{"id":52546,"date":"2020-02-20T06:41:58","date_gmt":"2020-02-20T05:41:58","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/quelle-est-la-theorie-du-cycle-diesel-moteur-diesel-definition\/"},"modified":"2020-02-20T06:42:59","modified_gmt":"2020-02-20T05:42:59","slug":"quelle-est-la-theorie-du-cycle-diesel-moteur-diesel-definition","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-theorie-du-cycle-diesel-moteur-diesel-definition\/","title":{"rendered":"Quelle est la th\u00e9orie du cycle diesel &#8211; Moteur diesel &#8211; D\u00e9finition"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Th\u00e9orie du cycle diesel &#8211; Moteur diesel.\u00a0Le cycle diesel comprend quatre processus thermodynamiques.\u00a0L&#8217;efficacit\u00e9 thermique d\u00e9pend du taux de compression et du coefficient de capacit\u00e9 thermique.\u00a0G\u00e9nie thermique<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-50 lgc-tablet-grid-50 lgc-mobile-grid-100 lgc-equal-heights lgc-first\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2>Cycle diesel &#8211; moteur diesel<\/h2>\n<p>Dans les ann\u00e9es 1890, un inventeur allemand,\u00a0<strong>Rudolf Diesel,<\/strong>\u00a0a brevet\u00e9 son invention d\u2019un moteur \u00e0 combustion interne efficace et \u00e0 combustion lente.\u00a0Le cycle initial propos\u00e9 par Rudolf Diesel \u00e9tait un cycle \u00e0 temp\u00e9rature constante.\u00a0Dans les ann\u00e9es qui suivirent, Diesel r\u00e9alisa que son cycle initial ne fonctionnerait pas et il adopta le cycle de pression constante, appel\u00e9\u00a0<strong>cycle Diesel<\/strong>\u00a0.<\/p>\n<p><strong>Le cycle diesel<\/strong>\u00a0est l\u2019un des\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-cycles\/\"><strong>cycles thermodynamiques<\/strong><\/a>\u00a0les plus courants\u00a0que l\u2019on puisse trouver dans les\u00a0<strong>moteurs d\u2019automobiles et<\/strong>\u00a0d\u00e9crit le fonctionnement d\u2019un moteur \u00e0 piston \u00e0 allumage par compression typique.\u00a0Le moteur diesel fonctionne de mani\u00e8re similaire au moteur \u00e0 essence.\u00a0La diff\u00e9rence la plus importante est que:<\/p>\n<ul>\n<li>Il n&#8217;y a pas d&#8217;essence dans le cylindre au d\u00e9but de la course de compression; par cons\u00e9quent, l&#8217;autoallumage ne se produit pas dans les moteurs diesel.<\/li>\n<li>Le moteur diesel utilise un allumage par compression au lieu d&#8217;un allumage par \u00e9tincelle.<\/li>\n<li>En raison de la temp\u00e9rature \u00e9lev\u00e9e d\u00e9velopp\u00e9e lors de la compression adiabatique, le carburant s&#8217;enflamme spontan\u00e9ment lors de son injection.\u00a0Par cons\u00e9quent, aucune bougie n&#8217;est n\u00e9cessaire.<\/li>\n<li>Avant le d\u00e9but de la course de puissance, les injecteurs commencent \u00e0 injecter du carburant directement dans la chambre de combustion. Par cons\u00e9quent, la premi\u00e8re partie de la course de puissance se produit approximativement \u00e0 la pression constante.<\/li>\n<li>Des taux de compression plus \u00e9lev\u00e9s peuvent \u00eatre atteints dans les\u00a0<strong>moteurs diesel<\/strong>\u00a0, par rapport aux moteurs Otto<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-50 lgc-tablet-grid-50 lgc-mobile-grid-100 lgc-equal-heights lgc-last\">\n<div class=\"inside-grid-column\">\n<p>Le moteur diesel fonctionne de mani\u00e8re similaire au moteur \u00e0 essence.\u00a0Sur cette image, il y a un moteur Otto, qui est allum\u00e9 par une bougie \u00e0 la place de la compression.<\/p>\n<figure id=\"attachment_17548\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-17548\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Four-Stroke-Engine-Otto-Engine.gif\"><img loading=\"lazy\" class=\"size-full wp-image-17548 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Four-Stroke-Engine-Otto-Engine.gif\" alt=\"Moteur quatre temps - Moteur Otto\" width=\"225\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Four-Stroke-Engine-Otto-Engine.gif\" \/><\/a><figcaption id=\"caption-attachment-17548\" class=\"wp-caption-text\">Moteur \u00e0 quatre temps &#8211; Moteur Otto<br \/>\nSource: wikipedia.org, oeuvre de Zephyris, CC BY-SA 3.0<\/figcaption><\/figure>\n<div class=\"su-youtube su-responsive-media-yes\"><iframe class=\"lazy-loaded\" src=\"https:\/\/www.youtube.com\/embed\/xflY5uS-nnw?\" width=\"340\" height=\"200\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\" data-lazy-type=\"iframe\" data-src=\"https:\/\/www.youtube.com\/embed\/xflY5uS-nnw?\" data-mce-fragment=\"1\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\"><span>Contrairement au\u00a0<\/span><a title=\"Cycle Otto - Moteur Otto\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-otto-cycle-otto-engine-definition\/\"><strong><span>cycle Otto<\/span><\/strong><\/a><span>\u00a0, le\u00a0<\/span><strong><span>cycle Diesel<\/span><\/strong><span>\u00a0n&#8217;ex\u00e9cute pas d&#8217;addition de chaleur isochore.\u00a0Dans un cycle Diesel id\u00e9al, le syst\u00e8me ex\u00e9cutant le cycle subit une s\u00e9rie de quatre processus: deux processus isentropiques (adiabatiques r\u00e9versibles) altern\u00e9s avec un processus isochore et un processus isobare.<\/span><span>\u00c9tant donn\u00e9 que\u00a0<\/span><a title=\"Principe de Carnot - La r\u00e8gle de Carnot\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/second-law-of-thermodynamics\/carnots-principle-carnots-rule\/\"><strong><span>le principe de Carnot<\/span><\/strong><\/a><span>\u00a0stipule qu&#8217;aucun moteur ne peut \u00eatre plus efficace qu&#8217;un moteur r\u00e9versible (\u00a0<\/span><strong><span>un moteur thermique Carnot<\/span><\/strong><span>\u00a0) fonctionnant entre les m\u00eames r\u00e9servoirs haute temp\u00e9rature et basse temp\u00e9rature, le moteur diesel doit avoir une efficacit\u00e9 inf\u00e9rieure \u00e0 l&#8217;efficacit\u00e9 Carnot.\u00a0Un\u00a0<\/span><strong><span>moteur automobile diesel<\/span><\/strong><span>\u00a0typique\u00a0fonctionne \u00e0 environ\u00a0<\/span><strong><span>30% \u00e0 35%<\/span><\/strong><span>\u00a0d&#8217;efficacit\u00e9 thermique.\u00a0Environ 65 \u00e0 70% est rejet\u00e9 comme chaleur r\u00e9siduelle sans \u00eatre converti en travail utile, c&#8217;est-\u00e0-dire travail livr\u00e9 aux roues.\u00a0En g\u00e9n\u00e9ral, les moteurs utilisant le cycle Diesel sont g\u00e9n\u00e9ralement plus efficaces que les moteurs utilisant le cycle Otto.\u00a0Le moteur diesel a le rendement thermique le plus \u00e9lev\u00e9 de tous les moteurs \u00e0 combustion pratiques.\u00a0<\/span><strong><span>Moteurs diesel \u00e0 basse vitesse<\/span><\/strong><span>(utilis\u00e9 sur les navires) peut avoir une efficacit\u00e9 thermique sup\u00e9rieure \u00e0\u00a0<\/span><strong><span>50%<\/span><\/strong><span>\u00a0.\u00a0Le plus gros moteur diesel au monde culmine \u00e0 51,7%.