Heat Transfer Performance And Start-up Characteristics Of Pulsating Heat Pipes

With the miniaturization of electronic components and equipments,their's heat transfer make pulsating heat pipes which are new and highefficiency heat transfer components gain more and more study. Pulsatingheat pipes are two-phase flow system which are related with severalsubjects and their's heat transfer mechanism is the unification of sensibleheat transfer, latent heat transfer and work. The work is used to overcomethe losing of the flow of fluid. The characteristics of pulsating heat pipesare different from the conventional heat pipes which only use latent heattransfer. It does not have clear knowledge about the circulation and heattransfer mechanism of PHPs, and some key problems don't have receivedperfect resolvement, such as how to optimize, ascertain the limit of heattransfer and the fluctuation of temperature, and so on.The subject of this paper is the heat transfer performance andstart-up characteristics of PHPs. The effect of many parameters on thethermal resistance were studied through the changing of parameters ofexperimental setup, gaining some results as following: the thermalresistance became smaller with the increasing of inclination angle at thesame heat transfer power, but the trend became smooth; the thermalresistance became smaller at first and after it reached the smallest point itbecame bigger with increasing of heat transfer power and charging ratio,and the smallest point was at the 50％charging ratio; the thermalresistance became smaller with the increasing of the number of loops; thethermal resistance became smaller with the increasing of inclination angleat different working fluids, but the thermal resistance of water was thebiggest and ethanol's was bigger than N-Hexane. The operation andstart-up of PHPs at the situation of zero weight and anti-weight heatingwere studied through changing the quantity of working fluid in theheating parts, and some results were gained: the PHPS can start-up andoperate at horizontal heating working condition when the number ofloops exceeded a certain amount and the heater had sufficient workingmedium and power. The basic theory, the heat transfer and mass transferof PHPs were tentatively studied. The steady-going mathematical model of PHPs was built with some assumptions, and it ascertained the successof mathematical model through comparing with the experimental results.Many further prospects on the coming study of PHPs were given in thispaper.