Heat Engine

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heat engine

[′hēt ‚en·jən]
(mechanical engineering)
A machine that converts heat into work (mechanical energy).
(thermodynamics)
A thermodynamic system which undergoes a cyclic process during which a positive amount of work is done by the system; some heat flows into the system and a smaller amount flows out in each cycle.

Heat Engine

 

an engine in which thermal energy is converted into mechanical work. Heat engines, which make up the largest group among prime movers, use natural energy sources in the form of chemical or nuclear fuel.

The basis of operation of a heat engine is a closed or arbitrarily closed thermodynamic cycle. The operating efficiency of an ideal heat engine is determined by its thermal efficiency. The operation of a real heat engine, which has additional losses—for example, heat losses and losses caused by friction and vortex formation—is evaluated by the actual efficiency, which is the ratio of the mechanical work at the output shaft of the engine to the heat energy supplied. The actual efficiency of heat engines ranges from 0.1 to 0.6.

Heat engines are divided into piston, rotary, and jet heat engines according to the type of machine carrying out the working thermodynamic process. Combinations of these types, such as turbojet and Wankel engines, are possible. According to the means of heating the working body, heat engines are subdivided into internal-combustion engines, in which both the combustion of fuel and conversion of heat into mechanical work occur in the same working chambers of the engine (the cylinders), and external-combustion engines, in which the working body is obtained or heated outside the engine proper in special devices (for example, the Stirling engine and the steam engine).

O. N. EMIN

References in periodicals archive ?
Schematic presentation of the processes occurring in the cavities of the plate makes the investigation easier and enables to prove that in the cavity of the plate there exists a heat engine cycle where mechanical energy is produced.
In the heat engine invented almost 200 years ago by Robert Stirling, a gas-filled cylinder is periodically heated and cooled so that the gas expands and contracts.
The Wankel rotary engine is the most known rotary heat engine, patented in 1954 by Felix Wankel.
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Now, let us imagine that there is a hypothetical little heat engine inside [S.
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batteries, combustion/coal/oil-fired heat engines, and other fuel cells.
The main innovative character of the project is determined by the conceptual approach toward technological solution of the challenging problems of heat engines with external heat supply.
I HAVE written to Ed Miliband, the minister for climate change, to point out that the steady rise in temperature in our world is because of the excess number of heat engines.
He includes numerous worked examples as well as an extensive collection of exercises as he covers basic concepts, equations of state, applications of the First and Second Laws of Thermodynamics to processes in closed systems, heat engines, power cycles, the thermodynamics of open systems, phase equilibria in one-component systems, the mathematics of thermodynamics, gas mixtures and nonaqueous solutions, phase diagrams and binary phase equilibria, chemical thermodynamics, electrochemistry, and biothermodynamics.
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