Cogeneration system based on large temperature difference heat transfer with stepwise utilization. (1st April 2023)

• Record Type: Journal Article
• Authors: Tian, Wenbiao; Teng, Shiyang; Xi, Huan
• Is Part Of: Energy conversion and management. Volume 281(2023)
• Publication Date: 2023-04-01
• Subjects: Organic Rankine cycle -- Absorption heat exchanger -- Cogeneration system -- Thermo-economic model -- Large temperature difference heat exchange; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2023.116843
• Languages: English
• ISSNs: 0196-8904

Abstract

Graphical abstract: Highlights: An absorption cogeneration system based on organic Rankine cycle is proposed. Economic, energy and exergy analyses were carried out for the AHEORC-CHP systems. The outlet temperature of waste heat source can be greatly reduced to 24.69 °C. The thermoelectric efficiency of the whole system can reach 90.9%. The profit ratio of investment can rise to 8.46. Abstract: Organic Rankine cycle (ORC) plays a critical role in systems such as waste heat recovery, cogeneration, renewable energy generation and energy storage. No matter which field ORC is applied in, the evaporator side of ORC has an extremely poor utilization of the thermal energy from heat source, resulting in the outlet temperature of hot side fluid being much higher than the inlet temperature of cold side fluid. In order to fully capitalize on the thermal energy, this study introduces the two-stage absorption heat exchanger (AHE) and integrates it into ORC to obtain an original high-efficiency cogeneration system (AHEORC-CHP), which is parametrically analyzed by constructing and operating thermo-economic model in terms of the expansion pressure ratio and working fluid of ORC, the type and flow rate of heat source, and the inlet temperature of generator in AHE. Due to the existence of pinch point temperature difference, conventional ORC design can only reduce the outlet temperature of the heat source with an inlet temperature of 130 °C to about 70 °C under the condition of ideal heat transfer. The AHEORC-CHP configuration proposed in this work can achieve a significant reduction in the final outlet temperature of waste heat source (as low as 24.69 °C) and realize heat exchange with large temperature difference and efficient utilization of the heat source. Besides, the thermoelectric efficiency and temperature effectiveness can reach 90.9% and 1.2 respectively, while the profit ratio of investment rises to 8.46. Further improving the performance of AHEORC-CHP system requires optimizing the design of the pressure in absorption heat pump (AHP) cycle as well as the concentration and flow rate of LiBr-H2 O solution. This study can provide a simulation pathway for the application of two-stage AHE in ORC, and likewise for future experimental investigations.