Design And Implementation Of Heat Recovery System From Automobile Exhaust Based On Heat Pipe

The energy produced by the combustion of automobile fuel has not been effectively utilized,40%of them are discharged into atmosphere with emissions in the form of heat dissipation.Recycling exhaust heat can effectively improve the utilization efficiency of vehicle fuel,which has important economic value and is of great significance for the construction of environment-friendly society.The paper designed an experimental platform for the study of exhaust heat recovery based on the data of flow rate and temperature of exhaust.Firstly,we designed the heat pipes which made of carbon steel and water according to the heat transfer and working temperature range.Secondly,the structure of heat pipe heat exchanger(HPHX)was determined by thinking about the specific content of the research.Finally,the measurement system was designed for the experimental platform and which was integrated into the car's exhaust system with HPHX.10 groups of experiments were carried out in the experimental platform.Based on the experimental results,we reached the following conclusions:(1)the number of heat pipes is an important factor affecting the performance of heat recovery device,when the operating condition of the vehicle is certain,the heat recovery efficiency can be improved by increasing the number of the heat pipe,and the heat recovery quantity will increase accordingly;(2)the arrangement has effect on the performance of heat recovery device,when the number of heat pipes is fixed,the effect of cross arrangement is slightly better than that of sequential arrangement;(3)the greater the pipe inclination angle in a certain range(condenser section is above evaporation section),the better performance of heat recovery device;(4)in the same section of HPHX,which is perpendicular to the flow direction of the exhaust,the exhaust temperature of middle position is lower than that of around;(5)the higher the engine speed,the better performance of the heat recovery device,in the experiments designed in this paper,when the engine speed is 2500rpm,the heat recovery device obtains 2.14kW heat from the automobile exhaust and the heat recovery efficiency is 29.43%.One of the innovations in this paper is that when designing the HPHX,we adopt a non fixed structure,in which the number and position of heat pipe can be adjusted according to the experimental target,therefore,we can use a set of experimental platform to complete different research contents.Another innovation is the use of experimental method to study the variation of exhaust temperature in HPHX,which act in cooperation with the popular numerical simulation and CFD simulation method.With the method,the paper not only reached conclusions,but also found some problems must be overcome in practical application,which has certain value to promote the development of automobile exhaust heat recovery.