Experimental Investigation of Injection and Combustion Processes in Marine Gas Engines Using Constant Volume Rig
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- Institutt for marin teknikk 
In circumstances of the strong demand for a reduction of harmful emissions from ships, one of the main pathways of the development of marine power plants is improvement of the existing and development of new gas engine concepts. Current status of technological development of marine gas engines indicates considerable progress towards maximum energy conversion efficiency and low emissions; however, there are still a number of issues and research gaps to be addressed. A significant part of these challenges and uncertainties is related to the combustion process. According to experience of automotive industry, optimization of the combustion process in ICE is often associated with a use of optical accessible experimental facilities that are capable to identify critical factors and fundamentally study relations between complex processes. Based on this background, the primary aim of this project was to develop an optical testbed to study the combustion control challenges in marine gas and dual fuel (DF) engines. The marine-scale pre-combustion type constant volume chamber was developed as a research facility that meets most of the functional requirements for a fundamental study of processes in the combustion chamber of different marine gas engines concepts. Moreover, the chamber was fitted with all necessary equipment to provide both operational exibility, experimental control and reproductivity of experimental results. Functionality of the combustion chamber was tested when approaching some of engines combustion control issues. Here the experimental investigations were conducted on injection performance of diesel and high-pressure gas injectors; and on biodiesel as an alternative fuel for conventional diesel. When summarizing all results of research and development, the following key contributions of this thesis could be underlined: - Identification of knowledge gaps related to control of combustion process and emission formation in marine gas engines. - Development of experimental setup that provides non-invasive investigation of in-chamber processes, that could potentially address the above-mentioned issues - Proposal for a method to control ambient conditions inside the precombustion type constant volume chamber. - Proposal for a method for parameter identi cation of diesel injector for DF engines with unknown architecture. - Identification of effects of non-circular nozzle ori ces on injection characteristics of high-pressure gas. - Identification of effects of replacement of conventional diesel fuel with biodiesel on the combustion and emission formation processes.