{"id":51423,"date":"2020-01-27T10:35:42","date_gmt":"2020-01-27T09:35:42","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/o-que-e-a-teoria-do-ciclo-diesel-motor-a-diesel-definicao\/"},"modified":"2020-01-27T10:36:35","modified_gmt":"2020-01-27T09:36:35","slug":"o-que-e-a-teoria-do-ciclo-diesel-motor-a-diesel-definicao","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-teoria-do-ciclo-diesel-motor-a-diesel-definicao\/","title":{"rendered":"O que \u00e9 a teoria do ciclo diesel &#8211; Motor a diesel &#8211; Defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Teoria do Ciclo Diesel &#8211; Motor Diesel.\u00a0O ciclo do diesel consiste em quatro processos termodin\u00e2micos.\u00a0A efici\u00eancia t\u00e9rmica depende da taxa de compress\u00e3o e da capacidade de aquecimento.\u00a0Engenharia T\u00e9rmica<\/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>Ciclo Diesel &#8211; Motor Diesel<\/h2>\n<p>Na d\u00e9cada de 1890, um inventor alem\u00e3o,\u00a0<strong>Rudolf Diesel<\/strong>\u00a0patenteou sua inven\u00e7\u00e3o de um eficiente, de combust\u00e3o lenta, igni\u00e7\u00e3o por compress\u00e3o, motor de combust\u00e3o interna.\u00a0O ciclo original proposto por Rudolf Diesel era um ciclo de temperatura constante.\u00a0Nos anos posteriores, Diesel percebeu que seu ciclo original n\u00e3o funcionaria e adotou o ciclo de press\u00e3o constante, conhecido como\u00a0<strong>ciclo de Diesel<\/strong>\u00a0.<\/p>\n<p><strong>O ciclo diesel<\/strong>\u00a0\u00e9 um dos\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-cycles\/\"><strong>ciclos termodin\u00e2micos<\/strong><\/a>\u00a0mais comuns\u00a0encontrados em\u00a0<strong>motores de autom\u00f3veis e<\/strong>\u00a0descreve o funcionamento de um motor de pist\u00e3o de igni\u00e7\u00e3o por compress\u00e3o t\u00edpico.\u00a0O motor Diesel \u00e9 semelhante em opera\u00e7\u00e3o ao motor a gasolina.\u00a0A diferen\u00e7a mais importante \u00e9 que:<\/p>\n<ul>\n<li>N\u00e3o h\u00e1 combust\u00edvel no cilindro no in\u00edcio do curso de compress\u00e3o; portanto, uma autoigni\u00e7\u00e3o n\u00e3o ocorre nos motores a diesel.<\/li>\n<li>O motor diesel usa igni\u00e7\u00e3o por compress\u00e3o em vez de igni\u00e7\u00e3o por fa\u00edsca.<\/li>\n<li>Devido \u00e0 alta temperatura desenvolvida durante a compress\u00e3o adiab\u00e1tica, o combust\u00edvel inflama espontaneamente \u00e0 medida que \u00e9 injetado.\u00a0Portanto, n\u00e3o s\u00e3o necess\u00e1rias velas de igni\u00e7\u00e3o.<\/li>\n<li>Antes do in\u00edcio do curso de for\u00e7a, os injetores come\u00e7am a injetar combust\u00edvel diretamente na c\u00e2mara de combust\u00e3o e, portanto, a primeira parte do curso de for\u00e7a ocorre aproximadamente \u00e0 press\u00e3o constante.<\/li>\n<li>Taxas de compress\u00e3o mais altas podem ser alcan\u00e7adas em\u00a0<strong>motores a diesel do<\/strong>\u00a0que em motores 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>O motor Diesel \u00e9 semelhante em opera\u00e7\u00e3o ao motor a gasolina.\u00a0Nesta foto, existe um mecanismo Otto, que \u00e9 acionado por uma vela de igni\u00e7\u00e3o em vez da pr\u00f3pria compress\u00e3o.<\/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=\"Motor a quatro tempos - motor 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\">Motor a quatro tempos &#8211; motor Otto<br \/>\nFonte: wikipedia.org, trabalho pr\u00f3prio da 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>Ao contr\u00e1rio do\u00a0<\/span><a title=\"Ciclo Otto - Otto Engine\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-o-ciclo-otto-otto-engine-definicao\/\"><strong><span>ciclo Otto<\/span><\/strong><\/a><span>\u00a0, o\u00a0<\/span><strong><span>ciclo Diesel<\/span><\/strong><span>\u00a0n\u00e3o executa adi\u00e7\u00e3o de calor isoc\u00f3rico.\u00a0Em um ciclo Diesel ideal, o sistema que executa o ciclo passa por uma s\u00e9rie de quatro processos: dois processos isentr\u00f3picos (adiab\u00e1ticos revers\u00edveis) alternados com um processo isoc\u00f3rico e um processo isob\u00e1rico.<\/span><span>Como\u00a0<\/span><a title=\"Princ\u00edpio de Carnot - regra de Carnot\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/second-law-of-thermodynamics\/carnots-principle-carnots-rule\/\"><strong><span>o princ\u00edpio de Carnot<\/span><\/strong><\/a><span>\u00a0afirma que nenhum motor pode ser mais eficiente do que um motor revers\u00edvel (\u00a0<\/span><strong><span>um motor a quente Carnot<\/span><\/strong><span>\u00a0) operando entre os mesmos reservat\u00f3rios de alta e baixa temperatura, o motor Diesel deve ter uma efici\u00eancia mais baixa que a efici\u00eancia de Carnot.\u00a0Um t\u00edpico\u00a0<\/span><strong><span>motor automotivo a diesel<\/span><\/strong><span>\u00a0opera com cerca de\u00a0<\/span><strong><span>30% a 35%<\/span><\/strong><span>\u00a0de efici\u00eancia t\u00e9rmica.\u00a0Cerca de 65-70% \u00e9 rejeitado como calor residual sem ser convertido em trabalho \u00fatil, ou seja, trabalho entregue \u00e0s rodas.\u00a0Em geral, os motores que usam o ciclo Diesel geralmente s\u00e3o mais eficientes do que os motores que usam o ciclo Otto.