| Abstract: |
A model of a counterflowing liquid-vapour heat pipe is developed. The model identifies the existence of two steady flow regimes for low heat fluxes; both a liquid dominated high saturation and a vapour dominated, low saturation regime. In contrast, for sufficiently large heat fluxes, the simple heat pipe process is unable to transport sufficient heat and the steady heat pipe solution breaks down. We then examine the interaction of such a heat pipe with a permeable aquifer which may supply or remove fluid from the heat pipe. We find that even with a very slow exchange of fluid, the external aquifer destabilises the liquid dominated mode. In contrast, in some situations, for higher pressures, the vapour dominated mode is stable. The analysis has some interesting implications for the role played by heat pipes in transporting heat through geothermal systems |