Weitzer M, Reiß S, Steger D, Kolb S, Karl J (2025)
Publication Language: English
Publication Type: Journal article
Publication year: 2025
Book Volume: 260
Article Number: 124872
DOI: 10.1016/j.applthermaleng.2024.124872
This paper presents a first detailed experimental characterization of a reversible heat pump – Organic Rankine Cycle pilot plant, highlighting its potential as a thermally integrated Carnot battery for efficient energy storage. A total of 150 stationary operating points were investigated in both heat pump and ORC modes. The study analyzes and discusses the main trends and interactions at both the system and component levels. As expected, heat pump and ORC operations exhibit an opposing behavior. While heat pump operation yields a maximum COP of 9.5 at a 15 K temperature lift, the peak net ORC efficiency reaches 4.4 % with a 40 K temperature gradient. Neglecting additional storage losses, this leads to a power-to-power (round-trip) efficiency of up to 41.8 % for the Carnot battery. The absence of a liquid receiver in the ORC mode leads to significant subcooling and increased condensation pressures, which affect the expander's power generation due to excess refrigerant accumulation. Moreover, the experimental results reveal that the reversible screw machine is the critical factor influencing efficiency. The screw machine's maximum isentropic efficiencies are 78 % and 60 % in compressor and expander operation, respectively. The reliability of the results was verified by means of an energy balance and reference operating points, underlining high reproducibility. Additionally, potential system improvements were derived from the experimental results. Altogether, this paper successfully demonstrates the concept of reversible heat pump – ORC systems and provides experimental results for further advancements in this field.
APA:
Weitzer, M., Reiß, S., Steger, D., Kolb, S., & Karl, J. (2025). Experimental characterization of a reversible heat pump – Organic Rankine cycle pilot plant as a thermally integrated Carnot battery. Applied Thermal Engineering, 260. https://doi.org/10.1016/j.applthermaleng.2024.124872
MLA:
Weitzer, Maximilian, et al. "Experimental characterization of a reversible heat pump – Organic Rankine cycle pilot plant as a thermally integrated Carnot battery." Applied Thermal Engineering 260 (2025).
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