{"id":2087,"date":"2019-09-18T03:01:18","date_gmt":"2019-09-18T03:01:18","guid":{"rendered":"https:\/\/thuvienxaydung.com.vn\/?p=2087"},"modified":"2019-09-18T03:03:35","modified_gmt":"2019-09-18T03:03:35","slug":"tieu-chuan-xay-dung-viet-nam-tcxdvn-2992003-ve-cach-nhiet-cac-dai-luong-vat-ly-va-dinh-nghia-do-bo-xay-dung-ban-hanh","status":"publish","type":"post","link":"https:\/\/tailieuxaydung.net\/?p=2087","title":{"rendered":"Ti\u00eau chu\u1ea9n x\u00e2y d\u1ef1ng Vi\u1ec7t Nam TCXDVN 299:2003 v\u1ec1 C\u00e1ch nhi\u1ec7t \u2013 C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng v\u1eadt l\u00fd v\u00e0 \u0111\u1ecbnh ngh\u0129a do B\u1ed9 X\u00e2y d\u1ef1ng ban h\u00e0nh"},"content":{"rendered":"

TI\u00caU CHU\u1ea8N X\u00c2Y D\u1ef0NG VI\u1ec6T NAM<\/strong><\/p>\n

TCXDVN 299: 2003<\/strong><\/p>\n

(ISO 7345: 1987)<\/strong><\/p>\n

C\u00c1CH NHI\u1ec6T – C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd V\u00c0 \u0110\u1ecaNH NGH\u0128A<\/p>\n

Thermal insulation- physical quantities and definitions<\/em><\/p>\n

L\u1eddi n\u00f3i \u0111\u1ea7u<\/strong><\/p>\n

TCXDVN 299: 2003 (ISO 7345:1987)- C\u00e1ch nhi\u1ec7t- C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng v\u1eadt l\u00fd v\u00e0 \u0111\u1ecbnh ngh\u0129a \u0111\u01b0\u1ee3c ch\u1ea5p nh\u1eadn t\u1eeb ISO 7345:1987- C\u00e1ch nhi\u1ec7t- C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng v\u1eadt l\u00fd v\u00e0 \u0111\u1ecbnh ngh\u0129a.<\/p>\n

TCXDVN 299: 2003 (ISO 7345:1987)- C\u00e1ch nhi\u1ec7t- C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng v\u1eadt l\u00fd v\u00e0 \u0111\u1ecbnh ngh\u0129a do Vi\u1ec7n Nghi\u00ean c\u1ee9u Ki\u1ebfn tr\u00fac ch\u1ee7 tr\u00ec bi\u00ean so\u1ea1n, V\u1ee5 Khoa h\u1ecdc C\u00f4ng ngh\u1ec7- B\u1ed9 X\u00e2y d\u1ef1ng \u0111\u1ec1 ngh\u1ecb v\u00e0 \u0111\u01b0\u1ee3c B\u1ed9 X\u00e2y d\u1ef1ng ban h\u00e0nh.<\/p>\n

Ph\u1ea7n gi\u1edbi thi\u1ec7u<\/strong><\/p>\n

TI\u00caU CHU\u1ea8N N\u00c0Y L\u00c0 M\u1ed8T TRONG C\u00c1C TI\u00caU CHU\u1ea8N V\u1ec0 THU\u1eacT NG\u1eee LI\u00caN QUAN \u0110\u1ebeN C\u00c1CH NHI\u1ec6T, BAO G\u1ed2M:<\/p>\n

– TCXDVN 300: 2003 (ISO 9251-1987). C\u00c1CH NHI\u1ec6T – C\u00c1C \u0110I\u1ec0U KI\u1ec6N TRUY\u1ec0N NHI\u1ec6T V\u00c0 C\u00c1C \u0110\u1eb6C T\u00cdNH C\u1ee6A V\u1eacT LI\u1ec6U – THU\u1eacT NG\u1eee.<\/p>\n

– ISO 9346. C\u00c1CH NHI\u1ec6T- TRUY\u1ec0N NHI\u1ec6T KH\u1ed0I- C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd V\u00c0 \u0110\u1ecaNH NGH\u0128A.<\/p>\n

