In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work. It does this by bringing a working substance from a high temperature state to a lower temperature state. A heat "source" generates thermal energy that brings the working substance to the high temperature state. The working substance generates work in the "working body" of the engine while transferring heat to the colder "sink" until it reaches a low temperature state. During this process some of the thermal energy is converted into work by exploiting the properties of the working substance. The working substance can be any system with a non-zero heat capacity, but it usually is a gas or liquid.
In general an engine converts energy to mechanical work. Heat engines distinguish themselves from other types of engines by the fact that their efficiency is fundamentally limited by Carnot's theorem. Although this efficiency limitation can be a drawback, an advantage of heat engines is that most forms of energy can be easily converted to heat by processes like exothermic reactions (such as combustion), absorption of light or energetic particles, friction, dissipation and resistance. Since the heat source that supplies thermal energy to the engine can thus be powered by virtually any kind of energy, heat engines are very versatile and have a wide range of applicability.
Heat engines are often confused with the cycles they attempt to mimic. Typically when describing the physical device the term 'engine' is used. When describing the model the term 'cycle' is used.
Other articles related to "heat engine, heat, heat engines, engine, engines":
... Cycle Process 1-2 (Compression) Process 2-3 (Heat Addition) Process 3-4 (Expansion) Process 4-1 (Heat Rejection) Notes Power cycles normally with external combustion - or heat pump cycles Bell Coleman ...
... Often, these additional forms of energy are produced by a heat engine, running on a source of high-temperature heat ... A heat engine can never have perfect efficiency, according to the second law of thermodynamics, therefore a heat engine will always produce a surplus of low-temperature heat ... This is commonly referred to as waste heat or "secondary heat", or "low-grade heat" ...
... This Timeline of heat engine technology describes how heat engines have been known since antiquity but have been made into increasingly useful devices since the ... In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot "source" and a cold "sink" ... Heat is transferred to the sink from the source, and in this process some of the heat is converted into work ...
... Carnot's theorem is a formal statement of this fact No engine operating between two heat reservoirs can be more efficient than a Carnot engine operating between those same reservoirs ... gives the maximum efficiency possible for any engine using the corresponding temperatures ... A corollary to Carnot's theorem states that All reversible engines operating between the same heat reservoirs are equally efficient ...
... For an arbitrary heat engine, the efficiency is where A is the work done per cycle ... Carnot's theorem states that all reversible engines operating between the same heat reservoirs are equally efficient ... Thus, any reversible heat engine operating between temperatures T1 and T2 must have the same efficiency, that is to say, the efficiency is the function of temperatures only In addition, a ...
Famous quotes containing the words engine and/or heat:
“Industrial mana sentient reciprocating engine having a fluctuating output, coupled to an iron wheel revolving with uniform velocity. And then we wonder why this should be the golden age of revolution and mental derangement.”
—Aldous Huxley (18941963)
“As in hoary winters night stood shivering in the snow,
Surprised I was with sudden heat which made my heart to glow;
And lifting up a fearful eye to view what fire was near,
A pretty Babe all burning bright did in the air appear;”
—Robert Southwell (1561?1595)