Thermal operational characteristics of a small-loop heat pipe

This study investigates the distinctive thermal operational characteristics of a small-loop heat pipe (LHP). Tests are conducted under varying heat load and condenser sink temperatures at different orientations of the LHP. Successful startups at heat loads as low as 5 W are demonstrated. To investigate the effect of accelerating forces, the small LHP is tested on a spin table. Accelerating forces impose an additional pressure drop and change the fluid distribution inside the LHP, thereby affecting the startup characteristics and the LHP operating temperature. Spin tests have demonstrated successful operation of the LHP under accelerating forces. The steady-state mathematical model proves to be useful for assessment of the main factors influencing the operating temperature when the LHP is subjected to accelerating forces. The mathematical modeling of the LHP performance characteristics becomes more difficult as the size of the LHP decreases. For a better prediction of the small LHP characteristics, more detailed modeling of the evaporator core is essential.