\u00a0O motor diesel tem a mais alta efici\u00eancia t\u00e9rmica de qualquer motor de combust\u00e3o pr\u00e1tico.\u00a0<\/span><strong><span>Motores diesel de baixa velocidade<\/span><\/strong><span>(como usado em navios) pode ter uma efici\u00eancia t\u00e9rmica superior a\u00a0<\/span><strong><span>50%<\/span><\/strong><span>\u00a0.\u00a0O maior motor diesel do mundo chega a 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>Ciclo Diesel &#8211; Processos<\/span><\/h2>\n<p><span>Em um ciclo Diesel ideal, o sistema que executa o ciclo passa por uma s\u00e9rie de quatro processos: dois processos isentr\u00f3picos (adiab\u00e1ticos revers\u00edveis) alternados com um processo isoc\u00f3rico e um processo isob\u00e1rico.<\/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=\"diagrama pV de um ciclo Diesel ideal\" 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>diagrama pV de um ciclo Diesel ideal<\/span><\/figcaption><\/figure>\n<p><strong><span>Compress\u00e3o isentr\u00f3pica<\/span><\/strong><span>\u00a0(curso de compress\u00e3o) &#8211; O ar \u00e9 comprimido adiabaticamente do estado 1 ao estado 2, conforme o pist\u00e3o se move do ponto morto inferior para o ponto morto superior.\u00a0O ambiente trabalha com o g\u00e1s, aumentando sua energia interna (temperatura) e comprimindo-o.\u00a0Por outro lado, a entropia permanece inalterada.\u00a0As mudan\u00e7as nos volumes e sua propor\u00e7\u00e3o (\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) s\u00e3o conhecidas como taxa de compress\u00e3o.<\/span><\/li>\n<li><strong><span>Expans\u00e3o isob\u00e1rica<\/span><\/strong><span>\u00a0(fase de igni\u00e7\u00e3o) &#8211; Nesta fase (entre o estado 2 e o estado 3), h\u00e1 uma transfer\u00eancia de calor de press\u00e3o constante (modelo idealizado) para o ar a partir de uma fonte externa (combust\u00e3o de combust\u00edvel injetado) enquanto o pist\u00e3o est\u00e1 se movendo em dire\u00e7\u00e3o ao V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0.\u00a0Durante o processo de press\u00e3o constante, a energia entra no sistema \u00e0 medida que o calor Q \u00e9\u00a0<\/span><sub><span>adicionado<\/span><\/sub><span>\u00a0e uma parte do trabalho \u00e9 feita movendo o pist\u00e3o.<\/span><\/li>\n<li><strong><span>Expans\u00e3o isentr\u00f3pica<\/span><\/strong><span>\u00a0(poder acidente vascular cerebral) &#8211; O g\u00e1s expande-se adiabaticamente de estado 3 para o estado 4, quando o pist\u00e3o se move da V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0a centro morto inferior.\u00a0O g\u00e1s trabalha nos arredores (pist\u00e3o) e perde uma quantidade de energia interna igual ao trabalho que sai do sistema.\u00a0Novamente a entropia permanece inalterada.\u00a0A taxa de volume (\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) \u00e9 conhecida como taxa de expans\u00e3o isentr\u00f3pica.<\/span><\/li>\n<li><strong><span>Descompress\u00e3o isoc\u00f3rica (curso de exaust\u00e3o)<\/span><\/strong><span>\u00a0&#8211; Nesta fase, o ciclo \u00e9 conclu\u00eddo por um processo de volume constante no qual o calor \u00e9 rejeitado do ar enquanto o pist\u00e3o est\u00e1 no ponto morto inferior.\u00a0A press\u00e3o do g\u00e1s de trabalho cai instantaneamente do ponto 4 para o ponto 1. A v\u00e1lvula de escape se abre no ponto 4. O curso de escape ocorre imediatamente ap\u00f3s esta descompress\u00e3o.\u00a0\u00c0 medida que o pist\u00e3o se move do ponto morto inferior (ponto 1) para o ponto morto superior (ponto 0) com a v\u00e1lvula de escape aberta, a mistura gasosa \u00e9 ventilada para a atmosfera e o processo recome\u00e7a.<\/span><\/li>\n<\/ul>\n<p><span>Durante o ciclo diesel, o trabalho \u00e9 realizado sobre o g\u00e1s pelo pist\u00e3o entre os estados 1 e 2 (\u00a0<\/span><strong><span>i\u00a0<\/span><\/strong><strong><span>compress\u00e3o sentropic<\/span><\/strong><span>\u00a0).\u00a0O trabalho \u00e9 realizado pelo g\u00e1s no pist\u00e3o entre os est\u00e1gios 2 e 3 (\u00a0<\/span><strong><span>i\u00a0<\/span><\/strong><strong><span>adi\u00e7\u00e3o de calor sob\u00e1rico<\/span><\/strong><span>\u00a0) e entre os est\u00e1gios 2 e 3 (\u00a0<\/span><strong><span>i\u00a0<\/span><\/strong><strong><span>expans\u00e3o sentr\u00f3pica<\/span><\/strong><span>\u00a0).\u00a0A diferen\u00e7a entre o trabalho realizado pelo g\u00e1s e o trabalho realizado com o g\u00e1s \u00e9 o trabalho l\u00edquido produzido pelo ciclo e corresponde \u00e0 \u00e1rea delimitada pela curva do ciclo.\u00a0O trabalho produzido pelos tempos de ciclo, a taxa do ciclo (ciclos por segundo) \u00e9 igual \u00e0 pot\u00eancia produzida pelo motor 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>Processo isentr\u00f3pico<\/span><\/h2>\n<p><span>Um\u00a0<\/span><a title=\"Processo isentr\u00f3pico\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-processo-isentropico-definicao\/\"><strong><span>processo isentr\u00f3pico<\/span><\/strong><\/a><span>\u00a0\u00e9 um\u00a0<\/span><a title=\"Processos termodin\u00e2micos\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-processo-termodinamico-definicao\/\"><strong><span>processo termodin\u00e2mico<\/span><\/strong><\/a><span>\u00a0, no qual a\u00a0<\/span><a title=\"O que \u00e9 entropia\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/what-is-entropy\/\"><strong><span>entropia<\/span><\/strong>\u00a0<\/a><span>do fluido ou g\u00e1s permanece constante.