Abstract
The present paper reports an investigation of the dryout quality for refrigerants flowing in horizontal evaporator tubes. Experiments were made for the flow of boiling HFC-134a and HCFC-22 inside smooth tubes and a spirally grooved (micro-fin) tube. At given conditions, dryout proceeded over a certain quality range. Therefore two dryout qualities were defined; dryout inception quality at which the circumferentially averaged (axially local) heat transfer coefficient began to decrease rapidly, and dryout completion quality at which the decrease in the heat transfer coefficient ended. Based on the experimental data, the characteristics of both dryout qualities were clarified, and thereby the dryout qualities were classified into three characteristic regimes for the smooth tube and two regimes for the micro-fin tube. A dimensionless correlation of each dryout quality, which can reproduce the measurement successfully, was developed for the respective tubes.
