{"id":48436,"date":"2019-11-10T12:36:23","date_gmt":"2019-11-10T11:36:23","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/o-que-e-entalpia-e-entropia-definicao\/"},"modified":"2020-01-29T12:13:57","modified_gmt":"2020-01-29T11:13:57","slug":"o-que-e-entalpia-e-entropia-definicao","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-entalpia-e-entropia-definicao\/","title":{"rendered":"O que \u00e9 entalpia e entropia &#8211; defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Entalpia \u00e9 a quantidade termodin\u00e2mica equivalente ao conte\u00fado total de calor de um sistema. Entropia \u00e9 uma medida de desordem ou da energia em um sistema para fazer o trabalho. Engenharia T\u00e9rmica<\/div>\n<\/div>\n<div><\/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-first\">\n<div class=\"inside-grid-column\">\n<h2><span>O que \u00e9 entalpia<\/span><\/h2>\n<figure id=\"attachment_16675\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-16675\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Thermodynamic-potentials-Enthalpy.png\"><img loading=\"lazy\" class=\"size-medium wp-image-16675 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Thermodynamic-potentials-Enthalpy-300x285.png\" alt=\"potenciais termodin\u00e2micos - entalpia\" width=\"300\" height=\"285\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Thermodynamic-potentials-Enthalpy-300x285.png\" \/><\/a><figcaption id=\"caption-attachment-16675\" class=\"wp-caption-text\"><span>Quatro potenciais termodin\u00e2micos comuns.\u00a0H = U + pV<\/span><\/figcaption><\/figure>\n<p><span>Na termodin\u00e2mica, a entalpia \u00e9 a medida de energia em um sistema termodin\u00e2mico.\u00a0\u00c9 a quantidade termodin\u00e2mica equivalente ao conte\u00fado total de calor de um sistema.\u00a0A\u00a0<\/span><strong><span>entalpia<\/span><\/strong><span>\u00a0\u00e9 definida como a soma da energia interna\u00a0<\/span><strong><span>E<\/span><\/strong><span>\u00a0mais o produto da press\u00e3o\u00a0<\/span><strong><span>pe<\/span><\/strong><span>\u00a0volume\u00a0<\/span><strong><span>V.<\/span><\/strong><span>\u00a0Em muitas an\u00e1lises termodin\u00e2micas, a soma da energia interna U e o produto da press\u00e3o pe volume V aparece, portanto, \u00e9 conveniente para dar \u00e0 combina\u00e7\u00e3o um nome, entalpia e um s\u00edmbolo distinto, H.<\/span><\/p>\n<p><span>A entalpia \u00e9 a express\u00e3o preferida das mudan\u00e7as de energia do sistema em muitas medi\u00e7\u00f5es qu\u00edmicas, biol\u00f3gicas e f\u00edsicas\u00a0<\/span><strong><span>a press\u00e3o constante<\/span><\/strong><span>\u00a0.\u00a0\u00c9 t\u00e3o \u00fatil que \u00e9 tabulado nas\u00a0<\/span><a title=\"Tabelas de Vapor - Propriedades Espec\u00edficas da \u00c1gua e Vapor\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/steam-tables\/\"><strong><span>tabelas de vapor,<\/span><\/strong><\/a><span>\u00a0juntamente com o\u00a0<\/span><a title=\"O que \u00e9 volume espec\u00edfico\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-specific-volume\/\"><span>volume\u00a0<\/span><\/a><a title=\"Energia interna espec\u00edfica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/internal-energy-thermal-energy\/specific-internal-energy\/\"><span>espec\u00edfico<\/span><\/a><span>\u00a0e\u00a0<a title=\"Energia interna espec\u00edfica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/internal-energy-thermal-energy\/specific-internal-energy\/\">a energia interna espec\u00edfica<\/a>\u00a0.