Study on the performance of a unit dew-point evaporative cooler with fibrous membrane and its application in typical regions

Abstract

In this paper, a new type of unit dew-point evaporative cooler with fibrous membrane was designed and constructed. The effects of three air state parameters (temperature, humidity, air velocity) on the outlet air temperature, wet-bulb efficiency and dew-point efficiency were studied, as well as the regional adaptability in four typical cities in China. The porous fibrous membrane can be used to improve the moisture permeability and diffusion characteristics of the wet channel. It was found that the wicking height rate of the porous fibrous membrane was 0.203 cm/min, the diffusivity rate was 0.118 cm2/s, which was better than the performance of Kraft Paper. The usage of this novel device in Urumqi and Lanzhou, as regions with lower relative humidity, showed better regional adaptability than in Beijing and Shanghai with higher relative humidity. When the inlet air velocity was 1 m/s, the temperature decreased from 33.4 °C to 24.2 °C and 31.3 °C–24.5 °C respectively in the former area, while, decreased from 33.6 °C to 28.1 °C and 34.6 °C–29.5 °C respectively in the latter area. With the inlet air velocity increasing from 1 m/s to 3 m/s, the outlet air temperature would rise, and the wet-bulb efficiency and dew-point efficiency would decrease, but the cooling capacity would increase.