Experimental Study on HVAC System for Electric Vehicles

Abstract

An HVAC (heating ventilation and air conditioning) system for electric vehicles based on heat pump technology is designed and set up in this paper. Unlike the existing HVAC system for vehicles using fossil fuel, this experimental HVAC system can work in heat pump mode rather than directly heating the PTC thermistor by electricity when heating is needed. This experimental HVAC system takes use of parallel flow exchangers, enclosed DC vortex compressor and the low voltage DC speed controller, which is used for controlling the compressor`s working frequency. After the experimental system is set, the influence of compressor`s speed and the environmental temperature to the performance of the HVAC system are tested and researched in refrigeration mode and heat pump mode respectively. Parameters like the compressor`s power input, the system`s refrigeration/heating capacity, and the coefficient of performance (COP) varied with compressor`s speed are recorded. Curves of those parameters are drawn and the reasons of their changing trends are analyzed respectively. The testing results of this experimental HVAC system are compared with references` results. According to the testing results, this experimental HVAC system can achieve better refrigeration and heating effects, and the cooling performance of the system increases with compressor speed; Part of the outside heat-exchanger gets frosted when the system works in heat pump mode, but the COP remains greater than 1, which means this experimental HVAC system is more energy-saving than the existing HVAC systems which are directly heating PTC thermistor by electricity for heating; In addition, compared with the sliding-vane compressor, the vortex compressor used in this paper has a better comprehensive performance and hence has a better application prospect.