Heat exchanger, outdoor unit including heat exchanger, and air-conditioning apparatus including outdoor unit

A heat exchanger comprising:

• a heat exchange body having a plurality of flat tubes arranged and spaced from each other;
• an upper header provided at an upper end of the heat exchange body;
• a lower header provided at a lower end of the heat exchange body, the lower end of the heat exchange body being located below the upper end of the heat exchange body;
• and
• a partition plate provided in at least one of the upper header and the lower header to partition the heat exchange body into a plurality of regions,
• wherein the partition plate is provided such that in each of the regions, refrigerant flows in the opposite direction to the flow direction of the refrigerant in an adjacent one of the regions, and is provided such that regarding the regions, the more downstream a region is relative to the flow of the refrigerant when the heat exchanger operates as a condenser, the smaller is a flow passage cross-sectional area of the region, and
• wherein the heat exchanger is configured such that the refrigerant flows upward in a region located most downstream relative to the flow of the refrigerant, when the heat exchanger operates as a condenser, and the flow of the refrigerant in the region located most downstream relative to the flow of the refrigerant has a flooding constant C greater than 1.