Multi-stage liquid-desiccant air-conditioner: Experimental performance and model development

An experimental study evaluated the performance of a novel multi-stage liquid-desiccant air-conditioner featuring parallel inter-stage flows of cooling and heating water, and semi-series flows of desiccant. The system was tested at different inlet cooling water temperatures, ranging from 8 °C to 20 °C, using a solution of LiBr and water as the desiccant. Average total air cooling rates between 8.4 kW and 19.7 kW were observed, with higher cooling rates achieved with lower cooling water temperatures. The system was able to provide high sensible cooling rates of up to 8.8 kW. The cooling water temperature impacted the sensible cooling, but did not have a discernible impact on the latent cooling rate. The inlet air humidity was shown to have an impact on the latent cooling rate, with higher humidity leading to higher latent cooling rates. The energy consumption of the system was low, with an average thermal coefficient of performance (COP) of 0.58 and electrical COP of 4.7. A variable effectiveness model was developed in TRNSYS and proven to be accurate at predicting the air cooling, but further experimental work is required to improve the thermal energy consumption model. The modular design philosophy of the model allows for easy changes to the design (e.g., number of stages, fluid flow paths, operating conditions, etc.) enabling future work to improve the regenerator modeling once further experimentation is completed.