Laminated header, heat exchanger, and air-conditioning apparatus

A laminated header comprising:

• a first passage plate having a flat-plate shape in which a first passage is formed;
• a second passage plate having a flat-plate shape in which a plurality of second passages are formed;
• a third passage plate having a flat-plate shape in which a plurality of third passages are formed;
• a first branch passage plate having a flat-plate shape in which an upstream side branch passage is formed, the upstream side branch passage branching the first passage into the plurality of second passages;
• and
• a second branch passage plate having a flat-plate shape in which a downstream side branch passage is formed, the downstream side branch passage branching each one of the plurality of second passages into the plurality of third passages,
• the first passage plate, the first branch passage plate, the second passage plate, the second branch passage plate, and the third passage plate being stacked in this order,
• wherein a maximum passage cross-sectional area of the upstream side branch passage, and each of the downstream side branch passages, respectively, decreases in this order,
• the upstream side branch passage including a first taper part, the upstream side branch passage being a part of a flow passage that extends from an inlet of the first passage to an outlet of the third passage,
• wherein the upstream side branch passage includes (a) a first branch part communicating with the first passage, the first branch part including ends, (b) an upper second branch part that extends upward from one of the ends of the first branch part, and (c) a lower second branch part that extends downward from another one of the ends of the first branch part,
• the first taper part is formed at least at the upper second branch part which extends upward in the direction of gravitational force, the first taper part having a passage cross-sectional area defined by an inner peripheral wall of the first taper part, the passage cross-sectional area being gradually decreasing downstream along a longitudinal direction of the upper second branch part to a terminal end at a connection part with one passage of the plurality of second passages, wherein an accumulation of liquid refrigerant in the terminal end before flowing into the connection part of the one passage of the plurality of second passages is prevented, and
• wherein a diameter of the first passage is smaller than a minimum value of a diameter of the upstream side branch passage, and a diameter of the second passage is smaller than a minimum value of a diameter of the downstream side branch passage.