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Diesel Engines - How Do They Work


Diesel Engines - How Do They Work

Have you ever looked in awe as a huge truck swerves up an uphill? Most likely not! It's not every day. But take a moment to think for a second about the process--how a massive weight is being constantly lifted against the overwhelming power of gravity, using only the use of a few glasses of very dirty fluid (fuel in other words)--and you'll likely be able to agree that what you're watching is quite amazing.


Diesel engines power the most powerful machines, including trucks and ships, trains, and submarines. In essence, they're like ordinary petrol engines, but they produce more power, more efficiently, and in a slightly different manner. Let's look at them more closely!


What is the diesel engine?

Similar to a petrol engine diesel engines are a kind that is an internal combustion engine. Combustion is a different term for burning, and the word "internal" means inside, therefore it is one where fuel is burnt in the central component inside the motor (the cylinders) which is where the power is generated.


This is very different from an engine that is externally fueled, such as those used by the old-fashioned steam locomotives. In steam engines, it has a huge flame at the end of a boiler which heats water to produce steam. The steam then flows through long tubes and into a cylinder located on the other side of the boiler, where it moves a piston back and forward, causing the wheels to move.


External combustion is the reason for this because the fire is not inside the piston (indeed generally about 6-7 meters, or 20-30 feet away). In a diesel or petrol engine, the petrol or diesel is burned inside the cylinders. Internal combustion is less wasteful of energy as the heat doesn't need to travel from the point where it's created to the cylinder.


Everything happens at the same time. This is why the internal combustion engine is more effective than those that use external combustion (they generate more energy from the same amount of fuel).


How is a diesel engine different from a petrol engine?

Diesel engines and petrol engines operate by internal combustion, however in slightly distinct ways. In a petrol-powered engine, air and fuel are introduced into small cylinders made of metal. The piston presses (squeezes) in the mix, which makes it explosive. Then, a tiny electric spark produced by the sparking bulb ignites the mixture.


This causes the mixture to explode and generates power that drives the piston along the cylinder. It then (through both the gears and crankshaft) rotates the wheels. It is possible to learn more about this and see an easy animation of how it operates in our article about automobile engines.


Diesel engines are similar to petrol engines but less complicated. The air enters the cylinder and then the piston compresses it, but far more than in the petrol engine. In a petrol engine, the mixture of fuel and air is compressed to around 10% of its initial volume. In diesel engines air is compressed by anywhere between 14 and 25 times. 1 If you've used a bicycle tire to pump it up and felt the compressor getting hotter in your hands as longer you utilized it.


It's because the process of compressing a gas produces heat. Imagine how much heat can be produced when you force air to fill 14-25 per cent of the amount of space it typically occupies. It is so hot actually that the air becomes very hot. Usually, it's at or near 500degC (1000degF) and occasionally extremely hot. After the air has been compacted, a mist fuel is sprayed into the piston typically (in the case of modern engines) via an electronic fuel-injection system that functions in a similar way to an aerosol can. (The quantity of fuel injected is dependent on the power level the driver would like the engine to generate.)


The temperature of the air is so high that the fuel immediately ignites and explodes, without the need for spark plugs. The controlled explosion causes the piston pulls back into the cylinder, generating the power needed to drive the machine or vehicle in which the engine is placed. When the piston is reinserted into the cylinder exhaust gases are forced out through an exhaust valve it repeats the process hundreds to thousands per minute!


What is the process by which diesel engines transform energy into power?


Four-stroke engines

As with petrol engines, diesel engines typically operate by repeating a sequence of four strokes or stages that are when the piston rotates both up and down (the crankshaft rotates twice, in other terms) throughout the course.

  1. Intake The air (light blue) is pulled into the cylinder by the air intake valve to the right as the piston is moved downwards.

  2. Compression: As the inlet valve is closed, the piston expands and compresses the air mix by heating it. The fuel (dark blue) is introduced into the hot gas via the central valve for fuel injection and ignites on its own. In contrast to a gas engine, there is no sparking plug needed to initiate this process.

  3. Power: When the air-fuel mixture burns and ignites it pushes the piston downwards to drive its crankshaft (red wheel on the lower) which transmits the power on the wheels.

  4. Exhaust The valve that is green on the left side opens to let exhaust gases that are pushed out by the piston return.

Two-stroke engines

In a diesel engine that has two strokes, the entire cycle is completed when the piston is moved upwards and downwards only once. It is a bit confusing, but there are actually three steps in a cycle:

  1. Exhaust and intake: New air is blown in the cylinder's side by pushing the exhaust out of the valves located at the top of the.

  2. Compression Inlet and Exhaust valves are closed. The piston rises and compresses air and then heats it. When the piston gets to its top fuel is injected, and it sparks spontaneously.