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Cycle Diesel &#8211; Processus<\/span><\/h2>\n<p><span>Dans un cycle Diesel id\u00e9al, le syst\u00e8me ex\u00e9cutant le cycle subit une s\u00e9rie de quatre processus: deux processus isentropiques (adiabatiques r\u00e9versibles) altern\u00e9s avec un processus isochore et un processus isobare.<\/span><\/p>\n<ul>\n<li>\n<figure id=\"attachment_18421\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-18421\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-pV-Diagram.png\"><img loading=\"lazy\" class=\"size-medium wp-image-18421 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-pV-Diagram-300x280.png\" alt=\"Diagramme pV d'un cycle Diesel id\u00e9al\" width=\"300\" height=\"280\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-pV-Diagram-300x280.png\" \/><\/a><figcaption id=\"caption-attachment-18421\" class=\"wp-caption-text\"><span>Diagramme pV d&#8217;un cycle Diesel id\u00e9al<\/span><\/figcaption><\/figure>\n<p><strong><span>Compression isentropique<\/span><\/strong><span>\u00a0(course de compression) &#8211; L&#8217;air est comprim\u00e9 de mani\u00e8re adiabatique de l&#8217;\u00e9tat 1 \u00e0 l&#8217;\u00e9tat 2, lorsque le piston se d\u00e9place du point mort bas au point mort haut.\u00a0Les environs agissent sur le gaz, augmentant son \u00e9nergie interne (temp\u00e9rature) et le compressant.\u00a0En revanche, l&#8217;entropie reste inchang\u00e9e.\u00a0L&#8217;\u00e9volution des volumes et de son rapport (\u00a0<\/span><em><span>V\u00a0<\/span><\/em><em><sub><span>1<\/span><\/sub><\/em><em><span>\u00a0\/ V\u00a0<\/span><\/em><em><sub><span>2<\/span><\/sub><\/em><span>\u00a0) est connue sous le nom de taux de compression.<\/span><\/li>\n<li><strong><span>Expansion isobare<\/span><\/strong><span>\u00a0(phase d&#8217;allumage) &#8211; Dans cette phase (entre l&#8217;\u00e9tat 2 et l&#8217;\u00e9tat 3) il y a un transfert de chaleur \u00e0 pression constante (mod\u00e8le id\u00e9alis\u00e9) vers l&#8217;air \u00e0 partir d&#8217;une source externe (combustion de carburant inject\u00e9) tandis que le piston se d\u00e9place vers le V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0.\u00a0Pendant le processus \u00e0 pression constante, l&#8217;\u00e9nergie p\u00e9n\u00e8tre dans le syst\u00e8me sous forme de chaleur Q\u00a0<\/span><sub><span>ajout\u00e9e<\/span><\/sub><span>\u00a0, et une partie du travail se fait en d\u00e9pla\u00e7ant le piston.<\/span><\/li>\n<li><strong><span>Expansion isentropique<\/span><\/strong><span>\u00a0(course de puissance) &#8211; Le gaz se d\u00e9tend adiabatiquement de l&#8217;\u00e9tat 3 \u00e0 l&#8217;\u00e9tat 4, lorsque le piston se d\u00e9place de V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0au point mort bas.\u00a0Le gaz travaille sur l&#8217;environnement (piston) et perd une quantit\u00e9 d&#8217;\u00e9nergie interne \u00e9gale au travail qui quitte le syst\u00e8me.\u00a0Encore une fois, l&#8217;entropie reste inchang\u00e9e.\u00a0Le rapport volumique (\u00a0<\/span><em><span>V\u00a0<\/span><\/em><em><sub><span>4<\/span><\/sub><\/em><em><span>\u00a0\/ V\u00a0<\/span><\/em><em><sub><span>3<\/span><\/sub><\/em><span>\u00a0) est connu comme le rapport d&#8217;expansion isentropique.<\/span><\/li>\n<li><strong><span>D\u00e9compression isochore (course d&#8217;\u00e9chappement)<\/span><\/strong><span>\u00a0&#8211; Dans cette phase, le cycle se termine par un processus \u00e0 volume constant dans lequel la chaleur est rejet\u00e9e de l&#8217;air tandis que le piston est au point mort bas.\u00a0La pression du gaz de travail chute instantan\u00e9ment du point 4 au point 1. La soupape d&#8217;\u00e9chappement s&#8217;ouvre au point 4. La course d&#8217;\u00e9chappement survient directement apr\u00e8s cette d\u00e9compression.\u00a0Lorsque le piston se d\u00e9place du point mort bas (point 1) au point mort haut (point 0) avec la soupape d&#8217;\u00e9chappement ouverte, le m\u00e9lange gazeux est \u00e9vacu\u00e9 vers l&#8217;atmosph\u00e8re et le processus recommence.<\/span><\/li>\n<\/ul>\n<p><span>Pendant le cycle Diesel, un travail est effectu\u00e9 sur le gaz par le piston entre les \u00e9tats 1 et 2 (\u00a0<\/span><strong><span>i\u00a0<\/span><\/strong><strong><span>compression sentropique<\/span><\/strong><span>\u00a0).\u00a0Le travail se fait par le gaz sur le piston entre les \u00e9tapes 2 et 3 (\u00a0<\/span><strong><span>i\u00a0<\/span><\/strong><strong><span>addition de chaleur sobarique<\/span><\/strong><span>\u00a0) et entre les \u00e9tapes 2 et 3 (\u00a0<\/span><strong><span>i\u00a0<\/span><\/strong><strong><span>expansion sentropique<\/span><\/strong><span>\u00a0).\u00a0La diff\u00e9rence entre le travail effectu\u00e9 par le gaz et le travail effectu\u00e9 sur le gaz est le travail net produit par le cycle et il correspond \u00e0 la zone d\u00e9limit\u00e9e par la courbe du cycle.\u00a0Le travail produit par le cycle multiplie la vitesse du cycle (cycles par seconde) par la puissance produite par le moteur Diesel.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Processus isentropique<\/span><\/h2>\n<p><span>Un\u00a0<\/span><a title=\"Processus isentropique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quel-est-le-processus-isentropique-definition\/\"><strong><span>processus isentropique<\/span><\/strong><\/a><span>\u00a0est un\u00a0<\/span><a title=\"Processus thermodynamiques\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-processus-thermodynamique-definition\/\"><strong><span>processus thermodynamique<\/span><\/strong><\/a><span>\u00a0, dans lequel l&#8217;\u00a0<\/span><a title=\"Qu'est-ce que l'entropie\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/what-is-entropy\/\"><strong><span>entropie<\/span><\/strong>\u00a0<\/a><span>du fluide ou du gaz reste constante.\u00a0Cela signifie que le\u00a0<\/span><strong><span>processus isentropique<\/span><\/strong><span>\u00a0est un cas particulier d&#8217;un\u00a0<\/span><strong><span>processus adiabatique<\/span><\/strong><span>\u00a0dans lequel il n&#8217;y a pas de transfert de chaleur ou de mati\u00e8re.\u00a0Il s&#8217;agit d&#8217;un\u00a0<\/span><strong><span>processus adiabatique r\u00e9versible<\/span><\/strong><span>\u00a0.