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13 October, 2008
GFS Diesel Dual Fuel Kit System - New Site
05 March, 2008
04 March, 2008
29 February, 2008
GFS Diesel Dual Fuel Kit System - Typical Savings Calculation
Assumptions :
Fuel Consumption = 3 km/liter
Distance Travel = 300 km
Fuel Consumption = 100 liter
Normal Diesel
Diesel Price : 100 liter x RM1.58 = RM 158.00
With GFS DDF
Diesel Price (50%) : 50 liter x RM1.58 = RM 79
NGV Price (50%) : 50 liter x RM0.68 = RM 34
Total Fuel Price = RM 113.00
Savings :
= Normal Diesel - With GFS DDF
= RM 158 - RM 113
= RM 45
= 28.5%
ROI is met at 45,000 km
GFS Diesel Dual Fuel Kit System - Performance
Compatible Diesel Engines
• 4-cycle
• Turbocharged
• Normally aspirated
• Mechanically fuel injected using in-line pump or common fuel rail
- some rotary / distributor-type pumps not compatible
- limited compatibility with electronic engines
- new kit under development that will be compatible with most electronic diesel engines
Gas-Diesel Ratio
Vehicle duty cycle is the most important variable for determining average gas-diesel ratio. In addition to duty cycle, gas composition, charge-air temperature as well as ambient conditions (temperature and altitude) may also play a factor relative to the knock limit of the air-gas mixture. In general, moderate to heavy engine loading (over the road conditions) will typically yield gas ratios between 60-75% (assumes high quality natural gas). Lower average engine loads (stop and go / high traffic conditions) will typically limit gas ratio to between 50-60%.
Gas Ratio vs. Duty Cycle
• Urban duty cycle typically yields 50% to 65% gas ratio
• On-highway duty cycle typically yields 65% to 75% gas ratio
• Mixed duty cycle will result in variable gas ratio
Combustion Process
Combustion in Gaseous Fuel mode follows the normal compression-ignition (CI) sequence. The air-gas mixture is admitted to the combustion chamber through the OEM air-intake valve and then compressed during the compression cycle. The high auto-ignition temperature of the lean air-gas mixture prevents ignition of the charge until the diesel injector is activated. The injected diesel fuel provides the necessary ignition source for the air-gas mixture which then combusts at a similar speed and pressure compared to 100% diesel operation. Although the injected diesel fuel acts as an ignition source for the air-gas mixture, it is also providing a portion of the total energy needed for combustion, based on the set gas-diesel mixture.
Air-Fuel Ratio / LEL
Operation in Gaseous Fuel mode does not appreciably change engine air-fuel ratio. At maximum allowable gas substitution rates (80%), the gas concentration in the intake air is typically less than 3.0% by volume, which is substantially below the 5.0% Lower Explosive Limit (LEL) of methane. Due to the lean condition of the air-gas charge, the possibility of ignition in the engine air-intake system due to backfire or other causes is minimized.
Governing
The Gaseous Fuel System allows the original engine governing system to control engine speed. No interface or tie-in is required between the Gaseous Fuel System and the engine governor. The Gaseous Fuel System is compatible with electro-mechanical and hydro-mechanical governors as well as some electronic injection based governing systems (contact GFS for details).
Power
Conversion to GFS Gaseous Fuel typically results in similar performance levels in terms of engine stability, HP, torque and response.
Lube Oil
Unless otherwise indicated by gas composition, no changes in engine lube oil specification are required for Gaseous Fuel operation. Natural gas burns with minimum particulate residues so that engine oil may be kept cleaner during Gaseous Fuel operation. This can possibly lead to longer average intervals between lube oil and oil filter changes and extended periods between engine overhauls. No changes should be made to the OEM’s recommended service intervals without complete engine oil and wear analysis and consultation with the OEM.
Operating Temperatures
Engine heat rejection rates while operating in Gaseous Fuel mode are largely similar to 100% diesel performance. Engine exhaust gas temperature, coolant temperature, oil temperature and manifold air temperature levels remain within the limits set by the engine manufacturer.
Efficiency
Because the Gaseous Fuel System utilizes a low restriction air-gas mixing device and maintains the excess-air operation of the diesel engine, net fuel efficiency (specific fuel consumption) is normally equivalent to 100% diesel operation. For each unit of diesel fuel displaced during Gaseous Fuel operation, a calorically equivalent unit of natural gas will be needed to maintain engine power. mmended. Please contact your dealer or GFS for catalyst specifications.
Emissions
Gaseous Fuel operation will typically reduce production of nitrogen oxides, sulfur oxides, reactive hydrocarbons, carbon dioxide and particulates. Exhaust opacity levels (visual emissions) are also typically reduced. For emissions sensitive applications, a 2-way oxidation catalyst
are recommended.