\u00a0Isso se deve ao fato de\u00a0<\/span><strong><span>simplificar a descri\u00e7\u00e3o da transfer\u00eancia de energia<\/span><\/strong><span>\u00a0.\u00a0Em press\u00e3o constante, a mudan\u00e7a de entalpia \u00e9 igual \u00e0 energia transferida do ambiente atrav\u00e9s do aquecimento\u00a0<\/span><strong><span>(Q = H\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0&#8211; H\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0)<\/span><\/strong><span>\u00a0ou outro trabalho que n\u00e3o o trabalho de expans\u00e3o.\u00a0Para um processo de press\u00e3o vari\u00e1vel, a diferen\u00e7a na entalpia n\u00e3o \u00e9 t\u00e3o \u00f3bvia.<\/span><\/p>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Entalpia em unidades extensivas<\/span><\/h2>\n<figure id=\"attachment_16538\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-16538\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Extensive-vs.-Intensive-properties-min.png\"><img loading=\"lazy\" class=\"size-medium wp-image-16538 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Extensive-vs.-Intensive-properties-min-238x300.png\" alt=\"Propriedades termodin\u00e2micas extensas vs. intensivas\" width=\"238\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Extensive-vs.-Intensive-properties-min-238x300.png\" \/><\/a><figcaption id=\"caption-attachment-16538\" class=\"wp-caption-text\"><span>Propriedades extensivas e intensivas do meio no pressurizador.<\/span><\/figcaption><\/figure>\n<p><em><strong><span>H = U + pV<\/span><\/strong><\/em><\/p>\n<p><strong><span>A entalpia<\/span><\/strong><span>\u00a0\u00a0\u00e9 uma quantidade extensa, depende do tamanho do sistema ou da quantidade de subst\u00e2ncia que ele cont\u00e9m.\u00a0A unidade SI de entalpia \u00e9 o joule (J).\u00a0\u00c9 a energia contida no sistema, excluindo a energia cin\u00e9tica do movimento do sistema como um todo e a energia potencial do sistema como um todo devido a campos de for\u00e7a externos.\u00a0\u00c9 a quantidade termodin\u00e2mica equivalente ao\u00a0<\/span><strong><span>conte\u00fado total de calor<\/span><\/strong><span>\u00a0de um sistema.<\/span><\/p>\n<p><span>Por outro lado, a energia pode ser armazenada nas liga\u00e7\u00f5es qu\u00edmicas entre os \u00e1tomos que comp\u00f5em as mol\u00e9culas.\u00a0Esse armazenamento de energia no n\u00edvel at\u00f4mico inclui energia associada a estados orbitais de el\u00e9trons, rota\u00e7\u00e3o nuclear e for\u00e7as de liga\u00e7\u00e3o no n\u00facleo.<\/span><\/p>\n<p><strong><span>A entalpia<\/span><\/strong><span>\u00a0\u00e9 representada pelo s\u00edmbolo\u00a0<\/span><strong><span>H<\/span><\/strong><span>\u00a0, e a altera\u00e7\u00e3o na entalpia em um processo \u00e9\u00a0<\/span><strong><span>H\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0&#8211; H\u00a0<\/span><sub><span>1<\/span><\/sub><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>Existem express\u00f5es em termos de vari\u00e1veis \u200b\u200bmais familiares, como\u00a0<\/span><a title=\"O que \u00e9 temperatura - F\u00edsica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-temperatura-fisica-definicao\/\"><span>temperatura<\/span><\/a><span>\u00a0e\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\/\"><span>press\u00e3o<\/span><\/a><span>\u00a0:<\/span><\/p>\n<p><em><strong><span>dH = C\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0dT + V (1-aT) dp<\/span><\/strong><\/em><\/p>\n<p><span>Onde\u00a0<\/span><strong><span>C\u00a0<\/span><sub><span>p<\/span><\/sub><\/strong><span>\u00a0\u00e9 a\u00a0<\/span><strong><span>capacidade calor\u00edfica a press\u00e3o constante<\/span><\/strong><span>\u00a0e\u00a0<\/span><strong><em><span>\u03b1<\/span><\/em><\/strong><span>\u00a0\u00e9 o coeficiente de expans\u00e3o t\u00e9rmica (c\u00fabico).