Experimental study on the effects of structural parameters on the heat transfer performance of sodium–potassium alloy high-temperature oscillating heat pipes

Liquid metal high-temperature oscillating heat pipes (LMHOHPs) can effectively operate in high-temperature environments, with the average temperature exceeding 500 °C, and the highest temperature capable of reaching above 800 °C. The influences of the turn number, inner diameter and length of adiabatic section on the heat transfer performance were studied in current paper. A semi-empirical model for heat transfer performance predicting based on experimental data has been established. The results showed that: (1) LMHOHPs with the turn number ranging from 2 to 8, inner diameter between 2 mm and 8 mm, and adiabatic length between 90 mm and 240 mm could start and achieve efficient heat transfer through the oscillation of the working fluid. (2) As the turn number and the inner diameter increased, the heat transfer performance improved, while an increase in the adiabatic length led to a reduction in thermal conductivity. The highest thermal conductivity achieved by the LMHOHP with an inner diameter of 8 mm reached 4805W/(m·°C). (3) The model's predictions were in reasonable accordance with the experimental results. The mean discrepancy between the predicted and experimental values was 13.12 %, and 89.47 % of the predicted values were within the ±25 % margin of error.