Electric Vehicle Battery Thermal Management Research Articles

Enhancing Electric Vehicle Battery Thermal Management using Phase Change Materials: A CFD Analysis for Improved Heat Dissipation

The adverse environmental issues and climate change has compelled world to shift to renewable energy systems. Conventional IC engines are the major contributor for air pollution which is the main cause for the global warming. Therefore, EVs (Electric Vehicle) are the future of the automotive industry. The important issues faced by EVS are battery heat generation. Hence in order to remove heat efficiently from the EV battery CFD analysis of a passive thermal management system using PCM for Li-ion batteries is studied for three different discharge rates. Compared to bare cell, the cell with passive BTMS reduces the maximum temperature rise by 2%, 2.1% and 1% at discharge rates of 1.5 C, 1.0 C and 0.5 C respectively thus implying that the BTMS adopted is effective in removing heat from the surface of the cell.

Performance optimization of electric vehicle battery thermal management based on the transcritical CO2 system

Thermal management of electric vehicles, especially battery thermal management, is critical to driving range and operational safety. To find a vehicle thermal management system with higher energy efficiency and environmental protection, an environmentally-friendly and efficient battery and cabin parallel cooling thermal management system was evaluated with CO2 as the working fluid. First, different control strategies of the evaporation temperature were compared regarding the battery cooling performance. Then, the effect of the battery cooling evaporation temperature on the coefficient of performance (COP) was explored. It was found that the maximum COP increased by 8.38% as the evaporation temperature decreased from 17 to 5.8 °C. Besides, it was found that the optimal battery cooling evaporation temperature range is 10.2–11 °C when the battery heating power is 0.4 kW. The vapor quality at the cold plate outlet should be lower than 0.95. Finally, the battery cooling performance under variable operating conditions was investigated. The influence of operating parameters on the battery cooling evaporation temperature and CO2 outlet vapor quality was also analyzed. Simulation results showed that the optimum evaporation temperature range varied significantly under different working conditions. The vapor quality at the cold plate outlet decreased slightly with the evaporation temperature.

Performance investigation of electric vehicle battery thermal management system using nano fluids as coolants on ANSYS CFX software

AbstractBecause of their sophisticated cell chemistry when compared to other types of cell technology now in use, lithium‐ion batteries are commonly used in electric vehicles. These lithium‐ion cells must be operated within certain range of working temperatures but as the energy requirements increase the cells cross the operating bandwidth of temperature and thus cooling of lithium‐ion batteries becomes necessary for its optimal performance. Battery cooling has thus emerged as an important area of research as lithium‐ion batteries do not perform well on higher temperature ranges. Thus, cooling of the batteries using a cooling system is been focused upon and various battery cooling techniques are developed using various coolants such as air, liquid, phase change material and many more. The current study is focused on the use of liquid cooling method for cooling the lithium‐ion battery pack. This paper focuses on the use of nano fluids as coolants for cooling of the lithium‐ion battery pack due to its enhanced thermal conductivity and low viscosity at higher temperature which cools the battery pack. Nanoparticles such as aluminium oxide, titanium dioxide and copper oxide which when mixed with water (base fluid) form the nano fluid solution whose properties are simulated using governing equations. The paper also validates the cooling performance of nano fluids over currently used coolants using ANSYS CFX solver. The findings reveal that using nano fluids as coolants definitely aids in lowering battery pack (BP) temperatures, and nano fluids have a higher heat rejection rate than water. Comparing aluminium oxide, copper oxide, titanium di‐oxide as a coolant for battery thermal management system, Al2O3 nano fluids exhibit the greatest temperature reduction, followed by CuO and TiO2 nano fluids, respectively.

