HORIZONTAL IN-TUBE CONDENSATION HEAT-TRANSFER IN A LOW-QUALITY TO NEGATIVE-QUALITY REGION

Condensation heat transfer in a low- to negative-quality region was analyzed using a nonequilibrium heat transfer model of stratified flow. This analysis predicted that a condensing flow remains two-phase until the thermal equilibrium quality becomes negative due to condensate subcooling. This phenomenon at thermal equilibrium zero quality brings about a much higher heat transfer coefficient than the liquid single-phase flow value. To examine the validity of this analysis, an experiment was conducted using Refrigerants R113 and R11 in the negative-quality region. Data obtained and other existing data for Refrigerants R11 and R12 supported the analysis.