– ISO 9288. C\u00c1CH NHI\u1ec6T- TRUY\u1ec0N NHI\u1ec6T B\u1eb0NG B\u1ee8C X\u1ea0 – C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd V\u00c0 \u0110\u1ecaNH NGH\u0128A<\/p>\n

 <\/p>\n

C\u00c1CH NHI\u1ec6T – C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd V\u00c0 \u0110\u1ecaNH NGH\u0128A<\/strong><\/p>\n

Thermal insulation- physical quantities and definitions<\/em><\/strong><\/p>\n

    \n
  1. Ph\u1ea1m vi v\u00e0 l\u0129nh v\u1ef1c \u00e1p d\u1ee5ng<\/strong><\/li>\n<\/ol>\n

    TI\u00caU CHU\u1ea8N N\u00c0Y \u0110\u1ecaNH NGH\u0128A C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd S\u1eec D\u1ee4NG TRONG L\u0128NH V\u1ef0C C\u00c1CH NHI\u1ec6T V\u00c0 \u0110\u01afA RA C\u00c1C K\u00dd HI\u1ec6U V\u00c0 \u0110\u01a0N V\u1eca T\u01af\u01a0NG \u1ee8NG.<\/strong><\/p>\n

    GHI CH\u00da: DO PH\u1ea0M VI C\u1ee6A TI\u00caU CHU\u1ea8N N\u00c0Y CH\u1ec8 GI\u1edaI H\u1ea0N TRONG L\u0128NH V\u1ef0C C\u00c1CH NHI\u1ec6T N\u00caN M\u1ed8T S\u1ed0 \u0110\u1ecaNH NGH\u0128A \u0110\u01afA RA \u1ede M\u1ee4C 2 KH\u00c1C V\u1edaI NH\u1eeeNG \u0110\u1ecaNH NGH\u0128A \u0110\u01afA RA \u1ede ISO 31\/4- C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd V\u00c0 C\u00c1C \u0110\u01a0N V\u1eca NHI\u1ec6T. \u0110\u1ec2 PH\u00c2N BI\u1ec6T S\u1ef0 KH\u00c1C NHAU \u0110\u00d3, TR\u01af\u1edaC C\u00c1C THU\u1eacT NG\u1eee C\u00d3 \u0110\u00c1NH D\u1ea4U SAO (*) .<\/strong><\/em><\/p>\n

      \n
    1. C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng v\u1eadt l\u00fd v\u00e0 \u0111\u1ecbnh ngh\u0129a<\/strong><\/li>\n<\/ol>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
      <\/td>\n\u0110\u1ea0I L\u01af\u1ee2NG<\/em><\/td>\n\u0110\u01a0N V\u1eca<\/em><\/td>\n<\/tr>\n
      2.1. NHI\u1ec6T; NHI\u1ec6T L\u01af\u1ee2NG<\/p>\n

       <\/td>\n

      		Q<\/strong><\/td>\nJ<\/strong><\/td>\n<\/tr>\n
      2.2.<\/strong> L\u01afU L\u01af\u1ee2NG D\u00d2NG NHI\u1ec6T: NHI\u1ec6T L\u01af\u1ee2NG TRUY\u1ec0N<\/strong><\/p>\n

      T\u1edaI HO\u1eb6C TRUY\u1ec0N T\u1eea M\u1ed8T H\u1ec6 TH\u1ed0NG CHIA CHO TH\u1edcI GIAN:<\/strong><\/p>\n

      f =<\/td>\n

      		f<\/strong><\/td>\nW<\/strong><\/td>\n<\/tr>\n
      2.3 C\u01af\u1edcNG \u0110\u1ed8 D\u00d2NG NHI\u1ec6T: L\u01afU L\u01af\u1ee2NG D\u00d2NG NHI\u1ec6T CHIA CHO DI\u1ec6N T\u00cdCH:<\/p>\n

      Q =<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong> T\u1eeb \u201cc\u01b0\u1eddng \u0111\u1ed9\u201d c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c thay th\u1ebf b\u1eb1ng thu\u1eadt ng\u1eef \u201cc\u01b0\u1eddng \u0111\u1ed9 b\u1ec1 m\u1eb7t\u201d khi n\u00f3 c\u00f3 th\u1ec2 nh\u1ea7m l\u1eabn v\u1edbi thu\u1eadt ng\u1eef \u201cc\u01b0\u1eddng \u0111\u1ed9 theo chi\u1ec1u d\u00e0i\u201d<\/em>(2.4)<\/td>\n

