Effect of parameters on moisture removal capacity in the desiccant cooling systems

Abstract

A mathematical model was developed to investigate the effect of crucial operating parameters, such as process inlet humidity ratio, inlet volume flow rate, R/P ratio (reactivation/process air flow), regenerative temperature and rotational speed on the performance of desiccant wheels in hot and humid climates, using wound silica gel and molecular sieve desiccants. The desiccant wheels were designed to operate in two modes, specifically, with 90° for reactivation and 270° for process (1:3 split) as well as with 180° for reactivation and 180° for process (1:1 split). The main results enabled to make the following observations: (i) higher regeneration air temperature leads to an improvement of dehumidification and reduction of the thermal coefficient of performance COPth, (ii) an increase in the process inlet volume flow rate causes a reduction in the process removed moisture; (iii) the greater R/P ratio is required to remove more moisture, while a lower R/P ratio implies the lower power consumption for regeneration; (iv) silica gel desiccant is preferred when greater moisture removal is required at high inlet relative humidity, while molecular sieve desiccant is preferred when low dew point is required at low inlet relative humidity. Keywords: Moisture, Desiccant, Cooling system, Silica gel, Molecular sieve, Indoor humidity