\u00a0Isso significa que o\u00a0<\/span><strong><span>processo isentr\u00f3pico<\/span><\/strong><span>\u00a0\u00e9 um caso especial de um\u00a0<\/span><strong><span>processo adiab\u00e1tico<\/span><\/strong><span>\u00a0no qual n\u00e3o h\u00e1 transfer\u00eancia de calor ou mat\u00e9ria.\u00a0\u00c9 um\u00a0<\/span><strong><span>processo adiab\u00e1tico revers\u00edvel<\/span><\/strong><span>\u00a0.\u00a0A suposi\u00e7\u00e3o de que n\u00e3o h\u00e1 transfer\u00eancia de calor \u00e9 muito importante, pois podemos usar a aproxima\u00e7\u00e3o adiab\u00e1tica apenas em\u00a0<\/span><strong><span>processos muito r\u00e1pidos<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><strong><span>Processo isentr\u00f3pico e a primeira lei<\/span><\/strong><\/p>\n<p><span>Para um sistema fechado, podemos escrever a\u00a0<\/span><strong><a title=\"Primeira lei em termos de entalpia 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>primeira lei da termodin\u00e2mica em termos de entalpia<\/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>Processo isentr\u00f3pico (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(para\u00a0<\/span><a title=\"O que \u00e9 o g\u00e1s ideal\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/what-is-ideal-gas\/\"><span>g\u00e1s ideal<\/span><\/a><span>\u00a0)<\/span><\/em><\/p>\n<p><strong><span>Processo isentr\u00f3pico do g\u00e1s ideal<\/span><\/strong><\/p>\n<p><span>O\u00a0<\/span><strong><span>processo isentr\u00f3pico<\/span><\/strong><span>\u00a0(um caso especial de processo adiab\u00e1tico) pode ser expresso com a\u00a0<\/span><a title=\"Lei do g\u00e1s ideal\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/\"><strong><span>lei dos gases ideais<\/span><\/strong><\/a><span>\u00a0como:<\/span><\/p>\n<p><strong><em><span>pV\u00a0<\/span><sup><span>\u03ba<\/span><\/sup><span>\u00a0= constante<\/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>k<\/span><\/sup><span>\u00a0= p\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0V\u00a0<\/span><sub><span>2\u00a0<\/span><\/sub><sup><span>k<\/span><\/sup><\/strong><\/em><\/p>\n<p><span>em que\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>\u00a0\u00e9 a propor\u00e7\u00e3o de\u00a0<a title=\"Capacidade t\u00e9rmica - Capacidade t\u00e9rmica espec\u00edfica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/laws-of-thermodynamics\/first-law-of-thermodynamics\/heat-capacity\/\"><strong>aquecimentos espec\u00edficos<\/strong><\/a>\u00a0(ou\u00a0<strong>capacidades de calor<\/strong>\u00a0) para o g\u00e1s.\u00a0Um para\u00a0<strong>press\u00e3o constante (c\u00a0<\/strong><strong><sub>p<\/sub><\/strong><strong>\u00a0)<\/strong>\u00a0e outro para\u00a0<strong>volume constante (c\u00a0<\/strong><strong><sub>v<\/sub><\/strong><strong>\u00a0)<\/strong>\u00a0.\u00a0Observe que essa raz\u00e3o\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>\u00a0\u00e9 um fator na determina\u00e7\u00e3o da velocidade do som em um g\u00e1s e em outros processos adiab\u00e1ticos.<\/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>Processo Isoc\u00f3rico<\/span><\/h2>\n<p><span>Um\u00a0<\/span><a title=\"Processo Isoc\u00f3rico - Processo Isom\u00e9trico\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-o-processo-isocorico-processo-isometrico-definicao\/\"><strong><span>processo isoc\u00f3rico<\/span><\/strong><\/a><span>\u00a0\u00e9 um processo termodin\u00e2mico, no qual o\u00a0<\/span><strong><span>volume<\/span><\/strong><span>\u00a0do sistema fechado\u00a0<\/span><strong><span>permanece constante<\/span><\/strong><span>\u00a0(V = const).\u00a0Ele descreve o comportamento do g\u00e1s dentro do recipiente, que n\u00e3o pode ser deformado.\u00a0Como o volume permanece constante, a transfer\u00eancia de calor para dentro ou para fora do sistema n\u00e3o\u00a0<\/span><a title=\"Trabalho p\u0394V - Trabalho de Fronteira e Trabalho 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>funciona<\/span><\/a><span>\u00a0, mas altera apenas a\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-energia-interna-energia-termica-definicao\/\"><strong><span>energia interna<\/span><\/strong><\/a><span>\u00a0(a temperatura) do sistema.<\/span><\/p>\n<p><strong><span>Processo isoc\u00f3rico e a primeira lei<\/span><\/strong><\/p>\n<p><span>A forma cl\u00e1ssica da\u00a0<\/span><a title=\"Primeira Lei da Termodin\u00e2mica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-primeira-lei-da-termodinamica-definicao\/\"><span>primeira lei da termodin\u00e2mica<\/span><\/a><span>\u00a0\u00e9 a seguinte equa\u00e7\u00e3o:<\/span><\/p>\n<p><strong><span>dU = dQ &#8211; dW<\/span><\/strong><\/p>\n<p><span>Nesta equa\u00e7\u00e3o, dW \u00e9 igual a\u00a0<\/span><strong><span>dW = pdV<\/span><\/strong><span>\u00a0e \u00e9 conhecido como\u00a0<\/span><a title=\"Trabalho p\u0394V - Trabalho de Fronteira e Trabalho 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>trabalho de fronteira<\/span><\/a><span>\u00a0.