{"id":51971,"date":"2020-02-02T09:15:36","date_gmt":"2020-02-02T08:15:36","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/o-que-e-perda-de-cabeca-perda-de-pressao-definicao\/"},"modified":"2020-02-02T09:18:50","modified_gmt":"2020-02-02T08:18:50","slug":"o-que-e-perda-de-cabeca-perda-de-pressao-definicao","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-perda-de-cabeca-perda-de-pressao-definicao\/","title":{"rendered":"O que \u00e9 perda de cabe\u00e7a &#8211; perda de press\u00e3o &#8211; defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Perda de carga ou perda de press\u00e3o representa resist\u00eancia ao fluxo por atrito. A perda de carga por atrito est\u00e1 relacionada \u00e0 energia da velocidade do l\u00edquido ao quadrado. Engenharia T\u00e9rmica<\/div>\n<\/div>\n<div><\/div>\n<div><\/div>\n<div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-60 lgc-tablet-grid-60 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\">\n<h2><span>Perda de Cabe\u00e7a &#8211; Perda de Press\u00e3o<\/span><\/h2>\n<p><span>Na an\u00e1lise pr\u00e1tica de sistemas de tubula\u00e7\u00e3o, a quantidade mais importante \u00e9 a\u00a0<\/span><strong><span>perda de press\u00e3o devido a efeitos viscosos<\/span><\/strong><span>\u00a0ao longo do comprimento do sistema, bem como\u00a0<\/span><strong><span>perdas de press\u00e3o adicionais<\/span><\/strong><span>\u00a0decorrentes de outros\u00a0<\/span><strong><span>equipamentos tecnol\u00f3gicos<\/span><\/strong><span>\u00a0como v\u00e1lvulas, cotovelos, entradas de tubula\u00e7\u00e3o, conex\u00f5es e T .<\/span><br \/>\n<span>A princ\u00edpio, uma\u00a0<\/span><a title=\"Equa\u00e7\u00e3o de Bernoulli estendida\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/extended-bernoullis-equation\/\"><strong><span>equa\u00e7\u00e3o de Bernoulli estendida<\/span><\/strong><\/a><span>\u00a0deve ser introduzida.\u00a0Essa equa\u00e7\u00e3o permite que a conta da viscosidade seja inclu\u00edda de maneira emp\u00edrica e quantifique isso com um par\u00e2metro f\u00edsico conhecido como\u00a0<\/span><strong><span>perda de carga<\/span><\/strong><span>\u00a0.<\/span><br \/>\n<a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Extended-Bernoulli-Equation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-14315 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Extended-Bernoulli-Equation.png\" alt=\"Equa\u00e7\u00e3o de Bernoulli estendida\" width=\"441\" height=\"64\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Extended-Bernoulli-Equation.png\" \/><\/a><\/p>\n<div class=\"su-accordion\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\"><\/div>\n<\/div>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-clearfix\"><\/div>\n<\/div>\n<p><strong><span>A perda de<\/span><\/strong><span>\u00a0carga (ou perda de press\u00e3o) representa a redu\u00e7\u00e3o na carga total ou na press\u00e3o (soma da carga de eleva\u00e7\u00e3o, carga de velocidade e carga de press\u00e3o) do fluido \u00e0 medida que flui atrav\u00e9s de um sistema hidr\u00e1ulico.\u00a0<\/span><strong><span>A perda de<\/span><\/strong><span>\u00a0carga tamb\u00e9m representa a energia usada na supera\u00e7\u00e3o do atrito causado pelas paredes do tubo e outros equipamentos tecnol\u00f3gicos.\u00a0A perda de carga \u00e9 inevit\u00e1vel em fluidos m\u00f3veis reais.\u00a0Est\u00e1 presente devido ao atrito entre as part\u00edculas de fluido adjacentes \u00e0 medida que elas se movem uma em rela\u00e7\u00e3o \u00e0 outra (especialmente em fluxo turbulento).