Comparison of different procedures for the optimisation of a combined Diesel engine and organic Rankine cycle system based on ship operational profile

Abstract

At a time of strong challenges in relation to economic and environmental performance, the potential of waste heat recovery for ships fuel consumption has proved a considerable potential. This paper presents the comparison of four different procedures for the optimisation of an organic Rankine cycle based on an increasing level of accounting of the ship operational profile and on the inclusion of engine control parameters to the optimisation procedure. Measured data from 2 years of operations of a chemical tanker are used for the application of the different procedures. The results suggest that for the investigated case study the application of a optimisation procedure which takes the operational profile into account can increase the savings of the installation of an organic Rankine cycle from 2.8% to 11.4% of the original yearly fuel consumption. The results of this study further suggest that i. simulating the part-load behavior of the ORC is important to insure its correct operations at low engine load and ii. allowing the engine control strategy to be part of the optimisation procedure leads to larger fuel savings than the optimisation of the waste recovery system alone.

Analysis of the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged heavy duty diesel power generator for marine applications

“…Baldi et al, in two different works [19,20], proposed the use of optimization techniques for diesel engine-ORC waste heat recovery systems based on the analysis of typical ships operating profiles. The case studies use, as baseline engines, MaK 8M32C fourstroke diesel engines with a power output of 3840 kW and some auxiliary units of about 683 kW.…”

Emissions reduction at the Netherlands ministry of defence: potential, possibilities and impact

“…-Increase propulsion line overall efficiency in off-design and transient conditions -Increase main engines' maximum efficiency -Increase propeller efficiency -Retrieve energy converting waste heat to mechanical energy -Decrease energy demand To estimate energy consumption and CO2 emissions reduction, we have to establish the potential to increase the overall efficiency of the powertrain and performance in off-design conditions and establish the operational profile. Figure 2 shows the operational profile encountered by a working class vessel and a Panamax product tanker (Baldi 2015). Load of the diesel engine is 50 % of the time between 80 % and 100 % of full load.…”

“…operational profile encountered by a working class vessel (left) and of a Panamax product tanker (right) (taken fromBaldi, 2015).…”

A Comparison of Organic and Steam Rankine Cycle Power Systems for Waste Heat Recovery on Large Ships

“…In these heat exchangers, the gas or vapor side was assumed to dominate the heat transfer processes resulting in a UA value variation governed by the gas or vapor mass flow rate. The UA value at any off-design point was assumed to vary according to the following function, which is commonly used for simulating off-design characteristics of heat exchangers in power cycles [16,18,19,35]:…”

“…Although this is a suitable approach for preliminary performance estimations, an off-design analysis must be carried out in order to fully evaluate and compare different WHR unit options by accounting for inherent variations in vessel operation. This point was highlighted by Baldi et al [16] who demonstrated the importance of accounting for variations in ship operation, when optimizing a marine machinery system. Larsen et al [17] studied the NO x emission and specific fuel oil consumption (SFOC) trade-off for a large marine diesel engine equipped with an ORC bottoming cycle unit while accounting for off-design operation.…”