{"id":47567,"date":"2019-11-05T11:09:56","date_gmt":"2019-11-05T10:09:56","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/o-que-e-o-numero-peclet-definicao\/"},"modified":"2020-01-23T20:14:09","modified_gmt":"2020-01-23T19:14:09","slug":"o-que-e-o-numero-peclet-definicao","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-o-numero-peclet-definicao\/","title":{"rendered":"O que \u00e9 o N\u00famero P\u00e9clet &#8211; Defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">O n\u00famero P\u00e9clet \u00e9 um n\u00famero sem dimens\u00e3o, nomeado ap\u00f3s o Jean CE P\u00e9clet.\u00a0O n\u00famero de P\u00e9clet \u00e9 definido como a raz\u00e3o entre a taxa de advec\u00e7\u00e3o e a taxa de difus\u00e3o.\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-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>O que \u00e9 o n\u00famero P\u00e9clet<\/h2>\n<p>O\u00a0<strong>n\u00famero P\u00e9clet<\/strong>\u00a0\u00e9 um n\u00famero sem dimens\u00e3o, nomeado em homenagem ao f\u00edsico franc\u00eas Jean Claude Eug\u00e8ne P\u00e9clet.\u00a0O\u00a0<strong>n\u00famero de P\u00e9clet<\/strong>\u00a0\u00a0\u00e9 definido como a raz\u00e3o entre a taxa de advec\u00e7\u00e3o de uma quantidade f\u00edsica pelo fluxo e a taxa de difus\u00e3o (mat\u00e9ria ou calor) da mesma quantidade, impulsionada por um gradiente apropriado.\u00a0Portanto, devemos distinguir entre o n\u00famero do peclet para transfer\u00eancia de massa e transfer\u00eancia de calor.<\/p>\n<h2>N\u00famero de Peclet em Transfer\u00eancia de Massa<\/h2>\n<p>Em problemas de transfer\u00eancia de massa, o n\u00famero de P\u00e9clet \u00e9 o produto do\u00a0<a title=\"N\u00famero de Reynolds\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\">n\u00famero de Reynolds<\/a>\u00a0, que descreve o\u00a0\u00a0<a title=\"Regime de fluxo\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/flow-regime\/\">regime de fluxo<\/a>\u00a0, e o\u00a0<a title=\"O que \u00e9 o n\u00famero Schmidt\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/heat-transfer\/introduction-to-heat-transfer\/characteristic-numbers\/what-is-schmidt-number\/\">n\u00famero de Schmidt<\/a>\u00a0, usado para caracterizar fluxos de fluidos nos quais h\u00e1 processos simult\u00e2neos de convec\u00e7\u00e3o de momento e difus\u00e3o de massa.<\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/peclet-number-definition-formula-mass.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20359 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/peclet-number-definition-formula-mass.png\" alt=\"n\u00famero do peclet - defini\u00e7\u00e3o - f\u00f3rmula - massa\" width=\"484\" height=\"292\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/peclet-number-definition-formula-mass.png\" \/><\/a><\/p>\n<p>Onde:<\/p>\n<ul>\n<li><strong>u<\/strong>\u00a0\u00a0\u00e9 a velocidade do fluxo,<\/li>\n<li><strong>L<\/strong>\u00a0\u00a0\u00e9 uma\u00a0<strong>\u00a0dimens\u00e3o linear caracter\u00edstica<\/strong>\u00a0(comprimento percorrido do fluido;\u00a0\u00a0<a title=\"Di\u00e2metro hidr\u00e1ulico\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/internal-flow\/hydraulic-diameter-2\/\">di\u00e2metro hidr\u00e1ulico<\/a>\u00a0\u00a0etc.)<\/li>\n<li><strong>D<\/strong>\u00a0\u00e9 a difusividade da massa [m\u00a0<sup>2<\/sup>\u00a0\/ s]<\/li>\n<\/ul>\n<h2>N\u00famero de Peclet em Transfer\u00eancia de Calor<\/h2>\n<p>Em problemas de transfer\u00eancia de calor, o n\u00famero de P\u00e9clet \u00e9 a propor\u00e7\u00e3o da energia t\u00e9rmica convectada ao fluido pela energia t\u00e9rmica conduzida dentro do fluido.