Deep Eutectic Solvents as Designer Phase-Change Materials for Organic Rankine Cycle Applications

-pentane are the working fluids reaching the highest thermal and exergetic efficiency, while choline chloride plus suberic acid and choline chloride plus 4-hydroxybenzoic acid are the best PCMs, far exceeding the exergetic performance of paraffin wax. Furthermore, adding a TEA improves the quality of energy delivery, increasing the exergetic efficiency by up to 95%. These findings highlight the practicality of using hydrocarbons in ORCs in conjunction with TEAs. Additionally, the analysis indicates that PCMs with a higher-melting-temperature and fusion enthalpy offer the most promising solution for ORCs with TEAs, thereby providing valuable insights for the design and optimization of ORC systems.