{"id":39875,"date":"2024-09-06T11:35:17","date_gmt":"2024-09-06T09:35:17","guid":{"rendered":"https:\/\/obera.fr\/non-classifiee\/ce-este-o-transformare-adiabatica-reversibila\/"},"modified":"2025-04-15T09:41:48","modified_gmt":"2025-04-15T07:41:48","slug":"transformation-adiabatique-reversible","status":"publish","type":"post","link":"https:\/\/obera.fr\/ro\/sfatul-nostru\/transformation-adiabatique-reversible\/","title":{"rendered":"Ce este o transformare adiabatic\u0103 reversibil\u0103?"},"content":{"rendered":"\n<p><strong>Transformarea<\/strong> <strong>adiabatic\u0103 reversibil\u0103<\/strong> este un proces termodinamic idealizat care joac\u0103 un rol central \u00een analiza sistemelor energetice. Prin excluderea oric\u0103rui transfer de c\u0103ldur\u0103 cu lumea exterioar\u0103, aceast\u0103 transformare este guvernat\u0103 exclusiv de legile termodinamicii \u0219i de ecua\u021biile de stare. Ea este deosebit de bine descris\u0103 \u0219i aplicat\u0103 \u00een cazul gazelor perfecte. Care sunt caracteristicile distinctive ale acestei transform\u0103ri adiabatice? Ce ecua\u021bii matematice \u00eei definesc comportamentul? \u0218i care sunt aplica\u021biile practice ale <strong>reversibilit\u0103\u021bii adiabatice <\/strong>\u00een sistemele termice \u0219i motorii?     <\/p>\n\n<h2 class=\"wp-block-heading\">Defini\u021bie \u0219i principii de baz\u0103<\/h2>\n\n<figure class=\"wp-block-image alignright size-full is-resized\"><img decoding=\"async\" width=\"760\" height=\"647\" src=\"https:\/\/obera.fr\/wp-content\/uploads\/2024\/09\/thermodynamique.png\" alt=\"Termometru cu o s&#x103;geat&#x103; care merge &#xEE;n sus &#x219;i cealalt&#x103; care merge &#xEE;n jos\" class=\"wp-image-33976\" style=\"width:329px;height:auto\" srcset=\"https:\/\/obera.fr\/wp-content\/uploads\/2024\/09\/thermodynamique.png 760w, https:\/\/obera.fr\/wp-content\/uploads\/2024\/09\/thermodynamique-300x255.png 300w\" sizes=\"(max-width: 760px) 100vw, 760px\" \/><\/figure>\n\n<h3 class=\"wp-block-heading\">Ce este o transformare adiabatic\u0103?  <\/h3>\n\n<h4 class=\"wp-block-heading\">Defini\u021bie  <\/h4>\n\n<p>O <strong>transformare adiabatic\u0103 <\/strong>este un proces termodinamic \u00een care nu exist\u0103 transfer de c\u0103ldur\u0103 cu mediul, adic\u0103 Q=0, unde Q reprezint\u0103 cantitatea de c\u0103ldur\u0103 schimbat\u0103 cu exteriorul. Ca urmare, ecua\u021bia primului principiu al termodinamicii este simplificat\u0103 \u0219i poate fi exprimat\u0103 ca U= W, unde U reprezint\u0103 schimbarea energiei interne \u0219i W reprezint\u0103 lucrul efectuat \u00een timpul unei <a href=\"https:\/\/obera.fr\/ro\/sfatul-nostru\/racitoare-adiabatice-de-aer-functionare-si-beneficii\/\">transform\u0103ri adiabatice<\/a>. <\/p>\n\n<h4 class=\"wp-block-heading\">Caracteristicile unei transform\u0103ri adiabatice<\/h4>\n\n<p>Energia intern\u0103 a sistemului variaz\u0103 numai \u00een func\u021bie de lucrul efectuat asupra sau de c\u0103tre sistem, f\u0103r\u0103 schimb de c\u0103ldur\u0103 cu lumea exterioar\u0103.  <\/p>\n\n<p><strong> Transformarea adiabatic\u0103 poate fi reversibil\u0103,<\/strong> atunci c\u00e2nd procesul are loc \u00een mod ideal, f\u0103r\u0103 disipare de energie, sau ireversibil\u0103, atunci c\u00e2nd sunt prezente fenomene precum frecarea, turbulen\u021ba sau alte forme de disipare.<\/p>\n\n<h3 class=\"wp-block-heading\">Ce este o transformare adiabatic\u0103 reversibil\u0103?