Dynamic simulation of a trigeneration scheme for domestic purposes based on hybrid techniques

In this paper, the design of a system providing electricity by coupling photovoltaic/thermal (PVT) collectors and a wind turbine (WT), sanitary hot water (SHW) coming from the PVT and evacuated tube collectors (ETCs) and fresh water (FW) produced in two seawater desalting facilities (membrane distillation, MD, and reverse osmosis, RO), has been carefully analyzed by means of a dynamic model developed in TRNSYS®. This analysis is compulsory to operate a lab-scale pilot plant that is being erected at Zaragoza, Spain. A new model-type has been included in TRNSYS® in order to include the MD unit in the scheme. A sensitivity analysis of some free-design variables, such that the ETC surface, PVT and ETC tilt, water storage tank, batteries capacities, and mass flow rates delivered to the SHW service and/or feeding the MD unit has been performed in order to propose the definite design of the scheme. The proposed base case was able to produce up to 15,311 L per year in the MD system and cover an electric energy demand of 1890 kWh. Coverage of SHW, water (including RO and MD) and power is respectively 99.3%, 100% and 70%. However, daily and yearly assessment of FW, SHW and power produced with the optimized design gave a better coverage of water and energy demands for a typical single family home. The improved and definite design was able to increase its MD production in 35% and the electric energy in 7% compared with base case.