冷启动时PTC-base喷油器内高压瞬变流场传热研究

Study on Heat Transfer of Transient and High-pressure Flow Field in PTC-base Injector during Cold-start

汽车在冷启动时有害物质排放很高,这和燃油温度有很大关系。本研究提出一种基于PTC的喷油器,该喷油器是在普通喷油器内部油路周围嵌入PTC材料,并以车载电源供电。当温度低于居里温度时,PTC材料的电阻很小,因此可产生大量热量,这些热量可以使流经管路的燃油得到加热。当温度达到居里温度时,PTC材料电阻变得很大,材料停止发热。利用PTC材料的这种特殊的阻温特性,我们可以在车辆启动时把喷油器出口的燃油温度控制在一个理想的范围。本研究的主要工作是对PTC-base喷油器建立模型并对不同条件下该喷油器的燃油传热进行分析。分析结果表明,冷启动时,在PTC-base喷油器中,燃油可以得到很好的加热。这对降低汽车冷启动排放将产生重要的作用。

The vehicle has a high harmful material emission during cold-start.It has a close relationship with temperature of the fuel oil.In this paper,a PTC-base injector is presented,in which PTC material is embedded around the fuel ducts of common injector and powered by car inverter.The PTC material possesses a low resistance and quickly generates heat while its temperature is lower than Curie point.This heat will be transferred to the fuel oil.And while the temperature coming to the Curie point,the resistance sharply rises and the PTC material almost stops generating heat.Utilizing this special resistance-temperature performance,the fuel oil temperature of nozzle can be controlled in an ideal scope while cold-start.The main work of this paper is modeling for PTC-base injector and analyzing fuel oil transfer heat in different conditions.According to the simulation results,a conclusion is drawn that the fuel oil can be heated very well in PTC-base injector.This result shows that PTC-base injector will produce important effect to reducing emission.