The document discusses dual fuel engines, which can operate using a mixture of two different fuels, such as diesel and natural gas. It describes how dual fuel engines work by premixing the primary fuel (usually natural gas) with air in the cylinder, then igniting it with a small amount of injected diesel fuel. Converting a diesel engine to a dual fuel engine involves modifying parts like adding gas injection valves and fuel controls. Dual fuel engines can reduce operating costs and emissions compared to diesel alone while maintaining power output. They allow engines to switch between gas and diesel fuels.

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DUAL FUEL ENGINE
SEMINAR REPORT
(PRAVAT NAYAK)

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Contents
• Introduction
• What is dual fuel engine
• Dual fuel engine conversion
• Performance of dual fuel engine
• Major modified engine parts
• Reductions
• Features of dual fuel engine
• Knock control in dual engine
• Advantages
• Disadvantages
• Conclusion
• Reference

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Introduction
Interest in the efficient utilization of gaseous fuel resources for the production of
power using conventional internal combustion engines, has been increasing
worldwide in view of the inevitable declining resources of petroleum and projected
limitations on the availability of refined liquid fuels, particularly those of the right
quality. This is in contrast to statements made that the proven reserves of natural gas
are increasing and that there are potentially enormous reserves of natural gas2 that
can be utilized as fuels in engine applications. Moreover, there is increased perceived
availability of other forms of gaseous fuels such as liquid petroleum gases, gas fuel
mixtures produced from the processing and up grading of various fossil fuel
resources such as coal, oil sands and shalesand from the processing of organic and
vegetable wastes in the form of bio- gas.
Operation of diesel engines on gaseous fuels is neither new nor recent. It is
possible to trace its origin back to the beginning of the century when Dr. Rudolph
Dierel patented a compression ignition engine to run on a gaseous fuel, coal gas3.
Subsequently, more successful commercial applications appear to have been made,
mostly for stationary applications, prior to the war. During the second world war,
some efforts were directed towards using coal gas mixtures, sewage gas or
methane as well as stocks of poor quality gasoline in the form of gasified Vapour to

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run conventional diesel engines for a variety of applications.
1
What is dual fuel Engine
Engines that can operate using a mixture of two different fuels are called dual
fuel engines. Frequently, diesel and natural gas fuels are used together within dual
fuel engines. Often, dual fuel engines that mix diesel and natural gas can also operate
using diesel fuel only if the natural gas is temporarily unavailable..
Beyond natural gas and diesel, some dual fuel engines can also use varying
mixtures of biodiesel, landfill gas, bio-gas and other fuels.
Engine cycle

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A dual-fuel engine is an internal combustion engine in which the primary
fuel (usually natural gas) is mixed more or less homogeneously with the air in the
cylinder, as in a spark-ignition engine. Unlike a spark-ignition engine, however, the
air/fuel mixture is ignited by injecting a small amount of diesel fuel (the “pilot”) as
the piston approaches the top of the compression stroke. This diesel pilot fuel
rapidly undergoes pre flame reactions and ignites due to the heat of compression,
just as it would in a diesel engine. The combustion of the diesel pilot then ignites
the air-fuel mixture in the rest of the cylinder.
Because the air and the primary fuel are premixed in the cylinder, dual-fuel
engines have many features in common with spark-ignition, Otto-cycle engines.
Because they rely on compression-ignition of the diesel pilot, however, they also
share some characteristics with diesels, as well as some unique advantages and
drawbacks of their own. Among the advantages of dual-fuel engines is that - in
most cases - they can be designed to operate interchangeably on natural gas with a
diesel pilot, or on 100% diesel fuel. This makes them especially valuable in
circumstances where use of natural gas is desired for environmental or economic
reasons, but where gas supply may not be fully reliable. For example, a dual-fuel
truck could operate on compressed natural gas where that fuel was available - such
as urban areas suffering from severe air pollution. If the truck had to travel beyond
range of its compressed natural gas supply, however, it could still fall back on

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100% diesel fuel. Similarly, a generator set could operate most of the time on
relatively inexpensive pipeline gas, but switch instantly to 100% diesel if gas
supply were interrupted. Other potential applications in which this capability
would be important include diesel-electric locomotives, marine vessels, farm
equipment, construction and industrial equipment, and engines using biogas,
sewage gas, or other variable gas supplies.
Dual fuel Engine conversion

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The engine conversion mainly consists of rebuilding existing engine parts to
enable the installation of a gas safety system and a fuel injection system.
This includes exchanging the existing cylinder cover and fuel oil pipes, and adding
gas injection valves, gas control blocks, and gas chain pipes. Additional parts may
also need changing, which is determined by a detailed study of your engine.
Major modified engine parts and auxiliaries for conversion
Engine parts :
➢ Added parts :
• Gas admission system, knock detector :- The one fuel, gas, is admitted
just before the inlet valves during the induction stroke. Gas and air are intensively
mixed. The air factor is between 1.5 and 2.0. This is known as a 'poor' mixture.
50 to 100% more air volume is present than required to fully burn all the
fuel chemically.
Knock behavior in diesel-dual-fuel (DDF) engine is more complex, more
severe, and different than those of traditional engines. We investigate a type of
diesel-dual-fuel engines, where CNG is multipoint-injected at the intake ports
as main fuel and diesel is directly injected in smaller amount, mainly for
ignition purpose, resulting in lower fuel cost. Knock behavior in diesel-dual-
fuel (DDF) engine is more complex, more severe, and different than those of
traditional engines. We investigate a type of diesel-dual-fuel engines, where

