Abstract: A heat exchanger includes: stacked tubes through which a refrigerant flows; and a fin joined to the tube to increase a heat exchange area with air flowing around the tube. A cross-section of the fin perpendicular to a flow direction of the air is shaped in a wave shape that has: planar sections substantially parallel to the flow direction of the air; and a top for connecting between the adjacent planar sections. A clearance is defined in the planar section of the fin. When a portion of the fin where the shortest distance from a center line between the adjacent planar sections becomes the maximum is set as a furthest section in a cross-section perpendicular to a stacking direction of the tubes, the clearance is defined in one furthest section or at least one of a plurality of furthest sections.

Abstract: Each tube and a corresponding fin satisfy all of the following relationships: Lp?t?0.03Tr+0.22; Lp?t?0.115Tr2?1.14Tr+2.35; and Lp?t?5Tr2?8.3Tr+3, where Lp denotes a width of a sub-passages, Tr denotes a refrigerant passage height, and t denotes a plate thickness of the fin. The amount of a brazing material, which is present through an entire extent of the width of the sub-passage, is set to satisfy a relationship of 0.005?S/L<0.5, where S denotes a size of a cross-sectional area of the brazing material, and L denotes a length of a center line of a corresponding portion of the fin, which is present through the entire extent of the width of the sub-passage.

Abstract: A heat exchanger includes a heat exchange portion in which at least tubes of refrigerant tubes or coolant tubes are stacked and at least one of refrigerant or coolant exchanges heat with air. An air passage is formed in a space formed between tubes of the refrigerant tubes and the coolant tubes which are adjacent to each other. An upstream heat exchange portion located on an upstream side in a flow direction of air and a downstream heat exchange portion located downstream of the upstream heat exchange portion in the flow direction of air are provided as the heat exchange portion. A ratio of the number of the refrigerant tubes to the total number of tubes of the upstream heat exchange portion is different from a ratio of the number of the refrigerant tubes to the total number of tubes of the downstream heat exchange portion.

Abstract: Each tube and a corresponding fin satisfy all of the following relationships: Lp?t?0.03Tr+0.22; Lp?t?0.115Tr2?1.14Tr+2.35; and Lp?t?5Tr2?8.3Tr+3, where Lp denotes a width of a sub-passages, Tr denotes a refrigerant passage height, and t denotes a plate thickness of the fin. The amount of a brazing material, which is present through an entire extent of the width of the sub-passage, is set to satisfy a relationship of 0.005?S/L<0.5, where S denotes a size of a cross-sectional area of the brazing material, and L denotes a length of a center line of a corresponding portion of the fin, which is present through the entire extent of the width of the sub-passage.