Abstract: Disclosed is a refrigeration or air conditioning system comprising a refrigeration cycle that uses a refrigerant mixture of at least two kinds of refrigerants consisting of 45 to 55 weight percent of R32 and 55 to 45 weight percent of R125, and that includes at least a compressor, a condenser, a throttling device, and an evaporator. In some cases the temperature and pressure in a line leading from the inlet of the evaporator to the suction port of the compressor is controlled below a specific temperature and pressure point corresponding to the critical decomposition point of a clathrate that contains water as a host solution and the refrigerant mixture as guest molecules, and within a prescribed control range bounded by a formation limit line of the clathrate and a saturated liquid pressure line representing the pressure versus temperature relationship of saturated liquid of the refrigerant mixture (a first control mode), and a dryer for moisture removal is provided in the refrigeration cycle.