KARAKTERISTIK PERPINDAHAN PANAS PADA LOOP THERMOSYPHON DENGAN FLUIDA KERJA R–134a BERTEKANAN 0,8 MPa

Abstract

Abstract : Loop thermosyphon heat exchanger (LTHE) is a flexible equipment and has a great economical benefit. In thermosyphon, fluid with gas phase carry an amount of latent heat from evaporator towards condensor. In this research, the thermosyphon consist of three parts,i.e. evaporator with diameter of ¾ inch and length of 3.5 cm, the place where fluid absorbs heat and change the liquid fluid into gas fluid. The second part of the thermosyphon is condensor with diameter of ¾ inch and length of 15 cm, the place where the gas fluid is condensed and release heat. The third part is adiabatic part where in this part no heat in and out from system and as a vapour line with diameter of ¾ inch and length of 25 cm and a liquid line with diameter of 3/8 inch and length of 27 cm. The research of this loop thermosyphon heat exchanger has objectives to study the effectivity and the thermal resistance of this heat exchanger with working fluid of refrigerant 134a at 0,8 MPa. The research was conducted at three air velocities (fluid which would be heated) of 0.8 m/s, 1 m/s, and 1.2 m/s and at three evaporator temperatures of 40°C, 50°C, and 60°C. The research was carried out experimentally where the heat source for evaporator from electric heater of 16 W, 36 W, and 60 W. From the research can be concluded that the effectivity of the LTHE with working fluid of R134a is about 22-35% and higher than LTHE with working fluid of air that is 14-21%. The thermal resistance of LTHE with working fluid R134a is 0.3-0.45 oC/W and lower than LTHE with working fluid of air that is 0.95-1.9 oC/W.

Keywords : Loop thermosyphon, Refrigerant R134a, Effectivity, Thermal resistance, Heat transfer