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Current Status on the Thermal Management of Electric Vehicles

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "E: Electric Vehicles".

Deadline for manuscript submissions: closed (15 December 2022) | Viewed by 8444

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Special Issue Editors

Prof. Dr. Feng Cao

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Guest Editor

School of Energy and Power Engineering, Xi’an Jiaotong University, 28 Xianning West Road, Xi’an 710049, China
Interests: thermal management of electric vehicle; transcritical carbon dioxide refrigeration and heat pump system

Dr. Xiang Yin

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Guest Editor

Dr. Yulong Song

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Guest Editor

Special Issue Information

Dear Colleagues,

Electric vehicles have become an important strategy to shoulder multiple historical missions, such as future travel, low carbon development, energy security and air quality improvement, but they must also become one of the most important links to build a safer, more comfortable, energy-saving, and environmentally friendly future electric vehicle by developing green and low-carbon thermal management technology, improving the efficiency of thermal management, improving the temperature control accuracy of batteries and motors, and creating a more comfortable interior environment.

The progress of society must be accompanied by change in technology, and the adoption of the thermal management solution with eco-friendliness and energy-saving characteristics is mandatory in order to mitigate the contemporary environmental challenges and to respect the different regulations on the progressive ban of hydrofluorocarbons.

The purpose of this Special Issue is to attract state-of-the-art research and review articles on the thermal management technologies of electric vehicles. Topics of interest include but are not limited to the following:

Transcritical CO₂ technology;
AC, HP, and thermal management of vehicles;
Low temperature heat pump technology;
Thermal management technology of passenger cars, commercial vehicles, and rail vehicles;
Mixtures based on natural working fluid;
HFO-based mixtures;
Integrated thermal management technology (cabin comfort and battery/motor/ECU temperature management);
Intelligent optimization;
Control strategy;
System and component modeling;
NVH technology;
CFD analyses for carriage air distribution etc.;
Experimental investigations;
Exergy-based assessments;
Life cycle climate performance and life cycle assessment;
Expanders, ejectors, and others;
Vortex tubes;
Safety issues and risk assessment for flammable refrigerants.

Prof. Dr. Feng Cao
Dr. Xiang Yin
Dr. Yulong Song
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (5 papers)

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Research

21 pages, 3977 KiB

Open AccessArticle

A Comprehensive Assessment of the Refrigerant Charging Amount on the Global Performance of a Transcritical CO₂-Based Bus Air Conditioning and Heat Pump System

by Yulong Song, Hongsheng Xie, Mengying Yang, Xiangyu Wei, Feng Cao and Xiang Yin

Energies 2023, 16(6), 2600; https://doi.org/10.3390/en16062600 - 09 Mar 2023

Cited by 1 | Viewed by 1735

Abstract

To mitigate the contemporary environmental challenges and to respect the regulations on the progressive ban of hydrofluorocarbons (HFC), natural fluid CO₂ was selected as an ideal refrigerant alternative in the transportation domain. In this study, the optimal CO₂ charging amount and the refrigerant distribution in a bus air conditioning/heat pump system were analyzed in detail. The results showed that there was a plateau (so named by the best charging amount) of the CO₂ charging amount in which the system performance reached an optimal value and maintained it nearly unchanged during this plateau while the performance declined on both sides of the plateau. In addition, the ambient temperature was found to have little effect on the determination of the refrigerant charging plateau, while the refrigerant distribution was affected by the ambient temperature to some extent. Due to the large thermal load and thermal inertia on a bus, the data and conclusions obtained are different from those of ordinary electric small passenger vehicles. This article aims to discover some quantitative parameters and lay a theoretical foundation in this field which is lacking relevant research. Through the research based on the GT-Suite simulation platform, we simulated the transcritical CO₂ cycle applied on a bus, and the performance changes of the bus system (COP 1.2–2.2, refrigerating capacity 9.5–18 kW) under different charging rates (3–8 kg) were obtained. Full article

