Energy performance enhancement of a collective hot water production process equipped with a centralized storage tank

This paper investigates the thermal performance of a forced circulation collective solar water heater (SWH) equipped with a centralized storage tank, throughout hourly dynamic simulations. The main purpose of this study is to identify the parameters affecting the overall efficiency of the collective process, because the literature review focuses on individual SWHs, rather than collective hot water systems that are extensively integrated in the tertiary sector, such as hotels, hospitals, university residences, etc. Hence, being able to suggest general recommendations that would be helpful to guide hot water system designers. A typical residence located in Fez city (Morocco) that shelters 60 occupants was considered as a realistic case study, for which the thermal performances of the collective hot water production system were simulated. Several performance indicators were defined and miscellaneous dynamic simulations were carried out to enhance the process's efficiency. For instance, the incident energy on the solar collector panel, the supplementary consumptions for different storage tank volumes and load profiles, the useful energy gain from the collector's field and the solar fraction of the collective hot water process. The results showed that the Evacuated Tube Technology (ETC) is suitable for this collective hot water production application, because the solar fraction of the process remains higher with ETC, as opposed to the use of Flat Plate Collectors (FPC). Moreover, increasing the centralized storage tank volume enhances the annual solar fraction of the collective hot water process. Last but not least, the maximal annual averaged solar fraction was achieved by the ETC technology (78%). However, it is equal to 68% for (FPC) while maintaining 3000 l as a centralized storage capacity.