<\/span><\/p>\n<p><span>A perda de\u00a0<strong>carga<\/strong>\u00a0que ocorre nos tubos \u00e9 dependente da\u00a0<\/span><strong><span>velocidade<\/span><\/strong><span>\u00a0do\u00a0<strong>fluxo, di\u00e2metro<\/strong>\u00a0e\u00a0<\/span><strong><span>comprimento do\u00a0<\/span><\/strong><span><strong>tubo<\/strong>\u00a0, e um\u00a0<\/span><strong><span>fator de atrito<\/span><\/strong><span>\u00a0baseado na rugosidade do tubo e no\u00a0<\/span><strong><span>n\u00famero<\/span><\/strong><span>\u00a0de\u00a0<strong>Reynolds<\/strong>\u00a0do fluxo.\u00a0Embora a\u00a0<strong>perda de carga\u00a0<\/strong><\/span><strong><span>represente uma perda de energia<\/span><\/strong><span>\u00a0, ela\u00a0<\/span><strong><span>n\u00e3o representa uma perda de energia total<\/span><\/strong><span>\u00a0do fluido.\u00a0A energia total do fluido conserva como conseq\u00fc\u00eancia da\u00a0<\/span><strong><span>lei de conserva\u00e7\u00e3o de energia<\/span><\/strong><span>\u00a0.\u00a0Na realidade, a perda de carga devido ao atrito resulta em um\u00a0<\/span><strong><span>aumento<\/span><\/strong><span>\u00a0equivalente\u00a0<strong>na energia interna<\/strong>\u00a0(aumento da temperatura) do fluido.<\/span><\/p>\n<p><span>A maioria dos m\u00e9todos para avaliar a perda de carga por atrito \u00e9 baseada quase exclusivamente em\u00a0<\/span><strong><span>evid\u00eancias experimentais<\/span><\/strong><span> . Isso ser\u00e1 discutido nas pr\u00f3ximas se\u00e7\u00f5es.<\/span><\/p>\n<div class=\"su-accordion\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-clearfix\">\n<p>&nbsp;<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Classifica\u00e7\u00e3o da perda de cabe\u00e7a<\/span><\/h2>\n<p><strong><span>A perda<\/span><\/strong><span>\u00a0de\u00a0<strong>carga<\/strong>\u00a0de um sistema de tubula\u00e7\u00e3o \u00e9 igual \u00e0 produzida em uma tubula\u00e7\u00e3o reta, cujo comprimento \u00e9 igual aos tubos dos sistemas originais mais a soma dos comprimentos equivalentes de todos os componentes do sistema.<\/span><\/p>\n<p><span>Como pode ser visto, a perda de carga do sistema de tubula\u00e7\u00e3o \u00e9 dividida em duas categorias principais, \u201c\u00a0<\/span><strong><span>grandes perdas<\/span><\/strong><span>\u00a0\u201d associadas \u00e0 perda de energia por comprimento de tubo e \u201c\u00a0<\/span><strong><span>pequenas perdas<\/span><\/strong><span>\u00a0\u201d associadas a curvas, conex\u00f5es, v\u00e1lvulas, etc.<\/span><\/p>\n<ul>\n<li><a title=\"Perda de Cabe\u00e7a Maior - Perda de Fric\u00e7\u00e3o\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/\"><strong><span>Perda<\/span><\/strong><\/a><span>\u00a0de carga<a title=\"Perda de Cabe\u00e7a Maior - Perda de Fric\u00e7\u00e3o\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/\"><strong>\u00a0principal<\/strong><\/a>\u00a0&#8211; devido ao atrito em tubula\u00e7\u00f5es e dutos.<\/span><\/li>\n<li><a title=\"Menor Perda de Cabe\u00e7a - Perdas Locais\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/minor-head-loss-local-losses\/\"><strong><span>Menor perda de carga<\/span><\/strong><\/a><span>\u00a0&#8211; devido a componentes como v\u00e1lvulas, conex\u00f5es, dobras e T.