\u00a0Para o g\u00e1s ideal \u03b1T = 1 e, portanto:<\/span><\/p>\n<p><strong><em><span>dH = C\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0dT<\/span><\/em><\/strong><\/p>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Exemplo: Pist\u00e3o sem atrito &#8211; Calor &#8211; Entalpia<\/span><\/h2>\n<figure id=\"attachment_16678\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-16678\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Enthalpy-example-min.png\"><img loading=\"lazy\" class=\"size-medium wp-image-16678 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Enthalpy-example-min-224x300.png\" alt=\"Entalpia - Exemplo - Um pist\u00e3o sem atrito\" width=\"224\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Enthalpy-example-min-224x300.png\" \/><\/a><figcaption id=\"caption-attachment-16678\" class=\"wp-caption-text\"><span>Calcule a temperatura final, se 3000 kJ de calor forem adicionados.<\/span><\/figcaption><\/figure>\n<p><span>Um pist\u00e3o sem atrito \u00e9 usado para proporcionar uma press\u00e3o constante de\u00a0<\/span><strong><span>500 kPa<\/span><\/strong><span>\u00a0num cilindro contendo vapor (\u00a0<\/span><a title=\"Vapor superaquecido\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/materials-nuclear-engineering\/properties-steam-what-is-steam\/superheated-steam\/\"><span>vapor sobreaquecido<\/span><\/a><span>\u00a0) de um volume de\u00a0<\/span><strong><span>2 m\u00a0<\/span><sup><span>3<\/span><\/sup><\/strong><span>\u00a0\u00a0a\u00a0<\/span><strong><span>500 K<\/span><\/strong><span>\u00a0.\u00a0Calcule a temperatura final, se\u00a0<\/span><strong><span>3000 kJ<\/span><\/strong><span>\u00a0de\u00a0<\/span><strong><span>calor<\/span><\/strong><span>\u00a0forem adicionados.<\/span><\/p>\n<p><strong><span>Solu\u00e7\u00e3o:<\/span><\/strong><\/p>\n<p><span>Usando\u00a0<\/span><a title=\"Tabelas de Vapor - Propriedades Espec\u00edficas da \u00c1gua e Vapor\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/steam-tables\/\"><span>tabelas de vapor<\/span><\/a><span>\u00a0, sabemos que a\u00a0<\/span><strong><span>entalpia espec\u00edfica<\/span><\/strong><span>\u00a0desse vapor (500 kPa; 500 K) \u00e9 de cerca de\u00a0<\/span><strong><span>2912 kJ \/ kg<\/span><\/strong><span>\u00a0.\u00a0Como nessa condi\u00e7\u00e3o o vapor possui densidade de 2,2 kg \/ m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0, sabemos que h\u00e1 cerca de\u00a0<\/span><strong><span>4,4 kg de vapor<\/span><\/strong><span>\u00a0no pist\u00e3o na entalpia de 2912 kJ \/ kg x 4,4 kg =\u00a0<\/span><strong><span>12812 kJ<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>Quando usamos simplesmente\u00a0<\/span><strong><span>Q = H\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0&#8211; H\u00a0<\/span><sub><span>1<\/span><\/sub><\/strong><span>\u00a0, a entalpia resultante do vapor ser\u00e1:<\/span><\/p>\n<p><span>H\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0= H\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0+ Q =\u00a0<\/span><strong><span>15812 kJ<\/span><\/strong><\/p>\n<p><span>Nas\u00a0<\/span><strong><span>tabelas de vapor<\/span><\/strong><span>\u00a0, esse vapor superaquecido (15812 \/ 4,4 = 3593 kJ \/ kg) ter\u00e1 uma temperatura de\u00a0<\/span><strong><span>828 K (555 \u00b0 C)<\/span><\/strong><span>\u00a0.