Abstract: In some special places, some small style desalinating units are needed for living, and heat pump may be considered to carry out it because of its efficiency and saving energy. For designing the small desalinating heat pumps system, it is a basic aim that the units can provide 3.6 kg pure water in an hour. According to different working conditions (condensation temperature and evaporation temperature being changed), heat transfer coefficient in heat exchangers and heat transfer area of heat exchangers are computed, besides of those, length of capillary tube is calculated too, and some relationships among condensation temperature, evaporation temperatures and those parameters are analyzed and presented. Those results are helpful to machining and assemble of the small desalinating heat pumps.

Key words: Components matching, Desalination, Heat pump, Working conditions’ choice