Research On Waste Heat Recovery Method Of Aero-engine Under Extreme Conditions

In this paper,a waste heat recovery and utilization system based on heat pipe is proposed.Taking heat pipe as the core part of heat transfer in the system as the main research object,the theoretical analysis of heat pipe after the treatment of flattening and bending is carried out.Finally,the fixed-point bending and the whole bending of the compressed heat pipe are explored under the test conditions,and the feasibility of the application of heat pipe in this system is obtained.The main work of the paper is as follows:(1)According to the location and recovery mechanism of aircraft waste heat,this paper proposes a kind of aircraft waste heat recovery and utilization system based on heat pipe.The system model of the waste heat recovery system is established,and the four modules of the system(heat pipe heat capture module,heat transfer fluid module,phase change heat storage module,and Rankine cycle module)are introduced in detail,and the potential operation mode of the system is explained.(2)Due to the limitation of installation position and space,the system adopts the bending and flattening heat pipe.The method of "equivalent substitution" for the study of flattening heat pipe is proposed.It is assumed that the effective diameter of the flattening heat pipe is the same as that of the conventional heat pipe,and a mathematical model is established by using Matlab.The results show that the heat transfer performance of the flattening heat pipe under the bending state changes the same as that of the conventional heat pipe,but decreases with the increase of the bending Angle.(3)On the basis of theoretical analysis,the fixed-point bending test of heat pipe was conducted.This test with bent pressure flat heat pipe,heat pipe for room temperature sintering suction fluid core is divided into plane bending and bending of surface,under the same experimental conditions has carried on the comparative experimental study,the experimental results show that under the condition of the limit bending Angle 90 °,two kinds of heat pipe can be normal and stable work,isothermal characteristics of heat pipe has good;The bending Angle of the two heat pipes increased from 30° to 90°,and the thermal resistance increased by more than 60%.The heat transfer capacity of the flat bent heat pipe was better than that of the curved heat pipe.The cross sections of two kinds of bending heat pipes show that the deformation of curved heat pipes is serious.(4)Using the similarity principle,the evaporation section of the flat conventional heat pipe was treated as a whole bending,and a small test device was built to conduct experimental research on the heat transfer performance of the compressed heat pipe with the overall bending of the evaporation section.The results show that the heat storage capacity of the heat pipe is related to the temperature of the heat source.The higher the temperature of the heat source,the better the heat transfer performance of the heat pipe is.Experimental investigation on heat transfer enhancement of heat pipe regenerator shows that the heat transfer performance of heat pipe regenerator increases by 6% when strip aluminum is added to PCM.