Optimal Management of Reversible Heat Pump/Organic Rankine Cycle Carnot Batteries

In the view of reducing the global greenhouse gas emissions, it becomes fundamental to exploit the renewable energy sources at their maximum potential by developing effective strategies for their flexible use. Among the available solutions to realize these strategies are the electric energy storage including the innovative pumped thermal energy storage technology (included in the Carnot battery concept). This can become very interesting in these applications where different energy flows must be handled (both electric and thermal), thanks to the possibility of adding the contribution of a waste heat source, in a thermally integrated energy storage. However, despite the several advantages, the state-of-the-art still lacks experiments and investigation of efficient control strategy for the Carnot battery when inserted into the process. As an original contribution to the current literature, this paper presents the off-design model of a reversible organic Rankine cycle (ORC)/heat pump (HP) Carnot battery configuration with the aim of employing it to simulate the performance of such system and discuss its optimal management when inserted into a generic process. An existing reversible HP/ORC kW-size prototype is considered as reference and its optimal control in both HP and ORC mode under different boundary conditions is assessed.