\u00a0L&#8217;hypoth\u00e8se d&#8217;absence de transfert de chaleur est tr\u00e8s importante, car nous ne pouvons utiliser l&#8217;approximation adiabatique que dans\u00a0<\/span><strong><span>des processus tr\u00e8s rapides<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><strong><span>Processus isentropique et premi\u00e8re loi<\/span><\/strong><\/p>\n<p><span>Pour un syst\u00e8me ferm\u00e9, on peut \u00e9crire la\u00a0<\/span><strong><a title=\"Premi\u00e8re loi en termes d'enthalpie dH = dQ + Vdp\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/first-law-in-terms-of-enthalpy-dh-dq-vdp\/\"><span>premi\u00e8re loi de la thermodynamique en termes d&#8217;enthalpie<\/span><\/a><\/strong><span>\u00a0:<\/span><\/p>\n<p><strong><span>dH = dQ + Vdp<\/span><\/strong><\/p>\n<p><strong><span>ou<\/span><\/strong><\/p>\n<p><strong><span>dH = TdS + Vdp<\/span><\/strong><\/p>\n<p><strong><span>Processus isentropique (dQ = 0):<\/span><\/strong><\/p>\n<p><strong><span>dH = Vdp \u2192 W = H\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><strong><span>\u00a0&#8211; H\u00a0<\/span><\/strong><strong><sub><span>1<\/span><\/sub><\/strong><strong><span>\u00a0\u00a0\u00a0\u00a0\u00a0\u2192 H\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><strong><span>\u00a0&#8211; H\u00a0<\/span><\/strong><strong><sub><span>1<\/span><\/sub><\/strong><strong><span>\u00a0=\u00a0<\/span><em><span>C\u00a0<\/span><\/em><\/strong><strong><em><sub><span>p<\/span><\/sub><\/em><\/strong><strong><em><span>\u00a0(T\u00a0<\/span><\/em><\/strong><strong><em><sub><span>2<\/span><\/sub><\/em><\/strong><strong><em><span>\u00a0&#8211; T\u00a0<\/span><\/em><\/strong><strong><em><sub><span>1<\/span><\/sub><\/em><\/strong><strong><em><span>\u00a0) \u00a0\u00a0\u00a0<\/span><\/em><\/strong><em><span>\u00a0(pour\u00a0<\/span><a title=\"Qu'est-ce que le gaz parfait\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/what-is-ideal-gas\/\"><span>le gaz parfait<\/span><\/a><span>\u00a0)<\/span><\/em><\/p>\n<p><strong><span>Processus isentropique du gaz parfait<\/span><\/strong><\/p>\n<p><span>Le\u00a0<\/span><strong><span>processus isentropique<\/span><\/strong><span>\u00a0(un cas particulier du processus adiabatique) peut \u00eatre exprim\u00e9 avec la\u00a0<\/span><a title=\"Loi du gaz parfait\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/\"><strong><span>loi du gaz parfait<\/span><\/strong><\/a><span>\u00a0comme:<\/span><\/p>\n<p><strong><em><span>pV\u00a0<\/span><sup><span>\u03ba<\/span><\/sup><span>\u00a0= constant<\/span><\/em><\/strong><\/p>\n<p><span>ou<\/span><\/p>\n<p><em><strong><span>p\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0V\u00a0<\/span><sub><span>1\u00a0<\/span><\/sub><sup><span>\u03ba<\/span><\/sup><span>\u00a0= p\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0V\u00a0<\/span><sub><span>2\u00a0<\/span><\/sub><sup><span>\u03ba<\/span><\/sup><\/strong><\/em><\/p>\n<p><span>dans laquelle\u00a0<\/span><strong><span>\u03ba = c\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0\/ c\u00a0<\/span><sub><span>v<\/span><\/sub><\/strong><span>\u00a0est le rapport des\u00a0<a title=\"Capacit\u00e9 calorifique - Capacit\u00e9 calorifique sp\u00e9cifique\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/heat-capacity\/\"><strong>chaleurs sp\u00e9cifiques<\/strong><\/a>\u00a0(ou\u00a0<strong>capacit\u00e9s calorifiques<\/strong>\u00a0) pour le gaz.\u00a0Un pour\u00a0<strong>une pression constante (c\u00a0<\/strong><strong><sub>p<\/sub><\/strong><strong>\u00a0)<\/strong>\u00a0et un pour\u00a0<strong>un volume constant (c\u00a0<\/strong><strong><sub>v<\/sub><\/strong><strong>\u00a0)<\/strong>\u00a0.\u00a0Notez que ce rapport\u00a0<strong>\u03ba\u00a0\u00a0<\/strong><strong>= c\u00a0<\/strong><strong><sub>p<\/sub><\/strong><strong>\u00a0\/ c\u00a0<\/strong><strong><sub>v<\/sub><\/strong>\u00a0est un facteur d\u00e9terminant la vitesse du son dans un gaz et d&#8217;autres processus adiabatiques.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights \">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Processus isochorique<\/span><\/h2>\n<p><span>Un\u00a0<\/span><a title=\"Processus isochorique - Processus isom\u00e9trique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-processus-isochorique-processus-isometrique-definition\/\"><strong><span>processus isochore<\/span><\/strong><\/a><span>\u00a0est un processus thermodynamique, dans lequel le\u00a0<\/span><strong><span>volume<\/span><\/strong><span>\u00a0du syst\u00e8me ferm\u00e9\u00a0<\/span><strong><span>reste constant<\/span><\/strong><span>\u00a0(V = const).\u00a0Il d\u00e9crit le comportement du gaz \u00e0 l&#8217;int\u00e9rieur du conteneur, qui ne peut pas \u00eatre d\u00e9form\u00e9.\u00a0\u00c9tant donn\u00e9 que le volume reste constant, le transfert de chaleur dans ou hors du syst\u00e8me ne fonctionne pas avec le\u00a0<\/span><a title=\"Travaux p\u0394V - Travaux aux limites et travaux V\u0394p\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/p%ce%b4v-work-boundary-work-and-v%ce%b4p-work\/\"><span>p\u2206V<\/span><\/a><span>\u00a0, mais modifie uniquement l&#8217;\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lenergie-interne-energie-thermique-definition\/\"><strong><span>\u00e9nergie interne<\/span><\/strong><\/a><span>\u00a0(la temp\u00e9rature) du syst\u00e8me.<\/span><\/p>\n<p><strong><span>Processus isochorique et premi\u00e8re loi<\/span><\/strong><\/p>\n<p><span>La forme classique de la\u00a0<\/span><a title=\"Premi\u00e8re loi de la thermodynamique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-premiere-loi-de-la-thermodynamique-definition\/\"><span>premi\u00e8re loi de la thermodynamique<\/span><\/a><span>\u00a0est l&#8217;\u00e9quation suivante:<\/span><\/p>\n<p><strong><span>dU = dQ &#8211; dW<\/span><\/strong><\/p>\n<p><span>Dans cette \u00e9quation, dW est \u00e9gal \u00e0\u00a0<\/span><strong><span>dW = pdV<\/span><\/strong><span>\u00a0et est connu comme le\u00a0<\/span><a title=\"Travaux p\u0394V - Travaux aux limites et travaux V\u0394p\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/p%ce%b4v-work-boundary-work-and-v%ce%b4p-work\/\"><span>travail<\/span><\/a><span>\u00a0aux\u00a0<a title=\"Travaux p\u0394V - Travaux aux limites et travaux V\u0394p\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/p%ce%b4v-work-boundary-work-and-v%ce%b4p-work\/\">limites<\/a>\u00a0.\u00a0Alors:<\/span><\/p>\n<p><strong><span>dU = dQ &#8211; pdV<\/span><\/strong><\/p>\n<p><span>Dans le\u00a0<\/span><strong><span>processus isochore<\/span><\/strong><span>\u00a0et le\u00a0<\/span><strong><span>gaz parfait<\/span><\/strong><span>\u00a0, toute la chaleur ajout\u00e9e au syst\u00e8me sera utilis\u00e9e pour augmenter l&#8217;\u00e9nergie interne.<\/span><\/p>\n<p><strong><span>Processus isochorique (pdV = 0):<\/span><\/strong><\/p>\n<p><strong><span>dU = dQ \u00a0\u00a0\u00a0\u00a0<\/span><\/strong><em><span>(pour le gaz parfait)<\/span><\/em><\/p>\n<p><strong><span>dU = 0 = Q &#8211; W \u2192 W = Q \u00a0\u00a0<\/span><em>\u00a0\u00a0\u00a0\u00a0<\/em><\/strong><em><span>(pour le gaz parfait)<\/span><\/em><\/p>\n<p><strong><span>Processus isochorique du gaz parfait<\/span><\/strong><\/p>\n<p><span>Le\u00a0<\/span><strong><span>processus isochore<\/span><\/strong><span>\u00a0peut s&#8217;exprimer avec la\u00a0<\/span><a title=\"Loi du gaz parfait\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/\"><strong><span>loi du gaz parfait<\/span><\/strong><\/a><span>\u00a0comme:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isochoric-process-equation-1.