Experiments Of Condensation Heat Transfer In Micro Channel Heat Exchanger

The application of micro scale devices are in active exploration, the system will become more and more complex, in micro-scale flow and heat transfer of basic theory and experiment technology, people are in the process of growing demand. The micro channel flow condensation process is used in electronic chip heat pipe, heat exchanger, compact micro refrigeration system cooling, sensors and laser diode cooling system of key areas such as heat physical process, micro channel has important engineering application prospect and academic value. Now the passage of single-phase flow and boiling flow has gotten thorough research, but in micro channel flow of condensing ware relative deficiency.This paper introduces the structure and micro channel heat exchanger, set up the assembly, test and analysis of data collected experimental data. Designed test system of micro channel heat exchanger (MCHX). The key of MCHX design and test are: 1) In high temperature and high pressure, The seal of micro channels and corrosive refrigerants in relation to the success or failure of the experiment, because the test system has to higher compression capacity (0.85MPa) and to test and requirements of micro channel flow visualization observation, because to find the restrictions, transparent material to seal is difficulty, and the organic material cannot be welded. Finally solved the sealing structure of heat exchanger .2) Each element of the heat capacity is of important, experimental flow within 10W, any parts of the thermal loss may be bad for a considerable proportion of heat transfer, and not just want to consider, also should consider to heat and water contact with refrigerants parts of the heat capacity, the heat capacity test of stability. This heat capacity of experiment materials is smaller and smaller. For refrigerant and the water side of heat transfer, using a piece of only 1mm thick PEEK to transfer and heat capacity of thermal resistance is much less.3) Controlling small flow is difficultly, the experimental condition of refrigerant mass flow is fairly small, using the existing valve to control the refrigerant has the certain difficulty, because this is not a closed loop system.The analysis of experimental results obtained as follows several conclusions: 1) Experimental data and the Koyama correlation forecast are closer. We summarized the experimental in the measurement range for the micro channel in low Reynolds number of condensing heat.2) We summarized micro channel flow resistance properties. Friction coefficient compare with Choi et al. equation and Pfahler,Blasius equation, and data are closer to the forecast by Wu&Little equation, the absolute errors are much lower.In micro channel flow field of the heat, comparing the test data and Fluent simulation results, we found the simulation software used in micro channel heat is not very accurate calculation, but in the trend is right on the qualitative, for example, Fluent in general conditions simulated condensation position is correct, but in every place of the condensate differ.