SUPERHEATING EFFECTS ON PARTIAL CONDENSATION OF R32 INSIDE A PLATE HEAT EXCHANGER PROTOTYPE

It is well known that when a superheated gas reaches a cold surface, the condensation starts immediately only if the wall temperature is lower than the dew temperature of the refrigerant; in this case, the heat transfer phenomenon can be also affected by the superheating temperature. This paper presents the experimental measurements of the heat transfer coefficient carried out during partial condensation of superheated R32 refrigerant in a commercial brazed plate heat exchanger prototype. The present work aims at highlighting the effects of the superheating during the partial condensation of R32 by imposing 5, 10, 15, and 25 K of vapour superheating at the inlet of the brazed plate heat exchanger prototype. The experimental measurements were carried out by varying the specific mass velocity between 15 and 40 kg m-2 s-1 and the outlet vapour quality between 0.0 and 0.65. The experimental data were collected at around 36.5°C saturation temperature (saturation pressure of 2.27 MPa). The analysis of the partial condensation of superheated vapour varying mass velocities permits to understand the effect of vapour quality on the heat transfer coefficient; the present data can be used to study the phenomenon in order to validate the reliability of a condensation heat transfer model recently developed by the present authors.