Heat exchanger having plate members

A heat exchanger comprising a plurality of plate members which are stacked together to form a plurality of refrigerant passages and a plurality of fluid passages, wherein the heat exchanger is configured to exchange heat between a refrigerant flowing through the plurality of refrigerant passages and a fluid flowing through the plurality of fluid passages, wherein at least one plate member among the plurality of plate members includes:

• a flow inlet which is placed at one end portion of a corresponding refrigerant passage among the plurality of refrigerant passages, wherein the corresponding refrigerant passage is formed at the at least one plate member, and the flow inlet is configured to input the refrigerant into the corresponding refrigerant passage;
• a flow outlet which is placed at another end portion of the corresponding refrigerant passage and is configured to output the refrigerant conducted through the corresponding refrigerant passage;
• a recess which is placed adjacent to one of the flow inlet and the flow outlet and is communicated with the corresponding refrigerant passage;
• a communication passage which is configured to communicate the one of the flow inlet and the flow outlet to the recess;
• a partition wall which partitions between the corresponding refrigerant passage and the communication passage;
• and
• a through-passage which is formed at the recess and extends through the at least one plate member, wherein the through-passage is configured to conduct the refrigerant through the at least one plate member without supplying the refrigerant to the corresponding refrigerant passage.