Design Of Cryogenic Condensation Visualization Experimental Device And Simulation Study On Condensation On A Vertical Wall

Air separation units become larger and larger because of mass application of industrial gas, thus the energy consumption problem of which is becoming a growing problem. There is much room for enhancing the heat transfer and flow arrangement of nitrogen condensation in the main condenser-evaporator. The main mechanism is cryogenic condensation. Cryogenic condensation refers to the condensation phenomenon vapor below120K. Crucial distinctions between cryogenic fluids and room temperature fluids exist, resulting in many specificities of cryogenic condensation, which needs to be specially studied. The information of flow regimes is very important to study the condensate two-phase flow in micro channels accurately and thoroughly. Thus the advanced means of visualization is needed.A set of visualized experimental device for studying cryogenic condensation in micro-channels has been designed and established for the first time. The test section is designed with3visible windows and sealed by metal ring. The condensation surface is removable and changeable in order to study the condensation on vertical wall surface or in various types of plate-fin channels. The experimental device runs steadily on preliminary tests. The vacuum performance is satisfactory and the influence of heat leakage is rather small. The two-phase flow phenomenon of nitrogen during condensation process can be clearly observed with a high speed camera. Experimental results of condensation on vertical wall agree with the calculation results, proving rationality of the experiment device.A two-dimensional model of condensation on vertical wall has been established by virtue of Fluent software. The VOF model has been applied to trace the gas-liquid interface, and a UDF has been written to calculate the mass transfer process of condensation. The temperature field, velocity field and the condensate film thickness have been investigated. Simulation results show that the temperature field and velocity field are reasonable. The condensate film thickness is in agreement with the theoretical calculation result, proving the correctness of the two-dimensional model. And this dissertation points out the improving direction for the model at last.