\u00a0O\u00a0\u00a0<strong>n\u00famero de P\u00e9clet<\/strong>\u00a0\u00a0\u00e9 simplesmente definido como o produto do\u00a0<a title=\"N\u00famero de Reynolds\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\">n\u00famero de Reynolds<\/a>\u00a0, que descreve o\u00a0<a title=\"Regime de fluxo\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/flow-regime\/\">regime de fluxo<\/a>\u00a0, e o\u00a0\u00a0<a title=\"O que \u00e9 o n\u00famero Prandtl\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/heat-transfer\/introduction-to-heat-transfer\/characteristic-numbers\/what-is-prandtl-number\/\">n\u00famero de Prandtl<\/a>\u00a0, que descreve a rela\u00e7\u00e3o entre difusividade de momento e difusividade t\u00e9rmica.\u00a0Se Pe \u00e9 pequeno, a condu\u00e7\u00e3o \u00e9 importante.<\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/peclet-number-definition-formula-heat.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20360 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/peclet-number-definition-formula-heat.png\" alt=\"n\u00famero do peclet - defini\u00e7\u00e3o - f\u00f3rmula - calor\" width=\"374\" height=\"273\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/peclet-number-definition-formula-heat.png\" \/><\/a><\/p>\n<p><span>Onde:<\/span><\/p>\n<ul>\n<li><strong><span>u<\/span><\/strong><span>\u00a0\u00a0\u00e9 a velocidade do fluxo,<\/span><\/li>\n<li><strong><span>L<\/span><\/strong><span>\u00a0\u00a0\u00e9 uma\u00a0<\/span><strong><span>\u00a0dimens\u00e3o linear caracter\u00edstica<\/span><\/strong><span>\u00a0(comprimento percorrido do fluido;\u00a0\u00a0<\/span><a title=\"Di\u00e2metro hidr\u00e1ulico\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/internal-flow\/hydraulic-diameter-2\/\"><span>di\u00e2metro hidr\u00e1ulico<\/span><\/a><span>\u00a0\u00a0etc.)<\/span><\/li>\n<li><strong><span>\u03b1<\/span><\/strong><span>\u00a0\u00a0\u00e9\u00a0\u00a0<\/span><strong><a title=\"Difusividade t\u00e9rmica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-difusividade-termica-definicao\/\"><span>difusividade t\u00e9rmica<\/span><\/a><\/strong><span>\u00a0\u00a0[m\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0\/ s]<\/span><\/li>\n<\/ul>\n<p><a title=\"Difusividade t\u00e9rmica\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-difusividade-termica-definicao\/\"><strong><span>A difusividade t\u00e9rmica<\/span><\/strong><\/a><span>\u00a0representa a rapidez com que o calor se difunde atrav\u00e9s de um material e possui unidades m<\/span><sup><span>\u00a02<\/span><\/sup><span>\u00a0\/ s.\u00a0Em outras palavras, \u00e9 a medida da\u00a0<\/span><strong><span>\u00a0in\u00e9rcia t\u00e9rmica<\/span><\/strong><span>\u00a0\u00a0de determinado material.\u00a0Difusividade t\u00e9rmica \u00e9 geralmente denotada \u03b1 e \u00e9 dada por:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-diffusivity-equation.png?d484e7\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20168 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-diffusivity-equation.png?d484e7\" alt=\"difusividade t\u00e9rmica\" width=\"358\" height=\"191\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/thermal-diffusivity-equation.png?d484e7\" \/><\/a><\/p>\n<p><span>Como pode ser visto, ele mede a capacidade de um material de conduzir\u00a0\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-energia-interna-energia-termica-definicao\/\"><span>energia t\u00e9rmica<\/span><\/a><span>\u00a0(representada pelo fator k) em rela\u00e7\u00e3o \u00e0 sua capacidade de armazenar energia t\u00e9rmica (representada pelo fator \u03c1.c\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0).