ABSTRACT
A vapour compression heat pump system can be designed as single vapour compression system with a throttling valve or similar device separating the low-and high-pressure sides. Heat exchangers, mainly called condensers and evaporators, are applied to transfer energy between the heat pump system working fluid and the surroundings. The working fluid changes phase from vapour to liquid as it flows through the condenser and releases energy to the heat sink. This direction of energy transfer requires a higher temperature in the heat pump fluid than in the heat sink. Simultaneously, the working fluid changes phase from a liquid and vapour mixture to vapour by boiling in the evaporator while receiving energy from the heat source. This direction of energy transfer also requires lower temperature in the evaporating fluid than in the heat source. These processes take place in a closed cycle as the working fluid flows through condensers, evaporators, compressors and throttling devices. The energy transfer obeys the statements of the first and the second laws of thermodynamics. In addition, the energy exchange occurs in accordance with the mechanisms of heat conduction, convection, sublimation, condensation and evaporation.