\u00a0Uma vez que nesta entalpia do vapor tem a densidade de 1,31 kg \/ m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0, \u00e9 \u00f3bvio que se expandiu em cerca de 2,2 \/ 1,31 = 1,67 (+ 67%).\u00a0Portanto, o volume resultante \u00e9 de 2 m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0x 1,67 = 3,34 m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0e \u2206V = 3,34 m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0&#8211; 2 m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0= 1,34 m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0.<\/span><\/p>\n<p><span>A\u00a0parte\u00a0<\/span><strong><span>p\u2206V<\/span><\/strong><span>\u00a0da entalpia, ou seja, o trabalho realizado \u00e9:<\/span><\/p>\n<p><strong><span>W = p\u2206V = 500 000 Pa x 1,34 m\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0= 670 kJ<\/span><\/strong><\/p>\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<div class=\"su-spacer\"><\/div>\n<h2><span>O que \u00e9 entropia<\/span><\/h2>\n<p><span>Na termodin\u00e2mica e na f\u00edsica estat\u00edstica, a\u00a0<\/span><strong><span>entropia<\/span><\/strong><span>\u00a0\u00e9 uma medida quantitativa de desordem ou da energia em um sistema para realizar o trabalho.<\/span><\/p>\n<p><span>Na f\u00edsica estat\u00edstica, a entropia \u00e9 uma medida do dist\u00farbio de um sistema.\u00a0A que desordem se refere \u00e9 realmente o\u00a0<\/span><strong><span>n\u00famero de configura\u00e7\u00f5es microsc\u00f3picas<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><span>W<\/span><\/strong><span>\u00a0, que um sistema termodin\u00e2mico pode ter quando em um estado especificado por determinadas vari\u00e1veis \u200b\u200bmacrosc\u00f3picas (\u00a0<\/span><a title=\"O que \u00e9 volume - F\u00edsica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-volume-physics\/\"><span>volume<\/span><\/a><span>\u00a0,\u00a0<\/span><a title=\"O que \u00e9 energia - F\u00edsica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/\"><span>energia<\/span><\/a><span>\u00a0,\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\/\"><span>press\u00e3o<\/span><\/a><span>\u00a0e\u00a0<\/span><a title=\"O que \u00e9 temperatura - F\u00edsica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-temperatura-fisica-definicao\/\"><span>temperatura<\/span><\/a><span>\u00a0).\u00a0Por &#8220;estados microsc\u00f3picos&#8221;, queremos dizer os estados exatos de todas as mol\u00e9culas que comp\u00f5em o sistema.<\/span><\/p>\n<p><span>Matematicamente, a defini\u00e7\u00e3o exata \u00e9:<\/span><\/p>\n<p><strong><span>Entropia = (constante k de Boltzmann) x logaritmo do n\u00famero de estados poss\u00edveis<\/span><\/strong><\/p>\n<p><em><strong><span>S = k\u00a0<\/span><sub><span>B<\/span><\/sub><span>\u00a0logW<\/span><\/strong><\/em><\/p>\n<p><span>Essa equa\u00e7\u00e3o, que relaciona os detalhes microsc\u00f3picos, ou microestados, do sistema (via\u00a0<\/span><em><span>W<\/span><\/em><span>\u00a0) ao seu estado macrosc\u00f3pico (via\u00a0<\/span><strong><span>entropia\u00a0<\/span><em><span>S<\/span><\/em><\/strong><span>\u00a0), \u00e9 a ideia principal da mec\u00e2nica estat\u00edstica.\u00a0Em um sistema fechado, a entropia nunca diminui; portanto, no universo, a entropia est\u00e1 aumentando irreversivelmente.\u00a0Em um sistema aberto (por exemplo, uma \u00e1rvore em crescimento), a entropia pode diminuir e a ordem pode aumentar, mas apenas \u00e0 custa de um aumento na entropia em outro lugar (por exemplo, no Sol).