Analysis of thermal and dehumidification performances of a silica-gel desiccant wheel regenerated with a low temperature medium

Advantages of desiccant-based air conditioning systems with respect to conventional ones based on the dehumidification by cooling have been highlighted in many research papers. The energy saving and the reduction of the environmental impact are higher when the desiccant material is regenerated by using “free” thermal energy (for example, waste heat from cogenerators or solar energy). In order to evaluate the performance of a silica-gel desiccant wheel, a test facility was realized at University of Sannio. The desiccant material is regenerated by means of low temperature thermal energy (about 65 °C) from a microcogenerator; the rotor is installed in an air handling unit that provides cooling energy for space cooling purposes, configuring the system as a microtrigeneration device. In this paper, experimental data collected during several tests are presented: the dehumidification process was monitored to correlate thermal and dehumidification performances of the wheel, temperature, flow rate and humidity ratio of both inlet process and outlet regeneration air flows, and regeneration temperature.Experimental results were further worked out in order to assess modifications in process air temperature and humidity at the outlet of the desiccant wheel as a function of the operating conditions. A simple descriptive model has been developed to provide a mechanistic framework for the interpretation of the results.