      		Q<\/strong><\/td>\nW\/M2<\/sup><\/strong><\/td>\n<\/tr>\n
      2.4. C\u01b0\u1eddng \u0111\u1ed9 theo chi\u1ec1u d\u00e0i c\u1ee7a d\u00f2ng nhi\u1ec7t:<\/strong> L\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t chia cho chi\u1ec1u d\u00e0i:<\/p>\n

      q1<\/sub> =<\/td>\n

      		Q1<\/sub><\/strong><\/td>\nW\/M<\/strong><\/td>\n<\/tr>\n
      2.5. H\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t:<\/strong> \u0110\u1ea1i l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh theo bi\u1ec3u th\u1ee9c d\u01b0\u1edbi \u0111\u00e2y:<\/p>\n

      q = – l grad T<\/em><\/p>\n

      Ghi ch\u00fa:<\/em><\/strong> Kh\u00e1i ni\u1ec7m ch\u00ednh x\u00e1c v\u1ec1 h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t cho \u1edf ph\u1ea7n ph\u1ee5 l\u1ee5c. Kh\u00e1i ni\u1ec7m n\u00e0y c\u0169ng li\u00ean quan t\u1edbi vi\u1ec7c s\u1eed d\u1ee5ng kh\u00e1i ni\u1ec7m h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t cho v\u1eadt li\u1ec7u x\u1ed1p \u0111\u1eb3ng h\u01b0\u1edbng ho\u1eb7c d\u1ecb h\u01b0\u1edbng, \u1ea3nh h\u01b0\u1edfng c\u1ee7a nhi\u1ec7t \u0111\u1ed9 v\u00e0 c\u00e1c \u0111i\u1ec1u ki\u1ec7n th\u1eed nghi\u1ec7m.<\/em><\/td>\n

      		l<\/strong><\/td>\nW\/(M.K)<\/strong><\/td>\n<\/tr>\n
      2.6 Nhi\u1ec7t tr\u1edf su\u1ea5t:<\/strong> \u0110\u1ea1i l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi h\u1ec7 th\u1ee9c d\u01b0\u1edbi \u0111\u00e2y:<\/p>\n

      grad T<\/em> = – rq<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong> Kh\u00e1i ni\u1ec7m ch\u00ednh x\u00e1c v\u1ec1 nhi\u1ec7t tr\u1edf su\u1ea5t cho \u1edf ph\u1ea7n ph\u1ee5 l\u1ee5c.<\/td>\n

      		R<\/strong><\/p>\n

      \u00a0<\/strong><\/td>\n

      		(M.K)\/W<\/strong><\/td>\n<\/tr>\n
      2.7 *Nhi\u1ec7t tr\u1edf<\/strong> 1)<\/sup> : Ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 chia cho c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t trong tr\u1ea1ng th\u00e1i \u1ed5n \u0111\u1ecbnh<\/p>\n

      R =<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong><\/p>\n

      1. \u0110\u1ed1i v\u1edbi m\u1ed9t l\u1edbp ph\u1eb3ng khi s\u1eed d\u1ee5ng kh\u00e1i ni\u1ec7m h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t v\u00e0 khi t\u00ednh ch\u1ea5t n\u00e0y kh\u00f4ng \u0111\u1ed5i ho\u1eb7c tuy\u1ebfn t\u00ednh v\u1edbi nhi\u1ec7t \u0111\u1ed9 (xem ph\u1ee5 l\u1ee5c) th\u00ec:<\/em><\/p>\n

      R =<\/p>\n

      Trong \u0111\u00f3 d l\u00e0 chi\u1ec1u d\u00e0y c\u1ee7a l\u1edbp.<\/em><\/p>\n

      C\u00e1c \u0111\u1ecbnh ngh\u0129a n\u00e0y gi\u1ea3 thi\u1ebftt \u0111\u1ecbnh ngh\u0129a hai nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu T1<\/sub>, T2<\/sub> v\u00e0 m\u1ed9t di\u1ec7n t\u00edch m\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t truy\u1ec1n qua \u0111\u00f3 l\u00e0 \u0111\u1ed3ng nh\u1ea5t<\/em><\/p>\n