Iterative Dynamic Programming Strategy for Electric Vehicle Battery Thermal Management Optimization

AbstractLithium‐ion batteries are extensively used in electric vehicles because of their superior performance in the general environment of global energy shortage. However, lithium‐ion batteries generate large amounts of heat as the battery packs are charged and discharged. If this accumulated heat is not dissipated timely, then the power supply system will fail, resulting in safety accidents. Therefore, a high‐efficiency and energy‐saving optimization strategy is required for both ensuring operating temperature of the battery and saving energy. Herein, a lumped thermal model is established on the basis of the heat generation characteristics of batteries and Newton's law of cooling, and its exactitude is proven by comparison with a liquid cooling system established using AMESim. In addition, to reduce computation time and enhance the real‐time capability, an iterative dynamic programming (IDP) method is proposed to determine the optimal values iteratively in a multidimensional search space, in view of the high nonlinearity and time‐variability of a battery thermal management system as well as the complexity of dynamic programming (DP). Thus, the results from co‐simulations performed in Matlab and AMESim verify that the proposed strategy has high cooling efficiency and can save considerable energy for cooling system compared with PID and DP.

A novel liquid cooling plate concept for thermal management of lithium-ion batteries in electric vehicles

In this paper, an innovative liquid cooling plate (LCP) embedded with phase change material (PCM) is designed for electric vehicle (EV) battery thermal management. The proposed cooling plate is named “hybrid cooling plate” as it takes advantage of both active (liquid) and passive (PCM) cooling methods. The hybrid LCP is 36% lighter than a volumetrically equivalent traditional aluminum LCP, and in addition to the cooling capability, it provides a heating solution to slow the temperature loss of the batteries during the cold stop. The thermal behavior of the hybrid LCP for two different scenarios including the cooling performance under a real driving cycle, and the cold stop temperature performance are investigated and compared with a traditional aluminum LCP using a computational fluid dynamics (CFD) model. An experimental test bench is developed to test a prototype of the hybrid LCP and verify the CFD model. The cooling performance results indicate that the use of hybrid LCP could reduce the energy consumption of the pump required for circulating the coolant up to 30% in comparison with an aluminum LCP. Moreover, the novel designed LCP improves the temperature uniformity effectively. It was also found that the hybrid LCP could significantly delay the temperature drop at the cold stop situation of the EV and therefore, reduce the energy needed for the active heating of the batteries after short-term parking. These imply that the hybrid liquid cooling plate concept could be a promising thermal management solution for EVs.

Electric Vehicle Battery Thermal and Cabin Climate Management Based on Model Predictive Control

Abstract Energy management plays a critical role in electric vehicle (EV) operations. To improve EV energy efficiency, this paper proposes an effective model predictive control (MPC)-based energy management strategy to simultaneously control the battery thermal management system (BTMS) and the cabin air conditioning (AC) system. We aim to improve the overall energy efficiency and battery cycle-life, while retaining soft constraints from both BTMS and AC systems. The MPC-based strategy is implemented by optimizing the battery operations and discharging schedules to avoid a peak load and by directly utilizing the regenerative power instead of recharging the battery. Compared with the benchmark system without any control coordination between BTMS and AC, the proposed MPC-based energy management has shown a 4.3% reduction in the recharging energy and a 6.5% improvement for the overall energy consumption. Overall, the MPC-based energy management is a promising solution to enhance the battery efficiency for EVs.

Thermal Management of Stationary Battery Systems: A Literature Review

Stationary battery systems are becoming increasingly common worldwide. Energy storage is a key technology in facilitating renewable energy market penetration and battery energy storage systems have seen considerable investment for this purpose. Large battery installations such as energy storage systems and uninterruptible power supplies can generate substantial heat in operation, and while this is well understood, the thermal management systems that currently exist have not kept pace with stationary battery installation development. Stationary batteries operating at elevated temperatures experience a range of deleterious effects and, in some cases, serious safety concerns can arise. Optimal thermal management prioritizes safety and balances costs between the cooling system and battery degradation due to thermal effects. Electric vehicle battery thermal management has undergone significant development in the past decade while stationary battery thermal management has remained mostly stagnant, relying on the use of active and passive air cooling. Despite being the default method for thermal management, there is an absence of justifying research or comparative reviews. This literature review seeks to define the role of stationary battery systems in modern power applications, the effects that heat generation and temperature have on the performance of these systems, thermal management methods, and future areas of study.

