DISTRIBUTED STUDY OF AIR-TEMPERATURE INSIDE A DRY-EXPANSION EVAPORATOR

A distributed steady and transient model is presented for studying air temperature distribution inside dry-expansion evaporators. The evapor ating two-phase flow inside coils is described by a drift-flux flow. T he model is capable of predicting distributions of refrigerant velocit y, void fraction, temperature, tube wall temperature, air temperature and humidity, in both position and time domains. Comparison between th e prediction and experimental measurements on a commercial evaporator is satisfactory for both steady and transient responses. The results i ndicate that an even air temperature distribution off the evaporator m ay be obtained by controlling liquid dry-out point at the two ends of the coil.