\u00a0Ent\u00e3o:<\/span><\/p>\n<p><strong><span>dU = dQ &#8211; pdV<\/span><\/strong><\/p>\n<p><span>No\u00a0<\/span><strong><span>processo isoc\u00f3rico<\/span><\/strong><span>\u00a0e no\u00a0<\/span><strong><span>g\u00e1s ideal<\/span><\/strong><span>\u00a0, todo o calor adicionado ao sistema ser\u00e1 usado para aumentar a energia interna.<\/span><\/p>\n<p><strong><span>Processo isoc\u00f3rico (pdV = 0):<\/span><\/strong><\/p>\n<p><strong><span>dU = dQ \u00a0\u00a0\u00a0\u00a0<\/span><\/strong><em><span>(para g\u00e1s ideal)<\/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>(para g\u00e1s ideal)<\/span><\/em><\/p>\n<p><strong><span>Processo isoc\u00f3rico do g\u00e1s ideal<\/span><\/strong><\/p>\n<p><span>O\u00a0<\/span><strong><span>processo isoc\u00f3rico<\/span><\/strong><span>\u00a0pode ser expresso com a\u00a0<\/span><a title=\"Lei do g\u00e1s ideal\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/\"><strong><span>lei dos gases ideais<\/span><\/strong><\/a><span>\u00a0como:<\/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=\"processo isoc\u00f3rico - equa\u00e7\u00e3o 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=\"processo isoc\u00f3rico - equa\u00e7\u00e3o 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>Em um\u00a0<\/span><strong><span>diagrama pV<\/span><\/strong><span>\u00a0, o processo ocorre ao longo de uma linha horizontal que possui a equa\u00e7\u00e3o V = constante.<\/span><\/p>\n<p><span>Veja tamb\u00e9m:\u00a0\u00a0<\/span><a title=\"Lei de Guy-Lussac\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-lei-de-gay-lussac-definicao\/\"><span>Lei 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>Processo isob\u00e1rico<\/span><\/h2>\n<p><span>Um\u00a0<\/span><strong><span>processo isob\u00e1rico<\/span><\/strong><span>\u00a0\u00e9 um\u00a0<\/span><a title=\"Processos termodin\u00e2micos\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-processo-termodinamico-definicao\/\"><span>processo termodin\u00e2mico<\/span><\/a><span>\u00a0, no qual a\u00a0<\/span><a title=\"O que \u00e9 press\u00e3o - F\u00edsica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-pressure-physics\/\"><strong><span>press\u00e3o<\/span><\/strong><\/a><span>\u00a0do sistema\u00a0<\/span><strong><span>permanece constante<\/span><\/strong><span>\u00a0(p = const).\u00a0A transfer\u00eancia de calor para dentro ou para fora do sistema funciona, mas tamb\u00e9m altera a energia interna do sistema.<\/span><\/p>\n<p><span>Como existem mudan\u00e7as na\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-energia-interna-energia-termica-definicao\/\"><span>energia interna<\/span><\/a><span>\u00a0(dU) e no volume do sistema (\u2206V), os engenheiros costumam usar a\u00a0<\/span><a title=\"O que \u00e9 entalpia\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/what-is-enthalpy\/\"><strong><span>entalpia<\/span><\/strong><\/a><span>\u00a0do sistema, que \u00e9 definida como:<\/span><\/p>\n<p><em><strong><span>H = U + pV<\/span><\/strong><\/em><\/p>\n<p><strong><span>Processo isob\u00e1rico e a primeira lei<\/span><\/strong><\/p>\n<p><span>A forma cl\u00e1ssica da\u00a0<\/span><a title=\"Primeira Lei da Termodin\u00e2mica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-primeira-lei-da-termodinamica-definicao\/\"><span>primeira lei da termodin\u00e2mica<\/span><\/a><span>\u00a0\u00e9 a seguinte equa\u00e7\u00e3o:<\/span><\/p>\n<p><strong><span>dU = dQ &#8211; dW<\/span><\/strong><\/p>\n<p><span>Nesta equa\u00e7\u00e3o, dW \u00e9 igual a\u00a0<\/span><strong><span>dW = pdV<\/span><\/strong><span>\u00a0e \u00e9 conhecido como\u00a0<\/span><a title=\"Trabalho p\u0394V - Trabalho de Fronteira e Trabalho 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>trabalho de fronteira<\/span><\/a><span>\u00a0.\u00a0Em um processo isob\u00e1rico e no g\u00e1s ideal,\u00a0<\/span><strong><span>parte do calor adicionado<\/span><\/strong><span>\u00a0ao sistema ser\u00e1 usada para\u00a0<\/span><strong><span>realizar o trabalho<\/span><\/strong><span>\u00a0e\u00a0<\/span><strong><span>parte do calor<\/span><\/strong><span>\u00a0adicionado aumentar\u00e1 a\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-energia-interna-energia-termica-definicao\/\"><strong><span>energia interna<\/span><\/strong><\/a><span>\u00a0(aumentar\u00e1 a temperatura).\u00a0Portanto, \u00e9 conveniente usar a\u00a0<\/span><strong><span>entalpia em<\/span><\/strong><span>\u00a0vez da energia interna.<\/span><\/p>\n<p><strong><span>Processo isob\u00e1rico (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>Na entropia constante<\/span><\/strong><span>\u00a0, ou seja, no processo isentr\u00f3pico, a\u00a0<\/span><strong><span>mudan\u00e7a de entalpia<\/span><\/strong><span>\u00a0\u00e9 igual ao\u00a0<\/span><strong><span>trabalho do processo de fluxo<\/span><\/strong><span>\u00a0realizado no sistema ou pelo mesmo.