Experimental investigation of the effect of different channel configurations on the performance of pulsating heat pipes

In this thesis, the thermal performance and flow characteristics of flat plate closed loop pulsating heat pipes with different channel configurations are experimentally investigated. Ethanol was used as the working fluid for the pulsating heat pipes manufactured using copper material. The experiments were performed using five different geometrical heat sinks, various inclination angles (-90⁰, 0⁰, 30⁰, 60⁰, and 90⁰), filling ratios (20%, 40%, 50%, 60%, and 80%), and heat loads. The geometric structure, featuring a gradual change in cross-sectional area, enhanced the oscillating flow characteristics through unbalanced capillary forces, enabling pulsating heat pipes with a limited number of turns to operate without gravitational support. Flow phenomena were examined using a high-speed camera. The study also involved the experimental analysis of polymeric pulsating heat pipes fabricated through stereolithography (SLA). The experiments were conducted in a vertical position, constant filling ratio (50%), and different heat loads, using FC-72 as the working fluid. The results indicated that non-uniform channel configurations provide better heat transfer performance, fluid distribution, and operational stability.