<\/span><\/p>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Unidades de Entropia<\/span><\/h2>\n<p><span>O SI\u00a0<\/span><strong><span>unidade de entropia<\/span><\/strong><span>\u00a0\u00e9\u00a0<\/span><strong><span>J \/ K<\/span><\/strong><span>\u00a0.\u00a0Segundo Clausius, a entropia foi definida atrav\u00e9s da mudan\u00e7a na entropia S de um sistema.\u00a0A mudan\u00e7a na entropia S, quando uma quantidade de calor Q \u00e9 adicionada a ela por um processo revers\u00edvel a temperatura constante, \u00e9 dada por:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Entropy-Equation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-16710 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Entropy-Equation.png\" alt=\"Equa\u00e7\u00e3o da entropia\" width=\"102\" height=\"74\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Entropy-Equation.png\" \/><\/a><\/p>\n<p><span>Aqui\u00a0<\/span><strong><span>Q<\/span><\/strong><span>\u00a0\u00e9 a\u00a0<\/span><strong><span>energia transferida<\/span><\/strong><span>\u00a0como calor para ou do sistema durante o processo, e T \u00e9 a temperatura do sistema em Kelvins durante o processo.\u00a0Se assumirmos um\u00a0<\/span><strong><span>processo isot\u00e9rmico<\/span><\/strong><span>\u00a0revers\u00edvel\u00a0, a altera\u00e7\u00e3o total da entropia \u00e9 dada por:<\/span><\/p>\n<p><em><strong><span>\u2206S = S\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0&#8211; S\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0= Q \/ T<\/span><\/strong><\/em><\/p>\n<p><span>Nesta equa\u00e7\u00e3o, o\u00a0<\/span><strong><span>quociente Q \/ T<\/span><\/strong><span>\u00a0est\u00e1 relacionado ao aumento do dist\u00farbio.\u00a0Uma temperatura mais alta significa maior aleatoriedade de movimento.\u00a0Em temperaturas mais baixas, a adi\u00e7\u00e3o de calor Q causa um aumento fracion\u00e1rio substancial no movimento molecular e na aleatoriedade.\u00a0Por outro lado, se a subst\u00e2ncia j\u00e1 estiver quente, a mesma quantidade de calor Q adiciona relativamente pouco ao maior movimento molecular.<\/span><\/p>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Exemplo<\/span><\/h2>\n<p><span>Calcule a\u00a0<\/span><strong><span>varia\u00e7\u00e3o na entropia<\/span><\/strong><span>\u00a0de 1 kg de gelo a 0 \u00b0 C, quando derretida reversivelmente em \u00e1gua a 0 \u00b0 C.<\/span><\/p>\n<p><span>Por se tratar de um processo isot\u00e9rmico, podemos usar:<\/span><\/p>\n<p><em><strong><span>\u2206S = S\u00a0<\/span><sub><span>2<\/span><\/sub><span>\u00a0&#8211; S\u00a0<\/span><sub><span>1<\/span><\/sub><span>\u00a0= Q \/ T<\/span><\/strong><\/em><\/p>\n<p><span>portanto, a altera\u00e7\u00e3o da entropia ser\u00e1:<\/span><\/p>\n<p><span>\u2206S = 334 [kJ] \/ 273,15 [K] =\u00a0<\/span><strong><span>1,22 [kJ \/ K]<\/span><\/strong><\/p>\n<p><span>onde s\u00e3o necess\u00e1rios 334 quilojoules de calor para derreter 1 kg de gelo (calor latente de fus\u00e3o = 334 kJ \/ kg) e esse calor \u00e9 transferido para o sistema a 0 \u00b0 C (273,15 K).<\/span><\/p>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Diagramas em Ts<\/span><\/h2>\n<figure id=\"attachment_16713\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-16713\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Specific-Entropy-T-s-Diagram.png\"><img loading=\"lazy\" class=\"size-medium wp-image-16713 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Specific-Entropy-T-s-Diagram-300x273.png\" alt=\"Diagrama de Ts de um ciclo termodin\u00e2mico\" width=\"300\" height=\"273\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Specific-Entropy-T-s-Diagram-300x273.png\" \/><\/a><figcaption id=\"caption-attachment-16713\" class=\"wp-caption-text\"><span>Diagrama Ts do ciclo de Rankine<\/span><\/figcaption><\/figure>\n<p><span>Em geral, as fases de uma subst\u00e2ncia e os relacionamentos entre suas propriedades s\u00e3o mais comumente mostrados nos\u00a0<\/span><strong><span>diagramas de propriedades<\/span><\/strong><span>\u00a0.