The efficiency of the engine depends to a large extend upon the next criteria:
·Compression | |
· Combustion Process | |
· Air/Fuel Mixture | |
· Mechanical Design | |
· Lubrication |
1) Compression
The higher the Compression Ratio or the pre-compression pressure, thence the higher is the thermal efficiency of the internal combustion engine. This results inwards a improve fuel usage as well as to a greater extent than ability is developed piece less fuel is consumed. The maximum compression is even thence limited past times the Octane Rating of the Gasoline that volition live used. The higher the Octane Rating the higher the compression tin be.
Unfortunately, higher Octane Gasoline costs to a greater extent than to hit than depression Octane Gasoline. Therefore the growth inwards fuel efficiency tin live offset past times growth inwards fuel costs.
The Compression Ratio is based on the mechanical pattern of the engine as well as is expressed as:
Where:
e = Compression Ratio
Vh = Cylinder swept Volume
Vc = Combustion infinite Volume of Cylinder
Even to a greater extent than of import than Compression Ratio is the actual pre-compression pressure level also called Final Compression Pressure. Although its value tin live also described as well as figured out mathematically, it is ever substantially less than the mathematical result. The actual Final Compression Pressure can live reliably obtained solely past times a mensuration alongside a exceptional tool, the Compression Tester.
It is even thence of import to know what the Final Compression Pressure should live for the detail engine. This specification tin live commonly constitute inwards a "Shop Manual" for the detail engine. The departure betwixt the measured as well as specified values for the Final Compression Pressure determines the "Sealing Quality" of the combustion chamber.
The character of the combustion sleeping accommodation sealing past times agency of the Piston Rings and the Valves is a mensurate of the status of the engine. Lubricant tin also touching on the character of the sealing betwixt the Rings and the Cylinder bore.
When the Final Compression Pressure is too high on a used engine, it commonly agency that the combustion sleeping accommodation as well as the piston crown guide maintain excessive amounts of carbon deposits that guide maintain been formed due to whatever of the following:
- incomplete combustion
- use of hapless character fuel
- use of hapless character lubricant
If the Final Compression Pressure is too low on a used engine, it commonly agency that the engine has whatever of the next problems:
has excessive amount of cylinder article of apparel (due to hapless lubrication) | |
has sticking piston rings (poor lubricant) | |
has burned exhaust valves (poor fuel or wrong ignition timing) | |
has damaged cylinder caput gasket | |
has sticking intake or exhaust valves (poor lubricant) |
2) Combustion Process
For the character of the combustion procedure it is of prime number importance that the fuel mixes intimately alongside the air, thence that it tin live burnt equally completely equally possible. It is of import that the flaming front end progresses spatially as well as inwards regular shape during the ability stroke, until the whole mixture has been burnt. The combustion procedure is considerably influenced past times the signal inwards the combustion sleeping accommodation at which the mixture is ignited, as well as past times the mixture ratio equally good equally the fashion inwards which it is fed into the combustion chamber.
Combustion is optimal as well as the efficiency of the engine is at its best when the remainder gases comprise no unburned fuel as well as equally niggling of Oxygen as possible. The Hydrocarbons are broken upward during the combustion into their factor parts, they are Hydrogen and Carbon. On consummate combustion the Carbon and Hydrogen burn to form Carbon Dioxide and Water vapor. When the combustion is incomplete the exhaust gases also comprise other undesirable constituents.
3) Air/Fuel Mixture
The Specific Fuel Consumption of an engine is defined equally the amount of expose energy produced per given amount of fuel consumed inwards the combustion process. The amount of fuel is quoted inwards grams or kilograms as well as the amount of expose energy produced inwards Kilo-Watt-Hours or Horsepower per hour.
Internal combustion engines tin swallow equally niggling equally 300 grams per kWh or equally much equally 1,200 grams per kWh.
In full general the Specific Fuel Consumption is at its greatest (least efficient) when the engine is subjected to depression loads, such equally idle. This is because the ratio betwixt the idling losses (due to friction, leaks, as well as hapless fuel distribution) as well as the brake horsepower is the most unfavorable.
Most engines guide maintain the lowest Specific Fuel Consumption at three-quarter load, which is at 75% of the maximum ability output as well as at most 2,000 RPM.
The Specific Fuel Consumption of engine is for the most usage dependent on the mixture ratio of the Air/Fuel mixture. Consumption is at its lowest alongside an Air/Fuel Ratio of to a greater extent than or less xv pounds of Air to i pound of Fuel. This agency that 10,000 gallons of Air are needed to mail away i gallon of Gasoline.
4) Mechanical Design
The mechanical pattern of the internal combustion engine has non changed since its invention inwards 1876, mainly because it works. The occupation is, that it has been invented long earlier in that place was thorough agreement of thermodynamics or of the chemic reactions during combustion process. Further inexpensive as well as plentiful fuel -- Gasoline was easily available as well as until few years agone in that place was no describe of piece of work concern alongside conservation or pollution.
As a trial the internal combustion engine is an expose energy efficiency dinosaur that refuses to die.
To hand you lot some stance why that is so, let’s catch this:
Gasoline contains most 42 to 43.5 Mega-Joules of expose energy inwards i Kilogram that is equal to most 18,060 to 18,705 Btu per pound.
The pie nautical chart on side past times side page volition exhibit you lot where all that expose energy that is available inwards Gasoline goes: