Abstract: Anew staked microchannel heat exchanger is studied as a gas cooler for super-critical CO2. Through the experiments, by changing the inlet pressure of CO2 and mass flow rates of water, the capacity of heat transfer and the total heat transfer coefficient of this gas cooler are obtained in different conditions. The heat transfer capacity goes up with the mass flow rate of water and the coefficient of performance(COP) goes down with the increasing of inlet pressure of CO2. The heat transfer coefficient reaches 700 W/(m2•K) while the heat transfer capacity reaches 9 kW. By using finite volume method(FVM) and TDMA method in the simulation program, the heat transfer process of the gas cooler is simulated for the conclusion that decreasing the outlet temperature of carbon dioxide benefit the increase of outlet temperature of water side and the COP. During the simulation, the proper correlations of both water and carbon dioxide are selected. The simulation deviation is small enough. The microchannel gas cooler is optimized with the program by calculating the heat transfer coefficient and heat transfer capacity. It is found that the outlet temperature of water can be increased by reducing the distance of channels of both side and increasing the rows of channels, as well as increasing the hydraulic diameter of water side and the row of channels. The optimized construction is obtained based on regulations, which lead the outlet temperature of water side to above 60 ℃.

Key words: supercritical;carbon dioxide;microchannels;gas cooler;optimization