What Is a Diesel Engine? Its Diagram, Applications, Parts, Advantages And Disadvantages
Diesel engines, a continuation of gasoline engines, are highly efficient and potent engines used in various industrial applications. They power locomotives, construction equipment, automobiles, and more through adiabatic compression, a mechanical process that heats air in the cylinder and ignites the fuel.
A diesel engine, also known as a compression-ignition or CI engine, is a reliable form of an internal combustion engine, utilizing heat generated by compressing air in the cylinder to ignite fuel.
Founded by Rudolf Diesel, a student of Polytctechnikum in Munich, this engine offers higher efficiency and lower emissions due to its high expansion ratio and inherent lean burn, allowing heat dissipation by excess air.
A diesel engine is a complex system that converts chemical energy into mechanical energy. It comprises a block, pistons, cylinder head, fuel injector, valves, crankshaft, connecting rod, and camshaft.
The block contains the internal combustion process, with an open space for each cylinder. The pistons compress air, leading to combustion. The cylinder head closes the top of the open space, allowing fuel to enter the cylinder and burn.
The fuel injector sprays fuel in precise patterns, while valves allow fresh air in and exhaust gases out. The crankshaft transfers the combustion process into a rotational motion, while the connecting rods carry the combustion force.
Diesel engines have become increasingly important in various applications, including passenger cars, locomotives, and industrial generators. Passenger cars require smooth operation and high low-end torque, and diesel engines are used for large trucks, bigger cars, and smaller commercial vehicles.
Modern powerplants are usually turbocharged and have direct injection. Diesel locomotives, first introduced in 1913, are designed for continuous operation and powering electric generators. They have become the prime mover on all non-electrified railroads in the industrialized world.
Marine diesel engines vary based on their application, with mass usage in military and medium-size boats suitable for medium-speed four-stroke diesel engines. Large ships use extremely efficient, low-speed two-stroke diesel engines, reaching efficiencies of up to 55%.
Stationary diesel engines are commonly used for electricity generation, powering refrigerator compressors, and other types of compressors or pumps. Non-road diesel engines are common for construction equipment, offering fuel efficiency, reliability, and ease of maintenance.
Aviation applications of diesel engines have existed before World War II, but the likelihood of a general aviation diesel in the near future is remote. In recent years, diesel engines have found use in unmanned aircraft (UAV) due to their reliability, durability, and low fuel consumption.
In early 2019, AOPA reported that a diesel engine model for general aviation aircraft is “approaching the finish line.”
Four-stroke engines are a type of diesel engine designed for two- or four-stroke cycles. In a typical four-stroke engine, intake and exhaust valves are located in the cylinder head, with dual valve arrangements often used.
Two-stroke cycles can eliminate the need for one or both valves, while exhaust can be through ports in the cylinder liner. This simplifies engine construction and provides better performance.
A diesel engine works by compressing air into a combustion chamber, which is then injected with fuel. The compressed air, which is naturally ignited due to its high temperature, is introduced into the combustion chamber.
The combustion process occurs at a constant pressure during the initial part of the power stroke. As the piston descends further, the combustion gases expand, driving the piston downward and supplying power to the crankshaft.
Diesel engines offer several advantages over gasoline engines, including high efficiency, a wide range of fuel options, low fuel costs, good lubrication properties, and low fire risk. They also have good exhaust-emission behavior.
However, diesel engines have disadvantages such as higher costs, higher fuel costs in most regions, higher maintenance and repair costs, limited access to fuel, and a lack of lubricating qualities.
Additionally, starting a diesel engine in cold weather can be challenging, and they make more noise than gasoline engines. Overall, diesel engines offer a more efficient and cost-effective choice for combustion engines.
FAQs
What is the meaning of a diesel engine?
Rudolf Diesel, a German engineer, developed the compression-ignition engine, an internal combustion engine that ignites fuel due to mechanical compression, resulting in an elevated temperature in the cylinder, thereby enhancing combustion efficiency.
What is the main function of the diesel engine?
The diesel engine converts chemical energy into mechanical energy, powering large tractors and marine vessels. It also powers automobiles and electric-power generator sets, ensuring efficient transportation and power generation.
What is the difference between a petrol and a diesel engine?
The major difference between a diesel engine and a petrol engine lies in the compression of air before fuel injection, while petrol engines mix gas and air and use a different type of fuel.