       <\/td>\n

      		R<\/em><\/td>\n(m2<\/sup>.K)\/W<\/td>\n<\/tr>\n
      1) Theo ISO 31\/4 th\u00ec \u201cnhi\u1ec7t tr\u1edf\u201d c\u00f2n g\u1ecdi l\u00e0 \u201cv\u1eadt c\u00e1ch nhi\u1ec7t\u201d ho\u1eb7c \u201ch\u1ec7 s\u1ed1 c\u00e1ch nhi\u1ec7t\u201d, k\u00fd hi\u1ec7u l\u00e0 M<\/em><\/td>\n<\/tr>\n
      Nhi\u1ec7t tr\u1edf c\u00f3 th\u1ec3 li\u00ean quan t\u1edbi v\u1eadt li\u1ec7u, c\u1ea5u tr\u00fac ho\u1eb7c b\u1ec1 m\u1eb7t. N\u1ebfu T1<\/sub> ho\u1eb7c T2<\/sub> kh\u00f4ng ph\u1ea3i l\u00e0 nhi\u1ec7t \u0111\u1ed9 c\u1ee7a b\u1ec1 m\u1eb7t ch\u1ea5t r\u1eafn m\u00e0 c\u1ee7a b\u1ec1 m\u1eb7t ch\u1ea5t l\u1ecfng, th\u00ec nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu ph\u1ea3i \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh trong m\u1ed7i tr\u01b0\u1eddng h\u1ee3p c\u1ee5 th\u1ec3 (c\u00f3 tham chi\u1ebfu v\u1edbi s\u1ef1 truy\u1ec1n nhi\u1ec7t \u0111\u1ed1i l\u01b0u t\u1ef1 do hay c\u01b0\u1ee1ng b\u1ee9c v\u00e0 b\u1ee9c x\u1ea1 nhi\u1ec7t t\u1eeb c\u00e1c v\u1eadt xung quanh, v.v…)<\/em><\/p>\n

      \u00a0Khi x\u00e1c \u0111\u1ecbnh gi\u00e1 tr\u1ecb nhi\u1ec7t tr\u1edf th\u00ec ph\u1ea3i bi\u1ebft T1 v\u00e0 T2<\/em><\/p>\n

      \u00a02. \u201cNhi\u1ec7t tr\u1edf\u201d c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c thay th\u1ebf b\u1eb1ng thu\u1eadt ng\u1eef \u201cNhi\u1ec7t tr\u1edf b\u1ec1 m\u1eb7t\u201d khi n\u00f3 c\u00f3 th\u1ec3 nh\u1ea7m l\u1eabn v\u1edbi thu\u1eadt ng\u1eef \u201cNhi\u1ec7t tr\u1edf theo chi\u1ec1u d\u00e0i\u201d (2.8).<\/em><\/td>\n

      		<\/td>\n<\/td>\n<\/tr>\n
      2.8 * Nhi\u1ec7t tr\u1edf theo chi\u1ec1u d\u00e0i1)<\/sup>:<\/strong> Ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 chia cho c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t theo chi\u1ec1u d\u00e0i trong \u0111i\u1ec1u ki\u1ec7n \u1ed5n \u0111\u1ecbnh:<\/p>\n

      R1<\/sub> =<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong> Gi\u1ea3 thi\u1ebft hai nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu l\u00e0 T1<\/sub>, T2<\/sub> v\u00e0 chi\u1ec1u d\u00e0i m\u00e0 c\u01b0\u1eddng \u0111\u1ed9 theo chi\u1ec1u d\u00e0i c\u1ee7a d\u00f2ng nhi\u1ec7t l\u00e0 \u0111\u1ed3ng nh\u1ea5t<\/em><\/p>\n

      N\u1ebfu b\u00ean trong h\u1ec7 th\u1ed1ng T1<\/sub> ho\u1eb7c T2<\/sub> kh\u00f4ng ph\u1ea3i l\u00e0 nhi\u1ec7t \u0111\u1ed9 c\u1ee7a b\u1ec1 m\u1eb7t ch\u1ea5t r\u1eafn m\u00e0 l\u00e0 c\u1ee7a b\u1ec1 m\u1eb7t ch\u1ea5t l\u1ecfng th\u00ec nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu \u0111\u00f3 ph\u1ea3i \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh trong t\u1eebng tr\u01b0\u1eddng h\u1ee3p c\u1ee5 th\u1ec3 (c\u00f3 ch\u00fa \u00fd \u0111\u1ebfn truy\u1ec1n nhi\u1ec7t \u0111\u1ed1i l\u01b0u hay c\u01b0\u1ee1ng b\u1ee9c v\u00e0 b\u1ee9c x\u1ea1 nhi\u1ec7t t\u1eeb c\u00e1c m\u1eb7t xung quanh, v.v…)<\/em><\/p>\n

