The present invention relates to a heat exchanger, and more particularly to a microchannel heat exchanger for use as an evaporator under conditions in which moisture is present, such as within a refrigerated merchandiser.
Refrigerated merchandisers are used by grocers to store and display food items in a product display area that must be kept at a predetermined temperature. These merchandisers generally include a case that has an integrated refrigeration system.
Microchannel heat exchangers include an array of aligned microchannel flow tubes, the ends of which are connected to an inlet manifold or header and an outlet manifold or header, respectively. Fins are brazed between the tubes, and at low operating temperatures, the heat exchanger is susceptible to frost formation, especially near the air inlet to the heat exchanger. Such frost formation can damage the evaporator and necessitate more frequent and thorough defrost cycles.