EFFECT OF ALUMINA NANOFLUIDS WITH DIFFERENT VOLUME FRACTION WITH DIFFERENT FILL CHARGE RATIO ON THE HEAT TRANSFER PERFORMANCE OF SELF OSCILLATING MULTI HEAT PIPE

摘要

This experiment study was performed to investigate the effect of different volume fraction of alumina (Al_2O_3) with different fill charge ratio to the heat transfer performance of a self-oscillating multi heat pipe at different constant heat flux. Working fluid employed was alumina (Al_2O_3) with 0.1%, 0.5%, 1.0% and 5.0% volume fraction. The fill charge ratio f_(cr) was varied from 30% to 100% at 10% interval. Heat pipe is consisted of an evaporation section, a condenser section and an adiabatic section. Evaporation and condenser sections have the same size and are connected by four circular parallel tubes. External dimension of evaporation and condenser section were a 45mm of length, a 45mm of width and a thickness of 8mm, also the internal dimension were 42mm, 42mm, and 5mm respectively. Adiabatic section (four circular parallel tubes) with a length of 45mm long, an inner diameter of 5mm and an outer diameter of 6mm was employed. The evaporation section is heated at constant heat flux for each different volume fraction and heat flux was 5W/cm~2 to 30W/cm~2 at 5W/cm~2 interval. 5 temperature measurements, 4 at the corner and center of the evaporation section and 3 temperature measurements at along the center line of condenser section were employed. 15°C of cooling water was supplied to the condenser section (to cool) in water tank at rate of 3.5l/min. A 7400Pavacuum pressure was maintained to create self-oscillating heat transfer. The thermal performance of higher volume fraction of nanofluids was enhanced in comparison with lower volume case.