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17465 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isochoric-process-equation-1.png\" alt=\"processus isochore - \u00e9quation 1\" width=\"138\" height=\"52\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isochoric-process-equation-1.png\" \/><\/a><\/p>\n<p><span>ou<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isochoric-process-equation-2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17466 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isochoric-process-equation-2.png\" alt=\"processus isochore - \u00e9quation 2\" width=\"86\" height=\"66\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isochoric-process-equation-2.png\" \/><\/a><\/p>\n<p><span>Sur un\u00a0<\/span><strong><span>diagramme pV<\/span><\/strong><span>\u00a0, le processus se produit le long d&#8217;une ligne horizontale qui a l&#8217;\u00e9quation V = constante.<\/span><\/p>\n<p><span>Voir aussi:\u00a0\u00a0<\/span><a title=\"Loi de Guy-Lussac\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-loi-gay-lussac-definition\/\"><span>Loi de Guy-Lussac<\/span><\/a><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Processus isobare<\/span><\/h2>\n<p><span>Un\u00a0<\/span><strong><span>processus isobare<\/span><\/strong><span>\u00a0est un\u00a0<\/span><a title=\"Processus thermodynamiques\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-processus-thermodynamique-definition\/\"><span>processus thermodynamique<\/span><\/a><span>\u00a0, dans lequel la\u00a0<\/span><a title=\"Qu'est-ce que la pression - Physique\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-pressure-physics\/\"><strong><span>pression<\/span><\/strong><\/a><span>\u00a0du syst\u00e8me\u00a0<\/span><strong><span>reste constante<\/span><\/strong><span>\u00a0(p = const).\u00a0Le transfert de chaleur dans ou hors du syst\u00e8me fonctionne, mais modifie \u00e9galement l&#8217;\u00e9nergie interne du syst\u00e8me.<\/span><\/p>\n<p><span>Puisqu&#8217;il y a des changements d&#8217;\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lenergie-interne-energie-thermique-definition\/\"><span>\u00e9nergie interne<\/span><\/a><span>\u00a0(dU) et des changements de volume du syst\u00e8me (\u2206V), les ing\u00e9nieurs utilisent souvent l&#8217;\u00a0<\/span><a title=\"Qu'est-ce que l'enthalpie\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/what-is-enthalpy\/\"><strong><span>enthalpie<\/span><\/strong><\/a><span>\u00a0du syst\u00e8me, qui est d\u00e9finie comme:<\/span><\/p>\n<p><em><strong><span>H = U + pV<\/span><\/strong><\/em><\/p>\n<p><strong><span>Processus isobare et premi\u00e8re loi<\/span><\/strong><\/p>\n<p><span>La forme classique de la\u00a0<\/span><a title=\"Premi\u00e8re loi de la thermodynamique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-premiere-loi-de-la-thermodynamique-definition\/\"><span>premi\u00e8re loi de la thermodynamique<\/span><\/a><span>\u00a0est l&#8217;\u00e9quation suivante:<\/span><\/p>\n<p><strong><span>dU = dQ &#8211; dW<\/span><\/strong><\/p>\n<p><span>Dans cette \u00e9quation, dW est \u00e9gal \u00e0\u00a0<\/span><strong><span>dW = pdV<\/span><\/strong><span>\u00a0et est connu comme le\u00a0<\/span><a title=\"Travaux p\u0394V - Travaux aux limites et travaux V\u0394p\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/p%ce%b4v-work-boundary-work-and-v%ce%b4p-work\/\"><span>travail<\/span><\/a><span>\u00a0aux\u00a0<a title=\"Travaux p\u0394V - Travaux aux limites et travaux V\u0394p\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/p%ce%b4v-work-boundary-work-and-v%ce%b4p-work\/\">limites<\/a>\u00a0.\u00a0Dans un proc\u00e9d\u00e9 isobare et le gaz parfait, une\u00a0<\/span><strong><span>partie de la chaleur ajout\u00e9e<\/span><\/strong><span>\u00a0au syst\u00e8me sera utilis\u00e9e pour\u00a0<\/span><strong><span>faire le travail<\/span><\/strong><span>\u00a0et une\u00a0<\/span><strong><span>partie de la chaleur<\/span><\/strong><span>\u00a0ajout\u00e9e augmentera l&#8217;\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lenergie-interne-energie-thermique-definition\/\"><strong><span>\u00e9nergie interne<\/span><\/strong><\/a><span>\u00a0(augmentera la temp\u00e9rature).\u00a0Par cons\u00e9quent, il est commode d&#8217;utiliser l&#8217;\u00a0<\/span><strong><span>enthalpie<\/span><\/strong><span>\u00a0au lieu de l&#8217;\u00e9nergie interne.<\/span><\/p>\n<p><strong><span>Processus isobare (Vdp = 0):<\/span><\/strong><\/p>\n<p><strong><span>dH = dQ \u2192 Q = H\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><strong><span>\u00a0&#8211; H\u00a0<\/span><\/strong><strong><sub><span>1<\/span><\/sub><\/strong><\/p>\n<p><strong><span>\u00c0 entropie constante<\/span><\/strong><span>\u00a0, c&#8217;est-\u00e0-dire dans un processus isentropique, le\u00a0<\/span><strong><span>changement d&#8217;enthalpie<\/span><\/strong><span>\u00a0est \u00e9gal au\u00a0<\/span><strong><span>travail de processus d&#8217;\u00e9coulement<\/span><\/strong><span>\u00a0effectu\u00e9 sur ou par le syst\u00e8me.<\/span><\/p>\n<p><strong><span>Processus isobare du gaz parfait<\/span><\/strong><\/p>\n<p><span>Le\u00a0<\/span><strong><span>processus isobare<\/span><\/strong><span>\u00a0peut s&#8217;exprimer avec la\u00a0<\/span><a title=\"Loi du gaz parfait\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/\"><strong><span>loi du gaz parfait<\/span><\/strong><\/a><span>\u00a0comme:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isobaric-process-equation-2.png?a34b7f\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17430 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isobaric-process-equation-2.png?a34b7f\" alt=\"processus isobare - \u00e9quation - 2\" width=\"134\" height=\"63\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isobaric-process-equation-2.png?a34b7f\" \/><\/a><\/p>\n<p><span>ou<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isobaric-process-equation-3.png?a34b7f\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17431 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isobaric-process-equation-3.png?a34b7f\" alt=\"processus isobare - \u00e9quation - 3\" width=\"77\" height=\"67\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/isobaric-process-equation-3.png?a34b7f\" \/><\/a><\/p>\n<p><span>Sur un\u00a0<\/span><strong><span>diagramme pV<\/span><\/strong><span>\u00a0, le processus se produit le long d&#8217;une ligne horizontale (appel\u00e9e isobare) qui a l&#8217;\u00e9quation p = constante.