Air Dehumidification with the Porous Hydrophobic Wall in Underground Tunnel

Air can be dehumidified with the porous hydrophobic wall in mostly underground tunnel in constant zone of subsurface temperature. For water vapor through the wall, it must produce a concentration difference between both sides of the wall. According to this principle, a test is done combined with repair works on an underground tunnel. The hydrophobic porous mortar is scraped on geotextile, which is pasted on the painted original tunnel wall as hydraulic conductivity layer where vapor condense and water flow away. It is recognized that temperature and mass transfer rate is relative to tunnel air velocity, air temperature and partial pressure of water vapor, the temperature in constant zone of subsurface temperature and the saturated water vapor partial pressure. Comparative test results show that the condensation dew on the wall is disappeared completely, the wall dehumidifies air effectively, and saving dehumidifier power is more than 50% in normal humidity range.