Multi objectives optimization and transient analysis of an off-grid building with water desalination and waste heat recovery units

Abstract

In this study, an off-grid apartment of a five-story building with a 150 m2 area, is considered. Building is considered in a remote area; therefore, all occupants' requirements are provided without using electricity and gas from the grid. For producing water, reverse osmosis (RO) desalination system is used. HVAC system is optimized for achieving the lowest CO2 emission and the best occupant’s thermal comfort simultaneously. Also, the use of two different sources, waste heat of diesel generator and solar collector, to provide domestic hot water for the building were investigated and compared. The roof-mounted PV panel is considered for supplying building's energy consumption. Due to the limited available area of the rooftop for each flat, the diesel generator is considered a backup power supplier for the building. Produced power is stored in the battery. Results show that the optimal scale factor of the heat pump is 0.9, and the cooling capacity of the heat pump should be 5.35 kW to supply thermal comfort. Regarding the results of optimization, the annual CO2 emission production of the diesel generator is 4.79 tons and PPD is 12.4%.