Abstract:The paper presents the main results of a research project directed to the development of mathematical models for the design and simulation of combined Gas Turbine-Steam or Diesel-Steam plants for marine applications. The goal is to increase the energy conversion efficiency of both gas turbines and diesel engines, adopted in ship propulsion systems, by recovering part of the thermal energy contained in the exhaust gases through Waste Heat Recovery (WHR) dedicated installations. The developed models are used to identify the best configuration of the combined plants in order to optimize, for the different applications, the steam plant layout and the performance of WHR plant components. This research activity has allowed to obtain significant improvements in terms of energy conversion efficiency, but also on other important issues: dimensions and weights of the installations, ship load capacity, environmental compatibility, investment and operating costs. In particular, the main results of the present study can be summarized as follows: (a) the quantitative assessment of the advantages (and limits) deriving by the application of a Combined Gas And Steam (COGAS) propulsion system to a large container ship, in substitution of the traditional two-stroke diesel engine; (b) the proposal of optimized WHR propulsion and power systems for an oil tanker, for which a quantitative evaluation is given of the attainable advantages, in terms of fuel consumption and emissions reduction, in comparison with more traditional solutions.

In this article, some configurations of waste heat recovery systems are described, analysed and compared, in order to\ud find the optimal plant layout. Starting from the availability of performance data of a two-stroke diesel engine, adopted for\ud the propulsion plant of a crude oil tanker ship, the authors examined different solutions for the waste heat recovery\ud from the diesel engine exhaust gas ensuring the best fulfilment of the vessel needs in terms of mechanical, electric and\ud thermal energies. The considered waste heat recovery systems can adopt either steam turbine and gas turbine or simply\ud steam turbine for power generation. As regards the steam plant, two basic layouts are considered, optimized and compared:\ud the first plant scheme is a typical steam plant currently adopted for waste heat recovery purposes and the second\ud one is a solution proposed by the authors. Considering the different options, in this article, four different system layouts,\ud applied to the mentioned diesel engine, are singly optimized and compared between them in order to find the most suitable\ud plant and the steam cycle parameters that provide its best operation at the engine normal continuous rating. The\ud performance of the optimized waste heat recovery systems is evaluated also by comparing them under off-design engine\ud load conditions, in the engine power range between 50% and 100% of its maximum continuous rating

No abstract

No abstract

No abstract