<\/span><\/li>\n<\/ul>\n<p><span>A perda de carga pode ent\u00e3o ser expressa como:<\/span><\/p>\n<p><strong><em><span>h\u00a0<\/span><\/em><em><sub><span>perda<\/span><\/sub><\/em><em><span>\u00a0= \u03a3 h\u00a0<\/span><\/em><em><sub><span>principais_perdi\u00e7\u00f5es<\/span><\/sub><\/em><em><span>\u00a0+ \u03a3 h\u00a0<\/span><\/em><em><sub><span>menores_perdi\u00e7\u00f5es<\/span><\/sub><\/em><\/strong><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-40 lgc-tablet-grid-40 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\">\n<h2><span>Resumo:<\/span><\/h2>\n<ul>\n<li><strong><span>Perda de carga<\/span><\/strong><span>\u00a0ou\u00a0<\/span><strong><span>perda de press\u00e3o<\/span><\/strong><span>\u00a0s\u00e3o a redu\u00e7\u00e3o na\u00a0<\/span><a title=\"Cabe\u00e7a hidr\u00e1ulica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/hydraulic-head\/\"><strong><span>carga total<\/span><\/strong><\/a><span>\u00a0(soma da\u00a0<\/span><a title=\"Cabe\u00e7a de eleva\u00e7\u00e3o\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/elevation-head-2\/\"><span>cabe\u00e7a potencial<\/span><\/a><span>\u00a0,\u00a0<\/span><a title=\"Cabe\u00e7a de velocidade\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/velocity-head\/\"><span>cabe\u00e7a de velocidade<\/span><\/a><span>\u00a0, e\u00a0<\/span><a title=\"Cabe\u00e7a de press\u00e3o\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/pressure-head-2\/\"><span>cabe\u00e7a de press\u00e3o<\/span><\/a><span>\u00a0) de um fluido causado pelo\u00a0<\/span><strong><span>atrito<\/span><\/strong><span>\u00a0presente no movimento do fluido.<\/span><\/li>\n<li><strong><span>Perda de carga e perda de press\u00e3o<\/span><\/strong><span>\u00a0representam o mesmo fen\u00f4meno &#8211;\u00a0<\/span><strong><span>perdas por atrito<\/span><\/strong><span>\u00a0em tubula\u00e7\u00f5es e perdas em componentes hidr\u00e1ulicos, mas s\u00e3o expressas em\u00a0<\/span><strong><span>unidades diferentes<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>A perda de carga do sistema hidr\u00e1ulico \u00e9 dividida em\u00a0<\/span><strong><span>duas categorias principais<\/span><\/strong><span>\u00a0:<\/span>\n<ul>\n<li><strong><span>Perda de Cabe\u00e7a Maior<\/span><\/strong><span>\u00a0&#8211; devido ao atrito em tubos retos<\/span><\/li>\n<li><strong><span>Menor perda de carga<\/span><\/strong><span>\u00a0&#8211; devido a componentes como v\u00e1lvulas, curvas\u2026<\/span><\/li>\n<\/ul>\n<\/li>\n<li><a title=\"Equa\u00e7\u00e3o de Darcy-Weisbach\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/darcy-weisbach-equation\/\"><strong><span>A equa\u00e7\u00e3o de Darcy<\/span><\/strong><\/a><span>\u00a0pode ser usada para calcular<\/span><strong><span>\u00a0grandes perdas<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>Uma\u00a0<\/span><strong><span>forma especial da equa\u00e7\u00e3o de Darcy<\/span><\/strong><span>\u00a0pode ser usada para calcular\u00a0<\/span><strong><span>pequenas perdas<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>O\u00a0<\/span><a title=\"Fator de atrito de Darcy\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-o-fator-de-atrito-de-darcy-definicao\/\"><strong><span>fator de atrito<\/span><\/strong><\/a><span>\u00a0para o fluxo de fluido pode ser determinado usando um\u00a0<\/span><a title=\"Moody Diagram\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/moody-diagram\/\"><strong><span>gr\u00e1fico Moody<\/span><\/strong><\/a><span>\u00a0.<\/span><\/li>\n<\/ul>\n<h2><span>Por que a perda de cabe\u00e7a \u00e9 muito importante?<\/span><\/h2>\n<p><span>Como pode ser visto na figura, a perda de carga \u00e9 a\u00a0<\/span><strong><span>principal caracter\u00edstica<\/span><\/strong><span>\u00a0de qualquer sistema hidr\u00e1ulico.\u00a0Nos sistemas em que uma certa vaz\u00e3o deve ser mantida (por exemplo, para fornecer refrigera\u00e7\u00e3o ou transfer\u00eancia de calor suficiente a partir do\u00a0<\/span><a title=\"N\u00facleo do reator\" href=\"https:\/\/www.reactor-physics.com\/what-is-reactor-core-definition\/\"><span>n\u00facleo do reator<\/span><\/a><span>\u00a0),\u00a0<\/span><strong><span>o equil\u00edbrio<\/span><\/strong><span>\u00a0da\u00a0<\/span><strong><span>perda de carga<\/span><\/strong><span>\u00a0e da\u00a0\u00a0<\/span><strong><span>carga adicionada<\/span><\/strong><span>\u00a0por uma bomba determina a vaz\u00e3o atrav\u00e9s do sistema.