<\/h3>\n\n<h4 class=\"wp-block-heading\">Defini\u021bie<\/h4>\n\n<p>O <strong>transformare adiabatic\u0103 reversibil\u0103 <\/strong>este un proces termodinamic \u00een care un sistem evolueaz\u0103 f\u0103r\u0103 a schimba c\u0103ldur\u0103 cu mediul s\u0103u (adiabatic) \u0219i \u00een care fiecare etap\u0103 a procesului este perfect reversibil\u0103. Cu alte cuvinte, sistemul poate reveni la starea sa ini\u021bial\u0103 f\u0103r\u0103 a l\u0103sa schimb\u0103ri permanente \u00een sistemul \u00eensu\u0219i sau \u00een mediul s\u0103u. Aceasta \u00eenseamn\u0103 c\u0103, dac\u0103 procesul este inversat, sistemul \u0219i mediul s\u0103u revin exact la starea lor anterioar\u0103, f\u0103r\u0103 nicio disipare de energie sau modificare ireversibil\u0103.  <\/p>\n\n<h4 class=\"wp-block-heading\">Caracteristicile unei transform\u0103ri adiabatice reversibile<\/h4>\n\n<p>Legea conserv\u0103rii energiei: energia intern\u0103 a sistemului variaz\u0103 exclusiv \u00een func\u021bie de lucrul efectuat asupra sau de c\u0103tre sistem, f\u0103r\u0103 schimb de c\u0103ldur\u0103 cu lumea exterioar\u0103.<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Proces cvasi-static<\/strong>: transformarea are loc lent, permi\u021b\u00e2nd sistemului s\u0103 treac\u0103 printr-o serie de st\u0103ri succesive de echilibru. Este vorba mai degrab\u0103 de o succesiune de opera\u021bii infinitezimale dec\u00e2t de o transformare brusc\u0103, brusc\u0103.   <\/li>\n\n\n\n<li><strong>Echilibrul termodinamic<\/strong>: pe tot parcursul procesului, sistemul r\u0103m\u00e2ne \u00een echilibru termodinamic. Exist\u0103 continuitate \u00eentre m\u0103rimile intensive, cum ar fi presiunea \u0219i temperatura, asigur\u00e2ndu-se c\u0103 sistemul se afl\u0103 \u00een echilibru intern \u0219i extern pe parcursul transform\u0103rii. <\/li>\n\n\n\n<li><strong>Transformare izentropic\u0103<\/strong>: datorit\u0103 caracterului s\u0103u reversibil \u0219i absen\u021bei fenomenelor disipative, se spune c\u0103 procesul este izentropic. Aceasta \u00eenseamn\u0103 c\u0103 nu se produce entropie, iar entropia total\u0103 a \u00eentregului r\u0103m\u00e2ne neschimbat\u0103 \u00een timpul transform\u0103rii, adic\u0103 S=0. <\/li>\n<\/ul>\n\n<h2 class=\"wp-block-heading\">Ecua\u021biile relevante pentru o transformare adiabatic\u0103 reversibil\u0103<\/h2>\n\n<h3 class=\"wp-block-heading\">Rela\u021bii generale<\/h3>\n\n<p>Pentru o <strong>transformare adiabatic\u0103 reversibil\u0103<\/strong>:<\/p>\n\n<p>Nu exist\u0103 transfer de c\u0103ldur\u0103: dQ=0<\/p>\n\n<p>Modificarea entropiei este zero: dS=0<\/p>\n\n<p>Ecua\u021bia primei legi a termodinamicii pentru o transformare <a href=\"https:\/\/obera.fr\/ro\/sfatul-nostru\/comprendre-systeme-adiabatique-fonctionnement-applications\/\">adiabatic\u0103<\/a> reversibil\u0103 este: dU = -PdV<\/p>\n\n<p>  cu :<\/p>\n\n<ul class=\"wp-block-list\">\n<li>U este energia intern\u0103 ;<\/li>\n\n\n\n<li>P este presiunea ;<\/li>\n\n\n\n<li>Q reprezint\u0103 c\u0103ldura schimbat\u0103 ;<\/li>\n\n\n\n<li>S este entropia ;<\/li>\n\n\n\n<li>V este volumul.<\/li>\n<\/ul>\n\n<h3 class=\"wp-block-heading\">Gaze perfecte<\/h3>\n\n<p>Pentru un gaz perfect care sufer\u0103 <strong>o transformare adiabatic\u0103 reversibil\u0103<\/strong>, modificarea energiei interne se exprim\u0103 astfel: dU = Cv dT<\/p>\n\n<p>cu :<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Cv este capacitatea termic\u0103 la volum constant ;<\/li>\n\n\n\n<li>dT este varia\u021bia temperaturii.