Emerging Technologies: Microchannel Heat Exchangers

This is the tenth article covering one of several energy-saving technologies evaluated in a recent U.S. Department of Energy report. The complete report is at www.eren.doe.gov/buildings/documents.

Microchannel heat exchangers (MCHXs) consist of flat microchannels connected in parallel between two headers with fan-fold fins brazed between adjacent tubes (Figure 1). Each microchannel tube is typically 0.05 in. to 0.1 in. (1 to 2.5 mm) thick and 0.5 in. to 1 in. (12 to 25 mm) wide and has multiple internal passages. The parallel flow arrangement enables use of MCHXs for largercapacity HVAC applications because it avoids the excessive pressure drop created by single-tube multi-pass designs. In fabrication, a manufacturer assembles the MCHX from its constituent