Liquid desiccant latent load handling simulation for building HVAC applications with a DOAS module

Abstract

Liquid desiccant dehumidification represents a promising research avenue for HVAC applications. This research presents a case study exploring a novel membrane desiccant absorber that we have characterized extensively at the bench scale in previous work, and in this study we present the simulation to consider the feasibility of scaling up the system to building room scale in terms of pumping costs and air mass exchanger fan cost. As part of an ongoing research pilot building project in Singapore, the simulation examines scaling up the liquid desiccant system to match the loading observed in the solid desiccant wheel in a dedicated outdoor air supply (DOAS) unit in hot and humid Singapore conditions. The liquid desiccant dehumidification system is composed of a novel combination of hydrophilic alkoxylated siloxane liquid desiccant and nonporous, vapour permeable Pebax® membrane. Such a configuration allows cooling with off-coil dehumidification, reducing the need to "over-cool" beyond the dewpoint, saving 40.0% - 61.6% in cooling energy. The corresponding liquid desiccant system would require a 66 x 66 tube array of shell-in-tube style minicontactors.