<\/span><\/p>\n<p><span>Voir aussi:\u00a0<\/span><a title=\"La loi de Charles\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-loi-de-charles-definition\/\"><span>Charles&#8217;s Law<\/span><\/a><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_17280\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-17280\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isentropic-Process-characteristics.png\"><img loading=\"lazy\" class=\"size-full wp-image-17280 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isentropic-Process-characteristics.png\" alt=\"Processus isentropique - caract\u00e9ristiques\" width=\"386\" height=\"609\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isentropic-Process-characteristics.png\" \/><\/a><figcaption id=\"caption-attachment-17280\" class=\"wp-caption-text\"><span>Processus isentropique &#8211; principales caract\u00e9ristiques<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights \">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_17463\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-17463\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isochoric-process-main-characteristics.png\"><img loading=\"lazy\" class=\"size-full wp-image-17463 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isochoric-process-main-characteristics.png\" alt=\"Processus isochorique - principales caract\u00e9ristiques\" width=\"382\" height=\"468\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isochoric-process-main-characteristics.png\" \/><\/a><figcaption id=\"caption-attachment-17463\" class=\"wp-caption-text\"><span>Processus isochorique &#8211; principales caract\u00e9ristiques<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_17426\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-17426\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isobaric-process-main-characteristics.png\"><img loading=\"lazy\" class=\"size-full wp-image-17426 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isobaric-process-main-characteristics.png\" alt=\"Processus isobare - principales caract\u00e9ristiques\" width=\"381\" height=\"717\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Isobaric-process-main-characteristics.png\" \/><\/a><figcaption id=\"caption-attachment-17426\" class=\"wp-caption-text\"><span>Processus isobare &#8211; principales caract\u00e9ristiques<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Comparaison des cycles diesel r\u00e9els et id\u00e9aux<\/span><\/h2>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Diesel-engine.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-18418 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Diesel-engine-300x274.png\" alt=\"cycle diesel r\u00e9el - Moteur diesel\" width=\"300\" height=\"274\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Diesel-engine-300x274.png\" \/><\/a><span>Dans cet article, il est montr\u00e9 un\u00a0<\/span><strong><span>cycle Diesel id\u00e9al<\/span><\/strong><span>\u00a0dans lequel il y a beaucoup d&#8217;hypoth\u00e8ses diff\u00e9rentes du\u00a0<\/span><strong><span>cycle Diesel r\u00e9el<\/span><\/strong><span>\u00a0.\u00a0Les principales diff\u00e9rences entre le moteur diesel r\u00e9el et le moteur diesel id\u00e9al apparaissent sur la figure.\u00a0En r\u00e9alit\u00e9, le cycle id\u00e9al ne se produit pas et il y a de nombreuses pertes associ\u00e9es \u00e0 chaque processus.\u00a0Pour un cycle r\u00e9el, la forme du diagramme pV est similaire \u00e0 l&#8217;id\u00e9al, mais la zone (travail) entour\u00e9e par le diagramme pV est toujours inf\u00e9rieure \u00e0 la valeur id\u00e9ale.\u00a0Le cycle Diesel id\u00e9al est bas\u00e9 sur les hypoth\u00e8ses suivantes:<\/span><\/p>\n<ul>\n<li><strong><span>Cycle ferm\u00e9<\/span><\/strong><span>\u00a0: La plus grande diff\u00e9rence entre les deux diagrammes est la simplification des courses d&#8217;admission et d&#8217;\u00e9chappement dans le cycle id\u00e9al.\u00a0Lors de la course d&#8217;\u00e9chappement, la chaleur Q\u00a0<\/span><sub><span>out<\/span><\/sub><span>\u00a0est \u00e9ject\u00e9e dans l&#8217;environnement (dans un vrai moteur, le gaz quitte le moteur et est remplac\u00e9 par un nouveau m\u00e9lange d&#8217;air et de carburant).<\/span><\/li>\n<li><strong><span>Ajout de chaleur isobare<\/span><\/strong><span>\u00a0.\u00a0Dans les moteurs r\u00e9els, l&#8217;apport de chaleur n&#8217;est jamais isobare.<\/span><\/li>\n<li><strong><span>Pas de transfert de chaleur<\/span><\/strong>\n<ul>\n<li><span>Compression &#8211; Le gaz est comprim\u00e9 adiabatiquement de l&#8217;\u00e9tat 1 \u00e0 l&#8217;\u00e9tat 2. Dans les moteurs r\u00e9els, il y a toujours des inefficacit\u00e9s qui r\u00e9duisent l&#8217;efficacit\u00e9 thermique.<\/span><\/li>\n<li><span>Expansion.\u00a0Le gaz se d\u00e9tend adiabatiquement de l&#8217;\u00e9tat 3 \u00e0 l&#8217;\u00e9tat 4.<\/span><\/li>\n<\/ul>\n<\/li>\n<li><strong><span>Combustion compl\u00e8te<\/span><\/strong><span>\u00a0du m\u00e9lange.<\/span><\/li>\n<li><strong><span>Aucun travail de pompage<\/span><\/strong><span>\u00a0.\u00a0Le travail de pompage est la diff\u00e9rence entre le travail effectu\u00e9 pendant la course d&#8217;\u00e9chappement et le travail effectu\u00e9 pendant la course d&#8217;admission.\u00a0Dans les cycles r\u00e9els, il existe une diff\u00e9rence de pression entre les pressions d&#8217;\u00e9chappement et d&#8217;entr\u00e9e.<\/span><\/li>\n<li><strong><span>Aucune perte de purge<\/span><\/strong><span>\u00a0.\u00a0La perte de purge est caus\u00e9e par l&#8217;ouverture pr\u00e9coce des soupapes d&#8217;\u00e9chappement.\u00a0Il en r\u00e9sulte une perte de rendement de travail pendant la course d&#8217;expansion.<\/span><\/li>\n<li><strong><span>Pas de perte par coup<\/span><\/strong><span>\u00a0.\u00a0La perte par soufflage est caus\u00e9e par la fuite de gaz comprim\u00e9s \u00e0 travers les segments de piston et autres crevasses.<\/span><\/li>\n<li><strong><span>Pas de pertes par friction<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<\/ul>\n<p><span>Ces hypoth\u00e8ses et pertes simplificatrices conduisent au fait que la zone ferm\u00e9e (travail) du diagramme pV pour un moteur r\u00e9el est significativement plus petite que la taille de la zone (travail) incluse par le diagramme pV du cycle id\u00e9al.\u00a0En d&#8217;autres termes, le cycle moteur id\u00e9al surestimera le travail net et, si les moteurs tournent \u00e0 la m\u00eame vitesse, une plus grande puissance produite par le moteur r\u00e9el d&#8217;environ 20% (de la m\u00eame mani\u00e8re que dans le cas du moteur Otto).<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Efficacit\u00e9 thermique pour le cycle diesel<\/span><\/h2>\n<p><span>En g\u00e9n\u00e9ral ,\u00a0le\u00a0<a title=\"Efficacit\u00e9 thermique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lefficacite-thermique-definition\/\"><strong>rendement thermique<\/strong><\/a><a title=\"Efficacit\u00e9 thermique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lefficacite-thermique-definition\/\">\u00a0,\u00a0<\/a><a title=\"Efficacit\u00e9 thermique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lefficacite-thermique-definition\/\"><strong><em>\u03b7\u00a0<\/em><\/strong><\/a><a title=\"Efficacit\u00e9 thermique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lefficacite-thermique-definition\/\"><strong><em><sub>e<\/sub><\/em><\/strong><\/a>\u00a0, d&#8217;un moteur thermique est d\u00e9finie comme \u00e9tant le rapport entre le\u00a0<a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-travail-en-thermodynamique-definition\/\">travail<\/a>\u00a0qu&#8217;elle fait,\u00a0<strong>W<\/strong>\u00a0, \u00e0 la\u00a0<a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-chaleur-en-physique-chaleur-definition\/\">chaleur<\/a>\u00a0d&#8217; entr\u00e9e \u00e0 la temp\u00e9rature \u00e9lev\u00e9e, Q\u00a0<sub>H<\/sub>\u00a0.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-formula-1.