Assessment of the energy performance of a solar/biomass hybrid system for the climatization of small- and medium-scale buildings

The H2020 EU-funded project Hybrid-BioVGE aims to develop an efficient system entirely based on solar energy and biomass for the climatization of buildings during both the heating and cooling seasons. The most innovative component of the concept is a solar-driven Variable Geometry Ejector (VGE) cooling cycle, which can adjust its internal geometry with two degrees of freedom, according to the effective operating conditions. This paper presents the components of the Hybrid-BioVGE concept and describes a demonstrator of the proposed solution installed in a single-family house in Porto (Portugal). The main characteristics of the building, the size and typology of thermal energy storages included in the system are presented as well. In order to demonstrate the energy-saving potential of the Hybrid-BioVGE concept, the numerical model of the demonstrator was implemented in the TRNSYS 18 environment. Outcomes of simulations include the system’s energy performance for both heating and cooling seasons, the achievable solar fraction and the VGE efficiency. Numerical results show that up to 98% of the system energy input derives from renewable sources, with a solar fraction of 61.5%, during the heating season. On the contrary, the seasonal performance factor in cooling operating mode is lower than expected. The VGE cooling cycle efficiency is mainly penalised by the heat rejection loop, which should be optimised to achieve the best performance.