Thermal-hydraulic characterization and system-level optimization of microchannel condensers for household refrigeration applications

This paper is aimed at evaluating the applicability of fan-supplied microchannel heat exchanger technology as condensers in household refrigerating appliances. A mathematical model was developed to predict the heat transfer rate and the air-side pressure drop of microchannel heat exchangers. Such a model was incorporated into a simulation platform for household refrigerators, which allowed correlating the geometry of the heat exchanger with the energy consumption of the appliance. Experiments were carried out in a closed-loop wind-tunnel facility and also in a climatic chamber, the former for leveraging the condenser characteristics whereas the latter provided data for validating the system simulation model. While the predictions for the heat transfer rate and the air-side pressure drop in the condenser remained within +/- 10% and +/- 20% error bands, the system simulation model was able to predict energy consumption with errors within +/- 3.5%. Sensitivity analyzes pointed out 13% energy consumption reduction when a 200-mm high, 180-mm wide and 72-mm deep microchannel condenser with 200 fins per meter and 46 rectangular channels of 1.2 mm of hydraulic diameter is adopted.