الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Natural gas is considered nowadays to be one of the
most vital sources of energy. It is extracted from different
area. Natural gas consists of different gases which differ
in percentages depending 011the extraction place, and also
differ within the same source from time to another. This
obviously results in variation in both the physical and
chemical properties; and hence particular considerations
should be taken when using natural gas as a fuel in internal
combustion engines.
The aim of this work is to study the effect of using
the associated natural gas as a fuel .on a natural gas engine
specified and adjusted with another natural gas fuel by the
engine manufacturer. The experimental work was
performed on a stationary gas engine generator set .on an
off shore platform for crude oil collection in the Gulf of
sue~. It has a brake power of 450 kW at 1200 rpm and
compression ratio of 7: 1. Appropriate adj ustrnents of the
engine fuel y tern, and the ignition timing \ ere
implemented to accommodate for the difference in gas
characteristics. The main differences between the two gases
are the calorific value and the Octane number.
The engine was loaded by different loads (1/4, 112,
3/4, and full load). The measurements include the values of
the brake power and the percentages of the dry volume
fractions of CO and O2 in the exhaust during each run.
Hence, the air/fuel ratio was calculated. Also, the
differential pressure between the gas and air at the mixer
entry was monitored.The results show that the brake power was the same
as the rated power specified by the manufacturer. This was
gained due to the adjustments done to air/fuel ratio and the
ignition timing according to the gas characteristics. Also
the engine performance was compared to the engine
performance data given by the manufacturer.
Also, this thesis includes a survey of some relevant
literatures in the use of natural gas in both petrol and diesel
engine. It also covers the technical aspects related to the
conver ion of both engines types to use natural gas instead.
Key words: Gas engines, Natural gas as an engine fuel,
Spark ignited reciprocating gas engine, Gas composition.