Sensibility analysis and environmental impact of a system combining a solar-assisted heat pump and PCM storages

This paper presents a new geometry of Latent Thermal Energy Storage (LTES), acting as both a plate heat exchanger and a storage unit, which can be charged and discharged simultaneously. The modelling of this LTES is presented in a solar-assisted heat pump. The dynamic models of the thermal panels and the LTES are based on the conservation of mass and energy equations. The aims of the study is to dynamically simulate this system combining solar-assisted heat pump and four Phase Change Material (PCM) storage units, for 7 days in winter and summer. A sensitivity study is carried out to determine the ideal system design parameters (LTES units set up in parallel and solar area), using multi-criteria decision-making methods. The winter selected configuration consists of 5 LTES units for each application (solar, heating and DHW) and 249.9 m 2 of solar panels. In summer, some LTES are disconnected and 3 cooling LTES are used. Then, a Life Cycle Assessment (LCA) is carried out on the system’s use life cycle phase. Finally, the ideal solar-assisted heat pump with LTES is compared with conventional technologies (electricity and natural gas) or the use of sensible TES in terms of energy and environmental criteria. The electrical energy consumed by the sensible and latent solar-assisted heat pumps is similar, resulting in a similar ecological footprint. The results show the benefits of these systems compared with conventional technologies. From an energy point of view, the savings are significant, with energy consumption 9 times lower than with a reversible heat pump using electricity. As a result, this system reduces the ecological footprint of the building needs by more than 75% compared with conventional technologies. Future work will focus on the optimisation of operating parameters such as flow rates, and the LCA over the entire life cycle of the system. • A sensitivity study is performed to determine the number of latent storages and the solar area. • TOPSIS method with Shannon entropy is used to select a compromise solution. • Environmental impact of system’s use is compared with that of conventional systems. • Power use and ecological footprint of systems with latent or water storages are compared. • Similar environmental footprint during use step is obtained with latent or sensible storages.