Integrated Thermal Management System Research Articles

Adaptive Integrated Thermal Management System for a Stable Driving Environment in Battery Electric Vehicles

With an increase in global warming, battery electric vehicles (BEVs), which are environmentally friendly, have been rapidly commercialized to replace conventional vehicles with internal combustion engines. Unlike traditional internal combustion engine vehicles, the powertrain system of BEVs operates with high efficiency, resulting in lower heat generation. This poses a challenge for cabin heating under low-temperature conditions. Conversely, under high-temperature conditions, the operating temperature of a high-voltage battery (HVB) is lower than the ambient air temperature, which makes cooling through ambient air challenging. To overcome these challenges, in this study, we proposed an integrated thermal management system (ITMS) based on a heat pump system capable of stable thermal management under diverse climatic conditions. Furthermore, to assess the ability of the proposed ITMS to perform thermal management under various climatic conditions, we integrated a detailed powertrain system model incorporating BEV specifications and the proposed ITMS model based on the heat pump system. The ITMS model was evaluated under high-load-driving conditions, specifically the HWFET scenario, demonstrating its capability to perform stable thermal management not only under high-temperature conditions, such as at 36 °C, but also under low-temperature conditions, such as at −10 °C, through the designated thermal management modes.

Uncertainty Propagation in a Simplified Integrated Thermal Management System

An integrated generic plate model that describes single-phase transport combining heat acquisition and rejection regimes is investigated. Transient processes and input uncertainty propagation impacting temperature variations in this simplified, dimensionless integrated thermal management system are discussed. The heat acquisition plate is surface-heated on one side, with the heat being conducted into a liquid. The heated liquid is assumed to be adiabatically advected to the heat rejection plate. Convection boundary conditions are considered for both plates. The range of mean values of dimensionless input parameters, such as the Biot and Prandtl numbers, is determined by the choice of a particular plate metal and flowing liquid, and their stochastic nature is described by the Gaussian distributions. Adiabatic solutions for the dimensionless temperature variations in the plates are obtained for different temperatures and Reynolds numbers. As is shown, even an assumed small standard deviation for the input parameters may result in a drastic increase in the stochastic spread in the temperature variation in the heat rejection plate. Unlike the temperature variation across the acquisition plate, the temperature variation profile for the heat rejection plate is sensitive to the temperature of the incoming liquid and heat input at the acquisition plate.

Study on an energy-saving thermal management system in outdoor base stations

In order to solve the poor heat dissipation in the outdoor mobile communication base station, especially in summer, high temperature alarm phenomenon occurs frequently, affecting the normal operation of building base band unite, this paper designs an energy-saving and efficient integrated thermal management system, which has achieved good results by applying the combined operation of heat pipe cooling and air conditioning system using the outdoor temperature switching mode. A mobile communication base station in Zhengzhou City was chosen for a pilot application. The measured results showed that the system ran stably, the temperature inside the cabinet was controlled between 12?C and 39?C with no high temperature alarm, the compressor running time was significantly reduced, the power consumption of the air conditioner was significantly reduced, and the annual power saving rate was as high as 58.63%.

NMPC-Based Integrated Thermal Management of Battery and Cabin for Electric Vehicles in Cold Weather Conditions

One of the major obstacles along the way of electric vehicles' (EVs') wider global adoption is their limited driving range. Extreme cold or hot environments can further impact the EV's range as a significant amount of energy is needed for cabin and battery temperature regulation while the battery's power and energy capacity are also impeded. To overcome this issue, we present an optimal control strategy based on nonlinear model predictive control (NMPC) for integrated thermal management (ITM) of the battery and cabin of EVs, where the proposed NMPC simultaneously optimizes the EV range and cabin comfort in real time. Firstly, the components of the designed ITM system are introduced and control-oriented modeling is done. Secondly, to demonstrate and validate the benefits of the proposed ITM, an optimal control problem is defined and dynamic programming (DP) is employed to find the global optimal solution. Thirdly, for practical implementation, NMPC-based control strategy is developed, where the cost function design and weights calibration are done in comparison with DP global optimal solution. Weight-tuning results show that our NMPC-based approach can achieve close driving range maximization as compared to the DP benchmark while ensuring cabin comfort. The developed NMPC-based ITM strategy is further illustrated by comparing its performance to two additional benchmark strategies, i.e., rule-based control and cabin heating only. Finally, our simulation results also identify several important factors that impact the benefits of the proposed NMPC-based ITM, which are used to summarize the operating conditions under which the proposed ITM is critically needed.