\u00a0Materiais de \u03b1 grande responder\u00e3o rapidamente a mudan\u00e7as em seu ambiente t\u00e9rmico, enquanto materiais de \u03b1 pequeno responder\u00e3o mais lentamente (o calor \u00e9 absorvido na maior parte), levando mais tempo para alcan\u00e7ar uma nova condi\u00e7\u00e3o de equil\u00edbrio.<\/span><\/p>\n<h2><span>Difus\u00e3o em massa e lei de Fick<\/span><\/h2>\n<p><span>A difusividade \u00e9 encontrada na lei de Fick, que declara:<\/span><\/p>\n<p><em><span>Se a concentra\u00e7\u00e3o de um soluto em uma regi\u00e3o for maior que em outra solu\u00e7\u00e3o, o soluto difunde da regi\u00e3o de maior concentra\u00e7\u00e3o para a regi\u00e3o de menor concentra\u00e7\u00e3o, com uma magnitude proporcional ao gradiente de concentra\u00e7\u00e3o.<\/span><\/em><\/p>\n<p><span>Em uma dimens\u00e3o (espacial), a lei \u00e9:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Ficks-Law-equation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15177 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Ficks-Law-equation.png\" alt=\"Lei de Ficks - equa\u00e7\u00e3o\" width=\"133\" height=\"66\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Ficks-Law-equation.png\" \/><\/a><\/p>\n<p><span>Onde:<\/span><\/p>\n<ul>\n<li><em><span>J<\/span><\/em><span>\u00a0\u00e9 o fluxo de difus\u00e3o,<\/span><\/li>\n<li><em><span>D<\/span><\/em><span>\u00a0\u00e9 o\u00a0<\/span><strong><span>coeficiente de difus\u00e3o,<\/span><\/strong><\/li>\n<li><em><span>\u03c6<\/span><\/em><span>\u00a0(para misturas ideais) \u00e9 a concentra\u00e7\u00e3o.<\/span><\/li>\n<\/ul>\n<p><span>O uso desta lei na\u00a0<\/span><strong><span>teoria de reatores nucleares<\/span><\/strong><span>\u00a0leva \u00e0\u00a0<\/span><a title=\"Teoria da difus\u00e3o de n\u00eautrons\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/neutron-diffusion-theory\/\"><strong><span>aproxima\u00e7\u00e3o de difus\u00e3o<\/span><\/strong><\/a><span>\u00a0.<\/span><\/p>\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>O n\u00famero P\u00e9clet \u00e9 um n\u00famero sem dimens\u00e3o, nomeado ap\u00f3s o Jean CE P\u00e9clet.\u00a0O n\u00famero de P\u00e9clet \u00e9 definido como a raz\u00e3o entre a taxa de advec\u00e7\u00e3o e a taxa de difus\u00e3o.\u00a0Engenharia T\u00e9rmica O que \u00e9 o n\u00famero P\u00e9clet O\u00a0n\u00famero P\u00e9clet\u00a0\u00e9 um n\u00famero sem dimens\u00e3o, nomeado em homenagem ao f\u00edsico franc\u00eas Jean Claude Eug\u00e8ne P\u00e9clet.\u00a0O\u00a0n\u00famero &#8230; <a title=\"O que \u00e9 o N\u00famero P\u00e9clet &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-o-numero-peclet-definicao\/\" aria-label=\"More on O que \u00e9 o N\u00famero P\u00e9clet &#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 o N\u00famero P\u00e9clet - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"O n\u00famero P\u00e9clet \u00e9 um n\u00famero sem dimens\u00e3o, com o nome de Jean C. 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