Interactions of Liquid Plugs in a Pulsating Heat Pipe

The interactions of two plugs in a pulsating heat pipe are important to mechanism and operation of the multi-plugs. Based on the experimental observation, the control volume of a pulsating heat pipe with two capillary passages and two liquid plugs is modeled. The operations of the two liquid plugs were described and solved by differential equations. The loci and velocities of the oscillating and moving liquid plugs were obtained. The results show that the bigger capillary diameter, the lower filling rate, the higher heating power and the initial stronger perturbations can all lead to faster movement of the liquid plugs, and it is better to the heat transfer. When the heating power is lower, the liquid plugs do not coalesce. While if the heating power is higher, then the liquid plugs may coalesce, further to form the single liquid plugs or the circular flow pattern. The results can explain the experimental visualizations qualitatively the interactions between the liquid plugs.