Microchannel tubing is a relatively new heat-exchanger technology which involvesinternal heat transfer enhancements. Although microchannel technology offerstremendous design flexibility, it is not well understood. As part of a project that alsoinculdes full-condenser modeling and single-port flow modeling, a single-tubeexperimental facility has been built to evaluate the heat transfer performancecharacteristics of microchannel tubes using pure refrigerant 134a with air in crossflow.The facility achieves energy balance between air and refrigerant heat transfer rateswithin ??3%, but two-phase data are presently not attainable.A brief review of heat transfer coefficient correlations is given to illustrate a fewtypical results. The design and construction of the facility is explained in detail,emphasizing the air loop. Subcooled, superheated, and two-phase data are collectedfor various microchannel port geometries, and data reduction techniques and theory areexplained. Although energy balance data are presented in this paper, only proprietaryheat transfer coefficients have been obtained thus far, and the facility is presently takingdata for the publication of non-proprietary heat transfer coefficients.
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