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Session: Session 4C: Waste heat (2)
Session starts: Tuesday 10 September, 14:00
Presentation starts: 15:00
Room: Templar's

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Sandhya Thantla (KTH Royal Institute of Technology)
Jonas Aspfors (Scania CV AB)
Jens Fridh (KTH Royal Institute of Technology)
Anders Christiansen Erlandsson (KTH Royal Institute of Technology)

Abstract:
To meet the strict legislations on the carbon-dioxide emissions, Organic Rankine Cycle (ORC) Waste Heat Recovery (WHR) technology is being extensively studied and applied in long haulage Heavy-Duty (HD) truck engines. It is necessary to maximize heat recovery from the HD engines to achieve the objective of reducing fuel consumption and improving efficiency. Volumetric expanders are being considered to be reliable technologies for ORC WHR systems in HD commercial vehicles. The focus of this paper is to characterize the ORC WHR system of a HD truck engine encompassing a volumetric expander, for the boundary conditions imposed by the engine coolant and the exhaust gas of the HD engine. Based on the quality of heat rejected from the engine at some chosen engine operating points, a study on changing the volume ratio and displacement volume of the expander is presented in this paper. Different WHR configurations integrated with the engine exhaust, engine coolant or both the exhaust and coolant as the heat sources are studied using the 1D simulation tool GT-suite. A Scroll-type volumetric expander is represented in the 1D model through maps of expander effectiveness and volumetric efficiency derived from a semi-empirical model of the expander. The main objective of this work is to achieve overall system efficiency using different configurations of the engine and WHR system, and expander sizing. By investigating with unconventional engine coolant temperatures as the heat source for WHR, an optimum engine coolant temperature is proposed based on the overall system performance when using the Scroll expander with R245fa as the working fluid. The optimum expander size and the number of expanders required for improved system efficiency is also determined and compared based on the subjected boundary conditions.