Design of an Experimental Facility for Frost Growth Study in Microchannel Heat Exchangers

Abstract

This report focused on the new experimental methodology developed to investigate the frost and defrost thermal hydraulic performances of louvered folded fin microchannel heat exchangers under initial frost cycle, defrost cycle, and subsequent re-frost cycles. The required laboratory conditions are 35/33 &degF dry-/wet-bulb temperature, with the air velocity around 100 ~ 300 fpm. In the air side, the required conditions were reached by a humidification, a cooling and a re-heating process with a fan, a refrigeration coil, a humidifier and a re-heating coil. In the refrigerant side, the required inlet coolant temperature was controlled by an automatically controlled heater and a plate heat exchanger connected with the chiller. The frost accumulation was measured by a precision scale for frost weight, and a videoscope for frost thickness. Uncertainties on U and hout were investigated based on both precision and bias uncertainties.