Tuning a Dual Source Heat Pump model in TRNSYS versus monitored data from the GEO4CIVHIC case study in Malta

Abstract The building sector accounts for approximately 40% of primary energy consumption in Europe. To support the green transition that is occurring in the European Union, a key priority is the decarbonization of the residential sector, from both an environmental and energy perspective. Currently, one of the most effective alternatives to traditional boilers, which are primarily fuelled by natural gas, is the adoption of reversible heat pumps. These systems can also be combined with other renewable energy sources to enhance performance and increase the share of green energy consumed. The GEO4CIVHIC project assesses the deployment of shallow geothermal systems for heating or cooling, including hybrid solutions that integrate various energy sources. Its goal is to promote the adoption of these highly efficient energy systems, which currently hold a limited market share, by introducing new technologies and tools to overcome common challenges and accelerate the energy transition. The aim of this thesis is to develop an energy model in TRNSYS environment that simulates the operation of a double-source heat pump system installed as a part of GEO4CIVHIC case study in Malta. The model is based on a heat pump component designed by the University of Padova, which differs from previous TRNSYS models in the literature because it is based on the compressor’s polynomial equation rather than manufacturer performance tables. This new model can be applied to various configurations, allowing for a wide range of studies focused on promoting the diffusion of highly sustainable and efficient energy systems. Among these studies, this thesis presents a performance comparison between the dual-source heat pump under examination and a traditional single-source air heat pump. Additionally, an analysis of the switch temperature is provided, addressing the issue of thermal drift in the ground. Finally, potential improvements for the model and possible application are discussed.