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-16945 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-formula-1.png\" alt=\"formule d'efficacit\u00e9 thermique - 1\" width=\"125\" height=\"82\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-formula-1.png\" \/><\/a><\/p>\n<p><span>L&#8217;\u00a0<\/span><strong><span>efficacit\u00e9 thermique<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><em><span>\u03b7\u00a0<\/span><\/em><\/strong><strong><em><sub><span>th<\/span><\/sub><\/em><\/strong><span>\u00a0, repr\u00e9sente la fraction de\u00a0<\/span><strong><span>chaleur<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><span>Q\u00a0<\/span><\/strong><strong><sub><span>H<\/span><\/sub><\/strong><span>\u00a0, qui est convertie\u00a0<\/span><strong><span>en travail<\/span><\/strong><span>\u00a0.\u00a0Puisque l&#8217;\u00e9nergie est conserv\u00e9e selon la\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-premiere-loi-de-la-thermodynamique-definition\/\"><strong><span>premi\u00e8re loi de la thermodynamique<\/span><\/strong><\/a><span>\u00a0et que l&#8217;\u00e9nergie ne peut pas \u00eatre convertie pour fonctionner compl\u00e8tement, l&#8217;apport de chaleur, Q\u00a0<\/span><sub><span>H<\/span><\/sub><span>\u00a0, doit \u00eatre \u00e9gal au travail effectu\u00e9, W, plus la chaleur qui doit \u00eatre dissip\u00e9e sous forme de\u00a0<\/span><strong><span>chaleur r\u00e9siduelle Q\u00a0<\/span><\/strong><strong><sub><span>C<\/span><\/sub><\/strong><span>\u00a0dans le environnement.\u00a0Par cons\u00e9quent, nous pouvons r\u00e9\u00e9crire la formule de l&#8217;efficacit\u00e9 thermique comme suit:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-formula-2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-16944 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-formula-2.png\" alt=\"formule d'efficacit\u00e9 thermique - 2\" width=\"352\" height=\"83\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-formula-2.png\" \/><\/a><\/p>\n<p><span>La chaleur absorb\u00e9e se produit pendant la combustion du m\u00e9lange carburant-air, lorsque l&#8217;\u00e9tincelle se produit, \u00e0 peu pr\u00e8s \u00e0 volume constant.\u00a0Puisqu&#8217;au cours d&#8217;un\u00a0<\/span><a title=\"Processus isochorique - Processus isom\u00e9trique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-processus-isochorique-processus-isometrique-definition\/\"><span>processus isochore,<\/span><\/a><span>\u00a0aucun travail n&#8217;est effectu\u00e9 par ou sur le syst\u00e8me, la\u00a0<\/span><strong><span>premi\u00e8re loi de la thermodynamique<\/span><\/strong><span>\u00a0dicte\u00a0<\/span><em><span>\u2206U = \u2206Q.\u00a0<\/span><\/em><span>Par cons\u00e9quent, la chaleur ajout\u00e9e et rejet\u00e9e est donn\u00e9e par:<\/span><\/p>\n<p><span>Q\u00a0<\/span><sub><span>add<\/span><\/sub><span>\u00a0= mc\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0(T\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0&#8211; T\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0)<\/span><\/p>\n<p><span>Q\u00a0<\/span><sub><span>out<\/span><\/sub><span>\u00a0= mc\u00a0<\/span><sub><span>v<\/span><\/sub><span>\u00a0(T\u00a0<\/span><sub><span>4<\/span><\/sub><span>\u00a0&#8211; T\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0)<\/span><\/p>\n<p><span>En substituant ces expressions \u00e0 la chaleur ajout\u00e9e et rejet\u00e9e dans l&#8217;expression pour l&#8217;efficacit\u00e9 thermique, on obtient:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-18419 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency.png\" alt=\"\" width=\"210\" height=\"71\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency.png\" \/><\/a><\/p>\n<p><span>Cette \u00e9quation peut \u00eatre r\u00e9organis\u00e9e \u00e0 la forme avec le taux de compression et le taux de coupure:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-18420 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency2.png\" alt=\"\" width=\"300\" height=\"65\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency2.png\" \/><\/a><\/p>\n<p><span>o\u00f9<\/span><\/p>\n<ul>\n<li><strong><span>\u03b7\u00a0<\/span><sub><span>Diesel<\/span><\/sub><\/strong><span>\u00a0est l&#8217;efficacit\u00e9 thermique maximale d&#8217;un cycle Diesel<\/span><\/li>\n<li><span>\u03b1 est le rapport de\u00a0<\/span><strong><span>coupure<\/span><\/strong><span>\u00a0V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0(c&#8217;est-\u00e0-dire le rapport des volumes \u00e0 la fin et au d\u00e9but de la phase de combustion)<\/span><\/li>\n<li><strong><span>CR<\/span><\/strong><span>\u00a0est le\u00a0<\/span><strong><span>taux de compression<\/span><\/strong><\/li>\n<li><strong><span>\u03ba = c\u00a0<\/span><\/strong><strong><sub><span>p<\/span><\/sub><\/strong><strong><span>\u00a0\/ c\u00a0<\/span><\/strong><strong><sub><span>v<\/span><\/sub><\/strong><strong><span>\u00a0= 1,4<\/span><\/strong><\/li>\n<\/ul>\n<p><span>C&#8217;est une conclusion tr\u00e8s utile, car il est souhaitable d&#8217;atteindre un taux de compression \u00e9lev\u00e9 pour extraire plus d&#8217;\u00e9nergie m\u00e9canique d&#8217;une masse donn\u00e9e de carburant.\u00a0Comme nous l&#8217;avons conclu dans la section pr\u00e9c\u00e9dente, l&#8217;efficacit\u00e9 thermique du cycle Otto standard de l&#8217;air est \u00e9galement fonction du taux de compression et de \u03ba.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-Otto-Cycle-Compression-ratio.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17560 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-Otto-Cycle-Compression-ratio.png\" alt=\"efficacit\u00e9 thermique - Cycle d'Otto - Taux de compression\" width=\"570\" height=\"80\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-efficiency-Otto-Cycle-Compression-ratio.png\" \/><\/a><\/p>\n<p><span>Lorsque nous les comparons \u00e0 des formules, nous pouvons voir que pour un taux de compression (CR) donn\u00e9, le cycle Otto sera plus efficace que le cycle Diesel.\u00a0Mais les moteurs diesel sont g\u00e9n\u00e9ralement plus efficaces car ils peuvent fonctionner \u00e0 des taux de compression plus \u00e9lev\u00e9s.<\/span><\/p>\n<p><span>Dans les moteurs Otto ordinaires, le taux de compression a ses limites.\u00a0Le taux de compression dans un moteur \u00e0 essence ne sera g\u00e9n\u00e9ralement pas beaucoup plus \u00e9lev\u00e9 que 10: 1.\u00a0Des taux de compression plus \u00e9lev\u00e9s soumettront les moteurs \u00e0 essence aux cognements du moteur, caus\u00e9s par l&#8217;auto-inflammation, en un m\u00e9lange non br\u00fbl\u00e9, si du carburant \u00e0 indice d&#8217;octane inf\u00e9rieur est utilis\u00e9.\u00a0Dans les moteurs diesel, le risque d&#8217;auto-inflammation du carburant est minime, car les moteurs diesel sont des moteurs \u00e0 allumage par compression et il n&#8217;y a pas de carburant dans le cylindre au d\u00e9but de la course de compression.