Unlocking the multi-mode energy-saving potential of a novel integrated thermal management system for range-extended electric vehicle

The thermal management system of range-extended electric vehicles (REEV) is essential for energy saving. There is a lack of modification methods for enhancing its performance under multiple operating modes. Herein, we present a combined cooling and power cycle-based basic integrated thermal management system (ITMS) for the REEV and propose a generalised performance improvement approach adapted to multiple operating modes. Composed of a waste heat recovery and a cooling subsystem, the basic ITMS can achieve heat recovery and thermal management of the range extender's coolant and recirculated exhaust gas and cools the passenger compartment and battery packs. The factors limiting the basic ITMS are identified through parametric analysis: the low evaporative pressures constrained by the low-temperature waste heat (engine coolant) and cooling target (passenger compartment). In order to unlock the multi-mode potential of the ITMS, we introduce the liquid-vapour separation condenser to separate the working fluid (zeotropic mixture) into two mixtures with different volatility. The high-volatility mixture is utilised to absorb the low-temperature engine coolant's waste heat and generate the low-temperature cooling energy for the passenger compartment, lifting evaporative pressures while keeping the condensation pressure unchanged. Then, a multi-mode comparison verifies the modified system. When the vehicle operates with the range extender on and with/without cooling demand, the vehicle fuel consumption rate can be reduced by 6.6% and up to 12.5%, respectively. When the vehicle runs in pure electric mode and with cooling demand, the ITMS's electrical consumption can be lowered by 7.4%. Accordingly, matching the volatility of the zeotropic working fluid and the thermal management objects enables REEV's ITMS to fulfil substantial energy savings in multiple operating modes.

Design of Control Scheme for Integrated Thermal Management System of New Energy Bus

With the gradual promotion and popularization of new energy vehicles, the safety of new energy vehicles has attracted more and more attention. The thermal management system (TMS) is the key to whether the key assembly of new energy can work normally. In this paper an optimized control method is developed for the intelligent control of the TMS with the lowest overall energy consumption by taking into account the performance requirements of each subsystem. To realize this, the simulation of the integrated TMS is carried out along with a real vehicle test platform to provide practical and feasible solutions. This study has improved the design depth and level of system intelligence and digitalization.

Flow Loss Analysis and Structural Optimization of Multiway Valves for Integrated Thermal Management Systems in Electric Vehicles

The multiway valve is the core component of the integrated thermal management system in an electric vehicle, and its heat transfer loss and pressure loss significantly impact the performance of the whole thermal management system. In this paper, heat transfer loss and pressure loss in multiway valves are investigated using three-dimensional unsteady numerical simulations. Heat transfer loss and pressure loss under different operating modes are revealed, and relationships between pressure loss and mass flow rate, inlet temperature, and valve materials are studied. The results show that the significant temperature gradient around the control shaft results in heat transfer loss and pressure loss mainly occurs around the junction of the control shaft and the shell, where the flow direction changes sharply. The pressure loss is nonlinearly and positively correlated with the mass flow rate. Furthermore, the main geometric parameters of the pipeline and the control shaft are optimized. The pressure loss firstly increases and then decreases, with the increasing curvature of the inner walls of the pipe corners in four flow channels. Compared with the structural optimization at the pipe corners, increasing the curvature of the inner wall of the control shaft and the shell corners reduces pressure loss continuously. Moreover, this study obtains an optimal structure with minimum pressure loss using coupled structure optimization at the control shaft and shell corners.

Different strategies in an integrated thermal management system of a fuel cell electric bus under real driving cycles in winter

Due to the climate crisis and the restriction measures taken in the last decade, electric buses are gaining popularity in the transport sector. However, one of the most significant disadvantages of this type of vehicle is its low autonomy. Many electric buses with proton-exchange membrane fuel cells (PEMFC) systems have been developed to solve this problem in recent years. These have an advantage over battery-electric buses because the autonomy depends on the capacity of the hydrogen tanks. As with batteries, thermal management is crucial for fuel cells to achieve good performance and prolong service life. For this reason, it is necessary to investigate different strategies or configurations of a fuel cell electric bus's integral thermal management system (ITMS). In the present work, a novel global model of a fuel cell electric bus (FCEB) has been developed, which includes the thermal models of the essential components. This model was used to evaluate different strategies in the FCEB integrated thermal management system, simulating driving cycles of the public transport system of Valencia, Spain, under winter weather conditions. The first strategy was to use the heat generated by the fuel cell to heat the vehicle's cabin, achieving savings of up to 7%. The second strategy was to use the waste heat from the fuel cells to preheat the batteries. It was found that under conditions where a high-power demand is placed on the fuel cell, it is advisable to use the residual heat to preheat the battery, resulting in an energy saving of 4%. Finally, a hybrid solution was proposed in which the residual heat from fuel cells is used to heat both the cabin and the battery, resulting in an energy saving of 10%.