  3. Power: When the fuel-air mixture is ignited it pushes the piston down, which drives the crankshaft which sends energy to the wheels.

Two-stroke engines weigh less and are lighter than four-stroke engines. They also are generally more efficient as they create energy once per rotation (instead of every two turns, as in the case of a four-stroke motor). This means that they require greater cooling, lubrication and cooling, and have a higher rate of wear and tear.


What is it that makes diesel engines more efficient?

Diesel engines can be up to twice more efficient as petrol engines - around 40-45 per cent efficient at the very highest. Simply put, this means that you can travel farther with similar amounts of petrol (or gain more miles from your budget). There are many reasons behind this. They are more compact and operate at higher temperatures.


The fundamental theory behind how engines operate that is known as Carnot's law is that the effectiveness of an engine is determined by the low and high temperatures at that it operates. An engine that runs through a larger temperature variation (a greater hottest temperature or lower temperatures) will be more effective. Additionally, the absence of a sparking-plug ignition mechanism allows for a more simple design that allows for the possibility of compressing the air significantly.


This causes the fuel to burn hotter and faster, thus releasing more energy. Another benefit to efficiency is. If a petrol engine is not operating at its full capacity it is necessary to provide greater amounts of petrol (or smaller amounts of air) to the cylinder in order to keep it functioning but diesel engines don't have this issue, so they require less fuel when operating at lower speeds.


Another factor to consider is that diesel-based fuel has less energy than petrol due to the molecules that it's made of having more energy in locking their atoms (in the sense that diesel has a greater power mass than petrol). Also, diesel is a superior fluid to petrol, which means the diesel engine will have less friction.


How is diesel fuel different?

The two fuels are completely different. This is evident If you've ever heard horror stories of those who have filled their vehicle or car with the wrong kind of fuel! In essence, diesel is a less refined, lower-grade product of petroleum that is made up of heavier hydrocarbons (molecules constructed from hydrogen atoms and carbon).


Diesel engines with crude fuel that do not have advanced fuel-injection systems are able to theoretically operate on virtually all hydrocarbon fuels, which is why there is a growing demand for biodiesel (a type of biofuel that is produced of, among other things the waste vegetable oil).


The person who invented the diesel engine Rudolf Diesel, successfully ran his first engines using peanut oil. He believed that his engine could do people a favour by removing people from dependence on fuels such as petrol and coal and centralized sources of energy. What if he had known!


The advantages and disadvantages of diesel engines

Diesels are among the most flexible fuel-burning engine in use today and are found everywhere from trains and cranes to bulldozers and submarines. In comparison to petrol engines, they're less complicated as well as more efficient and much more affordable. They're also safer since diesel fuel is more stable and its vapour is less dangerous than petrol.


Contrary to petrol engines they're specifically designed to move huge loads at low speeds, which is why they're perfect to be used in freight-hauling vessels and trucks, buses and locomotives. The higher compression of the components in a diesel engine is required to endure a lot more stress and strain than in petrol engines.


Diesel engines are required to be heavier and stronger and they were for a long time they were only used to power large machines and other machines. Although this could be an issue, it's because diesel engines are generally stronger and last longer than petrol engines.


Pollution is among the most significant drawbacks of diesel engines. They produce an array of pollutants, which include carbon monoxide, nitrogen oxides hydrocarbons, and soot particles that can be harmful to health. The theory is that diesel engines tend to be more effective, therefore they will consume less fuel, generate less CO2 (CO2) emissions and less contribute to global warming.


However, there's a bit of disagreement over whether this is the case. A few laboratory experiments have demonstrated that the emissions of diesel engines are just a little lower than that of petrol engines, but companies insist that if identical petrol and diesel vehicles are compared, diesel will be superior.


Another recent study suggests that even the newest diesel vehicles emit a lot of pollution. For instance, the European Environment Agency, for instance, says that an average, "clean" diesel car that is compliant with EURO 6 emissions standards produces approximately 10 times the amount of nitrogen oxide pollution than an equivalent petrol car.


What is the impact of CO2 emissions?


Based on the British Society of Motor Manufacturers and Traders: "Diesel cars have greatly contributed to the reduction of CO2 emissions. Since 2002, people who buy diesel have prevented nearly three million tons of carbon dioxide from being released out into the environment."


Diesel engines typically are more expensive than petrol engines, however, their lower operating expenses and longer operational life typically offset this. However, consumers aren't convinced anymore: there's been a dramatic decline in sales following the Volkswagen emissions scandal of 2015 in which the German automaker misrepresented the emissions from its diesel vehicles to make them appear less polluting.


