George Livanos

Techno-economical analysis of single pressure exhaust gas waste heat recovery systems in marine propulsion plants

In this article, the waste heat recovery (WHR) installations used for the production of saturated steam and electric power for the cases of a two-stroke and a four-stroke engine propulsion plant of a typical merchant ship are investigated. The examined WHR system is considered to be of the single steam pressure type with an external heat exchanger for the heating of feed water entering into the boiler drum. The option of using the engine air cooler for heating the feed water was also examined. The WHR installation was modeled under steady-state conditions, and the derived WHR installation parameters for various engine loads are presented and analyzed. Furthermore, using the simulation results, the improvement of Energy Efficiency Design Index (EEDI) of the examined ship is calculated, and the impact of the WHR on the ship EEDI is discussed. In addition, following the technical evaluation of the alternative options for the ship propulsion plant, an economic study was performed for a typical ship voyage. The derived results were presented and discussed leading to conclusions for the most techno-economical propulsion system configuration.

A decision support system for the development of voyage and maintenance plans for ships

The waterborne sector faces nowadays significant challenges due to several environmental, financial and other concerns. Such challenges may be addressed, among others, by optimising voyage plans, and diagnosing as early as possible engine failures that may lead to performance degradation. These two issues are addressed by the decision support system (DSS) presented herein, which focuses on the operation of merchant ships. For the development of voyage plans, a multicriteria decision problem is developed and handled with the PROMETHE method, while a multivariable control chart is used for the fault diagnosis problem. A MATLAB-based software implementation of the DSS has been developed adopting a modular architecture, while, in order to provide a generic software solution, the required input data are retrieved from dedicated web-services, following specific communication and data exchange protocols.

Accurate instantaneous engine speed recording by employing an optical measurement system-application to a typical low power industrial engine

The presented work concerns the development of a novel measurement system for determining the instantaneous rotational speed of an engine with high accuracy. The developed system is mainly based on a commercially available optical sensor and appropriate data acquisition / post-processing procedure. The accuracy of the system is high; speed recording with a resolution of one degree of crank angle has been succeeded when measuring the speed of a one cylinder four stroke S.I. motored engine. The deduced experimental results were compared with the corresponding theoretical ones obtained by appropriate simulations, validating the proper functionality of the developed system. Furthermore, the system was also integrated into a typical four cylinder low power industrial engine successfully. Key-features of the proposed measurement configuration are accuracy, simplicity and low-cost suggesting numerous potential applications.