermal management model, consisting of air conditioning, motor cooling and battery cooling systems, is integrated with the 1D control strategy model and powertrain model consisting of motor, battery, driver and vehicle models. The 3D model is established for the air flow around the full vehicle and through its underhood. The 3D model gives boundaries such as heat exchanger air flowrates and heat flows on some component surfaces to the 1D model, while 1D gives back boundaries such as heat exchanger heat loads, component surface temperatures and fan speed simultaneously. In this way, a complete closed-loop coupling is realized and no input boundary condition is required in the 1D-3D model for a certain road map. Realization of the 1D-3D online coupling method on an HPC platform is introduced, since it’s necessary for the simulations to be completed in a reasonable time period. For typical driving cycles including WLTC(35°C), NEDC(35°C) and 120kph(35°C), transient simulations are performed and the results are discussed. The simulation results reasonably reflect variations of the physical parameters, which proves the 1D-3D online coupling method to be useful tool, especially at early stages of development. At the next stage, full vehicle experiments will be performed to calibrate parameters including coolant temperatures and flowrates, component temperatures, refrigerant temperatures and pressures, as well as component electric consumptions of the 1D-3D model, which will be discussed in another paper due to space limitation.&lt;/div&gt;&lt;/div&gt;

Research on electric vehicle thermal management system with coupled temperature regulation between crew cabin and power battery pack

Based on the structure of the thermal management system for electric vehicles, complete the design of the thermal management system for the whole vehicle, and realize the coupling temperature regulation between the vehicle cabin and the power battery pack. A direct cooling system model containing electric compressors, electronic expansion valves, heat exchangers, power battery packs, and other components coupled to the air conditioning system is established. Based on this, a vehicle thermal management model of the entire vehicle including electric vehicle, electric motor, high and low voltage network, vehicle cabin, air conditioning system, and power battery pack is completed. Develop the logic threshold control strategy, compressor speed control strategy, and electronic expansion valve opening control strategy for the vehicle thermal management system. Through the comparative analysis of the temperature control effect of the thermal management system on the cabin and the power battery pack under different ambient temperatures, the effect of different temperatures on the vehicle range is analyzed. The results show that this vehicle thermal management system can meet the requirements for battery pack heat dissipation and vehicle cabin refrigeration.

Smart Approach for the Thermal Management of Electric Vehicles

Smart Approach for the Thermal Management of Electric Vehicles

Развитие технических требований к свойствам автомобильных моторных масел с учётом тенденций в защите климата на планете

Decarbonization of the natural environment during the operation of transport is a current trend in the world economy in recent decades. A significant increase in the number of road transport has led to its importance and an increase in its share in the increase in carbon dioxide emissions due to the use of fuels and oils. By the end of the second decade of the 21st century, emissions of carbon dioxide during the operation of transport increased by 83% and thus determined the increase in total CO2 emissions by 25% [1]. The tendency towards decarbonisation is mainly due to a significant limitation of carbon dioxide emissions from exhaust gases in piston engines and, in this regard, the properties of the used automobile engine oils. Lubricating oils perform additional functions in pure battery-powered vehicles and hybrid vehicles as opposed to vehicles powered by internal combustion engines. The amount of heat generated by electric vehicle batteries creates new demands on performance and thermal management of electric vehicles. At the same time, electric currents generated by an electric vehicle affect the performance properties of lubricants and their performance.

THERMAL ANALYSIS OF DIFFERENT HEAT PUMP SYSTEMS FOR HEATING PROCESS OF ELECTRIC VEHICLES

In this paper, three different 1D models of electric vehicle heating, ventilation, and air conditioning (HVAC) system integrated with the vehicle cabin model for heating process were developed. The numerical results were compared in terms of thermal performance to get the desired thermal conditions inside the vehicle cabin. The results of the hybrid heat pump 1D model including both HVAC components and an additional electrical heater showed better thermal performance than the others and it was proposed for the heating process of electric vehicles. At the end of the driving cycle, the average temperature inside the cabin was increased up to about 7°C and 14°C by using the conventional heat pump and innovative heat pump models, respectively, at -5°C ambient temperature and the target temperature cannot be reached. However, under the same conditions, the vehicle cabin could be heated up to about 25°C by using the hybrid heat pump model with a 1-kW electrical heater. In addition, the thermal performance of different heat pump systems can be improved by using electric vehicle thermal management system that allows performing transient simulations for the estimation of the dynamic behavior of system. This study also contributes to decrease of energy usage for HVAC processes that considerably affects the mileage of the vehicle and also life cycle of batteries. These 1D models can be used not only in thermal performance but also can be utilized for thermal comfort conditions of electric vehicles.

Numerical study of thermal cooling for Lithium-ion battery pack using phase change material

The objective of this study is to numerically investigate the battery thermal management of electric vehicles using phase change material. The lithium-ion batteries which are widely used in electric vehicles have an optimal operating temperature range from 25°C to 60°C, above which the battery does not operate effectively. There are various cooling methods such as active cooling method and passive cooling method. The present study is based on passive cooling method where the thermal performance of different phase change materials such as paraffin wax, extended graphene and capric acid are compared for different heat source intensities. The numerical simulation is performed using Ansys Fluent by considering the melting and solidification effects of the phase change materials. The investigation is performed by varying the thermo physical properties of the phase change materials and temperature of the battery packs. The results are analysed by plotting the temperature and velocity contours and the melting and heat transfer rates of different phase change materials are also compared. The results from the present study would be useful in identifying the ideal phase change material with improved thermal performance characteristics.

A thermal management system control strategy for electric vehicles under low-temperature driving conditions considering battery lifetime

Electric vehicle thermal management system (EVTMS) is essential for electric vehicles (EVs) to guarantee cabin thermal comfort and battery appropriate temperature. However, under low-temperature driving conditions, heating power demand for EVTMS affects system performance as well as battery lifetime. In this context, an effective EVTMS solution both for cabin thermal comfort and battery heating is investigated in this paper. The EVTMS performance and battery-lifetime loss characteristics under low temperatures are analyzed. Moreover, a battery-lifetime extension method which reduces battery-lifetime loss by the peak shifting and valley filling effect for battery current is advanced. A novel EVTMS fuzzy control strategy based on this method is proposed to maintain the proper temperature range of cabin and battery, which also regulate the heater load considering battery current. Using an EV and EVTMS model validated by low-temperature driving experiments, the proposed strategy was investigated by simulation and the control effect was carried out. The results showed that compared with the original strategy, battery-lifetime loss with the proposed strategy was reduced by 3.11–3.76% while the average temperatures for the cabin and battery were almost unaffected. Therefore, the strategy can reduce battery degradation while meeting the cabin and battery heating requirements.

Universal Electric Vehicle Thermal Management System

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;As the demand for Electric Vehicles (EVs) is increasing to limit global warming, observation shows that the significant application of EV is in cold and mild climate regions. Heat pump and CO2 system are two major Thermal Management Systems (TMS) used in these EVs. These TMS are constrained to cold climate applications securing better COP for heating function but sacrificing cooling COP when the same TMS applied to hot climate regions. This study presents a new Electric Vehicle Thermal Management System (EVTMS) limited to active liquid battery cooling for the application of Electric Vehicles in hot climate regions. The proposed system has integrated Battery Thermal Management System and Cabin HVAC using a shared electric compressor. This integrated solution also utilizes waste heat recovery to contribute for better system COP when compared to conventional TMS used for EV's. The decrease in the number of pipes and switching valves due to integrated solution also results in low refrigerant pressure drop preventing penalty on compressor duty. Battery cells target temperature of 27°C and, temperature delta of 4°C across battery cells is also considered as a prime motive during this study. Different strategies to control battery cells target temperature; the cabin HVAC system is studied. System simulation for typical thermal load in an EV is the first objective. The benefits of the proposed system are validated using an experimental test at a typical load condition. COP comparison for an existing system with proposed EVTMS proves the proposed system to be 50% energy efficient under typical thermal load from battery and cabin.&lt;/div&gt;&lt;/div&gt;