<\/li>\n<\/ul>\n\n<p>Prima lege a termodinamicii devine astfel : Cv dT = -P dV<\/p>\n\n<h3 class=\"wp-block-heading\">Ecua\u021biile Laplace<\/h3>\n\n<p>Ecua\u021biile lui Laplace rela\u021bioneaz\u0103 presiunea, volumul \u0219i temperatura unui gaz perfect \u00een timpul unei <strong>transform\u0103ri adiabatice reversibile. <\/strong>Ele sunt exprimate dup\u0103 cum urmeaz\u0103:<\/p>\n\n<p class=\"has-text-align-center\">PV = constant<\/p>\n\n<p class=\"has-text-align-center\">TV-1 = constant<\/p>\n\n<p class=\"has-text-align-center\">TP(1-\/) = constant\u0103<\/p>\n\n<p>Cu (gamma, numit \u0219i indice adiabatic sau coeficient Laplace) care este raportul capacit\u0103\u021bilor termice, definit ca = CpCv.<\/p>\n\n<p>cu :<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Cv este capacitatea termic\u0103 la volum constant ;<\/li>\n\n\n\n<li>Cp este capacitatea termic\u0103 la presiune constant\u0103.<\/li>\n<\/ul>\n\n<h3 class=\"wp-block-heading\">Exprimarea muncii \u00een condi\u021bii <strong>adiabatice reversibile<\/strong><\/h3>\n\n<p>Atunci c\u00e2nd gazul se dilat\u0103, adic\u0103 atunci c\u00e2nd volumul s\u0103u cre\u0219te (Vf&gt;Vi), acesta efectueaz\u0103 lucru \u00een exterior. \u00cen acest caz, lucrul este considerat pozitiv, deoarece gazul &#8222;d\u0103&#8221; energie mediului s\u0103u. Expresia pentru lucrul efectuat de gaz \u00een timpul acestei expansiuni este dat\u0103 de :  <\/p>\n\n<p class=\"has-text-align-center\">W= PiVi-PfVf-1<\/p>\n\n<p>unde :<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Pi \u0219i Vi sunt presiunea \u0219i volumul ini\u021biale;<\/li>\n\n\n\n<li>Pf \u0219i Vf sunt presiunea \u0219i volumul finale.<\/li>\n<\/ul>\n\n<p>Dimpotriv\u0103, atunci c\u00e2nd gazul este comprimat (volumul s\u0103u scade, Vf<vi un=\"\" travail=\"\" est=\"\" effectu=\"\" sur=\"\" le=\"\" gaz=\"\" par=\"\" l=\"\" toujours=\"\" consid=\"\" comme=\"\" positif=\"\" dans=\"\" ce=\"\" cas=\"\" car=\"\" de=\"\" au=\"\" pour=\"\" comprimer.=\"\" du=\"\" devient=\"\" :=\"\"><\/vi><\/p>\n\n<p class=\"has-text-align-center\">W= PfVf-PiVi-1<\/p>\n\n<h2 class=\"wp-block-heading\">Exemple de aplica\u021bii  <\/h2>\n\n<p>Ecua\u021biile <strong>transform\u0103rii adiabatice reversibile <\/strong>sunt omniprezente \u00een domenii precum energia, mecanica gazelor \u0219i ingineria, precum \u0219i \u00een \u0219tiin\u021bele atmosferice \u0219i astrofizice. Ele joac\u0103 un rol crucial \u00een aceste discipline, \u00een special \u00een sistemele termodinamice \u00een care obiectivul este optimizarea schimburilor de energie. Utilizate pentru a modela \u0219i analiza expansiunea sau comprimarea gazelor f\u0103r\u0103 schimb de c\u0103ldur\u0103 cu mediul \u00eenconjur\u0103tor, aceste transform\u0103ri sunt esen\u021biale pentru \u00een\u021belegerea \u0219i optimizarea multor sisteme. Iat\u0103 c\u00e2teva exemple de aplica\u021bii practice \u00een care <strong>transform\u0103rile adiabatice reversibile <\/strong>sunt fundamentale:   <\/p>\n\n<h3 class=\"wp-block-heading\">Cicluri termodinamice  <\/h3>\n\n<p>Ciclul Carnot, un model teoretic pentru motoarele termice, include <strong>faze adiabatice reversibile<\/strong> pentru a maximiza eficien\u021ba. Acest ciclu ideal este alc\u0103tuit din