Abstract: The present invention provides an air conditioning apparatus for automobiles equipped with a heat exchanger and a control method for the apparatus, by which the heat transfer area of the heat exchanger can be properly controlled to permit a stable cycle operation, even when the capacity of a condenser is relatively overly enhanced under a condition of the low atmospheric temperature. The apparatus and the control method are achieved with such an arrangement that either one or both of headers of a heat exchanger is provided with at least one refrigerant flow rate control valve capable of opening and closing refrigerant passages in each header, the heat exchanger has a refrigerant inlet provided in one header and a refrigerant outlet provided in the other header, and the control valve is opened and closed to change the number of the passages allowing the refrigerant to pass therethrough, for thereby changing the effective heat transfer area for heat exchange dependent on the atmospheric temperature.

Abstract: In a crossed fin-tube type heat exchanger wherein tubes are attached at right angles to a large number of fin elements arranged in parallel with one other, the surfaces of these fin elements are roughened to have an unevenness satisfying a relationR.apprxeq.1/cos.theta.where R is a ratio of the extended, uneven or roughened surface to the flat or smooth surface of the fin element; and .theta. is a contact angle for a liquid droplet in contact with the flat or smooth surface of the fin element.

Abstract: An evaporator comprising a tube plate having a number of through holes to which the upper ends of a plurality of U-tubes are fixed, a first cover plate secured to the tube plate and having a plurality of through holes aligned to some through holes of the tube plate, a second cover plate secured to the first cover plate and defining in cooperation therewith passages for introducing and distributing refrigerant, and an expansion valve assembly installed through the first and second cover plates and having a constriction formed therein. The first cover plate defines connecting passages and a collecting passage for the refrigerant in cooperation with the tube plate.