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Session: Session 6C: Volumetric Expanders (2)
Session starts: Wednesday 11 September, 09:00
Presentation starts: 09:40
Room: Templar's

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ChunWee Ng (Newcastle Research & Innovation Institute Singapore)
Ivan CK Tam (Newcastle University in Singapore)
Dawei Wu (Newcastle University, UK)

Abstract:
Installation of Organic Rankine Cycle (ORC) waste heat recovery systems have been reported on at least six sea-going ships since 2012 and is expected to gain more interest as a means to reduce fuel consumption to meet increasing stringent environmental regulations. In contrast with land-based ORC systems for biomass and geothermal applications, wide-spread application of ORC onboard ships can only be possible if it is optimised for weight, volume, power output to meet actual electrical demands and importantly address concerns of the shipowner in return on capital. Previous studies by the authors have explored the economic aspects by looking at potential fuel savings and payback time of such a system onboard a ship. Selection of expander type for the ORC system is very important and linear piston expanders are expected to yield economic and thermodynamic advantages due to their simpler design and high isentropic efficiency. This paper presents the feasibility of the application of ORC using a linear piston expander onboard a sea-going ship. The proposed ORC system using both thermal waste heat from main engines and waste cryogenic energy from Liquefied Natural Gas fuel considers the ship’s actual design like general arrangement plan and operational data like operational profile. A dynamic simulation method using a Siemens Simcenter Amesim will be used for the design and optimisation process. Results from the study show that the free piston linear generator to provide stable output suitable for electrical generation. However, the mechanical efficiency is found to be low which indicates that various parts of the expander design needs to be optimized. Due to this, the economics of an earlier study needs to be reduced from 7% to 5.9% for fuel savings and 2.7 years to 3.1 years for payback period which could impact project viability if the dynamics of the expander is considered.