Numerical Analysis of Cooling Plates with Different Structures for Electric Vehicle Battery Thermal Management Systems

The performance of lithium-ion batteries used in electric vehicles (EVs) is greatly affected by temperature. Hence, an efficient battery thermal management system (BTMS) is needed to ensure the safety of batteries and prolong the cycle life. In order to find a more efficient type of cooling plate for the rectangular batteries, the three-dimensional models of four common cooling plates with different internal structures are established. After a series of computational fluid dynamic simulations and comparisons, the most optimum structure of the cooling plate is obtained. Subsequently, the effect of different mass flow rates is investigated among the different cooling plates. It indicates that the cooling plate with convex structure has a better cooling performance than the other three, and the heat transfer performance of various cooling plates changes a lot with the increasing of mass flow rate. The convex structured cooling plate could be applied for optimizing the performance for electric vehicles.

Hierarchical MPC for Robust Eco-Cooling of Connected and Automated Vehicles and Its Application to Electric Vehicle Battery Thermal Management

Connected and autonomous vehicles (CAVs) have situational awareness that can be exploited for optimal power and thermal management. In this article, we develop a hierarchical model predictive control (H-MPC) strategy for eco-cooling of CAVs, which reduces energy consumption through real-time prediction and multi-timescale and multi-layer optimization. The application of the proposed H-MPC is studied for battery thermal and energy management of an electric vehicle (EV). Our H-MPC approach addresses the uncertainty in the long-term preview of the vehicle speed through robust constraint handling to prevent constraint violation. The simulation results show that compared with a conventional battery thermal management (BTM) strategy, the proposed robust H-MPC saves the battery energy by up to 5.4% under the uncertainties in the long-term vehicle speed predictions in an urban CAV operation scenario.

Electric vehicle battery thermal management system with thermoelectric cooling

An experimental investigation is performed on an advanced battery thermal management system for emerging electric vehicles. The developed battery thermal management system is a combination of thermoelectric cooling, forced air cooling, and liquid cooling. The liquid coolant has indirect contact with the battery and acts as the medium to remove the heat generated from the battery during operation. Forced air assisted heat removal is performed from the condenser side of the thermoelectric liquid casing. Detailed experiments are carried out on a simulated electric vehicle battery system. Experimental results reveal a promising cooling effect with a reasonable amount of power dissipation. Moreover, the experimental test shows that the battery surface temperature drops around 43 ºC (from 55 ºC to 12 ºC) using TEC-based water cooling system for a single cell with copper holder when 40 V is supplied to the heater and 12 V to the TEC module.

Heat transfer characteristics of plug-in oscillating heat pipe with binary-fluid mixtures for electric vehicle battery thermal management

The development of highly-efficient, cost-effective, and reliable cooling schemes of electric vehicle (EV) battery is still a big challenge for massive commercialization of EVs. In this work, a proof-of-concept plug-in oscillating heat pipe (OHP) with flat-plate evaporator and tube condenser has been developed and experimentally tested for the potential applications in EV battery thermal management. Pure water, ethanol, and binary-fluid mixtures of them at different mixing ratios (MRs) ranging from 1:1 to 4:1 were used at volumetric filling ratios (FRs) of 30%, 40% and 50%. Owing to the zeotropic properties in phase transition and the complex molecular interactions between the ethanol component and water component, the OHP charged with ethanol-water mixtures exhibited better start-up and heat transfer performance. The average battery pack temperature could be controlled below 46.5 °C under the power input of 56 W. Besides, well-satisfied temperature uniformity was achieved on the battery module and the maximum temperature differences were mostly in the range of 1–2 °C. The complementary features for ethanol-water mixture thermo-physical properties and temperature/concentration gradients induced mass transport account for the OHP performance improvement. The novel plug-in OHP associated with desirable heat transfer performance provides a promising candidate for battery thermal management system.