dou\u0103 <strong>procese adiabatice reversibile <\/strong>(expansiune \u0219i compresie) \u0219i dou\u0103 procese izoterme (la temperatur\u0103 constant\u0103). <\/p>\n\n<h3 class=\"wp-block-heading\">Compresoare \u0219i turbine<\/h3>\n\n<p>\u00cen compresoare \u0219i turbine cu gaze, compresia \u0219i expansiunea gazelor sunt adesea modelate ca <strong>procese adiabatice reversibile<\/strong>. Acest lucru maximizeaz\u0103 eficien\u021ba prin minimizarea pierderilor de energie sub form\u0103 de c\u0103ldur\u0103. <\/p>\n\n<h3 class=\"wp-block-heading\">Frigidere \u0219i pompe de c\u0103ldur\u0103<\/h3>\n\n<p>Ciclurile frigorifice \u0219i pompele de c\u0103ldur\u0103 utilizeaz\u0103 <strong>transform\u0103ri adiabatice reversibile<\/strong> \u00een timpul fazelor de compresie \u0219i expansiune a fluidului refrigerant. Aceste procese permit transferul eficient al energiei termice dintr-un loc \u00een altul, optimiz\u00e2nd eficien\u021ba energetic\u0103 a sistemului. <\/p>\n\n<h3 class=\"wp-block-heading\">Analiza proceselor industriale<\/h3>\n\n<p>Inginerii utilizeaz\u0103 <a href=\"https:\/\/obera.fr\/ro\/sfatul-nostru\/rafraichisseur-adiabatique-industriel-guide-complet\/\">reversibilitatea adiabatic\u0103<\/a><strong> <\/strong>pentru a analiza \u0219i proiecta diverse procese industriale, cum ar fi separarea gazelor \u0219i tratarea fluidelor. Aceste modele pot fi utilizate pentru optimizarea performan\u021bei \u0219i reducerea costurilor energetice. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>Transformarea adiabatic\u0103 reversibil\u0103 este un proces termodinamic idealizat care joac\u0103 un rol central \u00een analiza sistemelor energetice. Prin excluderea oric\u0103rui transfer de c\u0103ldur\u0103 cu lumea exterioar\u0103, aceast\u0103 transformare este guvernat\u0103 exclusiv de legile termodinamicii \u0219i de ecua\u021biile de stare. <\/p>\n","protected":false},"author":4,"featured_media":81228,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_seopress_robots_primary_cat":"none","_seopress_titles_title":"Transformare adiabatic\u0103 reversibil\u0103","_seopress_titles_desc":"Transformarea adiabatic\u0103 reversibil\u0103 este un proces termodinamic idealizat care joac\u0103 un rol central \u00een analiza sistemelor energetice.","_seopress_robots_index":"","footnotes":""},"categories":[144],"tags":[145],"class_list":["post-39875","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-sfatul-nostru","tag-entete-mic","generate-columns","tablet-grid-50","mobile-grid-100","grid-parent","grid-50","no-featured-image-padding","resize-featured-image"],"acf":[],"_links":{"self":[{"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/posts\/39875","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/comments?post=39875"}],"version-history":[{"count":3,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/posts\/39875\/revisions"}],"predecessor-version":[{"id":81418,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/posts\/39875\/revisions\/81418"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/media\/81228"}],"wp:attachment":[{"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/media?parent=39875"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/categories?post=39875"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/obera.fr\/ro\/wp-json\/wp\/v2\/tags?post=39875"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}