Experimental study of working fl uids in thermosyphon heat exchanger with annular fi ns for thermal performance enhancement

บทคัดย่อ

Abstract

This research study aims to investigate the effect of working fluids on thermal performance in a thermosyphon heat exchanger with and without annular fi ns. The thermosyphon heat exchangers were formed from the evaporator,adiabatic and condenser sections in which the lengths were 20, 10 and 20 cm respectively, made from steel, the tube had an outside diameter of 20 mm and a thickness of 3 mm. Distilled water, ethanol and R134a were used as the working fluids with a filling ratio of 50% by total volume of the evaporator section. The temperature of the hot air in the evaporator section was controlled at 60 70 and 80 ° C The results show that when the variable temperature increased from 60, 70 to 80°C the heat transfer rate and thermal effectiveness also increased. In addition, it was found that at all operating temperatures, the highest heat transfer rate and thermal effectiveness were with R134a as the working fluid. Moreover, the thermosyphon heat exchanger with annular fins had a higher heat transfer rate and thermal effectiveness than the thermosyphon heat exchanger without fi ns under all variables.

Keywords: Annular fins, Heat exchanger, Thermosyphon, Thermal performance, Working fluid