Feasibility study on a novel 3D vapor chamber used for Li-ion battery thermal management system of electric vehicle

In this paper, we explored the feasibility of a novel 3D vapor chamber (3DVC) to fulfill the requirement of energy utilization for electric vehicle (EV) battery thermal management system (BTMS). Compared with the flat shape of conventional vapor chambers (VC), the prepared 3DVC consists of three interconnected but non-coplanar chambers. A series of trials are implemented as the following subsequence. Initially, the performances of 3DVCs with 60% and 120% filling ratios are compared to understand the effect of filling ratio. The experimental results imply that the 3DVC with higher filling ratio (120%) performs better, especially at high heating powers, due to the sufficient liquid supplement. To validate the adaptability of 3DVC working under different road conditions and different installation locations, the impacts of orientation are investigated. The results confirm that the inclinations have slender influence on the performance of 3DVC owing to the capillary porous structures. Meanwhile, 3DVC based BTMS is tested both in high and low ambient temperatures to further characterize the thermal behaviors under various climates. It shows that 3DVC can maintain an appropriate temperature under the simulated weathers. The as-constructed 3DVC is expected to provide a promising strategy for energy management of EVs.

Experimental Investigation on Cooling/Heating Characteristics of Ultra-Thin Micro Heat Pipe for Electric Vehicle Battery Thermal Management

Due to the heat pipes’ transient conduction, phase change and fluid dynamics during cooling/heating with high frequency charging/discharging of batteries, it is crucial to investigate in depth the experimental dynamic thermal characteristics in such complex heat transfer processes for more accurate thermal analysis and design of a BTMS. In this paper, the use of ultra-thin micro heat pipe (UMHP) for thermal management of a lithium-ion battery pack in EVs is explored by experiments to reveal the cooling/heating characteristics of the UMHP pack. The cooling performance is evaluated under different constant discharging and transient heat inputs conditions. And the heating efficiency is assessed under several sub-zero temperatures through heating films with/without UMHPs. Results show that the proposed UMHP BTMS with forced convection can keep the maximum temperature of the pack below 40 °C under 1 ~ 3C discharging, and effectively reduced the instant temperature increases and minimize the temperature fluctuation of the pack during transient federal urban driving schedule (FUDS) road conditions. Experimental data also indicate that heating films stuck on the fins of UMHPs brought about adequate high heating efficiency comparing with that stuck on the surface of cells under the same heating power, but has more convenient maintenance and less cost for the BTMS. The experimental dynamic temperature characteristics of UMHP which is found to be a high-efficient and low-energy consumption cooling/heating method for BTMSs, can be performed to guide thermal analysis and optimization of heat pipe BTMSs.

Multidisciplinary and Multifidelity Design Optimization of Electric Vehicle Battery Thermal Management System

Battery thermal management system (BTMS) is a complex and highly integrated system, which is used to control the battery thermal conditions in electric vehicles (EVs). The BTMS consists of many subsystems that belong to different disciplines, which poses challenges to BTMS optimization using conventional methods. This paper develops a general variable fidelity-based multidisciplinary design optimization (MDO) architecture and optimizes the BTMS by considering different systems/disciplines from the systemic perspective. Four subsystems and/or subdisciplines are modeled, including the battery thermodynamics, fluid dynamics, structure, and lifetime model. To perform the variable fidelity-based MDO of the BTMS, two computational fluid dynamics (CFD) models with different levels of fidelity are developed. A low fidelity surrogate model and a tuned low fidelity model are also developed using an automatic surrogate model selection method, the concurrent surrogate model selection (COSMOS). An adaptive model switching (AMS) method is utilized to realize the adaptive switch between variable-fidelity models. The objectives are to maximize the battery lifetime and to minimize the battery volume, the fan's power, and the temperature difference among different cells. The results show that the variable-fidelity MDO can balance the characteristics of the low fidelity mathematical models and the computationally expensive simulations, and find the optimal solutions efficiently and accurately.

Experimental investigation on performance of lithium-ion battery thermal management system using flat plate loop heat pipe for electric vehicle application

The development of electric vehicle batteries has resulted in very high energy density lithium-ion batteries. However, this growth is accompanied by the risk of thermal runaway, which can cause serious accidents. Heat pipes are heat exchangers that are suitable to be applied in electric vehicle battery thermal management for their lightweight and compact size, and they do not require external power supply. This study examined experimentally a flat plate loop heat pipe (FPLHP) performance as a heat exchanger in the thermal management system of the lithium-ion battery for electric vehicle application. The heat generation of the battery was simulated using a cartridge heater. Stainless steel screen mesh was used as the capillary wick. Distilled water, alcohol, and acetone were used as working fluids with a filling ratio of 60%. It was found that acetone gave the best performance that produces a thermal resistance of 0.22 W/°C with 50 °C evaporator temperature at heat flux load of 1.61 W/cm2.

