Simulated hygrothermal performance of a desiccant-assisted hybrid air/water conditioning system in a mixed humid climate under dynamic load

• Published in: Energy and buildings 2015-01, Vol.86, p.45-57
• Main Authors: O’Kelly, Matthew, Walter, Mark E., Rowland, James R.
• Format: Article
• Language: English
• Subjects: Air conditioners; Cooling; Desiccant cooling; Desiccants; Dynamical systems; Dynamics; Energy conservation; Humidity; Mathematical models; Passivhaus; Prototypes; Separate sensible and latent heat removal; Solar Decathlon
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2014.09.068

•This paper details the dynamic simulation of a small Passivhaus structure.•The structure is simulated with a novel desiccant assisted heat pump.•The simulation exposes a means to better condition Passivhaus construction.•HAWC enables an elimination of high humidity events despite low sensible loads.•HAWC uses less energy than a conventional heat pump system. Previous work by the same authors has shown that in mixed-humid climates, tight, super-insulated residential structures can experience high humidity events in summer months. Standard, commercially available vapor compression-based air conditioners struggle to control humidity in such structures with low cooling loads. Therefore a desiccant-assisted heat pump system for tight, super-insulated residential structures is proposed. This paper first reviews solid desiccant cooling cycles. Then a hybrid desiccant cooling cycle is explained and a prototype machine based on the cycle is described. The machine, known as HAWC (hybrid air/water conditioner), accomplishes cooling, dehumidification, ventilation, and domestic hot water heating. This paper models the HAWC within the framework of dynamic building energy modeling software and concludes that a refined version of the HAWC prototype is capable of completely eliminating high humidity events in the summer time while still saving energy as compared to a traditional HVAC system.