Modeling and simulation of a Desiccant–Brayton Cascade refrigeration cycle

The increasing environmental concern associated with synthetic refrigerants has shed new light on the use of natural substances in refrigeration cycles. Accordingly, cycles that employ natural refrigerants, such as Brayton and Desiccant cooling cycles have been increasingly addressed. The present work proposes the combination of these two cycles into a cascade configuration: the Desiccant–Brayton Cascade (DBC) cycle. While in standard Brayton cycles the air can only be cooled back to ambient temperature in the regenerator, in the proposed DBC cycle it can be cooled below this limit, using the evaporative cooling effect provided by the desiccant cycle side. In addition, the DBC configuration requires no additional heat input for driving the desiccant cooling side, as the heat associated with the high compressor outlet temperature is used to regenerate the dehumidifier, rather than being dumped to the environment. The DBC cycle is modeled in terms of heat and mass balances and components’ performance characteristics, and a computational implementation is developed to solve the resulting non-algebraic system of equations. The operation of the proposed cycle is analyzed for a number of conditions, and the results show that cascade configuration can produce a significant performance improvement compared to the standard Brayton cycle.

► Original cycle combining the Desiccant and refrigeration Brayton cycle in a cascade configuration.
► Refrigeration cycle mathematical modeling.
► Waste heat recovery and CFC-free cycle.