Koopman Model Predictive Control of an Integrated Thermal Management System for Electric Vehicles

AbstractThis paper is concerned with energy efficient operation of an integral thermal management system (ITMS) for electric vehicles using a nonlinear model predictive control (MPC). Driven by a heat pump (HP), this ITMS can handle battery thermal management (BTM) while serving the need for cabin cooling or heating need. The objectives of the ITMS MPC control strategy include minimization of power consumption and achieving temperature setpoint regulation for the battery and cabin space based on predictive information of traction power and cabin thermal load. The control design is facilitated by a gray-box modeling framework, in which the nonlinear dynamics of HP subsystem are characterized with a data-driven Koopman subspace model, while the BTM subsystem dynamic is a bilinear physics-based model. The computational efficiency of the proposed MPC framework is improved with two aspects of convexification for the underlying receding-horizon constrained optimization problem: the Koopman-operator lifting and the McCormick envelopes implemented for handling the bilinear dynamics. The proposed control method is evaluated with simulation study, by developing a Modelica-Python cosimulation platform via the functional mockup interface (FMI), where the electric vehicle (EV)-ITMS plant is modeled in Modelica with Dymola and the MPC design is implemented in Python. By benchmarking against a recurrent-neural-networks (RNN) model based nonlinear MPC, the simulation results validate the effectiveness and improved computational efficiency of the proposed method.

Optimization of injection-port design for multi-level waste heat recovery in an electric vehicle heat pump system

A multi-level waste heat recovery (MWHR) is an effective heat recovery strategy to utilize a limited amount of waste heat in electric vehicles (EVs). Because the MWHR system relies on the vapor injection technique, the port hole design critically affects the system performance. However, none of previous studies presented the optimal design of injection port for MWHR system. In this study, the effect of port design on the MWHR system performance was investigated. A continuous injection model was developed to reflect the dynamic behavior of MWHR system and integrated into a transient heat pump model. Integrated thermal management system (ITMS) model was established by combining the transient heat pump model with electric device model. The effects of injection port location and size were analyzed with the ITMS model under cold-start conditions. The optimal port hole design was suggested as the dual port located at 600° with a radius of 2 mm from the perspective of total energy consumption. Total power consumptions were saved up to 12.0 % and 10.6 % with the optimal port size and angle, respectively. This study can provide reference data and an optimization methodology for designing the MWHR system port hole.

A Microencapsulated Phase-Change Material Suspension-Based Integrated Thermal Management System for Extended Range Electric Vehicle

Abstract In order to improve the temperature maintenance capacity for the battery of the extended-range electric vehicle (EREV) in a low-temperature environment, a microencapsulated phase-change material suspension (MPCMS)-based integrated thermal management system (ITMS) is proposed. The working modes of the proposed ITMS are divided based on series-parallel connections of the battery thermal management system (BTMS), motor thermal management system, motor thermal management system, and auxiliary power unit (APU) thermal management system; the structural parameters of the proposed ITMS are determined by robust design, and the system performance difference between the proposed ITMS and the traditional BTMS is verified through the comparative simulation in −20 °C environment. The results show that the proposed ITMS can significantly delay the decline of battery temperature in the charge-depleting (CD) stage and can reduce the time of the positive temperature coefficient (PTC) heater being on by 27.26%, and the total time being on by 54.82%. During the charge-sustaining (CS) stage, when the PTC heater is off, the average battery temperature will increase by 15.33 °C compared with the traditional BTMS. Based on the proposed ITMS, the temperature maintenance capability for the battery can be significantly improved, and the energy consumption of the PTC heater and vehicle can be reduced by 48.12–100% and 13.44–33.58%, respectively.

