Investigation of completeness of combustion in CNG fueled spark ignition engines.

Date of Award


Degree Type


Degree Name



Mechanical, Automotive, and Materials Engineering


Engineering, Automotive.




The focus of this study was to apply and evaluate two separate techniques for estimating of the completeness of combustion in a multi-cylinder engine fueled with compressed natural gas. The degree of correlation between such two independent estimates of the combustion completeness was sought. One technique, with better time resolution and viewed to be more accurate, calculates the completeness of combustion on a cycle-by-cycle basis using in-cylinder pressure measurements. The technique utilizes the normalized pressure rise parameter due to combustion to describe the completeness of combustion. The second technique evaluates the completeness of combustion based on time-averaged measurements of unburned hydrocarbons in engine exhaust gases. Both the in-cylinder pressure and exhaust gas composition data were obtained from a test multi-cylinder engine fuelled with compressed natural gas (CNG). The crank angle resolved pressure data were analyzed with combustion analysis software. The establishment of the correlation between the two estimates of the completeness of combustion could allow dispensing with elaborate in-cylinder pressure measurements. The successful aspect of this investigation was to propose and test a new parameter that is strongly related to completeness of combustion. The advantage of the new parameter is that its calculation does not require computations of the pressure rise due to combustion and avoids difficulties associated with that procedure in finding such parameters as the polytropic exponents, the start and end of combustion, etc.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2002 .A94. Source: Masters Abstracts International, Volume: 44-01, page: 0426. Thesis (M.A.Sc.)--University of Windsor (Canada), 2003.