Performance investigation of two stage Organic Rankine Cycle (ORC) architectures using induction turbine layouts in dual source waste heat recovery

• Main Authors: Anandu Surendran, Satyanarayanan Seshadri
• Format: Article
• Language: English
• Published: Elsevier 2020-04-01
• Series: Energy Conversion and Management: X
• Subjects: Organic Rankine Cycle; Dual pressure configuration; Two stage evaporation; Waste heat recovery; Dual heat sources
• Online Access: http://www.sciencedirect.com/science/article/pii/S2590174520300015

Improvement in performance of Organic Rankine Cycle (ORC) systems, particularly in the context of dual heat sources such as IC engines, leads to better return on investments. However, the choice of architecture to achieve the best performance is not evident from available literature. When two separate heat sources are present concurrently at different temperature levels with heat contents such as in IC engines, single stage pre-heated ORC and dual loop ORC are the two commonly deployed ORC architectures. In this study, two stage architectures: Series two stage ORC (STORC) and Parallel two stage ORC (PTORC) are analysed and their performance is compared against a single stage pre-heated ORC at sub-critical conditions in the utilization of high temperature (primary) exhaust gases (573–773 K) and low temperature (secondary) jacket water (353–393 K) representing IC engine waste heat conditions. Results show that STORC and PTORC are able to achieve the maximum net power output for an intermediate utilization of secondary heat source. The power output gains from two stage layouts improves significantly with a reduction in heat source temperature difference and for lower ratios of the heat available between the primary to secondary heat source. For a 2.9 MW natural gas IC engine operating at its design point, STORC delivers 8.5% more power output whereas PTORC delivers 0.3% less power output than pre-heated ORC. Compared to a dual–loop ORC, STORC presents a less complex and improved cycle architecture with a 13.1% increased power output and a 27.9% reduced heat exchanger requirements.