Comparison of Dehumidification Performance of Counter and Cross-flow type Liquid desiccant Dehumidifiers
liquid desiccant system, dehumidification, counter-flow, cross-flow, experiment
In HVAC systems, a liquid desiccant system has attracted research attentions due to its advantages on removing latent loads in a conditioned building with less energy consumption. The dehumidifier is the key component in a liquid desiccant system, whose heat and mass transfer performance directly affects the whole dehumidification performance. The coupled heat and mass transfer performance is affected not only by the properties of packing material and inlet conditions of air and desiccant solution, but also by the flow direction between air and desiccant solution. This paper experimentally investigates the dehumidification performance of the counter-flow type and cross-flow type liquid desiccant system under the same system operation conditions. In this study, Lithium chloride aqueous solution is used as a desiccant solution and Celdek structure packing is used. The enthalpy efficiency and moisture efficiency were adopted as the dehumidification performance indices. To investigate the impact of air and solution conditions on the two indices, five parameters were measured: liquid to gas ratio, the inlet air temperature and humidity ratio and solution temperature and concentration. As a result, the effects of flow directions between air and solution on the dehumidification process in various conditions were analysed. In additions, the correlations for predicting the performance of the two type of liquid desiccant system are proposed, which are good agreement with the experiment results and existing models.