A temperature and humidity decoupling control method was presented in this paper to resolve the coupling problem between temperature and humidity in air-conditioning variable dew point control system.

To get more accurate and efficient solution, a computer program based on economical thickness method is developed with functions of thermal insulation, cooling insulation and dew point check, etc.

Some problems of heat transfer are studied in this paper, they are dew point, boiling point, density, equilibrium constant, thermophysical properties and heat transfer calculation method.