The visualized startup and thermal performance of ammonia pulsating heat pipe

Abstract

This paper presents a novel study on performance of pulsating heat pipe (PHP) using ammonia as working fluid. The tested PHP, consisting of 6 turns, is fully made of quartz glass tubes with 6 mm outer diameter and 2 mm inner diameter. The visualization investigation is conducted to observe the oscillation and circulation flows in the PHP. The trends of temperature fluctuation and thermal resistance as input power increases at different inclination angles are highlighted. The results show that it is very easy to start up and circulate for the ammonia PHP at an inclining angle. The thermal resistance is low to 0.02℃/W, indicated the heat flux can be transferred from heating section to cooling section very quickly. It is found that the thermal resistance decreases as the inclination angle increases.