<\/span><\/p>\n<figure id=\"attachment_14299\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-14299\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Head-Q-H.png\"><img loading=\"lazy\" class=\"size-medium wp-image-14299 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Head-Q-H-300x207.png\" alt=\"Diagrama caracter\u00edstico de QH da bomba centr\u00edfuga e do gasoduto\" width=\"300\" height=\"207\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Head-Q-H-300x207.png\" \/><\/a><figcaption id=\"caption-attachment-14299\" class=\"wp-caption-text\"><span>Diagrama caracter\u00edstico de QH da bomba centr\u00edfuga e do gasoduto<\/span><\/figcaption><\/figure>\n<figure id=\"attachment_14305\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-14305\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Head-Hydraulic-Grade-Line-min.png\"><img loading=\"lazy\" class=\"size-medium wp-image-14305 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Head-Hydraulic-Grade-Line-min-300x230.png\" alt=\"Cabe\u00e7a Hidr\u00e1ulica - Linha Hidr\u00e1ulica\" width=\"300\" height=\"230\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Head-Hydraulic-Grade-Line-min-300x230.png\" \/><\/a><figcaption id=\"caption-attachment-14305\" class=\"wp-caption-text\"><span>Linha de classifica\u00e7\u00e3o hidr\u00e1ulica e linhas de cabe\u00e7ote total para um tubo de di\u00e2metro constante com atrito.\u00a0Em uma tubula\u00e7\u00e3o real, h\u00e1 perdas de energia devido ao atrito &#8211; elas devem ser levadas em considera\u00e7\u00e3o, pois podem ser muito significativas.<\/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>Perda de Cabe\u00e7a Maior &#8211; Perda por Fric\u00e7\u00e3o<\/span><\/h2>\n<p><span>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Perda de Cabe\u00e7a Maior - Perda de Fric\u00e7\u00e3o\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/\"><span>Perda de cabe\u00e7a maior &#8211; perdas por atrito<\/span><\/a><\/p>\n<p><strong><span>As principais perdas<\/span><\/strong><span>\u00a0associadas \u00e0\u00a0<\/span><strong><span>perda de energia de atrito<\/span><\/strong><span>\u00a0por comprimento do tubo dependem da\u00a0<\/span><strong><span>velocidade<\/span><\/strong><span>\u00a0do\u00a0<strong>fluxo, comprimento do tubo, di\u00e2metro do tubo e um fator de atrito<\/strong>\u00a0baseado na rugosidade do tubo, e se o fluxo \u00e9\u00a0<\/span><a title=\"Fluxo Laminar - Fluxo Viscoso\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-fluxo-laminar-fluxo-viscoso-definicao\/\"><span>laminar<\/span><\/a><span>\u00a0ou\u00a0<\/span><a title=\"Fluxo turbulento\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-fluxo-turbulento-definicao\/\"><span>turbulento<\/span><\/a><span>\u00a0(ou seja,\u00a0<\/span><a title=\"N\u00famero de Reynolds\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\"><span>Reynolds n\u00famero<\/span><\/a><span>\u00a0do fluxo).<\/span><\/p>\n<p><span>Embora a\u00a0<strong>perda de carga\u00a0<\/strong><\/span><strong><span>represente uma perda de energia<\/span><\/strong><span>\u00a0, ela\u00a0<\/span><strong><span>n\u00e3o representa uma perda de energia total<\/span><\/strong><span>\u00a0do fluido.\u00a0A energia total do fluido conserva como conseq\u00fc\u00eancia da\u00a0<\/span><strong><span>lei de conserva\u00e7\u00e3o de energia<\/span><\/strong><span>\u00a0.