Exergy analysis of a desiccant cooling cycle recovering heat from hot exhaust
Résumé
The manufacturing processes of industrial gases are major consumers of energy as electricity or fossil fuel. A big part of this energy ends up as heat in the process gas at temperatures around 150°C. Today, this thermal energy is generally released to the atmosphere through cooling towers. In this paper, the recovery of waste heat by the production of cooling capacity is considered via a desiccant cooling cycle. The liquid desiccant dehumidification and regeneration processes, uses lithium chloride (LiCl) as a liquid desiccant. The numerical model is upgraded permitting the calculation of the exergy destruction due to water evaporation rate in the regenerator, the desiccant temperature and concentration at the exit of the regenerator. An exergy analysis of the hot exhaust and the desiccant cooling cycle is performed, assessing the global exergy efficiency variation as a function of each operating parameter in the studied cycle and permitting the identification of the optimal design.