PURPOSE: To obtain stabled operability for an extended period of time, by preventing frosting semipermanently by covering gas side heating surface with hydrophobic substance at a gas cooling apparatus.

CONSTITUTION: Gas cooler 15 being used for heat exchanging between air and LNG at a LNG gas turbine, etc., cools heat pipe 16 and radiation fins 17 by the action of LNG 20 passing thru the inside of the metal heat pipe 16, subsequently, cooling air 19 which passes the outside of the heat pipe 16. Because the air 19 contains moisture and gas, solidification thereof is comparatively higher (CO2, H2S, etc.), these gases, humidity thereof is above their saturation humidity condensated and solidify, becoming ice, and adheres to the heating pipe 16 as frost, when it is of metalic material. However, by covering the surface of the pipe 16 and fin 17 with the hydrophobic substance 18 such as tetrafluoroethylene protection of frosting is performed.