A liquid desiccant enhanced two stage evaporative cooling system-development and performance evaluation of a test rig

Desiccant technology is found to be a good alternative to conventional cooling systems. It can provide better thermal comfort under hot and humid climatic conditions. The major component of a liquid desiccant cooling system is the desiccant dehumidifier which controls the latent cooling load. In this paper, a newly developed liquid desiccant enhanced evaporative cooling system has been tested experimentally. The effects of ambient conditions and other parameters on the performance of the system are investigated. The system performance curves which help to determine the air outlet conditions and coefficient of performance (COP) of the system are drawn for a wide range of ambient air humidity ratios (0.010–0.026 kg/kg), ambient air temperature (25–40 °C), process air flow rate (1.5–8.0 kg/m2·s), regeneration air flow rate (1.5–4.5 kg/m2·s), and regeneration temperature (55–85 °C). The results showed that better supply air conditions are achieved for hot and humid climatic conditions with effectiveness of the system largely dependent on process and regeneration air flow rates, regeneration temperature, and humidity ratio of process air. The dehumidification performance is increased by 62% for a change of ambient air humidity ratio from 0.01 to 0.025 kg/kg. The thermal coefficient of performance improved by 50% for the above variation in humidity ratio. This shows that such thermally activated systems are feasible options for hot and humid climatic conditions as indicated by better performance under these conditions.M. Mujahid Rafique, Shafiqur Rehman, Luai M. Alhems and Muhammad Ali Shaki