Simulation Analysis And Experimental Research Of Pulsating Heat Exchange System Based On New Type Diaphragm Booster

With the acceleration of the world's industrial development process,the demand for energy from mankind has continued to increase,leading to a series of environmental problems.Therefore,it has reached the goal of achieving energy conservation expectations and energy conservation,and improving energy efficiency has become a hot thesis in this century.Studies have shown that pulsating flow has an important effect on heat transfer,and most literatures have concluded that turbulent pulsation can enhance the heat transfer effect to different degrees.Based on the principle of hydraulic shock,the present invention develops a supplementary device that can effectively increase the pulsating pressure and thus enhance the heat exchange efficiency of pulsating flow.The system performance was improved and the heat transfer ability was enhanced.The main research work of this topic includes the following:An experiment was conducted to study the effect of pulsating flow on the heat transfer efficiency of a floor heating heat exchanger under the action of a diaphragm booster.A schematic diagram of the pulsating heat exchange system was developed and a pulsating heat exchange experiment bench was constructed according to the schematic diagram.The design meets the test requirements.New diaphragm booster.In the experiment,a comparison test was performed with the diaphragm booster function and no pressure booster device.The pressure and temperature changes of the system were measured at two flow rates and three different pulse frequencies,respectively.The pressure ratio P and the enhanced heat transfer ratio E_m of the heat exchanger.It was found that under the measurement conditions,the pulsation frequency f=2.23Hz and the Reynolds number Re=176455.The supercharging ratio of the diaphragm booster reached a maximum value of1.16.When the pulsation frequency f=1.43Hz and Reynolds number Re=165920,the convective enhanced heat transfer ratio E_m reaches the maximum 2.5.Under other operating conditions,the heat transfer efficiency of the pulsation system is improved when the diaphragm booster is used.It shows that the diaphragm booster can effectively strengthen the pulsating heat transfer.Based on the theory of three-dimensional non-steady-state heat conduction analysis by the finite element method,the Fourier function of the pressure of the diaphragm pressure booster during the pulsation process obtained by the experiment is loaded to the boundary conditions of the model by a user-defined function(UDF).The simulation calculation analyzes the convective heat transfer coefficient h and convection-enhanced heat transfer ratio E_m of the heat exchangers with and without diaphragm booster under different pulsation frequencies and different Reynolds numbers.The obtained heat transfer results and experimental results are carried out.By comparison,it is found that the maximum error between the enhanced heat transfer ratio of the heat exchanger and the experimental results did not exceed 6%,and by observing the velocity cloud diagram of the pulsating flow in the pipeline,it is found that the fluid velocity changes under the action of the booster system are more severe,and the pulsation frequency the higher the speed,the more obvious the vortex formation can be observed at the bend of the tube wall,which has also become the main factor to improve the pulsation-enhanced heat transfer efficiency.Through experimental research and simulation,it is found that the diaphragm booster device has a better strengthening effect on the pulsating heat transfer capacity with backflow under turbulent conditions,and the booster performance of the diaphragm booster device increases with the increase of the pulse frequency and Reynolds number.However,as the pulsation frequency increases,the enhanced heat transfer capacity of the diaphragm booster device decreases at lower frequencies.