| Under the severe situation of energy conservation, liquid desiccant cooling system has been widely used because of its significant advantages. In liquid desiccant cooling system, the most important two parts are dehumidification and regeneration. Thermal properties of liquid desiccants especially the surface vapor pressure has an important influence on the efficiency and performance of the system. Currently, most researches on liquid desiccants are concentrated in performance of pure lithium bromide, lithium chloride or calcium chloride solution. But the performance of other mixed liquid desiccants and their influence on the liquid desiccant cooling system have been rarely considered. Based on this question, the thesis made something as follow:Firstly, based on the performance of some pure solutions, a new local composition model-Chen-NRTL equation was proposed for indirectly predicting the vapor pressure of some multivariate mixed solutions. Then, this thesis built a liquid desiccant experimental device to test the dehumidification performance of mixed LiCl-CaCl2 solution in a variety conditions. The results proved that the theoretical predictions by the Chen-NRTL equation could be in good agreement with the experimental results. So, it can also be used to predict the vapor pressure of the LiBr/LiCl+CaCl2/MgCl2+water/methanol/ethanol solutions, some factors on dehumidification performance were also been analyzed. Regeneration performance and COP of the system may not be better despite better dehumidification, this thesis briefly studied the impact of these mixed solutions on the system performance through a compression refrigeration liquid desiccant cooling system model.The studies illustrated that some mixed solutions exhibited better cost-effective in dehumidification than pure solutions under the same conditions. And the use of an organic solvent (such as methanol, ethanol, etc.) could improve the dehumidification capacity of pure LiCl solution by about 10.9%. Besides, the COP of mixed solution system tends to dropping when compared to pure solution system, the most important reason was that the mixtures need more energy for regeneration. This thesis also analyzed some factors (such as:the inlet parameters of air and liquid desiccant) on the system performance. It is suggested that utilize of the return air in regeneration process could better improve the efficiency of the system. |
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