Parameter-Matching Algorithm and Optimization of Integrated Thermal Management System of Aircraft

The integrated thermal management system of aircraft is essential to maintain a suitable environment for the cabin crew and devices. The system is composed of the air-cycle refrigeration subsystem, the vapor-compression refrigeration subsystem, the liquid-cooling subsystem and the fuel-cycle subsystem, which are coupled with each other through heat exchangers. Due to the complex structure and large number of components in the system, it is necessary to design a corresponding parameter-matching algorithm for its special structure and to select the appropriate optimization design method. In this paper, the structure of an integrated thermal management system is analyzed in depth. A hierarchical matching algorithm of system parameters was designed and realized. Meanwhile, a sensitivity analysis of the system was performed, where key parameters were selected. Besides, a variety of optimization algorithms was used to optimize the design calculations. The results show that the particle swarm optimization and genetic algorithm could effectively find the global optimal solution when taking the fuel penalty as the objective function. Furthermore, the particle swarm optimization method took less time.

Conventional and enhanced exergy analyses of a parallel integrated thermal management system for pure electric vehicles

To improve the efficiency of the integrated thermal management system (ITMS) of pure electric vehicles, an enhanced exergetic analysis method was proposed. According to enhanced exergetic analysis, the exergy destruction distribution of main components of ITMS was detected in-depth. The results indicate that the exergy destruction within the evaporator entirely belonged to the endogenous part, and the exergy destruction of the condenser is mainly caused by the condenser itself; its endogenous exergy destruction (78.8%) is greater than the exogenous exergy destruction (21.2%). Meanwhile, the enhanced exergetic analysis suggested that the avoidable exergy destruction of the system accounts for about 68.7% of the total exergy destruction of the system; the potential for improvement of the system is huge. The interaction among the components is not strong, due to the 72.38% of exergy destruction in the system is endogenous. The highlights of the paper are: 1) thermodynamic modelling of the parallel ITMS is carried out; 2) enhanced exergetic analysis is applied to ITMS of pure electric vehicles; 3) avoidable exergy destruction is obtained, which represents the potential for system improvement; 4) the improvement priority for system components is acquired.

An Integrated Thermal Management System and Control Strategy for Cabin and Battery Heating in Range-Extended Electric Vehicles Under Low-Temperature Conditions

An Integrated Thermal Management System and Control Strategy for Cabin and Battery Heating in Range-Extended Electric Vehicles Under Low-Temperature Conditions

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.

Performance of an Integrated Thermal Management System for helicopter

The traditional environment control systems for helicopter are mainly the air cycle or evaporative refrigeration system and the engine bleed air heating system. But they have low exergy efficiency and high fuel mass penalty in order to work in all climatic conditions. In this paper, an Integrated Thermal Management System (ITMS) is proposed for helicopter to satisfy the heating and refrigerating demands. This ITMS is a Heat Pump Air Conditioning System (HPACS) based on waste heat recovery from the lubricating oil system. A performance evaluation method is set up to investigate its working performances using exergy, energy level and fuel mass penalty. In a hot day, the input exergy and exergy efficiency of ITMS are 3.2 kW and 34%, respectively, the energy level difference is 0.0274, and the total fuel mass penalty is 22.75 kg. In a cold day, the input exergy and exergy efficiency of ITMS are 3.8 kW and 53%, respectively, the energy level difference is 0.026, and the total fuel mass penalty is 24.76 kg. Therefore, the comparison results show the performance advantages of the proposed ITMS in different climate conditions.

Experimental and Numerical Investigation on an Integrated Thermal Management System for the Li-Ion Battery Module with Phase Change Material

Lightweight power battery modules with outstanding thermal performance are urgently required given the rapid development of electric vehicles. This study proposes a composite phase change material coupled with forced convection as an integrated thermal management system (ITMS) with the aim to control the temperature’s rising tendency and maintain the temperature distribution uniformly within an appropriate range among the battery modules. The thermal behavior effects of airflow rates on the thermal management system were investigated in detail by combining experiments and numerical simulations. Comparisons were conducted between an air cooling system with an optimum flow rate and the ITMS. Experimental results revealed that the cooling effect of the ITMS was better than that of the forced cooling system at a 3 m/s airflow rate. The maximum temperature in the designed battery module was limited to 63.2°C. The maximum temperature difference was limited to 4.8°C at a 4 C discharge rate. This research indicates that the ITMS is an effective and optimized approach to control and balance the temperature among battery modules, thereby providing engineers with design optimization strategies for similar systems.