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CNG is multipoint-injected at the intake ports as main fuel and diesel is directly
injected in smaller amount, mainly for ignition purpose, resulting in
lower fuel cost.
• Air /fuel ratio control system:- It is a dual fuel combustion strategy using
two fuels blends with different auto-ignition characteristics (low and high
reactive fuel) to control the combustion phasing and heat release rate (main
difficulties in homogeneous charge compression ignition and premixed charge
compression ignition modes) with reduced emissions.
• Oil mist ventilation system:- During the intake stroke, gas is admitted just
before the inlet valves. The liquid fuel ignites the air/gas mixture.
During the intake stroke, gas is admitted just before the inlet valves.
The liquid fuel ignites the air/gas mixture.
➢ Specification change parts
• Piston ring ,piston pin metal :- Piston rings are manufactured and
classified on the basis of function and usability. The primary usage of the
piston ring is to seal the chamber (where the piston is moving), which can be
a combustion chamber of a 2 stroke or a 4 stroke engine. In internal
combustion engines, the gudgeon pin (UK, wrist pin or piston pin US)

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connects the piston to the connecting rod, and provides a bearing for the
connecting rod to pivot upon as the piston moves
• Fuel injector , Plunger assembly, Fuel governor:- In gas-run dual-
fuel applications, gas is injected into the engine via the inlet manifold. In
order to ignite the gas, the gas ignition injector injects a small quantity of
diesel or marine diesel oil (MDO) into the compressed gas/air mixture
without the need for an electrical spark ignition. A dual-fuel system is
capable of using two types of fuel at the same time in a mixture. It usually
cranks up on one type of fuel, and a governor built into the system gradually
adds the secondary fuel source until the optimal mixture of the two fuels is
achieved for efficient running.
➢ Modification parts
• Cylinder head, piston, Liner, charge air duct, T/C matching
➢ Plant auxiliaries
• Gas supplying system
• Safety device for gas system
• Engine control panel
• Remote monitoring system
➢ Factors affecting combustion in a duel fuel engine

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• Pilot fuel quantity:- The pilot fuel consumption is between 5 and 10% of the
normal full load quantity required for straight diesel operation and it remains
fairly constant throughout the load range unless there is a gas shortage, in
which case any input energy shortfall is made up by an increase in
liquid fuel injected.
• Injection timing :- The engine will be tested using methane or propane as
the main fuel, while Diesel fuel is used as the pilot fuel. Three values of
injection timings of 25°, 27.5° and 30° BTDC are used in the present test.
• Catani number of pilot fuel :- Standard fuels with cetane numbers (C.N.) 30
to 55 were prepared and employed as ignition fuels in a dual fuel diesel
engine fueled by compressed natural gas (CNG) from the intake-pipe
as the main fuel
• Gaseous fuels :- Gas fuels used in dual fuel engines range from natural gas,
synthesis gas, and landfill gas to hydrogen and biogas. Liquid fuels may
include standard diesel, biodiesel, bio-oils, etc. In order to provide near-zero
carbon emissions, a combination of a 'renewable' gaseous and liquid
fuel must be found
• Effect of throttling
• Mixture strength

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Performance of dual fuel engine
Dual-fuel engines are capable of producing as much power when running
with a gaseous fuel as a primary fuel as when operating on liquid fuels only The
efficiency of the dual-fuel engine at part load is poor because of increased delay
periods at low mixture strength. This can be increased by increasing the excess
air or injecting more pilot fuel at part loads
Reductions
• Operation cost Approx.30% less
• Reduction in Operation Cost will fluctuate because of the operation
conditions of engines and the price level of fuel oil and natural gas in a
project site.
• CO2 Emission 30% less
• Sox Emission 95% less
• NOX Emission 20% less
(comparing with diesel oil firing)

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Features of duel fuel engine
➢ Less operation cost
• Main fuel: Natural Gas
➢ Environmental friendly
• Drastic reduction of NOx, SOX & CO2 emission
➢ Stable operation
• Pilot injection system
• Operatable on either fuel of natural gas or diesel oil
➢ Excellent dependability
• Main component: Diesel engine
➢ Clean combustion and Less maintenance cost
➢ Effective utilization of existing assets
Knock control in dual engine
• Excess supply of air
• Use of cold combustion air
• Increased cooling of piston
• Use of additives
• Reducing the pressure of the gaseous fuel

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Advantages of dual fuel engine
• Only a small amount of liquid fuel needed to run engine.
• Suitable for total energy installation (sewage gas)
• Clean combustion results in reduced wear of engine parts and reduced
consumption of lubricating oil.
• Can be used to produce synthetic gas, which is a mixture of CO and H2
• Gas burns without leaving any residue (no pollution)

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Disadvantages of dual fuel engine
• Tendency of vapor lock while using lighter fuels.
• Tendency of increased wear due to lower lubricity of gasoline.
• Requirement for injecting different volumes of fuel depending on their
heating values and compressibility.

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Conclusion
• Without much more modification of IC engine Biogas can be used as a
primary fuel.
• Quality of fuel is important factor for performance of the engine.
• Duel fuel engine generally used for power generation with long term period.
Bo tog0% of diesel can replace by biogas.
• Increasing the compression ratio improved the performance and cylinder
pressure of the engine.

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Reference
• https://en.wikipedia.org/wiki/Bi-fuel
• https://papers.sae.org/9/05/8/
• Old.shortsea.fr/wartsilaGasEngines.html
• A. Roskilly , ... H. Yu, in Comprehensive Renewable Energy, 2012
• Curtis B. US Ethanol Industry: The Next Inflection Point. 2007 Year
in Review. San Francisco, CA: B Curtis Energies & Resource Group;
2008. P. 52
• Goldemberg J. The challenge of biofuels. Energy & Environmental
Science. 2008;1:523-525