Post-dryout heat transfer to refrigerant flowing in horizontal evaporator tubes

摘要

Studies of the post-dryout heat transfer were made based on the experimental data for HFC-134a flowing in horizontal smooth and spirally grooved (micro-fin) tubes and the characteristics of the post-dryout heat transfer were clarified. The heat transfer coefficient at medium and high mass flow rates in the smooth tube was lower than the single-phase heat transfer coefficient of the superheated vapor flow, of which mass flow rate was given on the assumption that the flow was in a thermodynamic equilibrium. A prediction method of post-dryout heat transfer coefficient was developed to reproduce the measurement satisfactorily for the smooth tube. The post-dryout heat transfer in the micro-fin tube can be regarded approximately as a superheated vapor single-phase heat transfer.