|| This course introduces some heat transfer media concerning about refrigeration and air-conditioning technology. The chemical and physical properties of these media and their practical applications are also presented. The heat transfer media covered are important fluids such as refrigerants, brine and gases etc, and materials of system compoments and insulations. The estimation methods of their physical properties such as conductivity, viscosity, specific heat, diffusion coefficients are focused and verified to compensate the shortage of known data. The design of different types of heat exchanger are then performed to emphasize the importance of property- estimation.