Determination of mass transfer coefficient for air humidification packed bed using hollow plastic ball

This paper performed experimental tests on the mass transfer coefficient of humidification and dehumidification solar desalination device filled with hollow plastic ball as a packed bed and compared with the mass transfer coefficients of other material packed beds. We introduce the structure and operation of the test device and present the relationship of the mass transfer coefficient changing with different operating parameters. The experimental result indicates that this hollow plastic ball has a relatively high evaporation mass transfer coefficient due to the relatively high wet surface and interior porous water storage material. When the cooling water system and spray temperatures are 25℃ and 80℃, the mass transfer coefficient is about 8% higher than that using square wood as a packed bed. The experimental result also indicates that the effect of spraying amount and circulating flow on the mass transfer coefficient is generally positive, i. e., the mass transfer coefficient increases with the spraying amount and wind speed. However, when the wind speed reaches a certain extent, the increase of mass transfer coefficient with the circulating flow will become smaller. In addition, the concentration of sea water also has a great influence on the mass transfer coefficient.