Evaluation of a Liquid Desiccant Air Conditioning System with Solar Thermal Regeneration
Abstract
To investigate the feasibility of solar thermal air-conditioning systems in Canada, a 95m2 vacuum tube solar array was installed and instrumented to drive a liquid-desiccant (LD) dehumidifier. The novel low-flow LD unit was configured to operate as a dedicated outdoor air system. Phase I of the demonstration project focused on characterizing and modelling the LDAC using a gas fired boiler to simulate the solar heat input. As part of phase II, currently in progress, the TRNSYS simulation environment was used to model the performance of the system when driven by solar energy. Simulations were used as a design tool for the solar array which is currently being commissioned. The installed system was simulated for the months of July and August using Toronto, Canada weather data and the system was predicted to have an average solar fraction of 65% and average collector efficiency of 64% (based on absorber area). Latent cooling power was predicted to be between 13 and 23 kW (3.8-6.6 tons). Experimental operating results will be used to validate simulations and identify practical considerations not currently represented by system models. Performance of the system is predicted to improve with upgrades including variable speed pump control and the installation of desiccant storage.