      Khi x\u00e1c \u0111\u1ecbnh gi\u00e1 tr\u1ecb nhi\u1ec7t tr\u1edf theo chi\u1ec1u d\u00e0i th\u00ec ph\u1ea3i bi\u1ebft T1<\/sub> v\u00e0 T2<\/sub><\/em><\/td>\n

      		R1<\/sub><\/td>\n(m.K)\/W<\/td>\n<\/tr>\n
      2.9 H\u1ec7 s\u1ed1 trao \u0111\u1ed5i nhi\u1ec7t b\u1ec1 m\u1eb7t: c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t t\u1ea1i b\u1ec1 m\u1eb7t trong \u0111i\u1ec1u ki\u1ec7n \u1ed5n \u0111\u1ecbnh chia cho ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 gi\u1eefa b\u1ec1 m\u1eb7t \u0111\u00f3 v\u00e0 m\u00f4i tr\u01b0\u1eddng xung quanh:<\/strong><\/p>\n

      h =<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong> Gi\u1ea3 thi\u1ebft b\u1ec1 m\u1eb7t truy\u1ec1n nhi\u1ec7t, nhi\u1ec7t \u0111\u1ed9 b\u1ec1 m\u1eb7t Ts , nhi\u1ec7t \u0111\u1ed9 kh\u00f4ng kh\u00ed l\u00e0 Ta l\u00e0 x\u00e1c \u0111\u1ecbnh (c\u00f3 s\u1ef1 tham chi\u1ebfu v\u1edbi s\u1ef1 truy\u1ec1n nhi\u1ec7t \u0111\u1ed1i l\u01b0u t\u1ef1 do hay c\u01b0\u1ee1ng b\u1ee9c v\u00e0 b\u1ee9c x\u1ea1 nhi\u1ec7t t\u1eeb c\u00e1c m\u1eb7t xung quanh, v.v…)<\/em><\/td>\n

      		h<\/td>\nW\/(m2<\/sup>.K)<\/td>\n<\/tr>\n
      2.10 \u0110\u1ed9 d\u1eabn nhi\u1ec7t:<\/strong> S\u1ed1 ngh\u1ecbch \u0111\u1ea3o c\u1ee7a nhi\u1ec7t tr\u1edf t\u1eeb b\u1ec1 m\u1eb7t n\u00e0y t\u1edbi b\u1ec1 m\u1eb7t kia trong \u0111i\u1ec1u ki\u1ec7n c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t l\u00e0 \u0111\u1ed3ng nh\u1ea5t.<\/p>\n

      A =<\/p>\n

      Ghi ch\u00fa:<\/strong> \u201c\u0110\u1ed9 d\u1eabn nhi\u1ec7t\u201d \u0111\u01b0\u1ee3c thay th\u1ebf b\u1eb1ng \u201c\u0111\u1ed9 d\u1eabn nhi\u1ec7t b\u1ec1 m\u1eb7t\u201d khi n\u00f3 c\u00f3 th\u1ec3 b\u1ecb nh\u1ea7m l\u1eabn v\u1edbi thu\u1eadt ng\u1eef \u201c\u0111\u1ed9 d\u1eabn nhi\u1ec7t theo chi\u1ec1u d\u00e0i\u201d (2.11).<\/em><\/td>\n

      		A<\/td>\nW\/(m2<\/sup>.K)<\/td>\n<\/tr>\n
      2.11 \u0110\u1ed9 d\u1eabn nhi\u1ec7t theo chi\u1ec1u d\u00e0i:<\/strong> S\u1ed1 ngh\u1ecbch \u0111\u1ea3o c\u1ee7a nhi\u1ec7t tr\u1edf theo chi\u1ec1u d\u00e0i t\u1eeb b\u1ec1 m\u1eb7t n\u00e0y t\u1edbi b\u1ec1 m\u1eb7t kia trong \u0111i\u1ec1u ki\u1ec7n c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t l\u00e0 \u0111\u1ed3ng nh\u1ea5t.<\/p>\n