<\/span><\/p>\n<p><strong><span>Processo isob\u00e1rico do g\u00e1s ideal<\/span><\/strong><\/p>\n<p><span>O\u00a0<\/span><strong><span>processo isob\u00e1rico<\/span><\/strong><span>\u00a0pode ser expresso com a\u00a0<\/span><a title=\"Lei do g\u00e1s ideal\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/ideal-gas-law\/\"><strong><span>lei do g\u00e1s ideal<\/span><\/strong><\/a><span>\u00a0como:<\/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=\"processo isob\u00e1rico - equa\u00e7\u00e3o - 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=\"processo isob\u00e1rico - equa\u00e7\u00e3o - 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>Em um\u00a0<\/span><strong><span>diagrama de pV<\/span><\/strong><span>\u00a0, o processo ocorre ao longo de uma linha horizontal (chamada isobar) que possui a equa\u00e7\u00e3o p = constante.<\/span><\/p>\n<p><span>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Lei de Charles\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-lei-de-charles-definicao\/\"><span>Lei de Charles<\/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=\"Processo isentr\u00f3pico - caracter\u00edsticas\" 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>Processo isentr\u00f3pico &#8211; principais caracter\u00edsticas<\/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=\"Processo isoc\u00f3rico - principais caracter\u00edsticas\" 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>Processo isoc\u00f3rico &#8211; principais caracter\u00edsticas<\/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=\"Processo isob\u00e1rico - principais caracter\u00edsticas\" 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>Processo isob\u00e1rico &#8211; principais caracter\u00edsticas<\/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>Compara\u00e7\u00e3o de ciclos diesel reais e ideais<\/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=\"ciclo diesel atual - motor 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>Neste artigo, \u00e9 mostrado um\u00a0<\/span><strong><span>ciclo Diesel ideal,<\/span><\/strong><span>\u00a0no qual existem muitas suposi\u00e7\u00f5es diferentes do\u00a0<\/span><strong><span>ciclo Diesel real<\/span><\/strong><span>\u00a0.\u00a0As principais diferen\u00e7as entre o motor Diesel real e ideal aparecem na figura.\u00a0Na realidade, o ciclo ideal n\u00e3o ocorre e h\u00e1 muitas perdas associadas a cada processo.\u00a0Para um ciclo real, a forma do diagrama de pV \u00e9 semelhante ao ideal, mas a \u00e1rea (trabalho) delimitada pelo diagrama de pV \u00e9 sempre menor que o valor ideal.\u00a0O ciclo Diesel ideal \u00e9 baseado nas seguintes premissas:<\/span><\/p>\n<ul>\n<li><strong><span>Ciclo fechado<\/span><\/strong><span>\u00a0: A maior diferen\u00e7a entre os dois diagramas \u00e9 a simplifica\u00e7\u00e3o dos movimentos de admiss\u00e3o e escape no ciclo ideal.\u00a0No curso de escape, o calor Q\u00a0<\/span><sub><span>out<\/span><\/sub><span>\u00a0\u00e9 ejetado para o ambiente (em um motor real, o g\u00e1s sai do motor e \u00e9 substitu\u00eddo por uma nova mistura de ar e combust\u00edvel).<\/span><\/li>\n<li><strong><span>Adi\u00e7\u00e3o de calor isob\u00e1rico<\/span><\/strong><span>\u00a0.\u00a0Em motores reais, a adi\u00e7\u00e3o de calor nunca \u00e9 isob\u00e1rica.<\/span><\/li>\n<li><strong><span>Sem transfer\u00eancia de calor<\/span><\/strong>\n<ul>\n<li><span>Compress\u00e3o &#8211; O g\u00e1s \u00e9 comprimido adiabaticamente do estado 1 ao estado 2. Nos motores reais, sempre existem algumas inefici\u00eancias que reduzem a efici\u00eancia t\u00e9rmica.<\/span><\/li>\n<li><span>Expans\u00e3o.\u00a0O g\u00e1s se expande adiabaticamente do estado 3 para o estado 4.<\/span><\/li>\n<\/ul>\n<\/li>\n<li><strong><span>Combust\u00e3o completa<\/span><\/strong><span>\u00a0da mistura.<\/span><\/li>\n<li><strong><span>Nenhum trabalho de bombeamento<\/span><\/strong><span>\u00a0.\u00a0Trabalho de bombeamento \u00e9 a diferen\u00e7a entre o trabalho realizado durante o golpe de escape e o trabalho realizado durante o golpe de admiss\u00e3o.\u00a0Nos ciclos reais, h\u00e1 uma diferen\u00e7a de press\u00e3o entre as press\u00f5es de exaust\u00e3o e de entrada.<\/span><\/li>\n<li><strong><span>Sem perda de purga<\/span><\/strong><span>\u00a0.\u00a0A perda de purga \u00e9 causada pela abertura precoce das v\u00e1lvulas de escape.\u00a0Isso resulta em uma perda de produ\u00e7\u00e3o durante o curso de expans\u00e3o.<\/span><\/li>\n<li><strong><span>Sem perda de impacto<\/span><\/strong><span>\u00a0.\u00a0A perda soprada \u00e9 causada pelo vazamento de gases comprimidos atrav\u00e9s de an\u00e9is de pist\u00e3o e outras fendas.<\/span><\/li>\n<li><strong><span>Sem perdas por atrito<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<\/ul>\n<p><span>Essas suposi\u00e7\u00f5es e perdas simplificadoras levam ao fato de que a \u00e1rea fechada (trabalho) do diagrama de pV para um motor real \u00e9 significativamente menor que o tamanho da \u00e1rea (trabalho) envolvida pelo diagrama de pV do ciclo ideal.