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 evaporating two-phase flow inside coils is described by a drift-flux flow. The model is capable of predicting distributions of refrigerant velocity, void fraction, temperature, tube wall temperature, air temperature and humidity, in both position and time domains. Comparison between the prediction and experimental measurements on a commercial evaporator is satisfactory for both steady and transient responses. The results indicate that an even air temperature distribution off the evaporator may be obtained by controlling liquid dry-out point at the two ends of the coil.