Study On Reinforcement Dehumidification Mechanism And Application Of Composite Desiccant Based On Silica Gel

Desiccant dehumidification has high mass transfer efficiency. It can make use of low-grade heat energy as driving force, such as waste heat and solar energy. Furthermore it also can be applied in the following fields, for example humidity control, industry desiccant and so on. However traditional desiccant has smaller dynamic adsorption amounts, unstable dehumidification performance, and it needs high temperature to regenerate the conventional desiccant. In this paper a composite desiccant with bigger dynamic adsorption amounts, stable dehumidification performance and low regeneration temperature is developed. The new composite desiccant is composed of silica gel and lithium chloride. The lyolysis puzzled the application of composite desiccant. In this paper the craft of forced lyolysis is determined. Furthermore the lyolysis is avoided and the optimal mixture ratio of the composite desiccant is obtained. SEM-EDAX, ASAP2010 and dynamical mechanics/differential thermal analyzer are used to character the composite desiccant. The reinforce adsorption mechanism of composite desiccant is explored based on the couple of physics adsorption and chemical adsorption. The adsorption isotherm of composite desiccant and traditional desiccants (silica gel and 13X molecular sieve) are measured under the classic temperature (25℃,35℃,and 40℃). The experimental results indicate that adsorption capacity is higher than that of silica gel by about 67%～145%. This paper analysis the type of isotherm adsorption, adsorption heat and pore structure for composite desiccant. A water vapor equilibrium adsorption model of composite desiccant is put forward.The dipping and adhesion method of composite desiccant wheel is raised in this paper. A new composite desiccant wheel is made and experimental equipment of desiccant wheel is built up. The dynamic and steady dehumidification performance of the desiccant wheels are measured and compared with traditional silica gel wheel by means of the experimental equipment. The experimental results reveal that the optimal regeneration temperature of composite desiccant is lower than that of silica gel desiccant wheel under the same experimental conditions and the moisture removal amounts is higher than silica gel wheel by 30%~50%. Moreover the dehumidification predominance of the composite desiccant wheel is more obvious under low moisture climate. Especially a mathematical model for composite desiccant wheel based on ceramic is developed and validated by experimental data. On the base of valid model the effects of parameters on the optimal rotation speed are analyzed. These analytic results demonstrate the reinforce approach of heat and mass transfer.Hybrid air conditioner equipment that deals the latent heat and sensible heat separately is designed and established. The transfer rule of latent heat and energy conversion characteristic of the hybrid air conditioner are analyzed theoretically and experimentally. It illuminates the advantage and energy conversion potential of the hybrid air conditioner using the composite desiccant wheel. Moreover the performance is optimized according to the performance index.