Thermo-Fluidic Analysis of Pulsating Heat Pipes Charged with Water-Based Immiscible Fluid Pairs

Abstract

Immiscible fluids may provide operational flexibility for pulsating heat pipes (PHPs) due to thermo-hydrodynamic diversity lead by each pure component. In this regard, present paper focuses on the thermo-fluidic analysis of non-uniform pulsating heat pipes charged with water-based immiscible fluid pairs. Research parameters cover gravity effect via the inclination angles (IA) of 0o and 90o, and fluid pair effect via two different water-based immiscible binary fluids as Water (W) – Hexane (H), and Water (W) – Pentane (P). The volumetric mixing ratios are W:H=1:1, 1:4, 4:1, 1:0, 0:1, and W:P=1:1, 1:4, 4:1, 1:0, 0:1; and the non-uniform flat plate type pulsating heat pipe (FP-CLPHP) has alternating-sequence parallel channels. The experiments are performed at the filling ratio of 40% (FR=40%), and flow phenomena is visualized. As some conclusions; at vertical orientation, the FP-CLPHPs having binary fluids of water-pentane show better thermal performance compared to the pure counterparts. Especially, the heat transfer characteristics of W:P=1:1 are the best ones among all the pure and binary fluids. On the other hand, as a conclusion of combination of non-uniform design and suitable thermophysical properties, the FP-CLPHPs charged with pure pentane, pure hexane or binary fluid of W:P=1:4 can work independent from gravitational force.