Numerical model of a multi-turn Closed Loop Pulsating Heat Pipe: Effects of the local pressure losses due to meanderings

A numerical code has been developed to investigate the thermal performances of Closed Loop Pulsating Heat Pipes (CLPHP). The model takes into account the effects of the local pressure losses due to the presence of turns which have always been neglected by previous models; it can simulate CLPHPs working with different fluids (ethanol, R123 and FC-72 are shown), different number of turns, various inclination angles as well as different input heat fluxes at the evaporator. Numerical results show that the local pressure losses influence the device behavior in particular for high input heat fluxes and when the CLPHP is working in the horizontal position. The trends of the total liquid momentum, maximum tube temperatures, and equivalent thermal resistances, reveal good qualitative and quantitative accordance with the experimental data available in literature. Further direct experimental validations are mandatory to confirm whether this model can be used as a preliminary CLPHP thermal design tool.