Desiccant Contamination in Desiccant Cooling Systems

This paper presents the results of a desiccant contamination experiment and the impact of the obtained silica gel degradation data on the performance of a desiccant cooling system. A test apparatus was used to thermally cycle several desiccant samples and expose them to 'ambient' humid air or 'contaminated' humid air. The source of contamination was cigarette smoke. The exposed desiccant sampleswere removed after 0.5, 1, 2, or 4 months of exposure and their moisture capacities were measured. The silica gel samples thermally cycled with ambient air showed a 5% to 30% loss in their moisture capacity. The silica gel samples thermally cycled with smoked air lost 30% to 70% of their moisture capacity. Using the obtained degradation data in a system, the impact of desiccant degradation onthe performance of a desiccant cooling cycle was estimated. Depending on the degree of desiccant degradation, the decrease in thermal coefficient of performance (COP) and cooling capacity of the system was 10% to 35%. It was found that the COP and the cooling capacity of a system after desiccant degradation can be improved by increasing the rotational speed of the dehumidifier. This indicatesthat a simple engineering solution may exist to alleviate some type of degradations.