Abstract: There is disclosed a heat exchanger tube for conducting refigerant in a heat exchanger. The inner surface of the tube has a convex portion having a broad tip and a plurality of inner fins. The area of the tip of the convex portion is larger than that of the tip of the inner fins. The height of the convex portion can be set at more than that of the inner fin. A heat exchanger according to the invention has a plurality of plate fins, each having a hole therein. Heat exchanger tubes pass through the holes of the plate fins. A method of manufacturing a heat exchanger comprises the steps of stacking a plurality of plate fins, each having a hole, with a predetermined space therebetween. Heat exchanger tubes are inserted through the holes. Then, the tubes are expanded to engage the plate fins. A refrigerating circuit utilizing a heat exchanger is also described.

Abstract: An air conditioner control apparatus measures coolant temperatures and pressures at both inlet side and outlet side of a compressor, or detects a electric capacity of the coolant and the like in order to determine the kind of coolant. For example, when a CPU 31 detects that the coolant R22 is used, the apparatus selects a data item of a fluorocarbone-based coolant R22 stored in a data selection means 35 storing pressure-temperature data items, and calculates a super-heated rate or a super-cooled rate according to the ability of a compressor 1 so that the room temperature reaches the predetermined one set by the operator and setting a calculation result. Next, a vapor temperature is calculated by each indoor air conditioner side, and during a cooling operation, electronic expansion valves 9, 11 are controlled so that target super-heated temperature are reached to the temperatures in temperature sensors 17 and 19.

Abstract: An air conditioner employs a non-azeotropic refrigerant mixture without deteriorating the heat-exchange efficiency and air-conditioning capability of an indoor heat exchanger of the air conditioner. The indoor heat exchanger (3) has a fin on which a first path (33), a second path (34), and a third path (35) for passing the refrigerant mixture are arranged. The first path passes the refrigerant mixture from the leeward side toward the windward side of an air flow produced by an indoor fan (7), to form a counterflow of the refrigerant mixture against the air flow. The second path passes the refrigerant mixture from the windward side toward the leeward side of the air flow. Although the second path forms a parallel flow of the refrigerant mixture with respect to the air flow, it achieves moderate heat-exchange efficiency because the number of rows of piping on the leeward side is greater than that on the windward side and because the rows of piping do not overlap one another with respect to the air flow.

Abstract: In an air conditioner having at least an indoor unit 9 and an outdoor unit 11 through which a coolant flows, a saturation temperature of the coolant at 50.degree. C. is not less than 2500 kPa, and the indoor heat exchanger in the indoor unit satisfies a relationship of Hi.times.Li/(Di.sup.3 .times.Ni.sup.2).gtoreq.150 and the outdoor heat exchanger in the outdoor unit satisfies a relationship of Ho.times.Lo/(Do.sup.3 .times.No.sup.2).gtoreq. 60.

Abstract: An air conditioner having a compressor, an outdoor fan, and two indoor heat exchangers which are connected by an electric expansion valve. During a dehumidifying operation, the opening of the electric expansion valve is decreased, thereby decompressing the refrigerant flowing from the first indoor heat exchange into the second indoor exchanger. The first and second heat exchangers thereby function as a reheater and an evaporator, respectively. The second indoor heat exchanger cools and dehumidifies the indoor air, and the first indoor heat exchanger heats the indoor air again. The indoor air, first cooled, then dehumidified, and finally re-heated, is supplied into the room. During the dehumidifying operation, a deviation (T) of the indoor temperature (Ta) from a preset indoor temperature (Ts), and a change (.DELTA.T) in the deviation (T) are detected, and the deviation (H) of the indoor humidity (Ha) from a preset indoor humidity (Hs), and a change (.DELTA.H) are also detected.