Конспект лекций по термодинамике. Коренблит С.Э. - 63 стр.

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const à ¢­®¢¥á¨î ®â¢¥ç ¥â ¬¨­¨¬ã¬ 娬¯®â¥­æ¨ « , ¨ ¯à¨ ¤®áâ â®ç­®
ᨫ쭮¬ ¯®«¥ ­¥¨§¡¥¦­® s (T; P; H) > n(T; P; 0), â® s- á®áâ®ï­¨¥ áâ ­®-
¢¨âáï â¥à¬®¤¨­ ¬¨ç¥áª¨ ­¥¢ë£®¤­ë¬ ¨ ᢥàå¯à®¢®¤¨¬®áâì à §àãè ¥âáï
¯à¨ ­¥ª®â®à®¬ ªà¨â¨ç¥áª®¬ (¤«ï ¤ ­­®© ⥬¯¥à âãàë T ) §­ 祭¨¨ ¯®«ï
Hc (T ), ¯à¨ H > Hc(0) = Hcr , { áâ ­®¢¨âáï ¢®¢á¥ ­¥¢®§¬®¦­®©. ‘«¥¤®¢ -
⥫쭮, ­ ¯«®áª®á⨠(T; H) ªà¨¢ ï ¯¥à¥å®¤ Hc (T ) ¨¬¥¥â ¢¨¤ ã¡ë¢ î饩
ä㭪樨 T , 㤮¢«¥â¢®àïî饩 ãà ¢­¥­¨î ä §®¢®£® à ¢­®¢¥á¨ï (4.33):
          s (T; P; H) =) n(T; P; 0); 7 ! H = H   9 c (T; P )  Hc (T ); (6.56)
           Hcr = Hc (0) > Hc (T ) > Hc (Tcr ) = 0; = 7 ! (¨á. 6.3): (6.57)
           Tcr = Tc(0) > Tc(H) > Tc (Hcr ) = 0; ;
à®¤¨ää¥à¥­æ¨à㥬 ãà ¢­¥­¨¥ (6.56), á ãç¥â®¬ (6.55), ¯® T ¨ ¯® P ¢¤®«ì
ªà¨¢®© ¯¥à¥å®¤ H = Hc(T ), â.¥. ¯à¨  = const. à¥­¥¡à¥£ ï § ¢¨á¨¬®-
áâìî v s ®â T ¨ ®â P , á ãç¥â®¬ (6.53), â.¥. (4.37), ¨¬¥¥¬:
        ds !  d  (T; P; H (T )) =                             (6.58)
         dT  dT s            c
           @   !      @   ! 0 @H (T ) 1          @    !
           @T P;H + @ H T;P @T P =) @T0 P;H ; 1â.¥.: (6.59)
              s           s    @    c    A             n
      =
           @s ! + @n ! = s s = vs Hc(T ) @ @Hc(T ) A ;
                                                             =0



                                                                 (6.60)
           @T P;H @T P;H s n 0 4 1 @T P
      ¨ ­ «®£¨ç­®: vs vn = v sH4c(T ) @ @H@P     c (T ) A
                                                           :     (6.61)
                                                         T
à¨ H 6= 0 ¯¥à¥å®¤ ᮯ஢®¦¤ ¥âáï ᪠窮¬ ¬®«ïà­®© í­âய¨¨ ¨ ®¡ê¥¬ ,
â.¥. ï¥âáï ä §®¢ë¬ ¯¥à¥å®¤®¬ 1-£® த á ¬®«ïà­®© ⥯«®â®© ¯¥à¥å®¤ :
                                               0          1
                                   v
                 = T (ss sn) = T 4 s Hc (T ) @ @Hc (T ) A
                                                  @T P < 0;       (6.62)

â.¥. ⥯«® ¢ë¤¥«ï¥âáï ¯à¨ ¯¥à¥å®¤¥ ¨§ n 7! s ¨ ¯®£«®é ¥âáï ¯à¨ ®¡à â­®¬
¯¥à¥å®¤¥ ¨§ s 7! n ¢ ᮮ⢥á⢨¨ á à §ã¯®à冷祭­®áâìî ¯®á«¥¤­¥© ä §ë.
 §¤¥«¨¢ ¤à㣠­ ¤à㣠ãà ¢­¥­¨ï (6.60), (6.61), á ãç¥â®¬ á¢ï§¥© ⨯
(1.11), ¯à¨¤¥¬, ¥áâ¥á⢥­­®, ª ãà ¢­¥­¨î Š« ¯¥©à®­ -Š« 㧨ãá (4.38):
            ss sn = (@Hc=@T )P =) dP ! =                     :   (6.63)
            vs vn        (@Hc =@P )T          dT  T (v s vn)