Experimental investigation on dehumidification and heating performance of a heat pump system concerning dew or fog removal for electric vehicles

Dehumidification and heating of electric vehicle heat pump systems are of significance in ensuring comfort and safety in winter. This study purposes to investigate the dehumidification and heating performances of a new-designed heat pump system. A numerical model is established and serves for analyzing the ventilation conditions for dew or fog removal of the windshield. Both ventilation conditions of the heat pump and the inner surface temperature of the windshield were investigated as per experimental measurements. Meanwhile, dehumidification rates, effective heating capacity, and coefficients of performance were analyzed under different operating conditions. It is shown that the heat-pump's air outlet conditions are within the range of suitable ventilation conditions meeting the needs of dew or fog removal. At the same compressor speed, the inlet air humidity of the evaporator inlet decreases, the dew or fog removal is more effective, and the coefficient of performance for heating increases but the coefficient of performance for dehumidification decreases. In the case of the same inlet air humidity, the dew or fog removal effect is better with increasing compressor speed; Meantime, the coefficient of performance for heating and dehumidification both decrease. The lower compressor speed and lower inlet air humidity for the evaporator enable the heat pump system to meet the demand for dew or fog removal of the windshield and ensure thermal comfort in the cabin. This study verifies the effectiveness of heat pump systems for dehumidification and heating and would be valuable to promote heat pump systems.