Investigation of a heat pump reversible in an organic Rankine cycle and its application in the building sector

This thesis studies the concept of reversible heat pump / organic Rankine cycle (HP/ORC) and its application in the building sector. Chapter one describes this HP/ORC system and its possible applications. A tool based on operating maps is developed to determine the feasibility of such a system depending on the operating conditions of a given application. In Chapter two, the reversibility of volumetric machines is studied based on a theoretical comparison followed by experimental results collected on four different compressor/expander technologies. The comparison shows which technology should be used depending on the characteristics of an application. In Chapter three, the design and sizing methodology to optimize the performance of the reversible heat pump /organic Rankine cycle is described. This design and sizing optimisation is performed in the case of the residential application: the reversible HP/ORC system is coupled with a large solar absorber in a building to provide a polyvalent machine able to produce heat or electricity depending on the needs of the building. Steady-state models are then used to predict the annual performance of the system integrated in a building. As the theoretical results are promising in the case of the residential application, a test-rig is built and an experimental campaign is performed in both HP and ORC modes (Chapter four). A global methodology to improve the quality of experimental data is proposed based on two different mathematical tools. The method combines the reconciliation method and the Gaussian Processes sensitivity analysis. A model is calibrated based on experimentation to characterize the performance of the HP/ORC unit with an optimal control and with a wide range of inputs. Chapter five studies the reversible unit in the case of the building application based on advanced dynamic models. The global model combines validated sub-models: the reversible unit, the solar roof, the thermal energy storage, the horizontal ground heat exchanger and the building. An optimal control strategy is developed and presented. A parametric study is performed to observe the performance of the system in a wide range of typologies. The influence of different lights and appliances profiles, building envelopes, integration of batteries, roof tilt angles, locations, storage sizes is developed. Furthermore, a technical and economic comparison with one of the most mature technologies to get a positive energy building, namely photovoltaics panels combined with a heat pump in a passive house, is performed