The airside mass transfer characteristics of two-plate fin-and-tube heat exchangers with different fin spacings were experimentally studied under low ambient pressure and dehumidifying conditions. The experimental conditions comprised an ambient pressure range 40–100 kPa

inlet air velocity 0.5–4 m/s

inlet air relative humidity 50%–90%

inlet air dry bulb temperature 27 ℃

and water flow velocity 1.65 m/s. The effects of ambient pressure

air velocity

fin spacing

and relative humidity of the inlet air on the airside mass transfer characteristics of the heat exchanger were investigated. The results showed that under low ambient pressure

the effects of face air velocity

fin spacing

and inlet air relative humidity on the air side mass transfer coefficient of the heat exchanger is consistent with that under normal ambient pressure. When the ambient pressure increased from 40 kPa to 100 kPa

the air-side mass transfer coefficient decreased by 18.2%–23.6%. Under low air velocity and ambient pressure

the effects of fin spacing and inlet air relative humidity on the air-side mass transfer characteristics are more significant.