\u00a0Em outras palavras, o ciclo ideal do motor superestimar\u00e1 o trabalho l\u00edquido e, se os motores funcionarem na mesma velocidade, maior pot\u00eancia produzida pelo motor real em cerca de 20% (da mesma forma que no caso do motor 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>Efici\u00eancia t\u00e9rmica para ciclo diesel<\/span><\/h2>\n<p><span>Em geral, a\u00a0<a title=\"Efici\u00eancia t\u00e9rmica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-eficiencia-termica-definicao\/\"><strong>efici\u00eancia t\u00e9rmica<\/strong><\/a><a title=\"Efici\u00eancia t\u00e9rmica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-eficiencia-termica-definicao\/\">\u00a0,\u00a0<\/a><a title=\"Efici\u00eancia t\u00e9rmica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-eficiencia-termica-definicao\/\"><strong><em>\u03b7\u00a0<\/em><\/strong><\/a><a title=\"Efici\u00eancia t\u00e9rmica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-eficiencia-termica-definicao\/\"><strong><em><sub>th<\/sub><\/em><\/strong><\/a>\u00a0, de qualquer motor de calor \u00e9 definida como a raz\u00e3o entre o\u00a0<a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-trabalho-em-termodinamica-definicao\/\">trabalho<\/a>\u00a0que faz,\u00a0<strong>W<\/strong>\u00a0, para o\u00a0<a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-calor-na-fisica-calor-definicao\/\">calor<\/a>\u00a0de entrada a uma temperatura elevada, 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=\"f\u00f3rmula de efici\u00eancia t\u00e9rmica - 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>A\u00a0<\/span><strong><span>efici\u00eancia t\u00e9rmica<\/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, representa a fra\u00e7\u00e3o de\u00a0<\/span><strong><span>calor<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><span>Q\u00a0<\/span><\/strong><strong><sub><span>H<\/span><\/sub><\/strong><span>\u00a0, que \u00e9 convertida\u00a0<\/span><strong><span>em trabalho<\/span><\/strong><span>\u00a0.\u00a0Como a energia \u00e9 conservada de acordo com a\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-primeira-lei-da-termodinamica-definicao\/\"><strong><span>primeira lei da termodin\u00e2mica<\/span><\/strong><\/a><span>\u00a0e a energia n\u00e3o pode ser convertida para funcionar completamente, a entrada de calor, Q\u00a0<\/span><sub><span>H<\/span><\/sub><span>\u00a0, deve ser igual ao trabalho realizado, W, mais o calor que deve ser dissipado como\u00a0<\/span><strong><span>calor residual Q\u00a0<\/span><\/strong><strong><sub><span>C<\/span><\/sub><\/strong><span>\u00a0no meio Ambiente.\u00a0Portanto, podemos reescrever a f\u00f3rmula da efici\u00eancia t\u00e9rmica como:<\/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=\"f\u00f3rmula de efici\u00eancia t\u00e9rmica - 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>O calor absorvido ocorre durante a combust\u00e3o da mistura combust\u00edvel-ar, quando a fa\u00edsca ocorre, aproximadamente a volume constante.\u00a0Como durante um\u00a0<\/span><a title=\"Processo Isoc\u00f3rico - Processo Isom\u00e9trico\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-o-processo-isocorico-processo-isometrico-definicao\/\"><span>processo isoc\u00f3rico<\/span><\/a><span>\u00a0n\u00e3o h\u00e1 trabalho realizado pelo sistema ou sobre ele, a\u00a0<\/span><strong><span>primeira lei da termodin\u00e2mica<\/span><\/strong><span>\u00a0determina\u00a0<\/span><em><span>\u2206U = \u2206Q.\u00a0<\/span><\/em><span>Portanto, o calor adicionado e rejeitado \u00e9 dado por:<\/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>Substituindo essas express\u00f5es pelo calor adicionado e rejeitado na express\u00e3o por efici\u00eancia t\u00e9rmica, obt\u00e9m-se:<\/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>Essa equa\u00e7\u00e3o pode ser reorganizada na forma com a taxa de compress\u00e3o e a taxa de corte:<\/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>Onde<\/span><\/p>\n<ul>\n<li><strong><span>\u03b7\u00a0<\/span><sub><span>Diesel<\/span><\/sub><\/strong><span>\u00a0\u00e9 a efici\u00eancia t\u00e9rmica m\u00e1xima de um ciclo Diesel<\/span><\/li>\n<li><span>\u03b1 \u00e9 a\u00a0raz\u00e3o de\u00a0<\/span><strong><span>corte<\/span><\/strong><span>\u00a0V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0(ou seja, a raz\u00e3o de volumes no final e no in\u00edcio da fase de combust\u00e3o)<\/span><\/li>\n<li><strong><span>CR<\/span><\/strong><span>\u00a0\u00e9 a\u00a0<\/span><strong><span>taxa de compress\u00e3o<\/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>\u00c9 uma conclus\u00e3o muito \u00fatil, pois \u00e9 desej\u00e1vel alcan\u00e7ar uma alta taxa de compress\u00e3o para extrair mais energia mec\u00e2nica de uma determinada massa do combust\u00edvel.\u00a0Como conclu\u00edmos na se\u00e7\u00e3o anterior, a efici\u00eancia t\u00e9rmica do ciclo Otto padr\u00e3o do ar tamb\u00e9m \u00e9 uma fun\u00e7\u00e3o da taxa de compress\u00e3o e \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=\"efici\u00eancia t\u00e9rmica - Ciclo Otto - Taxa de compress\u00e3o\" 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>Quando as comparamos com as f\u00f3rmulas, pode-se observar que, para uma determinada taxa de compress\u00e3o (CR), o ciclo Otto ser\u00e1 mais eficiente que o ciclo Diesel.