      A1<\/sub> =<\/td>\n

      		A1<\/sub><\/td>\nW\/(m.K)<\/td>\n<\/tr>\n
      2.12 \u0110\u1ed9 truy\u1ec1n nhi\u1ec7t:<\/strong> L\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t \u1edf \u0111i\u1ec1u ki\u1ec7n \u1ed5n \u0111\u1ecbnh chia cho t\u00edch s\u1ed1 c\u1ee7a di\u1ec7n t\u00edch v\u00e0 ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 c\u1ee7a m\u00f4i tr\u01b0\u1eddng \u1edf hai ph\u00eda c\u1ee7a h\u1ec7 th\u1ed1ng:<\/p>\n

      U1 =<\/td>\n

      		U1<\/sub><\/td>\nW\/(m2<\/sup>.K)<\/td>\n<\/tr>\n
      Ghi ch\u00fa:<\/em><\/strong><\/p>\n

      1. Gi\u1ea3 thi\u1ebft h\u1ec7 th\u1ed1ng, hai nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu T1<\/sub>, T2<\/sub> v\u00e0 c\u00e1c \u0111i\u1ec1u ki\u1ec7n bi\u00ean kh\u00e1c l\u00e0 x\u00e1c \u0111\u1ecbnh. <\/em><\/p>\n

      2. \u201c\u0110\u1ed9 truy\u1ec1n nhi\u1ec7t\u201d \u0111\u01b0\u1ee3c thay th\u1ebf b\u1eb1ng thu\u1eadt ng\u1eef \u201c\u0110\u1ed9 truy\u1ec1n nhi\u1ec7t b\u1ec1 m\u1eb7t\u201d khi n\u00f3 c\u00f3 th\u1ec3 nh\u1ea7m l\u1eabn v\u1edbi thu\u1eadt ng\u1eef \u201c\u0110\u1ed9 truy\u1ec1n nhi\u1ec7t theo chi\u1ec1u d\u00e0i\u201d (2.13).<\/em><\/p>\n

      3. S\u1ed1 ngh\u1ecbch \u0111\u1ea3o c\u1ee7a \u0111\u1ed9 truy\u1ec1n nhi\u1ec7t l\u00e0 t\u1ed5ng nhi\u1ec7t tr\u1edf c\u1ee7a m\u00f4i tr\u01b0\u1eddng \u1edf hai ph\u00eda c\u1ee7a h\u1ec7 th\u1ed1ng:<\/em><\/td>\n

      		<\/td>\n<\/td>\n<\/tr>\n
      2.13 \u0110\u1ed9 truy\u1ec1n nhi\u1ec7t theo chi\u1ec1u d\u00e0i:<\/strong> L\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t \u1edf \u0111i\u1ec1u ki\u1ec7n \u1ed5n \u0111\u1ecbnh chia cho t\u00edch s\u1ed1 c\u1ee7a chi\u1ec1u d\u00e0i v\u00e0 ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 c\u1ee7a m\u00f4i tr\u01b0\u1eddng \u1edf hai ph\u00eda c\u1ee7a h\u1ec7 th\u1ed1ng:<\/p>\n

      U1 =<\/td>\n

      		U1<\/sub><\/td>\nW\/(m.K)<\/td>\n<\/tr>\n
      Ghi ch\u00fa: <\/em><\/strong><\/p>\n

      1. Gi\u1ea3 thi\u1ebft h\u1ec7 th\u1ed1ng, hai nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu T1<\/sub>, T2<\/sub> v\u00e0 c\u00e1c \u0111i\u1ec1u ki\u1ec7n bi\u00ean l\u00e0 x\u00e1c \u0111\u1ecbnh.<\/em><\/p>\n

      2. S\u1ed1 ngh\u1ecbch \u0111\u1ea3o c\u1ee7a \u0111\u1ed9 truy\u1ec1n nhi\u1ec7t theo chi\u1ec1u d\u00e0i l\u00e0 t\u1ed5ng nhi\u1ec7t tr\u1edf theo chi\u1ec1u d\u00e0i gi\u1eefa m\u00f4i tr\u01b0\u1eddng \u1edf hai ph\u00eda c\u1ee7a h\u1ec7 th\u1ed1ng:<\/em><\/td>\n