\u00a0Na realidade, a perda de carga devido ao atrito resulta em um\u00a0<\/span><strong><span>aumento<\/span><\/strong><span>\u00a0equivalente\u00a0<strong>na energia interna<\/strong>\u00a0(aumento da temperatura) do fluido.<\/span><\/p>\n<p><span>Pela observa\u00e7\u00e3o, a\u00a0<\/span><strong><span>maior perda de carga \u00e9 aproximadamente proporcional ao quadrado da vaz\u00e3o<\/span><\/strong><span>\u00a0na maioria dos fluxos de engenharia (vaz\u00e3o de tubula\u00e7\u00e3o turbulenta e totalmente desenvolvida).<\/span><\/p>\n<p><span>A equa\u00e7\u00e3o mais comum usada para calcular as principais perdas de carga em um tubo ou duto \u00e9 a\u00a0<\/span><strong><span>equa\u00e7\u00e3o de Darcy \u2013 Weisbach<\/span><\/strong><span>\u00a0(forma de perda de carga).<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Major-Head-Loss-head-form.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-14583 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Major-Head-Loss-head-form.png\" alt=\"Perda de Cabe\u00e7a Maior - forma da cabe\u00e7a\" width=\"199\" height=\"88\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Major-Head-Loss-head-form.png\" \/><\/a><\/p>\n<p><span>Onde:<\/span><\/p>\n<ul>\n<li><span>\u0394h = perda de carga devida ao atrito (m)<\/span><\/li>\n<li><em><span>f\u00a0<\/span><\/em><em><sub><span>D<\/span><\/sub><\/em><span>\u00a0= fator de atrito de Darcy (sem unidade)<\/span><\/li>\n<li><span>L = comprimento do tubo (m)<\/span><\/li>\n<li><span>D = di\u00e2metro hidr\u00e1ulico do tubo D (m)<\/span><\/li>\n<li><span>g = constante gravitacional (m \/ s\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0)<\/span><\/li>\n<li><span>V = velocidade m\u00e9dia do fluxo V (m \/ s)<\/span><\/li>\n<\/ul>\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<span>A avalia\u00e7\u00e3o da\u00a0<\/span><strong><span>equa\u00e7\u00e3o de Darcy-Weisbach<\/span><\/strong><span>\u00a0fornece informa\u00e7\u00f5es sobre os fatores que afetam a perda de carga em um oleoduto.<\/span><\/p>\n<ul>\n<li><span>Considere que o\u00a0<\/span><strong><span>comprimento do tubo<\/span><\/strong><span>\u00a0ou canal \u00e9\u00a0<\/span><strong><span>dobrado<\/span><\/strong><span>\u00a0, a\u00a0<\/span><strong><span>perda de carga de atrito<\/span><\/strong><span>\u00a0resultante\u00a0<strong>dobrar\u00e1<\/strong>\u00a0.<\/span><\/li>\n<li><span>Em vaz\u00e3o constante e comprimento do tubo, a\u00a0<\/span><strong><span>perda de carga \u00e9 inversamente proporcional \u00e0 quarta pot\u00eancia de di\u00e2metro<\/span><\/strong><span>\u00a0(para fluxo laminar) e, assim, reduzir o di\u00e2metro do tubo pela metade aumenta a perda de carga em um fator de 16. Isso \u00e9 um aumento muito significativo na perda de carga e mostra por que tubos de di\u00e2metro maior levam a requisitos de energia de bombeamento muito menores.<\/span><\/li>\n<li><span>Como a perda de carga \u00e9 aproximadamente proporcional ao quadrado da vaz\u00e3o, ent\u00e3o se a\u00a0<\/span><strong><span>vaz\u00e3o for duplicada<\/span><\/strong><span>\u00a0, a\u00a0<\/span><strong><span>perda de carga aumentar\u00e1 em um fator de quatro<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>A\u00a0<\/span><strong><span>perda de carga \u00e9 reduzida pela metade<\/span><\/strong><span>\u00a0(para fluxo laminar) quando a\u00a0<\/span><strong><span>viscosidade do fluido \u00e9 reduzida pela metade<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<\/ul>\n<figure id=\"attachment_14429\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-14429\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Moody-chart-min.jpg\"><img