A Polygeneration System Based on Desiccant Air Conditioning Coupled with an Electrical Storage

Abstract

This study presents an extension of a previous paper recently published by the authors. In particular, the current paper focuses on adding electrical storage to a polygeneration system developed for residential applications. Different from the previous work, it aims to design an off-grid facility. The polygeneration plant provides electricity, space heating and cooling, domestic hot water, and freshwater for a single-family dwelling in Almería, Spain. The main system technologies are photovoltaic/thermal collectors, reverse osmosis, and desiccant air conditioning. Lead-acid battery storage was added as a backup for the electrical system. The system was performed in the TRNSYS simulation environment for one year with a 5-min time step. A parametric study was carried out to investigate the grid dependence according to the number of batteries installed. Design optimization was also performed to provide the optimal system configuration for the off-grid case. A solar collector efficiency of 0.55 and a desiccant air-conditioning coefficient of performance of 0.42 were obtained. All demands were fully supplied, and the primary energy saving and CO2 saving achieved 100%. A minimum battery state of charge of 30% was reached for a few hours all year long.