Heat exchanger

A heat exchanger, comprising:

• a pair of header tanks spaced apart from each other by a predetermined distance and disposed in parallel with each other;
• a plurality of tubes having both ends fixed to the pair of header tanks to form channels for a refrigerant;
• and
• fins interposed between the tubes,
• wherein the tube is an extrusion tube, a width W of the tube is larger than a height H of the tube, and when the channel in the tube is partitioned into a plurality of holes disposed in parallel with each other in a width direction of the tube by a plurality of internal walls extending in a height direction of the tube, the heat exchanger has dimensions within a range in which a position X in the width direction from an end portion of the tube and a cross-sectional area A of the tube in a length direction at the position X in the width direction satisfy the following Expressions:
• A≤HL (0<X≤w0) Expression 1:
• A≥HL+2rL(√(1−(X/r−1)2−1) (0<X≤r), 0.15H<r<0.45H Expression 2:
• in which X is a position in the width direction, A is a cross-sectional area in the length direction, H is a height of the tube, r is a radius of a rounded corner of the tube, L is a length of the tube, w0 is a thickness of an outer wall in the width direction of the end portion of the tube in the width direction, and wc is a value of X at a tube-fin contact point.