CONDENSATION HEAT TRANSFER OF R-134a IN A HELICAL PIPE

Alternative refrigerant R-134a is considered to be ozone-friendly and a potential candidate for replacing the refrigerant R-12 in refrigeration and air-conditioning applications. This paper presents an experimental investigation on condensation heat transfer of the alternative refrigerant R-134a flowing inside a helicoidal pipe with the cooling water flowing through the annular helicoidal passage in a counter-flow direction. The heat transfer experiments were performed for R-134a mass flow flux ranging from 100 to 420 kg/m(2)s with the superheat of the inlet vapor of 2. 8 degrees C and 8. 3 degrees C, respectively. The average Nusselt numbers were experimentally determined for a helicoidal pipe with the helix axis of vertical direction. In addition, the obtained experimental results were compared with the results for R-134a condensation in straight and helicoidal pipes available in the open literature.