Comparative Study of Physics-Based Modeling and Neural Network Approach to Predict Cooling in Vehicle Integrated Thermal Management System

Vehicle integrated thermal management system (VTMS) is an important technology used for improving the energy efficiency of vehicles. Physics-based modeling is widely used to predict the energy flow in such systems. However, physics-based modeling requires several experimental approaches to get the required parameters. The experimental approach to obtain these parameters is expensive and requires great effort to configure a separate experimental device and conduct the experiment. Therefore, in this study, a neural network (NN) approach is applied to reduce the cost and effort necessary to develop a VTMS. The physics-based modeling is also analyzed and compared with recent NN techniques, such as ConvLSTM and temporal convolutional network (TCN), to confirm the feasibility of the NN approach at EPA Federal Test Procedure (FTP-75), Highway Fuel Economy Test cycle (HWFET), Worldwide harmonized Light duty driving Test Cycle (WLTC) and actual on-road driving conditions. TCN performed the best among the tested models and was easier to build than physics-based modeling. For validating the two different approaches, the physical properties of a 1 L class passenger car with an electric control valve are measured. The NN model proved to be effective in predicting the characteristics of a vehicle cooling system. The proposed method will reduce research costs in the field of predictive control and VTMS design.

Research progress in integrated thermal management of electric vehicles

Severe energy crisis and environmental pollution are the foremost problems in the world today. Electric vehicles have several advantages over traditional internal combustion engine-based vehicles, such as high energy efficiency and low emissions, which are effective in alleviating the energy crisis and environmental problems. However, the electric vehicles’ performance is greatly affected by temperature. An excessively high temperature during the charging and discharging process may accelerate the degradation rate of a battery cell and shorten its lifespan. In contrast, an excessively low temperature may reduce the battery’s efficiency and affect its discharge capacity. Air-conditioning systems in electric vehicles consume electricity to create a comfortable environment in the passenger compartment. However, excessive temperature of the motor drive will decrease its efficiency. Therefore, the battery, passenger compartment and motor drive system must be maintained at adequate temperatures to ensure the safety, comfort, and economy of the electric vehicles. Previous studies usually focused on a single thermal management system at a time, such as a battery thermal management system, air-conditioning systems in electric vehicles, and motor thermal management system. This means that the coupling relationships between the above-mentioned thermal management systems and the performance analysis of the integrated thermal management system at the vehicle level were not properly investigated. This study focused on the key issues in the construction of an integrated thermal management system for electric vehicles. Firstly, the heat generation models of the battery, passenger compartment, and motor drive system were summarized. Secondly, the existing thermal management methods for these three systems were systematically reviewed. Especially, the research status, operation control, and performance evaluation of the integrated thermal management system were especially analyzed. Finally, the deficiencies of the previous studies were summarized and the research prospects were proposed. It is pointed out that it is necessary to study the accurate heat generation models, develop the compact and efficient integrated thermal management system, and optimize the operation control of the integrated thermal management system under a comprehensive performance evaluation system in the near future.

Numerical investigation on integrated thermal management for a lithium-ion battery module with a composite phase change material and liquid cooling

A novel thermal management system was proposed based on paraffin (RT44HC)/expanded graphite (EG) composite phase change material (CPCM) coupled with liquid cooling to maintain the temperature rise and difference within a desirable range of lithium-ion batteries at a discharge rate of 3C. A numerical research was conducted by computational fluid dynamics (CFD) to investigate the effects of the battery’s thermal characteristics at an ambient temperature of 40 °C at various flow velocities, channel arrangement and CPCM with different mass fraction of EG. Furthermore, the thermal behavior of the integrated thermal management system (ITMS) in a charge–discharge cycles was analyzed. The results indicate that the heat dissipation of the battery pack is enhanced with an increase of the flow velocity, but when the flow velocity is greater than 0.08 m/s, the increase of the flow velocity imposes little effect on further improving heat dissipation performance of the ITMS. The channel layout of Type I indicates the optimal cooling performance at various flow velocities. Compared with the pure paraffin phase change material (PCM), the maximum temperature is reduced by 2.1 °C, and the temperature difference is only 2 °C in the ITMS, with an EG of 6 wt%. On charge–discharge duties, the maximum temperature and the initial temperature are constant at the lower liquid flow velocity of 0.04 m/s, and the ITMS with an EG of 6 wt% meets the requirements for heat dissipation.