Coupling Effect of Air Flow Rate and Operating Conditions on the Performance of Electric Vehicle R744 Air Conditioning System

Anci Wang,Paride Gullo,Yulong Song,Feng Cao,Jianmin Fang,Xiang Yin

doi:10.3390/app11114855

Anci Wang, Paride Gullo + Show 4 more

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https://doi.org/10.3390/app11114855

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Abstract

The air flow rate on the gas cooler side is one of the key parameters affecting the performance and running safety of transcritical CO2 electric vehicle air conditioning systems. After experimentally analyzing the effects of the air volume flow rate in the gas cooler on the cycle parameters and system performance, a novel method to evaluate the optimal air flow rate was proposed. In addition, the effect of the gas cooler air volume flow rate on the key performance parameters of the system (e.g., optimal discharge pressure) was explored. Finally, the coupling effects of the compressor speed, ambient temperature and optimal air flow rate on the system performance was also exhaustively assessed. It was found that as the discharge temperature, the CO2 temperature at the gas cooler outlet and the discharge pressure did not vary more than ±2%, the corresponding gas cooler air volume flow rate was optimal. For the single-row and dual-process microchannel evaporator used in this work, the recommended value of the optimal gas cooler air volume flow rate was 2500 m3·h−1. The results could provide reference for the fan speed design of electric vehicle CO2 air conditioning systems, especially for the performance under idling model.

Highlights

The test bench employed for evaluating the performance of the transcritical CO2 electric vehicle air conditioning system involved a compressor, a gas cooler, an internal heat exchanger (IHX), an expansion valve (EXV), a microchannel evaporator in the heating, ventilation and air conditioning (HVAC) unit and an accumulator (Figure 1)
In order to enhance the performance of electric vehicle R744 air conditioning units, the effects of the gas cooler air volume flow rate on the key parameters have been experimentally studied
The coupling influence of operating conditions and air flow rate on the system performance have been studied in detail

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Electric vehicles have been proved to be one of the most effective solutions to reduce greenhouse gas and air pollutant emissions in the transport sector, besides promoting low noise [1,2]. A considerable contribution to the environmental impact of cars is given by high global warming potential (GWP) refrigerants [3,4]. Ever-stricter regulations aiming at phasing out these working fluids are being implemented all over the world. Looking for new environmentally friendlier refrigerants for mobile air conditioning units has become one of the hottest research topics in the field of EVs in recent years [5]

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