Experimental investigation of a regenerative organic Rankine cycle (ORC) under different cryogenic cooling conditions

ABSTRACT

This study experimentally investigates a Regenerative Organic Rankine Cycle (RORC) system that operated under varied cryogenic conditions using liquid nitrogen (LN₂) as the heat sink. A three-fluid heat exchanger (TFHE) is applied to this system instead of a condenser and regenerator to realize the RORC system. The condensing pressure changes between 0.08 MPa and 0.6 MPa, and applying the R290 as the working fluid. The condensing pressure effect on system performances, including electrical power output, cold thermal efficiency, and exergetic efficiency, are investigated under different LN₂ flow rates. The comparisons between basic ORC (BORC) and RORC under the same working conditions are conducted. The results demonstrate that as the condensing pressure remains constant, the higher LN₂ flow rate is beneficial to the overall performance of the RORC system. The maximum cold thermal efficiency and power generation obtained in the RORC system are 13.35% and 738.81 W, which are obtained at the LN₂ flow rate of 120 kg/h and the condensing pressure of 0.25 MPa. Additionally, the RORC shows improved performance with an exergetic efficiency of 10.68%. The results would be a technological guide for the construction and improvement of the system with cold energy recovery.

KEYWORDS:

• Cryogenic cold energy
• condensing pressure
• three-fluid heat exchanger
• cold thermal efficiency
• organic Rankine cycle

Acknowledgements

The authors would like to thank the support from Shanghai Municipal Science and Technology Commission (22ZR1426900), the National Natural Science Foundation of China (Grant No. 51806136), Shanghai Sailing Program (Grant No. 18YF1409700). This work is also supported by the Shanghai Frontiers Science Center of “Full Penetration” Far-Reaching Offshore Ocean Energy and Power.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Notes on contributors

Wenzhong Gao

Wenzhong Gao is a renowned professor at Shanghai Maritime University, China, specializing in efficient waste heat utilization, ship and industrial heat transfer enhancement, and clean energy technologies. His research primarily focuses on Cryogenic Cold Energy Utilization and Oceanic Temperature Differential Power Generation.

Haoxian Wang

Haoxian Wang is currently pursuing a master's degree in Refrigeration and Cryogenic Engineering at the merchant marine college of Shanghai Maritime University. He completed his bachelor's degree in Energy and Power Engineering from the same university in 2016. His research interests encompass the efficient and comprehensive utilization of industrial waste heat, the enhancement of heat transfer, and the cascade utilization of LNG cold energy, with a primary focus on cold energy power generation.

Yuan Zhang

Yuan Zhang is an Associate Professor and Master's Supervisor at Shanghai Maritime University in China. He holds a Ph.D. in Engineering Thermophysics and completed a Postdoctoral Fellowship at the Institute of Engineering Thermophysics, Chinese Academy of Sciences. His research interests include cold energy utilization, compressed gas energy storage systems, and ocean thermal energy conversion (OTEC).

Zhen Tian

Zhen Tian is an Associate Professor and Master's Supervisor at Shanghai Maritime University in China. She holds a Ph.D. in Refrigeration and Cryogenic Engineering from Shanghai Jiao Tong University. With expertise in thermal management of new energy vehicles, flow boiling, and enhanced heat transfer, her research also extends to cold and thermal energy utilization in LNG dual-fuel ships, shipboard CO2, capture and storage technology, and energy efficiency analysis for ships.