      		<\/td>\n<\/td>\n<\/tr>\n
      2.14 Nhi\u1ec7t dung: <\/strong>\u0110\u1ea1i l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1eb1ng \u0111\u1eb3ng th\u1ee9c sau:<\/td>\nC<\/td>\nJ\/K<\/td>\n<\/tr>\n
      Ghi ch\u00fa:<\/em><\/strong> Khi nhi\u1ec7t \u0111\u1ed9 c\u1ee7a h\u1ec7 th\u1ed1ng t\u0103ng l\u00ean m\u1ed9t l\u01b0\u1ee3ng dT do s\u1ef1 t\u0103ng th\u00eam m\u1ed9t l\u01b0\u1ee3ng nh\u1ecf nhi\u1ec7t dQ th\u00ec \u0111\u1ea1i l\u01b0\u1ee3ng dQ\/dT g\u1ecdi l\u00e0 nhi\u1ec7t. dung<\/em><\/td>\n<\/td>\n<\/td>\n<\/tr>\n
      2.15 Nhi\u1ec7t dung ri\u00eang:<\/strong> Nhi\u1ec7t dung chia cho kh\u1ed1i l\u01b0\u1ee3ng.<\/td>\nc<\/td>\nJ\/(kg.K)<\/td>\n<\/tr>\n
      2.15.1 Nhi\u1ec7t dung ri\u00eang \u1edf \u00e1p su\u1ea5t kh\u00f4ng \u0111\u1ed5i.<\/td>\ncp<\/td>\nJ\/(kg.K)<\/td>\n<\/tr>\n
      2.15.2 Nhi\u1ec7t dung ri\u00eang \u1edf th\u1ec3 t\u00edch kh\u00f4ng \u0111\u1ed5i.<\/td>\ncv<\/td>\nJ\/(kg.K)<\/td>\n<\/tr>\n
      2.16 *H\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t \u0111\u1ed9: <\/strong>\u0110\u1ed9 d\u1eabn nhi\u1ec7t chia cho t\u00edch s\u1ed1 gi\u1eefa kh\u1ed1i l\u01b0\u1ee3ng ri\u00eang v\u00e0 nhi\u1ec7t dung ri\u00eang<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong><\/p>\n

      1. \u0110\u1ed1i v\u1edbi ch\u1ea5t l\u1ecfng, nhi\u1ec7t dung ri\u00eang th\u00edch h\u1ee3p l\u00e0 cp.<\/em><\/p>\n

      2. \u0110\u1ecaNH NGH\u0128A N\u00c0Y GI\u1ea2 THI\u1ebeT M\u00d4I TR\u01af\u1edcNG \u0110\u1ed2NG NH\u1ea4T, KH\u00d4NG TRONG SU\u1ed0T<\/em>.<\/p>\n

      3. H\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t \u0111\u1ed9 c\u00f3 li\u00ean quan t\u1edbi tr\u1ea1ng th\u00e1i kh\u00f4ng \u1ed5n \u0111\u1ecbnh v\u00e0 c\u00f3 th\u1ec3 \u0111o tr\u1ef1c ti\u1ebfp ho\u1eb7c t\u00ednh to\u00e1n b\u1eb1ng c\u00f4ng th\u1ee9c tr\u00ean t\u1eeb c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c \u0111o ri\u00eang r\u1ebd <\/em><\/p>\n

      4. Ngo\u00e0i ra, h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t \u0111\u1ed9 c\u00f3 k\u1ec3 \u0111\u1ebfn s\u1ef1 thay \u0111\u1ed5i nhi\u1ec7t \u0111\u1ed9 \u1edf b\u00ean trong kh\u1ed1i v\u1eadt li\u1ec7u khi nhi\u1ec7t \u0111\u1ed9 \u1edf b\u1ec1 m\u1eb7t thay \u0111\u1ed5i. H\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t \u0111\u1ed9 c\u1ee7a v\u1eadt li\u1ec7u c\u00e0ng cao th\u00ec nhi\u1ec7t \u0111\u1ed9 b\u00ean trong v\u1eadt li\u1ec7u c\u00e0ng nh\u1ea1y c\u1ea3m v\u1edbi s\u1ef1 thay \u0111\u1ed5i c\u1ee7a nhi\u1ec7t \u0111\u1ed9 b\u1ec1 m\u1eb7t.<\/em><\/td>\n

