新能源汽车热泵空调系统抑霜除霜研究进展OA

The heat pump air conditioning systems in new energy vehicles face the problem of frost formation on the evaporator surface during low-temperature heat-ing,which reduces the system's heating energy effi-ciency and shortens the driving range.The research progress of domestic and foreign scholars on the frost suppression and defrosting technology of heat ex-changer surfaces is analyzed,and the characteristics of different stages of frost formation on evaporator sur-faces at low temperatures as well as the methods of frost suppression and defrosting are summarized.For frost suppression during the frost crystal growth stage,there are two types of methods:surface modification,and application of external electromagnetic fields and ultrasonic waves.Both superhydrophobic and hydrophilic coatings can suppress frost,and they have no extra energy consumption and are environmentally friendly.However,these materials have difficulties in preparation,require a long production cycle,and also have the problem that their frost suppression effect fails after long-term use.The optimum conditions of ap-plying electromagnetic field,ultrasonic resonance and economy are still to be studied.Different temperature,humidity,wind speed,etc.all affect the growth rate of frost layer in the frost layer growth period.Applying a magnetic field can also delay the growth of the frost layer by changing the structure of water molecules,thereby reducing the thickness and density of the frost layer.During the full growth stage of the frost layer,it is necessary to use both frost suppression and defrost-ing methods in combination.The optimization of the heat exchanger structure can achieve frost suppression.Among defrosting methods,reverse cycle defrosting has a fast speed but consumes electricity and affects comfort;it can be optimized by combining with phase change materials or waste heat recovery.Hot gas by-pass defrosting has little impact on room temperature but is slow in speed;the temperature and opening de-gree of the bypassed hot gas affect its defrosting effect.Ultrasonic defrosting is superior to electric heating in terms of defrosting effect,with faster defrosting speed and fewer residual droplets.