Water vapor transmission behavior through porous and dense enthalpy exchange sheets treated with CaCl₂ LiCl and colloidal silica

This report is concerning the sheet to be utilized to the air-to-air heat exchanger. Observation on the characters of the moisture permeation for two types of the enthalpy sheet (porous and dense enthalpy sheets) has been conducted. To improve the efficiency of the moisture permeation through the enthalpy sheet, the moisture absorbents Cacl₂, LiCl and colloidal silica have been used. Throughout the wet cup test according to the ASTM standards, the tests of the moisture permeation according to the changes of the air gap have been conducted. For both of the porous and dense enthalpy sheets, it showed 2 to 2.5 times of increase for the permeability of water vapor when the air gap reduced from 13 mm to 6 mm. Also, according to the treatment of the moisture absorbent, the permeability of water vapor increased, but after the certain amount of the processing no further increase of the permeability was shown. For the dense enthalpy sheet compared with the porous enthalpy sheet, it showed more increase of permeability of water vapor due to the moisture absorbent and also it was seen that the dense enthalpy sheet has the similar permeability of water vapor to the porous enthalpy sheet's when processing the moisture absorbent.