Experimental Study And Numerical Simulation Of The Gas-Liquid Two-Phase Flow In Micro-Channel

Flow boiling in micro-channel is one of the most focused points in the field of Engineering Thermophysics. Because of benign features of heat transfer, more and more micro-channel facilities are used in system design of the electronic systems which produce high heat flux. Nevertheless, since there are no thorough researching results for boiling convection in micro-channel, in order to provide theoretical direction and practical experience, more exploration should be done to complete the research in this subject.The main content of this document is fluid’s flowing status and heat transfer characteristics when fluid is heated up and forms two-phase flow under different conditions like quantity of flow and heat flux. Main work are as the followings:a) A suit of experimental equipment used for gas-liquid two-phase flow boiling convection is designed and assembled. Wall temperature, heat flux, boiling location, vapor quality, heat transfer coefficients and other experimental parameters are carried out by recording and calculating the data as quantity of flow, voltage and temperature of the probe hole in the micro-channel module. Laws of the parameters when work fluid, voltage and quantity of flow changed are analyzed and compared.b) The experimental result shows that heat transfer coefficients decrease when vapor quality or heat flux increase. Under a same condition, heat transfer characteristics of water is better than that of ethanol.c) Based on the experiment, a gas-liquid two-phase flow physical model is established and the geometry model of micro-channel is meshed. By using the simulation software of Fluent, which combines with the User-Defined Function, to simulate and compute this model. Then by comparing with the results of the simulation and the results of the experiments, the conclusion, which shows that mathematical model is suitable for the simulation of boiling flow in micro-channel, is reached. By analyzing the simulated results on the cross sections in micro-channel, a new flow shape called "wedge flow" is discovered for the first time, and the existence of "bubbly flow"and "annular flow" is proven.d) Numerical simulations for micro-channel with different geometry shapes are done. In this case, water, ethanol, benzene and toluene are used as the work fluid. Laws of flow shapes in micro-channel with different length-width ratio are obtained. By comparing these flow shapes with the previous literature, the conclusion that the "slug flow" has periodicity is initially confirmed.