Performance Comparisons Of A Unitary Split System Using Microchannel and Fin-Tube Outdoor Coils, Part I: Cooling Tests

ABSTRACT This two-part paper investigates the performance of a unitary split system using microchannel heat exchangers instead of the conventional fin-tube designs as the outdoor coil for air conditioning and heat pumping applications. Microchannel heat exchangers are said to offer higher performance per unit weight and reduce refrigerant charge in vapor compression systems, but little is known about their performance characteristics in unitary equipment, especially with respect to the frosting and defrosting characteristics during heat pump mode. A commercially available 3-ton heat pump with a conventional outdoor heat exchanger served as the baseline system. Performance tests were conducted with the conventional outdoor coil and after replacing the outdoor coil with custom made microchannel heat exchangers. The tests consisted of standard ARI cooling and heating/defrosting tests. The Part I paper describes the microchannel heat exchanger configurations and presents the results obtained during the cooling tests. The Part II paper presents the results of the heating/defrosting tests.