loading=\"lazy\" class=\"size-large wp-image-14429 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Moody-chart-min-1024x642.jpg\" alt=\"Fonte: Donebythesecondlaw no idioma ingl\u00eas Wikipedia, CC BY-SA 3.0, https:\/\/commons.wikimedia.org\/w\/index.php?curid=4681366\" width=\"669\" height=\"419\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Moody-chart-min-1024x642.jpg\" \/><\/a><figcaption id=\"caption-attachment-14429\" class=\"wp-caption-text\"><span>Fonte: Donebythesecondlaw no idioma ingl\u00eas Wikipedia, CC BY-SA 3.0,<\/span><br \/>\n<span>https:\/\/commons.wikimedia.org\/w\/index.php?curid=4681366<\/span><\/figcaption><\/figure>\n<p><span>Com exce\u00e7\u00e3o do\u00a0<\/span><strong><span>fator de atrito de Darcy<\/span><\/strong><span>\u00a0, cada um desses termos (velocidade do fluxo,\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, comprimento de um tubo) pode ser facilmente medido.\u00a0O fator de atrito de Darcy leva em considera\u00e7\u00e3o as propriedades de densidade e viscosidade do fluido, al\u00e9m da\u00a0<\/span><strong><span>rugosidade<\/span><\/strong><span>\u00a0do\u00a0<strong>tubo<\/strong>\u00a0.\u00a0Esse fator pode ser avaliado pelo uso de v\u00e1rias rela\u00e7\u00f5es emp\u00edricas ou pode ser lido em gr\u00e1ficos publicados (por exemplo,\u00a0<\/span><strong><span>gr\u00e1fico Moody<\/span><\/strong><span>\u00a0).<\/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\"><\/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<h2><span>Menor perda de carga &#8211; perda de press\u00e3o local<\/span><\/h2>\n<p><span>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Menor Perda de Cabe\u00e7a - Perdas Locais\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/minor-head-loss-local-losses\/\"><span>Perda de carga menor &#8211; Perda de press\u00e3o local<\/span><\/a><\/p>\n<p><span>Na ind\u00fastria, qualquer sistema de tubula\u00e7\u00e3o cont\u00e9m\u00a0<\/span><strong><span>diferentes elementos tecnol\u00f3gicos<\/span><\/strong><span>\u00a0como\u00a0<\/span><strong><span>dobras<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><span>conex\u00f5es<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><span>v\u00e1lvulas<\/span><\/strong><span>\u00a0ou\u00a0<\/span><strong><span>canais aquecidos<\/span><\/strong><span>\u00a0.\u00a0Esses componentes adicionais aumentam a perda de carga geral do sistema.\u00a0Tais perdas s\u00e3o geralmente denominadas\u00a0<\/span><strong><span>perdas menores, embora geralmente representem uma parte importante da perda de carga<\/span><\/strong><span>\u00a0.\u00a0Para sistemas de tubula\u00e7\u00e3o relativamente curtos, com um n\u00famero relativamente grande de dobras e conex\u00f5es, pequenas perdas podem facilmente exceder grandes perdas (especialmente com uma v\u00e1lvula parcialmente fechada que pode causar uma\u00a0<\/span><strong><span>maior perda de press\u00e3o do<\/span><\/strong><span>\u00a0que um tubo longo, na verdade quando uma v\u00e1lvula \u00e9 fechada ou fechada). quase fechada, a perda menor \u00e9 infinita).<\/span><\/p>\n<p><span>As perdas menores s\u00e3o comumente medidas\u00a0<\/span><strong><span>experimentalmente<\/span><\/strong><span>\u00a0.\u00a0Os dados, especialmente para v\u00e1lvulas, dependem um pouco do projeto do fabricante.<\/span><\/p>\n<p><span>Geralmente, a maioria dos m\u00e9todos usados \u200b\u200bna ind\u00fastria define um\u00a0<\/span><strong><span>coeficiente K<\/span><\/strong><span>\u00a0como um valor para determinado componente tecnol\u00f3gico.