Journal of Chemical Engineering of Japan, Vol.36, No.7, 819-826, 2003
Process configurations and their performance estimations of an adsorptive desiccant cooling cycle for use in a damp climate
Typical adsorptive desiccant cooling process mainly consisting of a rotary dehumidifier and a sensible heat exchanger can be driven with low-temperature heat energy like solar energy or waste heat, and it has been expected to be alternative air conditioning equipment considering various energy/environmental problems such as global warming. However, the fact that the cooling performance is decreased significantly as ambient humidity increases was also found. This is mainly due to a simultaneous increase of humidity and temperature in the process outlet air of dehumidifier. For the use of the cooling process in high humid condition, two process configurations were proposed and investigated by means of simple calculation. One of the proposed configurations, the 4-wheel cycle with double stage dehumidification, indicated a sufficient cooling performance for the use in factories or laboratories even though the ambient humidity was nearly 20 g/kg. Furthermore, the process performance was improved more with water spray evaporative cooling at the inlet of a regeneration air stream in the pre-dehumidification section. This means that lower humidity and lower temperature of air supplied to the process inlet of the dehumidifier is strongly required to give the cooling process a sufficient performance for actual use. Meanwhile, it was found that lower temperature heat around 50-60degreesC could drive the 4-wheel desiccant cycle in a moderate ambient humidity. The other, a 3-wheel cycle equipped with a total heat exchanger, gave us a reasonable improvement in the cooling effect and COP with less additional investment than that for the 4-wheel cycle.