Selection of Desiccant Equipment at Altitude (RP-1339))
Abstract
ASHRAE Standard 139 provides parameters which are used in the desiccant industry to calculate the performance of a desiccant dehumidifier. These performance parameters can be obtained from any manufacturer by means of performance curves or selection software. However, solid desiccant dehumidifiers are generally rated at standard (sea level) conditions. Although some manufacturers provide a means for estimating the performance at altitude based on standard conditions, there is no methodology that is accepted by all. The scope of this paper involves investigating how performance parameters such as the moisture removal capacity (MRC), regeneration specific heat input (RSHI), process outlet temperature, and pressure drop through the wheel are affected by altitude and developing a ‘simple methodology’ that can be applied to any desiccant wheel to estimate these performance parameters. For development and validation of the methodology, data was obtained by testing a test cassette at Mississippi State University and the National Renewable Energy Laboratory.