Effect of Waste Heat Recovery Systems on the Fuel Economy of Dredging Vessels
Type:
Presented during:
WODCON XXIII - Dredging is changing - The Practice. The Science. The Business.
Authors:
J.A. Westhoeve, B.T.W. Mestemaker, L. van Biert, E.C. van der Blom
Abstract
"The maritime energy transition will have a large impact on the design choices made for dredging vessels in the coming years. Currently, most dredging vessels are powered by internal combustion engines (ICEs) due to their power density and robustness. The ICE however has a significant loss of energy due to the waste heat in the exhaust gas. Applying a waste heat recovery system (WHRS) offers the potential for significant fuel-savings as it captures and reuses the waste heat from the exhaust gases to generate additional mechanical and/or electrical work. This paper investigates the effect of applying bottoming cycles such as a WHR on the total system efficiency of marine diesel and dual-fuel engine powered dredging vessels. The steam Rankine cycle (SRC) and the organic Rankine cycle (ORC) are compared by means of a simulation study. Simplified steady-state models are developed with the goal to compare the energy recovery potential of both cycle types. The operational parameters influencing the recovery potential are addressed to understand the working principles of both cycle types. The fuel economy benefits are determined for several engine types, namely a medium-speed and a high-speed marine diesel engine as well as a dual-fuel and spark-ignited gas engine. The robustness of the WHR system is determined for several operational conditions and efficiency improvements are assessed. Overall, there is no uniform percentage of fuel saving that may be used as general rule, the range is between 2% and 5%. The potential depends on the engine size, engine turbocharger matching, type of fuel and environmental conditions. The results show that the waste heat recovery potential of both bottoming cycles are more sensitive to the exhaust gas temperature than to the exhaust gas mass flow. The paper also shows the fuel economy effects of the steam and organic Rankine cycle on dredging vessels. Design and operational aspects are assessed and selection criteria for WHR systems in dredging vessels are provided."
Keywords: waste heat recovery, energy efficiency, fuel saving, modelling, evaluation