It's a fact that diesel engines will continue to power large vessels--ships, trucks as well as railroad locomotives are all dependent on them. However, their future in lighter vehicles is increasingly uncertain. The move towards electric vehicles has given a huge motivation to reduce the weight of petrol engines, making them more affordable and cleaner, and these modern petrol engines are threatening the perceived benefits of using diesel in vehicles.


In the ever-growing competitiveness between electric vehicles that are affordable and petrol vehicles that are more efficient diesel may be eliminated completely. Diesels, however, evolve constantly. In 2011 it was reported that the US Department of Energy predicted that the future of diesel engines would increase in efficiency, from 40 % to 60%% or more. If this happens Diesel could be an option in smaller vehicles for years to come, particularly in the event that their emissions of soot can be addressed.


Who was the person who invented the diesel engine?

Unsurprisingly, it was German engineer Rudolf Diesel (1858-1913). The following is a brief summary of the tale:


Rudolf Diesel - Inventor of the diesel engine
Rudolf Diesel - Inventor of the diesel engine

  • 1861 French engineer, Alphonse Beau de Roches (1815-1893) exposes the basic theory behind the four-stroke engine. He submits a patent application for the concept on February 16th, 1862 however, he is unable to build a functional machine.

  • In 1876, German engineer Nikolaus Otto (1832-1891) creates the first four-stroke, efficient, and successful internal combustion engine.

  • In 1878, Scotsman Dugald Clerk (1854-1932) is the first person to develop the two-stroke engine.

  • 1880: At the age of 22, Rudolf Diesel goes to work for the refrigerator engineer Carl von Linde (1842-1934) He is exposed to thermodynamics (the science behind how heat is moved) and the way engines function.

  • 1909: Diesel discovers how to build a more efficient internal combustion engine that uses greater temperatures and pressures that don't require an ignition plug.

  • 1992: Diesel begins patenting his ideas in order to stop others from making money from the inventions.

  • 1893: Diesel builds a huge stationary engine that operates for a whole minute powered by itself, on the 17th of February, 1894.

  • 1895: Diesel's patent for the engine was granted to the United States on July 16 1895.

  • 1898: Thanks to Diesel's assistance the first commercial engine is constructed in a factory located in St Louis, Missouri, United States by Adolphus Busch (1839-1913) the brewer of Budweiser beer.

  • 1899: The production of diesel engines starts at Diesel's factory in Augsburg. Diesel begins to license his concepts to various companies and then becomes very rich.

  • 1903: Petit Pierre, one of the first diesel vessels is launched on the canal Marne-Rhine in France.

  • 1912: MS Selandia, the first ocean-going diesel vessel made its first journey.

  • 1913: Diesel dies in mysterious circumstances, reportedly drowning on the ship Dresden as it was en route between London, England to Germany. Rumours circulate that Diesel may have been killed or killed himself, however, there is no proof to support it.

  • 1931: Clessie Cummins, the founder of the Cummins Engine Co., constructs one of the very first popular diesel-powered cars. It demonstrates its effectiveness in driving the car across Indianapolis all the way to New York City on just $1.39 of fuel.

  • 1931: Caterpillar revolutionizes agriculture by introducing the Diesel Sixty, its first diesel-powered crawler tractor, which was based on the family Caterpillar Sixty.

  • 1936: Mercedes introduces the 260D as the first diesel-powered mass-produced passenger car. It continues to be produced until 1940. In the subsequent forty years, Mercedes is able to sell more than 2 million diesel automobiles.

  • 1939. General Motors unveils its EMD FT, a powerful diesel-electric motor, and takes the first model (Number 103) for a full year to show its value. It proves beyond doubt that diesel is superior to steam, it is the end of the road for steam engines.

  • The 1970s: A global fuel shortage has prompted a renewed interest in small and efficient diesel engines in automobiles.

  • 1987: The world-renowned Queen Elizabeth 2 (QE2) ship is refurbished and equipped with 9 diesel-electric engines (each as big as the double-decker bus) which make this the largest diesel-powered merchant vessel at the time.

  • The year 2000 is when Peugeot announces the world's very first particle filters (PF) specifically for engines powered by diesel in its 607 models, promising the reduction of 99 per cent in the emissions of soot.

  • The year 2015 is in full swing. Volkswagen gets sucked into a massive global scandal after repeatedly cheating on diesel emissions tests for engines. The sales of diesel cars plummet to the lowest level since.

  • 2017. Volvo will be the first big carmaker to switch away from diesel and petrol engines. Volvo announces that all new vehicles will be hybrids or completely electric by the year 2019.

CRD Specialists are your local Diesel Fuel Injection & Pump Mechanic Services Australia Wide. We offer quality and experienced fuel injection cleaning, repairs, rebuild, parts and service. Brisbane, Sydney, Canberra, Melbourne, Hobart, Adelaide, Perth, Darwin and all cities, towns and areas in between.

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