Exergy analysis of electric vehicle battery thermal management systems using transcritical CO2 vapour compression cycle

In this paper, performance analysis of a transcritical CO2-based electric vehicle battery thermal management system (EV BTMS) is investigated in a basic single-stage vapour compression cycle along with its various modifications that include internal heat exchanger (IHX), two-stage vapour compression and an intercooler. The system is compared against conventional cycles with various commercial refrigerants including R152a, R134a, R290, R600, R600a, R1234yf and Dimethylether and evaluated with respect to exergy-based thermodynamic, economic and environmental considerations. In the study, the efficiencies of each system and its components are calculated under various conditions and input parameters, and the corresponding component and exergy destruction-based costs and environmental impacts are determined. Based on the analyses, it is found that the exergy efficiency of the transcritical CO2-based system can be improved by up to 22% with two-stage compression and IHX. However, the efficiency of the improved system is still found out to be lower than the compared system using the studied refrigerants.

Effect of energy-regenerative braking on electric vehicle battery thermal management and control method based on simulation investigation

Battery thermal management is important for the safety and reliability of electric vehicle. Based on the parameters obtained from battery hybrid pulse power characterization test, a two-degree-of-freedom lumped thermal model is established. The battery model is then integrated with vehicle driving model to simulate real-time battery thermal responses. An active control method is proposed to reduce heat generation due to regenerative braking. The proposed control method not only subjects to the braking safety regulation, but also adjusts the regenerative braking ratio through a fuzzy controller. By comparing with other regenerative braking scenarios, the effectiveness of the proposed strategy has been validated. According to the results, the proposed control strategy suppresses battery temperature rise by modifying the charge current due to regenerative braking. The overlarge components of current are filtered out whereas the small ones are magnified. Therefore, with smaller battery temperature rise, more energy is recovered. Compared to the traditional passive heat dissipating, the proposed active methodology is feasible and provides a novel solution for electric vehicle battery thermal management.

Exergy analysis of electric vehicle battery thermal management systems using transcritical CO<SUB align="right">2 vapour compression cycle

In this paper, performance analysis of a transcritical CO2-based electric vehicle battery thermal management system (EV BTMS) is investigated in a basic single-stage vapour compression cycle along with its various modifications that include internal heat exchanger (IHX), two-stage vapour compression and an intercooler. The system is compared against conventional cycles with various commercial refrigerants including R152a, R134a, R290, R600, R600a, R1234yf and Dimethylether and evaluated with respect to exergy-based thermodynamic, economic and environmental considerations. In the study, the efficiencies of each system and its components are calculated under various conditions and input parameters, and the corresponding component and exergy destruction-based costs and environmental impacts are determined. Based on the analyses, it is found that the exergy efficiency of the transcritical CO2-based system can be improved by up to 22% with two-stage compression and IHX. However, the efficiency of the improved system is still found out to be lower than the compared system using the studied refrigerants.

Experimental and Theoretical Efficiency Investigation of Hybrid Electric Vehicle Battery Thermal Management Systems

In this study, a thermodynamic model of a hybrid electric vehicle battery thermal management system (TMS) is developed and the efficiency of the system is determined based on different parameters and operating conditions. Subsequently, a TMS test bench is used with a production vehicle (Chevrolet Volt) that is fully instrumented in order to develop a vehicle level demonstration of the study. The experimental data are acquired under various conditions using an IPETRONIK data acquisition system, along with other reported data in the literature, to validate the numerical model results. Based on the analyses, the condenser and evaporator pressure drop, compressor work and compression ratio, evaporator heat load and efficiency of the system are determined both numerically and experimentally. The predicted results are determined to be within 6% of the conducted experimental results and within 15% of the reported results in the literature.