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/minor-head-loss-equation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-14589 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/minor-head-loss-equation.png\" alt=\"perda de cabe\u00e7a menor - equa\u00e7\u00e3o\" width=\"238\" height=\"72\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/minor-head-loss-equation.png\" \/><\/a><\/p>\n<p><span>Como o atrito do tubo, as\u00a0<\/span><strong><span>menores perdas s\u00e3o aproximadamente proporcionais ao quadrado da vaz\u00e3o<\/span><\/strong><span>\u00a0e, portanto, podem ser facilmente integradas \u00e0\u00a0<\/span><strong><span>equa\u00e7\u00e3o de Darcy-Weisbach<\/span><\/strong><span>\u00a0.\u00a0K \u00e9 a soma de todos os coeficientes de perda no comprimento do tubo, cada um contribuindo para a perda de carga geral.<\/span><\/p>\n<p><span>Os m\u00e9todos a seguir s\u00e3o de import\u00e2ncia pr\u00e1tica nos c\u00e1lculos de perda de press\u00e3o local:<\/span><\/p>\n<ul>\n<li><strong><span>M\u00e9todo de comprimento equivalente<\/span><\/strong><\/li>\n<li><strong><span>M\u00e9todo K &#8211; M\u00e9todo do Coeficiente de Resist\u00eancia<\/span><\/strong><\/li>\n<li><strong><span>M\u00e9todo 2K<\/span><\/strong><\/li>\n<li><strong><span>M\u00e9todo 3K<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Veja tamb\u00e9m: Perda de carga menor &#8211; Perda de press\u00e3o local<\/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>Perda de carga do fluxo de fluido bif\u00e1sico<\/span><\/h2>\n<p><span>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Queda de press\u00e3o bif\u00e1sica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/two-phase-fluid-flow\/two-phase-pressure-drop\/\"><span>Queda de press\u00e3o bif\u00e1sica<\/span><\/a><\/p>\n<p><span>Ao contr\u00e1rio das quedas de press\u00e3o monof\u00e1sicas, o c\u00e1lculo e a previs\u00e3o de quedas de press\u00e3o bif\u00e1sicas s\u00e3o um problema muito mais sofisticado e os m\u00e9todos principais diferem significativamente.\u00a0Dados experimentais indicam que a\u00a0<\/span><strong><span>queda de press\u00e3o de atrito no fluxo bif\u00e1sico<\/span><\/strong><span>\u00a0(por exemplo, em um canal de ebuli\u00e7\u00e3o) \u00e9\u00a0<\/span><strong><span>substancialmente maior<\/span><\/strong><span>\u00a0do que no fluxo monof\u00e1sico com o mesmo comprimento e taxa de fluxo de massa.\u00a0As explica\u00e7\u00f5es para isso incluem um aparente aumento da rugosidade da superf\u00edcie devido \u00e0 forma\u00e7\u00e3o de bolhas na superf\u00edcie aquecida e maiores velocidades de fluxo.<\/span><\/p>\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>Perda de carga ou perda de press\u00e3o representa resist\u00eancia ao fluxo por atrito. A perda de carga por atrito est\u00e1 relacionada \u00e0 energia da velocidade do l\u00edquido ao quadrado. Engenharia T\u00e9rmica Perda de Cabe\u00e7a &#8211; Perda de Press\u00e3o Na an\u00e1lise pr\u00e1tica de sistemas de tubula\u00e7\u00e3o, a quantidade mais importante \u00e9 a\u00a0perda de press\u00e3o devido a &#8230; <a title=\"O que \u00e9 perda de cabe\u00e7a &#8211; perda de press\u00e3o &#8211; defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-perda-de-cabeca-perda-de-pressao-definicao\/\" aria-label=\"More on O que \u00e9 perda de cabe\u00e7a &#8211; perda de press\u00e3o &#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 perda de cabe\u00e7a - perda de press\u00e3o - defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"Perda de carga ou perda de press\u00e3o representa resist\u00eancia ao fluxo por atrito. 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