\u00a0Mas os motores a diesel geralmente s\u00e3o mais eficientes, pois s\u00e3o capazes de operar com taxas de compress\u00e3o mais altas.<\/span><\/p>\n<p><span>Nos motores Otto comuns, a taxa de compress\u00e3o tem seus limites.\u00a0A taxa de compress\u00e3o em um motor a gasolina geralmente n\u00e3o ser\u00e1 muito superior a 10: 1.\u00a0Taxas de compress\u00e3o mais altas sujeitar\u00e3o os motores a gasolina a bater no motor, causados \u200b\u200bpela autoigni\u00e7\u00e3o de uma mistura n\u00e3o queimada, se for usado combust\u00edvel com classifica\u00e7\u00e3o mais baixa de octanagem.\u00a0Nos motores a diesel, h\u00e1 um risco m\u00ednimo de autoigni\u00e7\u00e3o do combust\u00edvel, porque os motores a diesel s\u00e3o motores de igni\u00e7\u00e3o por compress\u00e3o e n\u00e3o h\u00e1 combust\u00edvel no cilindro no in\u00edcio do curso de compress\u00e3o.<\/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>Ciclo Diesel &#8211; Problema com a Solu\u00e7\u00e3o<\/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=\"diagrama pV de um ciclo Diesel ideal\" 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>diagrama pV de um ciclo Diesel ideal<\/span><\/figcaption><\/figure>\n<p><span>Vamos assumir o ciclo Diesel, que \u00e9 um dos\u00a0<\/span><strong><span>ciclos termodin\u00e2micos<\/span><\/strong><span>\u00a0mais comuns\u00a0encontrados em\u00a0<\/span><strong><span>motores de autom\u00f3veis<\/span><\/strong><span>\u00a0.\u00a0Um dos principais par\u00e2metros desses motores \u00e9 a mudan\u00e7a de volumes entre o ponto morto superior (TDC) e o ponto morto inferior (BDC).\u00a0A propor\u00e7\u00e3o desses 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) \u00e9 conhecida como\u00a0<\/span><strong><span>taxa de compress\u00e3o<\/span><\/strong><span>\u00a0.\u00a0Tamb\u00e9m a rela\u00e7\u00e3o de corte V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0, que \u00e9 a rela\u00e7\u00e3o dos volumes no final e no in\u00edcio da fase de combust\u00e3o.<\/span><\/p>\n<p><span>Neste exemplo, vamos assumir o ciclo Diesel com taxa de compress\u00e3o de CR = 20: 1 e taxa de corte \u03b1 = 2. O ar est\u00e1 a 100 kPa = 1 bar, 20 \u00b0 C (293 K) e o volume da c\u00e2mara \u00e9 de 500 cm\u00b3 antes do curso de compress\u00e3o.<\/span><\/p>\n<ul>\n<li><span>Capacidade t\u00e9rmica espec\u00edfica a press\u00e3o constante do ar \u00e0 press\u00e3o atmosf\u00e9rica e \u00e0 temperatura ambiente:\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>Capacidade t\u00e9rmica espec\u00edfica a um volume constante de ar \u00e0 press\u00e3o atmosf\u00e9rica e \u00e0 temperatura ambiente:\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>Calcular:<\/span><\/strong><\/p>\n<ol>\n<li><strong><span>a massa de entrada de ar<\/span><\/strong><\/li>\n<li><strong><span>a temperatura T\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><\/li>\n<li><strong><span>a press\u00e3o p\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><\/li>\n<li><strong><span>a temperatura T\u00a0<\/span><\/strong><strong><sub><span>3<\/span><\/sub><\/strong><\/li>\n<li><strong><span>a quantidade de calor adicionada pela queima da mistura combust\u00edvel-ar<\/span><\/strong><\/li>\n<li><strong><span>a efici\u00eancia t\u00e9rmica deste ciclo<\/span><\/strong><\/li>\n<li><strong><span>o deputado<\/span><\/strong><\/li>\n<\/ol>\n<p><strong><span>Solu\u00e7\u00e3o:<\/span><\/strong><\/p>\n<p><span>1)<\/span><\/p>\n<p><span>No in\u00edcio dos c\u00e1lculos, temos que determinar a quantidade de g\u00e1s no cilindro antes do curso de compress\u00e3o.\u00a0Usando a lei do g\u00e1s ideal, podemos encontrar a massa:<\/span><\/p>\n<p><em><span>pV = mR\u00a0<\/span><\/em><em><sub><span>espec\u00edfico<\/span><\/sub><\/em><em><span>\u00a0T<\/span><\/em><\/p>\n<p><span>Onde:<\/span><\/p>\n<ul>\n<li><em><span>p<\/span><\/em><span>\u00a0\u00e9 a press\u00e3o absoluta do g\u00e1s<\/span><\/li>\n<li><em><span>m<\/span><\/em><span>\u00a0\u00e9 a massa da subst\u00e2ncia<\/span><\/li>\n<li><em><span>T<\/span><\/em><span>\u00a0\u00e9 a temperatura absoluta<\/span><\/li>\n<li><em><span>V<\/span><\/em><span>\u00a0\u00e9 o volume<\/span><\/li>\n<li><em><span>R\u00a0<\/span><\/em><em><sub><span>espec\u00edfico<\/span><\/sub><\/em><span>\u00a0\u00e9 a constante de g\u00e1s espec\u00edfica, igual \u00e0 constante de g\u00e1s universal dividida pela massa molar (M) do g\u00e1s ou mistura.