Diesel engines are durable and powerful.
The diesel engine traces its history to 1892, when German engineer Rudolph Diesel filed a patent for an engine run on a stable byproduct of the petroleum refinement process dubbed diesel fuel. After mass manufacturing by brewer Adolphus Busch, military use in World War I and civilian applications beginning in the 1930s, diesel engines gained a reputation as loud, smoky workhorses. The modern diesel engine still serves as a solid workhorse, but it has made significant strides in terms of efficiency and eco-friendliness.
Basics
Diesel engines rely on the process of internal combustion for power. Like gasoline engines, diesel engines convert fuel into energy via a series of tiny explosions caused by the fuel's reaction to oxygen. This combustion-based energy propels pistons up and down inside the cylinders. In turn, the crankshaft changes the linear motion of the pistons into rotary motion, which allows vehicle wheels to turn. Most commonly, the diesel engine appears in industrial, agricultural, construction and on-highway transportation vehicles. Diesel engines are known as high-torque, long-lasting and fuel-efficient engines.
Versus Gasoline Engines
While sparks emitted from spark plugs cause combustion in gasoline engines, the fuel in diesel engines ignites on its own. To achieve this combustion - a process known as autoignition - diesel engines feature much higher air compression rates than gasoline engines. This heats the air inside the cylinders to an immense degree, allowing spontaneous combustion. High compression leads to increased efficiency when compared to a gasoline engine as it concentrates oxygen, which burns the fuel. Additionally, diesel fuel features a higher energy content per gallon than gasoline. Diesel fuel reacts to the concentrated oxygen of diesel engines to create more powerful combustion than that of a gasoline engine.
Four-Stroke Process
The four-stroke diesel engine has served as a prominent type of diesel engine since the inception of the technology. This type of engine operates in a pattern of four "strokes." First, the piston moves away from the engine's intake valve via the drawing in of oxygen, compressing and heating the oxygen in the process. In the second stroke, the movement of the piston causes fuel to ignite as it contacts heated oxygen. The third stroke involves the expansion of heated gases, which force the piston downward into a "power stroke." Finally, the piston returns upward, forcing spent gas out of the cylinder and starting the process once again. Throttles control the power of the engine by limiting the air-fuel mixture as it enters the cylinder.
Modern Diesel Engines
Modern diesel engines often feature direct-injection, which regulates fuel combustion to a contained area in the head of each piston. Computer systems ensure fuel injection directly into the cylinder, a type of precision impossible for the diesel engines of yore. Compared to their predecessors, modern diesel engines produce much lower amounts of carbon dioxide, carbon monoxide and unburned hydrocarbons. Modern engines that use biodiesel feature the same efficiency but produce less soot than those that use petroleum-based diesel.
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