WORKING FLUID

PURPOSE: To obtain a refrigerant that does not destruct ozone, has thermophysical properties that are the same as or better than those of chlorodifluoromethane, and can be used in existing apparatuses. CONSTITUTION: A refrigerant has a composition comprising 20 to 65wt.% (hereinafter referred to as %) trifluoroethane (R143a) and 35 to 80% cyclopropane (RC27 deg.), or 10 to 65% RC270 and 35 to 90% 1,1,2-tetrafluoroethane (R134a), or 65% or less R143a, 25 to 80% RC270, and the balance of R134a with the range excluding the part where the component ratio of R143a to RC270 is such that in the section enclosed by the points A1 to F1 in the figure and where the component ratio of any of R143a, RC270, and R134 becomes 0, or 30% or less R143a, 20% or less RC270, and the balance of R134a with the range excluding the part where the component ratio of R143a to RC270 is such that in the section enclosed by the points H1 to M1 in the figure and where the component ratio of any of R134a, RC270, and R134a becomes 0 with the composition having an ozone destruction coefficient being 0.