EXPERIMENTAL INVESTIGATION ON THE EFFECTS OF INCLINATION ANGLE ON HEAT TRANSFER PERFORMANCE OF A LIQUID METAL HIGH-TEMPERATURE OSCILLATING HEAT PIPE

The liquid metal high-temperature oscillating heat pipe (LMHOHP) is a kind of high efficiency heat transfer device, which can function in high-temperature environments above 500 degrees C. In this paper, the effects of inclination angle on the startup and heat transfer performance of a LMHOHP were investigated experimentally. The sodium potassium alloy (potassium 78%) was used as the working fluid of the LMHOHP and the filling ratio was 50%. The start-up characteristics and heat transfer performance of the LMHOHP at four inclination angles of 0 degrees, 30 degrees, 60 degrees and 90 degrees were tested when the operating temperatures were 150 degrees C and 400 degrees C, respectively. Experimental results show that (1) The LMHOHP can start-up and function at all the tested inclination angles, the maximum temperatures of the evaporator and condenser can exceed 1000 degrees C and 700 degrees C, respectively (2) The thermal resistance of the LMHOHP decreases with inclination angle increases, the thermal resistance at the inclination angle of 90 degrees decreases by up to 32.9%, 41.6% and 55.9% compared with that at the inclination angle of 60 degrees, 30 degrees and 0 degrees, respectively (3) When the input power exceeds 3000W the flow patterns of LMHOHP at the inclination angle of 90 degrees,60 degrees and 30 degrees can be changed from the oscillating motion to the unidirectional circulating flow. (4) Compared with the operating temperature of 150 degrees C, the heat transfer performance of the LMHOHP improves at the operating temperature of 400 degrees C, at the input power of 3457W and the inclination angle of 90 degrees, the minimum thermal resistance of LMHOHP is 0.075 degrees C/W The results shown that the LMHOHP has a good adaptability to working conditions which further extends the application range of oscillating heat pipe.