Experimental investigation of a reversible heat pump/organic Rankine cycle unit designed to be coupled with a passive house to get a Net Zero Energy Building

This paper presents an innovative reversible Heat Pump/Organic Rankine Cycle (HP/ORC) experimental unit designed to be coupled to a Net Zero Energy Building (connected to a 120 m² thermal solar roof and a ground heat exchanger). The system can operate in three different modes: an ORC mode to produce electricity when a large amount of heat is collected by the solar roof, a direct heating mode using exclusively the solar roof, and a HP mode for space heating during cold weather conditions. This paper describes a comprehensive experimental campaign carried out on a prototype unit using a modified HVAC scroll compressor (4 kWe). From the results, the technical feasibility of the system is demonstrated. A cycle efficiency of 4.2% is achieved in ORC mode (with condensation and evaporation temperature respectively of 25 °C and 88 °C) and a COP of 3.1 is obtained in HP mode (with condensation and evaporation temperature respectively of 61 °C and 21 °C).