الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Despite their initial successes, submarine pioneers were stilI eager to find some means
to free their boats from the necessity of surfacing frequently for access to the atmospheric
oxygen demanded by the gasoline or diesel engines that charged the batteries. Recently,
growing demand for longer underwater endurance has generated increasing interest in
promising AlP (Air-Independent Propulsion) technologies. Most of the studies encountered
are for inter gases with synthetic air to enhance the deterioration in combustion performance
due to synthetic air.
In the present study a three dimensions, multi zone model is established using
commercial Computational-Fluid Dynamic [CFD] code [Fluent 6.3] to model the combustion
process in a direct injection diesel engine running under synthetic atmosphere operating
conditions contaminated with different carbon dioxide concentrations. In addition, the
beneficial effect of adding hydrogen gas to the working above-mentioned fluid with different
concentrations is also investigated, meanwhile the effect of using the synthetic atmosphere
with different composition on pollutants emissions is studied. The complexity of the
combustion process either for conventional and non-air mixtures with its associated fuel
atomization, delay period, kinetics of reactions, turbulent mixing, non equilibrium effects,
heat release as well as heat transfer, etc, is taken into account. The gross indicated output is
used to identify the impact of compression, combustion and expansion processes on engine
performance and emissions. The engine performance as well as pollutants emissions due to
the presence of carbon dioxide and hydrogen respectively in the working fluid containing
constant 21 % oxygen by volume, as in normal air, have been investigated. The effects of
carbon dioxide concentrations and different carbon dioxide - hydrogen concentrations on
ignition delay period, specific fuel consumption, heat release, and soot formation and nitrogen
oxide concentration have been determined. The engine model is validated against the normal
diesel operation as well as closed cycle diesel operation.
The results show that, increasing carbon dioxide concentrations deteriorate engine
performance, increase soot formation and decrease nitrogen oxide concentrations due to in-
cylinder temperature decrease. On the other hand, the effect of admitting hydrogen with
different concentrations along with different carbon dioxide concentrations on the working
fluid resulting in engine performance improve, however the rate of improvement is not
significantly affected by increasing hydrogen concentrations, also the improvement is more