Design and Construction of a Condensation Heat Transfer Experimental Facility for Use with Microchannel Condenser Tubing

Microchannel tubing is a relatively new heat-exchanger technology which involves internal heat transfer enhancements. Although microchannel technology offers tremendous design flexibility, it is not well understood. As part of a project that also inculdes full-condenser modeling and single-port flow modeling, a single-tube experimental facility has been built to evaluate the heat transfer performance characteristics of microchannel tubes using pure refrigerant 134a with air in crossflow. The facility achieves energy balance between air and refrigerant heat transfer rates within ??3%, but two-phase data are presently not attainable. A brief review of heat transfer coefficient correlations is given to illustrate a few typical results. The design and construction of the facility is explained in detail, emphasizing the air loop. Subcooled, superheated, and two-phase data are collected for various microchannel port geometries, and data reduction techniques and theory are explained. Although energy balance data are presented in this paper, only proprietary heat transfer coefficients have been obtained thus far, and the facility is presently taking data for the publication of non-proprietary heat transfer coefficients.Air Conditioning and Refrigeration Center Project 2