\u00a0Um grande n\u00famero de propriedades diferentes foi definido e existem algumas depend\u00eancias entre as propriedades.<\/span><\/p>\n<p><span>Um\u00a0<\/span><strong><span>diagrama de entropia de temperatura<\/span><\/strong><span>\u00a0(\u00a0<strong>diagrama\u00a0<\/strong><\/span><strong><span>Ts<\/span><\/strong><span>\u00a0) \u00e9 o tipo de diagrama mais frequentemente usado para analisar os ciclos do sistema de transfer\u00eancia de energia.\u00a0\u00c9 usado na termodin\u00e2mica para visualizar altera\u00e7\u00f5es de temperatura e entropia espec\u00edfica durante um processo ou ciclo termodin\u00e2mico.<\/span><\/p>\n<p><span>Isso ocorre porque o\u00a0<\/span><strong><span>trabalho<\/span><\/strong><span>\u00a0realizado pelo ou no sistema e o\u00a0<\/span><strong><span>calor adicionado<\/span><\/strong><span>\u00a0ou\u00a0<\/span><strong><span>removido<\/span><\/strong><span>\u00a0do sistema podem ser visualizados no\u00a0<\/span><strong><span>diagrama Ts<\/span><\/strong><span>\u00a0.\u00a0Pela defini\u00e7\u00e3o de entropia, o\u00a0<\/span><strong><span>calor<\/span><\/strong><span>\u00a0transferido para ou de um sistema \u00e9 igual \u00e0\u00a0<\/span><strong><span>\u00e1rea sob a curva Ts<\/span><\/strong><span>\u00a0do processo.<\/span><\/p>\n<p><em><strong><span>dQ = TdS<\/span><\/strong><\/em><\/p>\n<p><span>Um\u00a0<\/span><strong><span>processo isentr\u00f3pico<\/span><\/strong><span>\u00a0\u00e9 representado como uma\u00a0<\/span><strong><span>linha vertical<\/span><\/strong><span>\u00a0em um diagrama Ts, enquanto um processo isot\u00e9rmico \u00e9 uma linha horizontal.\u00a0Em um estado idealizado, a compress\u00e3o \u00e9 uma bomba, a compress\u00e3o em um compressor e a expans\u00e3o em uma turbina s\u00e3o processos isentr\u00f3picos.\u00a0Portanto, \u00e9 muito \u00fatil em engenharia de energia, porque esses dispositivos s\u00e3o usados \u200b\u200bem ciclos termodin\u00e2micos de usinas de energia.<\/span><\/p>\n<p><span>Observe que, as premissas isentr\u00f3picas s\u00e3o aplic\u00e1veis \u200b\u200bapenas aos ciclos ideais.\u00a0Ciclos termodin\u00e2micos reais t\u00eam perdas de energia inerentes devido \u00e0 inefici\u00eancia de compressores e turbinas.<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n<div><\/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>Entalpia \u00e9 a quantidade termodin\u00e2mica equivalente ao conte\u00fado total de calor de um sistema. Entropia \u00e9 uma medida de desordem ou da energia em um sistema para fazer o trabalho. Engenharia T\u00e9rmica O que \u00e9 entalpia Quatro potenciais termodin\u00e2micos comuns.\u00a0H = U + pV Na termodin\u00e2mica, a entalpia \u00e9 a medida de energia em um &#8230; <a title=\"O que \u00e9 entalpia e entropia &#8211; defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-entalpia-e-entropia-definicao\/\" aria-label=\"More on O que \u00e9 entalpia e entropia &#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 entalpia e entropia - defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"Entalpia \u00e9 a quantidade termodin\u00e2mica equivalente ao conte\u00fado total de calor de um sistema. 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