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Cycle Diesel &#8211; Probl\u00e8me avec la solution<\/span><\/h2>\n<figure id=\"attachment_18421\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-18421\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-pV-Diagram.png\"><img loading=\"lazy\" class=\"size-medium wp-image-18421 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-pV-Diagram-300x280.png\" alt=\"Diagramme pV d'un cycle Diesel id\u00e9al\" width=\"300\" height=\"280\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-pV-Diagram-300x280.png\" \/><\/a><figcaption id=\"caption-attachment-18421\" class=\"wp-caption-text\"><span>Diagramme pV d&#8217;un cycle Diesel id\u00e9al<\/span><\/figcaption><\/figure>\n<p><span>Supposons le cycle Diesel, qui est l&#8217;un des\u00a0<\/span><strong><span>cycles thermodynamiques<\/span><\/strong><span>\u00a0les plus courants\u00a0que l&#8217;on puisse trouver dans les\u00a0<\/span><strong><span>moteurs d&#8217;automobiles<\/span><\/strong><span>\u00a0.\u00a0L&#8217;un des param\u00e8tres cl\u00e9s de ces moteurs est le changement de volume entre le point mort haut (TDC) et le point mort bas (BDC).\u00a0Le rapport de ces volumes (\u00a0<\/span><em><span>V\u00a0<\/span><\/em><em><sub><span>1<\/span><\/sub><\/em><em><span>\u00a0\/ V\u00a0<\/span><\/em><em><sub><span>2<\/span><\/sub><\/em><span>\u00a0) est appel\u00e9\u00a0<\/span><strong><span>taux de compression<\/span><\/strong><span>\u00a0.\u00a0\u00c9galement le rapport de coupure V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0, qui est le rapport des volumes \u00e0 la fin et au d\u00e9but de la phase de combustion.<\/span><\/p>\n<p><span>Dans cet exemple, supposons le cycle Diesel avec un taux de compression de CR = 20: 1 et un taux de coupure \u03b1 = 2. L&#8217;air est \u00e0 100 kPa = 1 bar, 20 \u00b0 C (293 K) et le volume de la chambre est de 500 cm\u00b3 avant la course de compression.<\/span><\/p>\n<ul>\n<li><span>Capacit\u00e9 thermique sp\u00e9cifique \u00e0 pression d&#8217;air constante \u00e0 pression atmosph\u00e9rique et temp\u00e9rature ambiante:\u00a0<\/span><strong><span>c\u00a0<\/span><\/strong><strong><sub><span>p<\/span><\/sub><\/strong><strong><span>\u00a0= 1,01 kJ \/ kgK.<\/span><\/strong><\/li>\n<li><span>Capacit\u00e9 calorifique sp\u00e9cifique \u00e0 volume d&#8217;air constant \u00e0 pression atmosph\u00e9rique et temp\u00e9rature ambiante:\u00a0<\/span><strong><span>c\u00a0<\/span><\/strong><strong><sub><span>v<\/span><\/sub><\/strong><strong><span>\u00a0= 0,718 kJ \/ kgK.<\/span><\/strong><\/li>\n<li><strong><span>\u03ba = c\u00a0<\/span><\/strong><strong><sub><span>p<\/span><\/sub><\/strong><strong><span>\u00a0\/ c\u00a0<\/span><\/strong><strong><sub><span>v<\/span><\/sub><\/strong><strong><span>\u00a0= 1,4<\/span><\/strong><\/li>\n<\/ul>\n<p><strong><span>Calculer:<\/span><\/strong><\/p>\n<ol>\n<li><strong><span>la masse d&#8217;air d&#8217;admission<\/span><\/strong><\/li>\n<li><strong><span>la temp\u00e9rature T\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><\/li>\n<li><strong><span>la pression p\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><\/li>\n<li><strong><span>la temp\u00e9rature T\u00a0<\/span><\/strong><strong><sub><span>3<\/span><\/sub><\/strong><\/li>\n<li><strong><span>la quantit\u00e9 de chaleur ajout\u00e9e par la combustion du m\u00e9lange air-carburant<\/span><\/strong><\/li>\n<li><strong><span>l&#8217;efficacit\u00e9 thermique de ce cycle<\/span><\/strong><\/li>\n<li><strong><span>le d\u00e9put\u00e9 europ\u00e9en<\/span><\/strong><\/li>\n<\/ol>\n<p><strong><span>Solution:<\/span><\/strong><\/p>\n<p><span>1)<\/span><\/p>\n<p><span>Au d\u00e9but des calculs, nous devons d\u00e9terminer la quantit\u00e9 de gaz dans le cylindre avant la course de compression.\u00a0En utilisant la loi du gaz parfait, nous pouvons trouver la masse:<\/span><\/p>\n<p><em><span>pV = mR\u00a0<\/span><\/em><em><sub><span>sp\u00e9cifique<\/span><\/sub><\/em><em><span>\u00a0T<\/span><\/em><\/p>\n<p><span>o\u00f9:<\/span><\/p>\n<ul>\n<li><em><span>p<\/span><\/em><span>\u00a0est la pression absolue du gaz<\/span><\/li>\n<li><em><span>m<\/span><\/em><span>\u00a0est la masse de substance<\/span><\/li>\n<li><em><span>T<\/span><\/em><span>\u00a0est la temp\u00e9rature absolue<\/span><\/li>\n<li><em><span>V<\/span><\/em><span>\u00a0est le volume<\/span><\/li>\n<li><em><span>R\u00a0<\/span><\/em><em><sub><span>sp\u00e9cifique<\/span><\/sub><\/em><span>\u00a0est la constante de gaz sp\u00e9cifique, \u00e9gale \u00e0 la constante de gaz universelle divis\u00e9e par la masse molaire (M) du gaz ou du m\u00e9lange.\u00a0Pour l&#8217;air sec R\u00a0<\/span><sub><span>sp\u00e9cifique<\/span><\/sub><span>\u00a0= 287,1 J.kg\u00a0<\/span><sup><span>-1<\/span><\/sup><span>\u00a0.K\u00a0<\/span><sup><span>-1<\/span><\/sup><span>\u00a0.<\/span><\/li>\n<\/ul>\n<p><span>Donc<\/span><\/p>\n<p><strong><span>m<\/span><\/strong><span>\u00a0= p\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0V\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0\/ R\u00a0<\/span><sub><span>sp\u00e9cifique<\/span><\/sub><span>\u00a0T\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0= (100000 \u00d7 500 \u00d7 10\u00a0<\/span><sup><span>-6<\/span><\/sup><span>\u00a0) \/ (287,1 \u00d7 293) =\u00a0<\/span><strong><span>5,95 \u00d7 10\u00a0<\/span><\/strong><strong><sup><span>-4<\/span><\/sup><\/strong><strong><span>\u00a0kg<\/span><\/strong><\/p>\n<p><strong><span>2)<\/span><\/strong><\/p>\n<p><strong><span>Dans ce probl\u00e8me, tous les volumes sont connus:<\/span><\/strong><\/p>\n<ul>\n<li><span>V\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0= V\u00a0<\/span><sub><span>4<\/span><\/sub><span>\u00a0= V\u00a0<\/span><sub><span>max<\/span><\/sub><span>\u00a0= 500 \u00d7 10\u00a0<\/span><sup><span>-6<\/span><\/sup><span>\u00a0m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0(0,5 l)<\/span><\/li>\n<li><span>V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0= V\u00a0<\/span><sub><span>min<\/span><\/sub><span>\u00a0= V\u00a0<\/span><sub><span>max<\/span><\/sub><span>\u00a0\/ CR = 25 \u00d7 10\u00a0<\/span><sup><span>-6<\/span><\/sup><span>\u00a0m\u00a0<\/span><sup><span>3<\/span><\/sup><\/li>\n<\/ul>\n<p><span>Notez que (V\u00a0<\/span><sub><span>max<\/span><\/sub><span>\u00a0&#8211; V\u00a0<\/span><sub><span>min<\/span><\/sub><span>\u00a0) x nombre de cylindres = cylindr\u00e9e totale du moteur<\/span><\/p>\n<p><span>Puisque le processus est adiabatique, nous pouvons utiliser la relation p, V, T suivante pour les processus adiabatiques:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/adiabatic-process-formula.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17558 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/adiabatic-process-formula.png\" alt=\"\" width=\"154\" height=\"84\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/adiabatic-process-formula.png\" \/><\/a><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/adiabatic-formula-example.