An Experimental Investigation of Moisture Buffering Value for Composite Hygroscopic Materials under Different Air-Flow Conditions

Hygroscopic materials used in contact with indoor air can assist in dampening the peaks of relative humidity and thus moderate the variation of indoor humidity environment. Considering convective boundary air layer’s effort, a series of experiments were set up to investigate the influence of air-flow rate and orientation on moisture buffering effect of two types of hygroscope materials. One is gypsum plaster mixed up with different percentage of microencapsulated phase change material (MPCM) and another is scallop shell scrum, blending with phase change material (PCM) slurry. A large climatic chamber, equipped with a wall of fans which could provide stable air-flow rate ranged between 0 and 2.73 m/s, was used to create a well-controlled experimental environment. The results showed that the boosted air-flow rate of environment could increase materials’ moisture ab/desorption, as well as MBV of materials in practical level. In addition, the differences between vertical and parallel samples amplified when air-flow rate raised. Detailed analysis revealed that air-flow rate influenced the initial absorption stage the most, considering its effect on evaporation process.