This paper presents an experimental study on the dehumidification performance of a finned-tube internally cooled contactor in comparison to that of an adiabatic contactor in liquid desiccant air conditioning systems with an ionic liquid. The contactor is the most significant component in liquid desiccant systems because it is the component responsible for the dehumidification and regeneration processes. When the absorptive solution is in contact with the air in the contactor, the absorption/desorption of the solution occurs because of the difference in vapor pressure. This results in the transfer of heat and mass between the air and the solution. Conventionally, adiabatic contactors that only entail air and solution interactions are used for the dehumidification/regeneration process of liquid desiccant systems. On the contrary, internally cooled contactors are recommended because they can realize a more efficient dehumidification process. This is possible because internally cooled contactors can maintain the dehumidification ability of the absorptive solution by utilizing cooling water as the third fluid in the contactor to remove the heat of absorption. In other words, internally cooled contactors can reduce the circulating solution mass flux and hence the power consumption of the solution pumps. In this study, the dehumidification ability of a finned-tube internally cooled contactor was investigated experimentally. To increase heat transfer in cooling water, aluminum, which has a high thermal conductivity, was used as the contactor material. Although lithium chloride solution is a conventional absorptive solution, it is corrosive to aluminum; therefore, an ionic liquid was used as the absorptive solution in this experiment because it does not cause any corrosive action on aluminum. Currently, research activities on this new combination of contactor and absorptive solution are not extensive. This study provides new and valuable information for future work. Moreover, the results were compared to those of an adiabatic contactor to analyze the difference in the dehumidification ability between the two contactors. As a result, outlet air dew point temperatures lower than the cooling water temperature were achieved, and this is indicative of the advantage of a liquid desiccant air conditioning system over conventional vapor compression air conditioning system. Furthermore, the outlet air dew point temperatures of the internally cooled contactor were lower than those of the adiabatic contactor at low mass fluxes, and converged at a higher solution mass flux. This suggests the significant effect of cooling water on the dehumidification ability of the absorptive solution. The experimental data regarding the dehumidification ability of this new combination of an aluminum finned-tube contactor and ionic liquid solution are promising in terms of further investigating the structure of contactors. Moreover, these results provide significant information for the improvement of liquid desiccant air conditioning system design.
展开▼