\u00a0Para ar seco R\u00a0<\/span><sub><span>espec\u00edfico<\/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>Portanto<\/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>espec\u00edfico<\/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>Nesse problema, todos os volumes s\u00e3o conhecidos:<\/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(0,5l)<\/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>m\u00e1x<\/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>Observe que (V\u00a0<\/span><sub><span>max<\/span><\/sub><span>\u00a0&#8211; V\u00a0<\/span><sub><span>min<\/span><\/sub><span>\u00a0) x n\u00famero de cilindros = cilindrada total do motor<\/span><\/p>\n<p><span>Como o processo \u00e9 adiab\u00e1tico, podemos usar a seguinte rela\u00e7\u00e3o p, V, T para processos adiab\u00e1ticos:<\/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>portanto<\/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>k &#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>Novamente, podemos usar a lei do g\u00e1s ideal para encontrar a press\u00e3o no final do curso de compress\u00e3o como:<\/span><\/p>\n<p><strong><span>P\u00a0<\/span><\/strong><strong><sub><span>2<\/span><\/sub><\/strong><span>\u00a0= mR\u00a0<\/span><sub><span>espec\u00edfico<\/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 x 10\u00a0<\/span><sup><span>-4<\/span><\/sup><span>\u00a0x 287,1 x 971\/25 x 10\u00a0<\/span><sup><span>-6<\/span><\/sup><span>\u00a0= 6.635.000 Pa =\u00a0<\/span><strong><span>66,35 barra<\/span><\/strong><\/p>\n<p><span>4)<\/span><\/p>\n<p><span>Como o processo 2 \u2192 3 ocorre a press\u00e3o constante, a equa\u00e7\u00e3o ideal de estado do g\u00e1s fornece<\/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>Para calcular a quantidade de calor adicionada pela queima da mistura combust\u00edvel-ar,\u00a0<\/span><sub><span>adicione<\/span><\/sub><span>\u00a0Q\u00a0, precisamos usar a primeira lei da termodin\u00e2mica para o processo isob\u00e1rico, que afirma:<\/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 x 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>Efici\u00eancia t\u00e9rmica para este ciclo Diesel:<\/span><\/p>\n<p><span>Como foi derivado na se\u00e7\u00e3o anterior, a efici\u00eancia t\u00e9rmica do ciclo Diesel \u00e9 uma fun\u00e7\u00e3o da taxa de compress\u00e3o, da taxa de corte e \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>Onde<\/span><\/p>\n<ul>\n<li><span>\u03b7\u00a0<\/span><sub><span>Diesel<\/span><\/sub><span>\u00a0\u00e9 a efici\u00eancia t\u00e9rmica m\u00e1xima de um ciclo Diesel<\/span><\/li>\n<li><span>\u03b1 \u00e9 a\u00a0raz\u00e3o de\u00a0corte V\u00a0<\/span><sub><span>3<\/span><\/sub><span>\u00a0\/ V\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0(ou seja, a raz\u00e3o de volumes no final e no in\u00edcio da fase de combust\u00e3o)<\/span><\/li>\n<li><span>CR \u00e9 a taxa de compress\u00e3o<\/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>Para este exemplo:<\/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>O MEP foi definido como:<\/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>Nesta equa\u00e7\u00e3o, o volume de deslocamento \u00e9 igual a V\u00a0<\/span><sub><span>max<\/span><\/sub><span>\u00a0&#8211; V\u00a0<\/span><sub><span>min<\/span><\/sub><span>\u00a0.\u00a0O trabalho l\u00edquido para um ciclo pode ser calculado usando o calor adicionado e a efici\u00eancia t\u00e9rmica:<\/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>Este artigo \u00e9 baseado na tradu\u00e7\u00e3o autom\u00e1tica do artigo original em ingl\u00eas. Para mais informa\u00e7\u00f5es, consulte o artigo em ingl\u00eas. Voc\u00ea pode nos ajudar. Se voc\u00ea deseja corrigir a tradu\u00e7\u00e3o, envie-a para: translations@nuclear-power.com ou preencha o formul\u00e1rio de tradu\u00e7\u00e3o on-line. Agradecemos sua ajuda, atualizaremos a tradu\u00e7\u00e3o o mais r\u00e1pido poss\u00edvel. Obrigado.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Teoria do Ciclo Diesel &#8211; Motor Diesel.\u00a0O ciclo do diesel consiste em quatro processos termodin\u00e2micos.\u00a0A efici\u00eancia t\u00e9rmica depende da taxa de compress\u00e3o e da capacidade de aquecimento.\u00a0Engenharia T\u00e9rmica Ciclo Diesel &#8211; Motor Diesel Na d\u00e9cada de 1890, um inventor alem\u00e3o,\u00a0Rudolf Diesel\u00a0patenteou sua inven\u00e7\u00e3o de um eficiente, de combust\u00e3o lenta, igni\u00e7\u00e3o por compress\u00e3o, motor de combust\u00e3o &#8230; <a title=\"O que \u00e9 a teoria do ciclo diesel &#8211; Motor a diesel &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-teoria-do-ciclo-diesel-motor-a-diesel-definicao\/\" aria-label=\"More on O que \u00e9 a teoria do ciclo diesel &#8211; Motor a diesel &#8211; Defini\u00e7\u00e3o\">Ler mais<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[14],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>O que \u00e9 a teoria do ciclo diesel - Motor a diesel - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"Teoria do Ciclo Diesel - Motor Diesel. O ciclo do diesel consiste em quatro processos termodin\u00e2micos. A efici\u00eancia t\u00e9rmica depende da taxa de compress\u00e3o e da capacidade de aquecimento. Engenharia T\u00e9rmica\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-a-teoria-do-ciclo-diesel-motor-a-diesel-definicao\/\" \/>\n<meta property=\"og:locale\" content=\"pt_BR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"O que \u00e9 a teoria do ciclo diesel - Motor a diesel - Defini\u00e7\u00e3o\" \/>\n<meta property=\"og:description\" content=\"Teoria do Ciclo Diesel - Motor Diesel. O ciclo do diesel consiste em quatro processos termodin\u00e2micos. A efici\u00eancia t\u00e9rmica depende da taxa de compress\u00e3o e da capacidade de aquecimento. 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