primary return air meaning in English

一次回风

There are four primary return air all - air systems in the building ; others are primary air fan coil systems
全楼共设一次回风式全空气系统4个，其余均为风机盘管加新风系统。
The study shows that compared with the energy consumption of conventional central air - conditioning system with primary return air , the heat pipe air - conditioning system can save cooling and reheating energy
研究结果表明：在相同的室内设计温度下，采用热管式空调机组处理空气的一次回风集中空调系统比常规的一次回风集中空调系统节省冷量和再热量。
Taking an office building in guangzhou as an example , this paper investigated the energy consumption of a central air - conditioning system with primary return air using heat pipe air - conditioner at different indoor design temperatures
摘要以广州地区的办公建筑为例，就一次回风集中空调系统在空气处理过程中采用热管式空调机组时，不同室内设计温度下的空调系统能耗进行了分析，并且与常规的一次回风集中空调系统的耗能量进行了比较。