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<onlyinclude>The '''Otto Cycle''', describes how [[heat engine]]s turn [[gasoline]] into [[kinetic energy|motion]]. Like other [[thermodynamic cycle]]s, this cycle turns [[chemical energy]] into [[thermal energy]] and then into motion. The Otto cycle describes how [[internal combustion engine]]s (that use gasoline) work, like [[Transportation|automobiles]] and [[lawn mower]]s.</onlyinclude>

==Application==
The Otto Cycle provides the energy for most [[transportation]] and was essential for the modern world. Specifically, the vast majority of automobiles seen on the road today use the Otto Cycle to convert gasoline into motion. Any machine (the list<ref>A partial list would include motorcycles, pick-up trucks, vans, SUVs, lawn mowers, cars, many boats and even some portable generators.</ref> would go on and on) that uses gasoline will be divided into two categories of engines as seen below.
<gallery caption="Types of engines that use the Otto Cycle" mode=packed heights=300px>
File:Two-Stroke-Engine.gif|Figure 1. A [[Two stroke engine|two stroke engine]]<ref>Wikimedia Commons [Online], Available:https://commons.wikimedia.org/wiki/File:Two-Stroke_Engine.gif</ref>
File:4StrokeEngine.gif|Figure 2. A [[Four stroke engine|four stroke engine]]<ref>"File:4StrokeEngine Ortho 3D Small.gif - Wikimedia Commons", Commons.wikimedia.org, 2018. [Online]. Available: https://commons.wikimedia.org/wiki/File%3A4StrokeEngine_Ortho_3D_Small.gif. [Accessed: 17- May- 2018]</ref>

</gallery>

The engines' pages will provide details on their unique mechanisms, and an explanation on how they use the Otto Cycle, which is slightly modified.

==The Ideal Otto Cycle==
[[File:P-V_Otto_cycle.png|right|300px|thumb|Figure 3. The [[pressure]]-[[volume]] diagram of an ideal Otto Cycle process. It consists of two [[isochore|isochoric]], two [[adiabatic]] and two [[Isobar|isobaric]] processes (for intake and exhaust)<ref>Wikimedia Commons [Online], Available: https://en.wikipedia.org/wiki/Otto_cycle#/media/File:P-V_Otto_cycle.svg</ref>]]

The [[PV diagram]] ([[pressure]]-[[volume]] diagram) of the ideal Otto cycle is shown in Figure 3. This diagram models how the changes in [[pressure]] and [[volume]] of the working fluid (gasoline and air fuel) change due to the [[combustion]] of [[hydrocarbon]]s which powers the movements of a piston, creating heat, to provide motion for a vehicle. There are expansion (increased volume chamber) piston motions—caused when the [[thermal energy]] is released from combustion—inducing work being done ''by the gas'' and ''on the piston.'' In contrast, when the piston does ''work on the gas'', the engine chamber is being compressed (decreasing in volume).<ref>Internal Combustion Engine Basics", Energy.gov, 2018. [Online]. Available: https://www.energy.gov/eere/vehicles/articles/internal-combustion-engine-basics. [Accessed: 28- May- 2018].</ref>

It is important to note that Figure 3 depicts an ''ideal'' process for any engine using the Otto cycle. It describes the basic working steps in a gasoline engine. The slight modification which depicts a more realistic situation of the Otto Cycle's PV diagram for a two stroke and four stroke engine is explained on their respective pages. The [[work]] done by the engine can be calculated by solving the area of the closed cycle.

The following describes what occurs during each step on the PV diagram, in which the combustion of the working [[fluid]]—gasoline and [[air]] (oxygen), changes the motion in the piston:

'''Green line:''' Referred to as the ''intake phase'', the piston is drawn down to the bottom to allow the volume in the chamber to increase so it can "intake" a fuel-air mixture. In terms of thermodynamics, this is referred to as an [[isobar|isobaric]] process.

'''Process 1 to 2:''' During this phase the piston will be drawn up, so it can compress the fuel-air mixture that entered the chamber. The compression causes the mixture to increase slightly in pressure and [[temperature]]—however, no [[heat]] is exchanged. In terms of thermodynamics, this is referred to as an [[adiabatic]] process. When the cycle reaches point 2, that is when the fuel is met by the [[spark plug]] to be [[ignition|ignited]].

'''Process 2 to 3:''' This is where [[combustion]] occurs due to the ignition of fuel by the spark plug. The combustion of the gas is complete at point 3, which results in a highly pressurized chamber that has a lot of heat (thermal energy). In terms of thermodynamics, this is referred to as an [[isochore|isochoric]] process.

'''Process 3 to 4:''' The thermal energy in the chamber as a result of combustion is used to do work on the piston—which pushes the piston down—increasing the volume of the chamber. This is also known as the ''[[power]] stoke'' because it is when the thermal energy is turned into motion to power the machine or vehicle.

'''Purple line (Process 4 to 1 and ''exhaust'' phase):''' From process 4 to 1, all [[waste heat]] is expelled from the engine chamber. As the heat leaves the gas, the molecules lose [[kinetic energy]] causing the decrease in pressure.<ref> I. Dinçer and C. Zamfirescu, Advanced power generation systems. London, UK: Academic Press is an imprint of Elsevier, 2014, p. 266. </ref> Then the ''exhaust phase'' occurs when the remaining mixture in the chamber is compressed by the piston to be "exhausted" out, without changing the pressure.

== For Further Reading ==
*[[Two stroke engine]] and [[Four stroke engine]]
*[[Heat engine]]
*[[PV diagram]]
*[[Combustion]]
*[[Gasoline]]
*[[Diesel vs gasoline engine]]

* Or explore a [[Special:Random| random page!]]

==References==
{{reflist}}

Otto cycle - Revision history

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energy>Jmdonev at 21:10, 25 July 2018