(This article belongs to the Special Issue Current Status on the Thermal Management of Electric Vehicles)

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13 pages, 4516 KiB

Open AccessArticle

Study on Optimization of Copper to Aluminum for Locomotive Finned Tube Radiator

by Ying Guan, Hongjiang Cui and Jiyou Fei

Energies 2023, 16(5), 2130; https://doi.org/10.3390/en16052130 - 22 Feb 2023

Cited by 3 | Viewed by 1131

Abstract

The influence of the improvement of the finned tube radiator unit structure on the fluid flow and heat transfer effect of the locomotive was studied. A saw-toothed fin structure with aluminum instead of copper was proposed to keep the position and size of the flat copper hot water pipe unchanged. CFD simulation analysis was carried out by ICEPAK17.0, under the conditions of an ambient temperature of 24.6 °C, atmospheric pressure of 85,040 Pa and air density ρ = 0.94 kg/m³, to compare the changes of velocity field, temperature field, turbulence field and field synergy angle. The sawtooth structure of the new heat sink increases the turbulence effect of the fluid, reduces the thickness of the outer boundary layer of the water pipe, and strengthens the heat transfer effect of the radiator. Finally, the baffle height, wing window width and sawtooth angle of the sawtooth structure were selected, and the heat transfer coefficient and pressure under three conditions of low, medium and high were used as indexes to analyze the influence of each parameter on the performance of the radiator. The results show that the heat dissipation effect of the serrated aluminum sheet is higher than that of the copper sheet, the heat transfer coefficient is increased by about 1.3%, the average pressure is reduced, the turbulence performance is improved, the synergy angle is reduced by about 2.3°, and the new radiator has better performance. The fin factor has the greatest influence on the heat transfer coefficient and the least influence on the pressure. When the baffle is about 0.15 mm high, the heat transfer coefficient is the largest, and the height change has the highest effect on the pressure. The included Angle factor has the least influence on the heat transfer effect, and the influence on the pressure is higher. By changing the fin window structure, the thermal performance of the finned tube radiator can be improved. Full article

(This article belongs to the Special Issue Current Status on the Thermal Management of Electric Vehicles)

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16 pages, 4226 KiB

Open AccessArticle

The Experimental Study of an R744 Heat Pump System for an Electric Vehicle for Cabin Cooling or Heating and Battery Fast Charging Cooling

by Xilong Wang, Keke Xu, Linjie Huang, Feng Cao and Yulong Song

Energies 2023, 16(4), 2061; https://doi.org/10.3390/en16042061 - 20 Feb 2023

Cited by 2 | Viewed by 2407

Abstract

In this paper, a new R744 heat pump system is studied. The gas cooler, evaporator, indoor heat core, and indoor gas cooler are all micro-channel heat exchangers. The R744 high pressure system adopts a combination of an accumulator and internal heat exchanger (ACCU/IHX). In addition, an electronic reversible regulating valve is added before the outdoor gas cooler, making the outdoor heat exchanger able to be used as a gas cooler or evaporator. The water-cooled condenser can improve the performance in the cooling or heating mode. The research contents contain the performance and optimal pressure under extreme conditions as a result of the experiments. The results show that the cooling capacity can reach 8.2 kW with a COP of 1.87, under a 40 °C external circulation intake. The cooling capacity on the battery side can reach 11 kW under an ambient temperature of 40 °C, which can provide a sufficient cooling capacity. Under an ambient temperature of −20 °C, the maximum heating capacity can reach 6.86 kW with a COP of 1.67. Under an ambient temperature of −15 °C, the heating capacity reaches 5.07 kW with a COP of 1.78, when the indoor air volume flow rate is 200 m³/h. Obviously, R744 heat pumps show a huge advantage, compared with the traditional PTC heating or R134a heat pumps at extremely low temperatures. Full article

