The Experimental Study Of Two-phase Flow And Heat Transfer In Micro-channels Under High-gravity Conditions

For the applications of flow boiling in the field of aerospace technology, the two-phase flow andheat transfer characteristics in micro-channel under high-gravity conditions has become one of the hotresearch spots. In this paper, the two-phase flow and heat transfer characteristics in micro-channelunder high-gravity conditions have been investigated experimentally.The experimental system has been designed, built, and tested. It is made of three parts, i.e.high-gravity simulation platform, fluid circulation system and information acquisition and processingsystem.R134a is used as the working fluid. The test sections are single round copper with insidediameters of4.004mm and1.299mm. The experiments of flow and heat transfer characteristicsinclude normal gravity condition and high-gravity condition. The data obtained in the normal gravitycondition are used to calibrate the experimental system. The test data of different conditions havebeen obtained by changing parameters, such as gravity, mass flow rate, heat flux, and vapor quality.Based on the experimental data, the effect of gravity on mass flow rate and vapor quality is analyzed,and some flow and heat transfer characteristics have been obtained.The results of the experiment under normal gravity conditions show that, in the experimentalcondition, when the other parameters are fixed, the pressure drop and heat transfer coefficient increasewith the increase of vapor quality, mass flow rate or heat flux, and the effect of heat flux on pressuredrop tends to be weak when the mass flow rate becomes larger.In the experiments of high-gravity condition, the test section is arranged along the tangentialdirection, and the direction of the high-gravity is perpendicular to the flow direction. The results of theexperiment show that the high-gravity has great effect on the flow and heat transfer of two-phase flowin micro-channel, and the greater the gravity, the more the effect. When the gravity is less than1g, theparameter changes have no obvious regularity. When the high-gravity is greater than1g, the massflow rate decreases, the vapor quality increases, the pressure drop decreases, and the heat transfercoefficient increases with the increase of high-gravity.