Abstract

Introduction of new environmentally-friendly refrigerants in refrigerating and air-conditioning systems requires theoretical and experimental research. The paper describes experimental investigitions into heat exchange and flow resistance during boiling flow of freon R134a in tube coils - the process that occurs in typical fan air coolers. The obtained results allow the determination of the heat tiansfer characteristics, including mean values of the refrigerant-side heat transfer coefficient α for the boiling zone in the form of an experiment-based correlation. The correlation lends itself to engineering calculations of air-fin cooller supplied through thermostatic expansion valves where the dryness fraclion x of the refrigerant changes during the boiling process from 0.15 to 1.