Experimental Study And Numerical Simulation Of Negative Pressure Condensation Characteristics In A Dynamic Heat Pipe Serpentine Condenser

The pump-assisted separate heat pipe which is the high efficient heat transfer device is used in engineering application broadly.Due to their complicated structure,We need to study the mechanism of negative pressure condensation flow in pump-assisted separate heat pipe deeply.In order to describe the negative pressure condensation characteristics of the serpentine condenser systematically,the paper combines experimental research and numerical simulation to study the condensation flow characteristics of the water in the serpentine tube under negative pressure.We build a test rig for negative pressure condensation characteristics in a pump-assisted serpentine heat pipe condenser.We study the heat transfer and pressure drop characteristics of the water condensation processes in the condition of different flow and vapor quality,and compare the experimental results with the calculated results of the four heat transfer models and five pressure drop models.The results show that the heat transfer coefficient increases with increasing vapor quality,and decreases with increasing flow rate of the working fluid.The deviation between the predicted value and the experimental value of the Hashimoto model in the four heat transfer models is the smallest.The pressure drop increases with increasing vapor quality and flow rate of cooling water,the deviation between the predicted result of the Zhang model and the experimental result is within the range of ±15%.We carry out the numerical simulation of the negative pressure condensation characteristics in serpentine condenser.We analyze and select the model in the simulation,and analyze the simulation results of the condensation flow of water in the state of negative pressure.The results show that the velocity and pressure at the bend of the pipe change drastically,and the position of the maximum velocity is obviously shifted downward,the position shift more obviously increasing velocity and two-phase fluid flow.The liquid temperature is lower than the vapor temperature because of the sub-cooling degree in condensation.Under the same vapor quality,the heat transfer coefficient of simulation increases with increasing two-phase fluid mass flow.Under the same vapor quality,the pressure drop of simulation increases with increasing two-phase fluid mass flow.The pressure drop of the elbow section decreases with increasing two-phase fluid mass flow.The pressure drop of the straight pipe section firstly increases,then decreases with increasing two-phase fluid flow.Though comparing the heat transfer result of simulation and the Hashimoto model,the pressure drop results of simulation and the Zhang model,We come to conclusion of the deviations are within the range of ±30%.