COOLING MEDIUM RADIATOR

A refrigerant radiator (12) for a heat pump cycle includes a plurality of tubes (121). The tubes (121) are disposed to satisfy the hollowing relationship: Re ‰¥ A × X 6 + B × X 5 + C × X 4 + D × X 3 + E × X 2 + F × X + G wherein ¸ is an inclination angle (°) formed by a flow direction of the refrigerant flowing through the tubes (121) and the horizontal direction; X is a dryness of the refrigerant in a predetermined position where the refrigerant flowing through the tubes (121) is a gas-liquid two-phase refrigerant; and Re is a Reynolds number of the refrigerant in the predetermined position determined from an average flow velocity (m/S) of the refrigerant flowing through the tube (121). The A to G are expressed by a function of 0, which suppresses the non-uniform loss in pressure of the refrigerant in the respective tubes (121) to reduce the difference in temperature of blown air in the refrigerant radiator