Performance analysis of a novel power/refrigerating combined-system driven by the low-grade waste heat using different refrigerants

• Published in: Energy (Oxford) 2014-08, Vol.73, p.543-553
• Main Authors: Li, You-Rong, Wang, Xiao-Qiong, Li, Xiao-Ping, Wang, Jian-Ning
• Format: Article
• Language: English
• Subjects: Applied sciences; Combined cycle; Electric power generation; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Exergy; Exergy efficiency; Flue gases; Inlet pressure; Refrigerants; Refrigerating engineering; Refrigerating engineering. Cryogenics. Food conservation; Refrigeration; Refrigeration capacity; Regenerator; Turbines; Waste heat; Working fluid; Working fluids
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2014.06.054

In this paper, a novel power/refrigerating combined-system driven by the low-grade waste heat of the flue gas was introduced. It coupled a transcritical organic Rankine cycle with a vapor compression refrigeration cycle. In order to understand basic characteristics of this novel combined-system, a detailed performance analysis was performed. Results show that the turbine inlet pressure, flue gas inlet temperature and condensation temperature are three important parameters influencing system performance. During the increase of the turbine inlet pressure, the refrigeration capacity and the exergy efficiency exhibit the maximum values. However, with the increase of the flue gas inlet temperature and the decrease of the condensation temperature, both the refrigeration capacity and the exergy efficiency corresponding to the optimal turbine inlet pressure increase. The use of regenerator can improve the system performance and reduce the optimal turbine inlet pressure. Under partial refrigeration load, there is a linear relationship between the electricity output and the refrigeration capacity at a fixed work output from the turbine. The total irreversible loss decreases and the exergy efficiency increases with the decrease of the power ratio. Finally, after screening and comparing various potential working fluids, R134a is recommended as the working fluid of this novel combined-system. •A novel power/refrigerating combined-system using three refrigerants is proposed.•Performance analysis on this combined-system is performed based on thermodynamics.•Variations of refrigeration capacity and efficiency with main parameters are given.•After screening different refrigerants, R134a is recommended as the working fluid.