Thermal resistance modeling of flat plate pulsating heat pipes

Abstract

Flat plate pulsating heat pipes (FP-PHP) represent a future technology, enabling a more efficient thermal management of high heat flux devices. Whereas established thermal resistance models exist for wicked heat pipes, there are no such comprehensive models for pulsating heat pipes. In this paper, a conduction-based approach for pseudo-steady heat transfer is presented which can be used for 3D thermal simulations. For the calculation of the internal thermal resistance, multi-fluid correlations for flow boiling and condensation are utilized. A saturated homogenized state in-channel is assumed which allows the temperature-dependent determination of thermophysical fluid properties. A good agreement for the external temperature field was achieved compared to two independent experiments. The simulations show a significant sensitivity to the condenser conditions. Interestingly no adiabatic zone exists along the channels. Furthermore, it is shown that consideration of thermal spreading effects is key for the interpretation of the overall thermal resistance, effective heat fluxes and the design of optimal FP-PHPs.