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17563 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/adiabatic-formula-example.png\" alt=\"\" width=\"155\" height=\"78\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/adiabatic-formula-example.png\" \/><\/a><\/p>\n<p><span>Donc<\/span><\/p>\n<p><span>T\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0= T\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0.\u00a0CR\u00a0<\/span><sup><span>\u03ba &#8211; 1<\/span><\/sup><span>\u00a0= 293.\u00a020\u00a0<\/span><sup><span>0,4<\/span><\/sup><span>\u00a0= 971 K<\/span><\/p>\n<p><span>3)<\/span><\/p>\n<p><span>Encore une fois, nous pouvons utiliser la loi du gaz parfait pour trouver la pression \u00e0 la fin de la course de compression comme:<\/span><\/p>\n<p><strong><span>p\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><span>\u00a0= mR\u00a0<\/span><sub><span>sp\u00e9cifique<\/span><\/sub><span>\u00a0T\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0= 5,95 \u00d7 10\u00a0<\/span><sup><span>-4<\/span><\/sup><span>\u00a0x 287,1 x\u00a0971\/25\u00a0\u00d7 10\u00a0<\/span><sup><span>-6<\/span><\/sup><span>\u00a0= 6635000 Pa =\u00a0<\/span><strong><span>66,35 bar<\/span><\/strong><\/p>\n<p><span>4)<\/span><\/p>\n<p><span>Comme le processus 2 \u2192 3 se produit \u00e0 pression constante, l&#8217;\u00e9quation d&#8217;\u00e9tat du gaz parfait donne<\/span><\/p>\n<p><span>T\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0= (V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0) x T\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0= 1942 K<\/span><\/p>\n<p><span>Pour calculer la quantit\u00e9 de chaleur ajout\u00e9e par la combustion du m\u00e9lange carburant-air,\u00a0<\/span><sub><span>ajoutons<\/span><\/sub><span>\u00a0Q\u00a0, nous devons utiliser le premi\u00e8re principe de la thermodynamique pour le processus isobare, qui stipule:<\/span><\/p>\n<p><span>Q\u00a0<\/span><sub><span>add<\/span><\/sub><span>\u00a0= mc\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0(T\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0&#8211; T\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0) = 5,95 \u00d7 10\u00a0<\/span><sup><span>-4<\/span><\/sup><span>\u00a0x 1010 x 971 =\u00a0<\/span><strong><span>583,5 J<\/span><\/strong><\/p>\n<p><span>5)<\/span><\/p>\n<p><span>Efficacit\u00e9 thermique pour ce cycle Diesel:<\/span><\/p>\n<p><span>Comme il a \u00e9t\u00e9 d\u00e9riv\u00e9 dans la section pr\u00e9c\u00e9dente, l&#8217;efficacit\u00e9 thermique du cycle Diesel est fonction du taux de compression, du taux de coupure et de \u03ba:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-18420 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency2.png\" alt=\"\" width=\"300\" height=\"65\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Diesel-cycle-Thermal-Efficiency2.png\" \/><\/a><span>o\u00f9<\/span><\/p>\n<ul>\n<li><span>\u03b7\u00a0<\/span><sub><span>Diesel<\/span><\/sub><span>\u00a0est l&#8217;efficacit\u00e9 thermique maximale d&#8217;un cycle Diesel<\/span><\/li>\n<li><span>\u03b1 est le rapport de coupure V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0(c&#8217;est-\u00e0-dire le rapport des volumes \u00e0 la fin et au d\u00e9but de la phase de combustion)<\/span><\/li>\n<li><span>CR est le taux de compression<\/span><\/li>\n<li><strong><span>\u03ba = c\u00a0<\/span><\/strong><strong><sub><span>p<\/span><\/sub><\/strong><strong><span>\u00a0\/ c\u00a0<\/span><\/strong><strong><sub><span>v<\/span><\/sub><\/strong><strong><span>\u00a0= 1,4<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Pour cet exemple:<\/span><\/p>\n<p><span>\u03b7\u00a0<\/span><sub><span>Diesel<\/span><\/sub><span>\u00a0= 0,6467 = 64,7%<\/span><\/p>\n<p><span>6)<\/span><\/p>\n<p><span>Le d\u00e9put\u00e9 europ\u00e9en a \u00e9t\u00e9 d\u00e9fini comme:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/mean-effective-pressure-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-17565 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/mean-effective-pressure-definition.png\" alt=\"\" width=\"300\" height=\"63\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/mean-effective-pressure-definition.png\" \/><\/a><\/p>\n<p><span>Si cette \u00e9quation, le volume de d\u00e9placement est \u00e9gal \u00e0 V\u00a0<\/span><sub><span>max<\/span><\/sub><span>\u00a0&#8211; V\u00a0<\/span><sub><span>min<\/span><\/sub><span>\u00a0.\u00a0Le travail net pour un cycle peut \u00eatre calcul\u00e9 en utilisant la chaleur ajout\u00e9e et l&#8217;efficacit\u00e9 thermique:<\/span><\/p>\n<p><strong><em><span>W\u00a0<\/span><\/em><\/strong><strong><em><sub><span>net<\/span><\/sub><\/em><\/strong><em><span>\u00a0=\u00a0<\/span><\/em><em><span>Q\u00a0<\/span><\/em><em><sub><span>add<\/span><\/sub><\/em><em><span>\u00a0.\u00a0\u03b7\u00a0<\/span><\/em><em><sub><span>Otto<\/span><\/sub><\/em><em><span>\u00a0=\u00a0<\/span><\/em><em><span>583,5 x 0,6467 =\u00a0<\/span><strong><span>377,3 J<\/span><\/strong><\/em><\/p>\n<p><strong><em><span>MEP<\/span><\/em><\/strong><em><span>\u00a0= 377,3 \/ (<\/span><\/em><span>\u00a0500 \u00d7 10<\/span><sup><span>\u00a0-6<\/span><\/sup><span>\u00a0&#8211; 25 \u00d7 10<\/span><sup><span>\u00a0-6\u00a0<\/span><\/sup><em><span>) = 794,3 kPa =\u00a0<\/span><strong><span>7,943 bar<\/span><\/strong><\/em><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div><\/div>\n<div>\n<p>&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.<\/p>\n<p>Cet article est bas\u00e9 sur la traduction automatique de l&#8217;article original en anglais. Pour plus d&#8217;informations, voir l&#8217;article en anglais. Pouvez vous nous aider Si vous souhaitez corriger la traduction, envoyez-la \u00e0 l&#8217;adresse: translations@nuclear-power.com ou remplissez le formulaire de traduction en ligne. Nous appr\u00e9cions votre aide, nous mettrons \u00e0 jour la traduction le plus rapidement possible. Merci<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Th\u00e9orie du cycle diesel &#8211; Moteur diesel.\u00a0Le cycle diesel comprend quatre processus thermodynamiques.\u00a0L&#8217;efficacit\u00e9 thermique d\u00e9pend du taux de compression et du coefficient de capacit\u00e9 thermique.\u00a0G\u00e9nie thermique Cycle diesel &#8211; moteur diesel Dans les ann\u00e9es 1890, un inventeur allemand,\u00a0Rudolf Diesel,\u00a0a brevet\u00e9 son invention d\u2019un moteur \u00e0 combustion interne efficace et \u00e0 combustion lente.\u00a0Le cycle initial propos\u00e9 &#8230; <a title=\"Quelle est la th\u00e9orie du cycle diesel &#8211; Moteur diesel &#8211; D\u00e9finition\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-theorie-du-cycle-diesel-moteur-diesel-definition\/\" aria-label=\"En savoir plus sur Quelle est la th\u00e9orie du cycle diesel &#8211; Moteur diesel &#8211; D\u00e9finition\">Lire la suite<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[8],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Quelle est la th\u00e9orie du cycle diesel - Moteur diesel - D\u00e9finition<\/title>\n<meta name=\"description\" content=\"Th\u00e9orie du cycle diesel - Moteur diesel. 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