(This article belongs to the Special Issue Current Status on the Thermal Management of Electric Vehicles)

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16 pages, 3652 KiB

Open AccessArticle

The Collaborative Optimization of the Discharge Pressure and Heat Recovery Rate in a Transcritical CO₂ Heat Pump Used in Extremely Low Temperature Environment

by Zhongkai Wu, Feifei Bi, Jiyou Fei, Zecan Zheng, Yulong Song and Feng Cao

Energies 2023, 16(4), 2059; https://doi.org/10.3390/en16042059 - 20 Feb 2023

Cited by 1 | Viewed by 1043

Abstract

Considering the excellent environmental properties and heating capability under wide running conditions of the natural fluid CO₂, the transcritical CO₂ heat pump system has widely been used in the application of water heaters, commercial heating and cooling, electric vehicle thermal management, etc. Since the performance was highly affected by the discharge pressure and heat recovery rate in a transcritical CO₂ system, the collaborative optimization of these two parameters was analyzed in detail in this study. The results showed that the optimal value of the system heating COP, which was the ration of heating capacity to power consumption, was better under a higher heat recovery rate and relatively lower discharge pressure, which is why these kinds of operating conditions are highly recommended from the perspective of collaborative optimization. Additionally, the heat recovery rate had a positive effect on the system performance when the discharge pressure was lower than its optimal value, while the heat recovery rate would present a passive effect on the system performance when the discharge pressure was higher than its optimal value. The relevant conclusions of this study provide a good theoretical basis for the efficient and stable operation of the transcritical CO₂ heat pump technology under the conditions of a wide ambient temperature range. Full article

(This article belongs to the Special Issue Current Status on the Thermal Management of Electric Vehicles)

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14 pages, 4307 KiB

Open AccessArticle

CFD Simulation Study on the Air Side of a CO₂ Evaporator in a Motor Train Unit Air Conditioning System

by Hongjiang Cui, Xiaoke Su, Ying Guan and Jiyou Fei

Energies 2023, 16(3), 1037; https://doi.org/10.3390/en16031037 - 17 Jan 2023

Cited by 2 | Viewed by 1296

Abstract

At present, China’s high-speed rail is in a period of rapid development. Most of the refrigerants used in Chinese motor train units at this stage are still R134a and R407c, which have an impact on the environment. In response to the environmental protection concept of green travel, it is of great significance to study the air conditioning system of motor train units using CO₂ refrigerant. Using CFD simulation analysis technology, the heat transfer performance of the air side of the CO₂ finned tube evaporator used in the air conditioning system of the motor train unit is studied. We select the air outlet temperature, pressure drop, heat transfer factor, and resistance factor as the objective function, in addition, monitoring points are set up in the air flow channel to monitor the turbulent flow field and pipe wall pressure. Our research shows that the cooling capacity of the CO₂ evaporator can reach up to 29.76 kW, which can meet the heat exchange required in the air conditioning system of the motor train unit. In order to obtain a better structure and the conditions of the heat transfer effect, structural optimization was conducted. The simulation results demonstrate several trends: (i) With the augment of the air inlet velocity, the cooling capacity of the evaporator increases and the heat exchange effect improves; when the air inlet v_e > 2.2 m/s, the effect of continuing to augment v_e on heat exchange is weak. (ii) Following appropriate reduction of the diameter of the heat exchange tube, the wind resistance is reduced and the cooling capacity of the evaporator is improved. (iii) With the enlargement of the fin spacing, the turbulent motion in the flow channel can be fully developed, there is a peak in the change in the heat exchange tube area optimization factor, and the optimal fin spacing is between 1.6 mm and 1.7 mm; at this time, the average turbulent kinetic energy of the air side is larger and the turbulent dissipation rate is smaller. These results provide a reference for the practical application of CO₂ refrigerant in the motor train unit. Full article

(This article belongs to the Special Issue Current Status on the Thermal Management of Electric Vehicles)

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