Copper micro-channel thermosyphon fins for heat sink application

Fins are commonly used to increase surface area for enhancing heat transfer to the ambient air or other coolants. The finite thermal conductivity of the fin material is a limiting factor in the heat transfer because of the thermal resistance and temperature drop across the length of the fins. The ideal system should have fins of very high thermal conductivity, resulting in isothermal fins and 100% fin efficiency. To take advantage of the very high apparent conductivity of thermosyphons, a loop thermosyphon system has been designed to keep a set of fins close to isothermal conditions. In the experimental system, the condenser of the thermosyphon loop was embedded within copper fins in a set of micro-channel tubes, with propane as the working fluid. Experimental results showed that this integrated arrangement of thermosyphon and fins results in reasonably isothermal fins, producing high fin efficiency. The specific volume of the working fluid was determined and used to characterize the system performance and stability.