INTERNATIONAL ENERGY JOURNAL

Volume 20, No. 02, Month JUNE, Year 2020, Pages 169 - 180

The theoretical framework of the modified organic rankine cycles for improved energy and exergy performances

Zubair Ali Shah, Qun Zheng, Ghazanfar Mehdi, Naseem Ahmad, Waleed Raza, Aseed ur Rehman, Asif Raza

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Rapidly increasing of the energy crises, depletion of fossil fuels and its severe environmental hazards, demanded to establish the green processes. The best available solution is to convert low-grade waste heat into useful work by using the organic Rankine cycle (ORC), which reduces not only the energy shortage but also environmental problems simultaneously. This work presents the theoretical and numerical methodology using Engineering Equation Solver (EES) software to evaluate both energy and exergy analysis of the basic and three modified organic Rankine cycles. R-113 was used as a working fluid. The basic ORC system was modified by integrating internal heat exchanger, regeneration, and the combination of both. Among these four cycles, the ORC system integrating with both the internal heat exchanger and regeneration proved the best cycle, which gave the highest thermal efficiency (22.43%), exergy efficiency (33.82%), and lowest exergy destruction (44.5kW) at evaporator pressure of 2.5MPa. Furthermore, it has been concluded that the evaporator played a significant role in ORC system performance because its exergy destruction was maximum, which was enhanced by increasing its pressure.

Keywords

energy and exergy analysis, exergy destruction, internal heat exchanger, organic Rankine cycle, regeneration.

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