Research On Hybrid Electric Vehicle Engine Heating-up Process And Fuel Consumption By Applying Auxiliary Heaters

With the increasing population of the world and the rapid development of economy and technology,energy consumption has been increasing year by year.As the decrease of petroleum resources,auto industry needs to break through the bottleneck of technology to decrease the consumption of the energy,in recent years,hybrid electric vehicles have emerged.The hybrid electric vehicles could meet the requirements of driving mileage and reducing fuel consumption when electric vehicles have not been widely used,so it has great research value.When the car is running,for the poor fuel atomization and the low fluidity of the lubrication oil in the cold start stage of the engine,so the pollutant emissions and engine wear account take up a large part of the overall operation of the vehicle.If the engine coolant heating-up time can be shortened and the fuel consumption can be reduced in the stage of the cold start,the fuel consumption of the whole operating process will be greatly reduced.If the engine coolant heating-up time and fuel consumption of the hybrid power system can be optimized,the engine fuel consumption of hybrid electric vehicles can be further reduced on the basis of energy saving.Therefore,this work uses the heater to heat the engine coolant to shorten the engine coolant heating-up time,further reduces the fuel consumption?engine wear account and improve the driving experience,and alleviates the pressure of energy shortage.This work is based on “Research on heat flux characteristics and heating-up control of hybrid power system” supported by Jilin Natural Science Foundation.The purpose of this work is to shorten the engine coolant heating-up time and reduce the fuel consumption of engine cold start and warm-up by means of auxiliary heating.In this work,the engine coolant is heated by fuel heater and PTC electric heater.The author determines five heating mode(reference,synchronous heating,preheating,warm start,combine warm start with synchronous heating)and do the bench experiment.By adjusting the heating mode,heating power,preheating temperature,warm start temperature and other parameters,the influence of each mode on the engine coolant heating-up time and engine fuel consumption have been analyzed.Furthermore,the engine cooling system and the engine cooling system with the auxiliary heater have been built by one-dimensional simulation software.The influence of ambient temperature on the heating-up time of the engine coolant and the improvement of engine coolant heating-up time with the auxiliary heater have been analyzed.The experiment results show that both the fuel heater and the PTC electric heater can shorten the engine coolant heating-up time and reduce the engine fuel consumption in the mode of synchronous heating.The fuel heater and the PTC electric heater could shorten the coolant heating-up time to 311 s and 274 s respectively;The fuel heater and the PTC electric heater could reduce the engine fuel consumption to 233.92 g and 217.19 g respectively.With the increase of the heating power,the coolant heating-up time and the fuel consumption decrease gradually.Both the fuel heater and the PTC electric heater can improve the engine cold start performance and reduce the engine fuel consumption in the preheating mode.Compared with the reference heating mode,the fuel heater and PTC electric heater could shorten the coolant heating-up time to 451 s and 501 s respectively,and the fuel heater and PTC electric heater could reduce the engine fuel consumption to 373.31 g and 361.59 g respectively when the preheating temperature is 60 degrees.With the increase of the preheating temperature,the engine operating time and engine fuel consumption decrease gradually.Compared with the warm start,the combined heating mode of warm start and synchronous heating shortens the heating-up time of engine coolant and reduces fuel consumption.Compared with the warm start,the combination of warm start and fuel heater synchronous heating and the combination of warm start and PTC electric heater synchronous heating could shorten the heating-up time to 193 s and 152 s respectively,and reduce the fuel consumption to 105.81 g and 117.76 g respectively.With the increase of the warm start temperature,the engine coolant heating-up time and engine fuel consumption decrease gradually.The simulation results show that the lower ambient temperature will cause longer engine coolant heating-up time.Compared with the ambient temperature of 0 degrees,the ambient temperature of 25 degrees below zero could prolong the heating-up time to 261 s.Using the auxiliary heater in the engine cooling system can obviously shorten the engine coolant heating-up time.Compared with the without auxiliary heater,the auxiliary heater could shortens the heating-up time to 275 s when the ambient temperature is 25 degrees below zero.It has certain guiding significance for improving the engine cold start performance.