Hereinafter, the amount of refrigerant circulating per second when the air conditioner

**1** is in operation at a rated cooling capacity of the air conditioner

**1** is referred to as refrigerant circulation flow rate Gr [kg/s], and the number of inflow paths

**121** to which the distribution/collection header

**131** distributes the refrigerant, i.e., the number of branches of the distribution section

**133**, is referred to as the number of paths N. The number of paths N is equal to the number of outflow paths

**122** and the number of connection pipes

**151**. The rated cooling capacity of the air conditioner

**1** refers to an output of the air conditioner

**1** when room air is cooled to a temperature of 27° C., under the condition where a temperature of outdoor air is 35° C. and a relative humidity of the room air is 45%.