A preliminary investigation on visualization of oscillating heat pipe with non-destructive test

Oscillating Heat Pipe (OHP) is a passive heat exchanger operating on two phase flow principle. As one of the newest members of the heat pipe family, OHP has a complicated operating mechanism of working fluid flow. OHP is a potential device, which can be used for saving energy and cost. Although, OHP is a promising two-phase heat transfer device with excellent performance, simple structure and low cost but its operational characteristic is still not clear yet and debatable. As one of the non-destructive test, neutron radiography uses neutron beam techniques to penetrate heavy materials while beam are absorbed by lighter materials. This method is very suitable for use in visualization technique of the two-phase flow of heat transfer device with hydrogen-based fluids. In this paper, the visualization method is coupled with thermocouple temperature measurement. Aluminium OHP with 12 turns has been manufactured and tested. The dimension of aluminium OHP is made fit with the neutron beam size. DI Water with filing ratio 35 % has been chosen as the working fluid for the close loop OHP. Three level of heating power was applied to the evaporator section of OHP. The result showed that this preliminary study could reveal the temperature fluctuation of the thermocouple data. The condensation and evaporation also can be observed adequately with this method.