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Diesel engine.
Diesel cycle

What Is an Engine? Concept and Definition

What is an engine? Concept and definition

The engine is a machine capable of transforming a source of energy, which can be in chemical (in the presence of a fuel), electrical or thermal form, into mechanical energy or mechanically continuous work, typically used in field application purposes with the propulsion of various types of vehicles.

In a philosophical sense, an engine is the organism that causes movement or change in other affiliated institutions: Aristotle spoke of an immobile engine, a term also picked up by other philosophers, to indicate the cause of the universe, that is, the object or subject that (according to his philosophy) was at the beginning.

Engine is also used in computer science (graphics engine, search engine, database engine...) to designate a program that "automatically and constantly" transforms something into something else. More precisely in computing, an engine is a program that, during its normal operation:

  • it never ends, unless you have technical problems or are not deliberately arrested;
  • processes its output from a set of data and/or predefined procedures;
  • It is intended to be used by other programs and not directly by humans

What Are the General Principles of an Engine?

All real physical engines of any kind are subject to the laws of conservation of energy and the fact that energy along the way is dispersed and will therefore provide less total work than the energy contained in the spent fuel for its functioning. for example, in thermodynamics, the ratio of the work provided to the energy expended by a particular engine is its gross output, which comprises the fraction of energy expended for the internal operation of the engine. It is always less than the thermodynamic efficiency, the efficiency (not measured, but calculated) for an identical motor considered "ideal", that is, without internal energy dissipation.

In particular, the efficiency of heat engines strictly depends on the initial and final temperature of their cycle, and for a given temperature jump (ΔT will however be less than the Carnot cycle by the same ΔT).

Most commonly used motors are reciprocating and/or rotary, producing work in the form of torque or force on a shaft; others produce only a linear force.

Engines History

One of the prime movers as understood today was the steam engine, in which it is the product of superheated steam in a boiler which then, expanding in a cylinder, produces thrust on a piston. Such reciprocating motion made with other mechanical devices can be transferred to a wheel or flywheel through a connecting rod-crank mechanism, in order to make vehicle motion possible. During the 19th century, steamboats replaced sailboats and towards the end of the same century, the development of the internal combustion engine made possible the great development of the automotive industry and, later, the birth of the aeronautical industry.

After World War II, the use for aeronautical flight called for the development of jet engines, while the birth of space flight led to widespread development of rocket engines and, in particular, of a chemical rocket engine.

In recent years, the requirements of interplanetary flight are driving research for new solutions, particularly in the field of non-chemical rocket engines such as space sails.

In the field of engines for automotive applications, research is strongly oriented towards solutions that reduce consumption and emissions of pollutants into the environment

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Published: May 21, 2018
Last review: May 21, 2018