A method and device refrigerate a fluid by adding a volatile liquid mist to a flow of a gas to saturate the gas with vapor of the volatile liquid, to cause a large amount of misty minute liquid drops of the volatile liquid to float in the gas and to form a cooling gas. The cooling gas is directed through a first flow passage of a heat exchanger having first and second flow passages. The fluid to be refrigerated is directed through the second flow passage of the heat exchanger, so that heat from the fluid is transferred to the cooling gas, while the cooling gas passes through the first flow passage of the heat exchanger to elevate the temperature of the cooling gas. A portion of the minute liquid drops floating in the cooling gas are allowed to vaporize due to the elevated temperature of the cooling gas. The temperature of the cooling gas is continuously lowered by the heat of vaporization of the vaporizing minute liquid drops. The fluid passing through the heat exchanger is thus continuously refrigerated with the cooling gas having the continuously lowered temperature.