      		a<\/td>\nm2\/s<\/td>\n<\/tr>\n
      2.17 H\u1ec7 s\u1ed1 h\u00e0m nhi\u1ec7t: <\/strong>C\u0103n b\u1eadc hai c\u1ee7a t\u00edch s\u1ed1 gi\u1eefa \u0111\u1ed9 d\u1eabn nhi\u1ec7t, kh\u1ed1i l\u01b0\u1ee3ng ri\u00eang v\u00e0 nhi\u1ec7t dung ri\u00eang<\/p>\n

      b = \u00d6lrc<\/td>\n

      		b<\/td>\nJ\/(m2<\/sup>.Ks1\/2<\/sup>)<\/td>\n<\/tr>\n
      Ghi ch\u00fa: <\/em><\/strong><\/p>\n

      1. \u0110\u1ed1i v\u1edbi ch\u1ea5t l\u1ecfng, nhi\u1ec7t dung ri\u00eang th\u00edch h\u1ee3p l\u00e0 cp.<\/em><\/p>\n

      2. \u0110\u1eb7c t\u00ednh n\u00e0y li\u00ean quan t\u1edbi \u0111i\u1ec1u ki\u1ec7n kh\u00f4ng \u1ed5n \u0111\u1ecbnh. N\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u0111o ho\u1eb7c t\u00ednh to\u00e1n b\u1eb1ng c\u00f4ng th\u1ee9c tr\u00ean t\u1eeb c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng \u0111o ri\u00eang r\u1ebd. Ngo\u00e0i ra, h\u1ec7 s\u1ed1 h\u00e0m nhi\u1ec7t th\u1ec3 hi\u1ec7n s\u1ef1 thay \u0111\u1ed5i c\u1ee7a nhi\u1ec7t \u0111\u1ed9 b\u1ec1 m\u1eb7t v\u1eadt li\u1ec7u khi c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t \u0111i qua b\u1ec1 m\u1eb7t thay \u0111\u1ed5i. H\u1ec7 s\u1ed1 h\u00e0m nhi\u1ec7t c\u1ee7a v\u1eadt li\u1ec7u c\u00e0ng th\u1ea5p th\u00ec nhi\u1ec7t \u0111\u1ed9 b\u1ec1 m\u1eb7t c\u00e0ng nh\u1ea1y c\u1ea3m v\u1edbi s\u1ef1 thay \u0111\u1ed5i c\u1ee7a d\u00f2ng nhi\u1ec7t t\u1ea1i b\u1ec1 m\u1eb7t.<\/em><\/td>\n

      		<\/td>\n<\/td>\n<\/tr>\n
      3. \u0110\u1eb7c t\u00ednh n\u0103ng l\u01b0\u1ee3ng c\u1ee7a c\u00f4ng tr\u00ecnh:<\/strong><\/p>\n

      3.1 H\u1ec7 s\u1ed1 t\u1ed5n th\u1ea5t nhi\u1ec7t theo th\u1ec3 t\u00edch:<\/strong> L\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t t\u1eeb c\u00f4ng tr\u00ecnh chia cho t\u00edch s\u1ed1 th\u1ec3 t\u00edch v\u00e0 ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 gi\u1eefa m\u00f4i tr\u01b0\u1eddng b\u00ean trong v\u00e0 b\u00ean ngo\u00e0i:<\/p>\n

      Ghi ch\u00fa:<\/em><\/strong> L\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t c\u00f3 th\u1ec3 bao g\u1ed3m:c\u00e1c t\u00e1c \u0111\u1ed9ng truy\u1ec1n nhi\u1ec7t qua v\u1ecf bao che c\u1ee7a c\u00f4ng tr\u00ecnh, h\u1ec7 th\u1ed1ng th\u00f4ng gi\u00f3, b\u1ee9c x\u1ea1 m\u1eb7t tr\u1eddi, v.v…Trong \u0111\u00f3 \u0111\u1ea1i l\u01b0\u1ee3ng th\u1ec3 t\u00edch V ph\u1ea3i \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh.<\/em><\/p>\n

      \u00a0Khi \u00e1p d\u1ee5ng h\u1ec7 s\u1ed1 t\u1ed5n th\u1ea5t nhi\u1ec7t theo th\u1ec3 t\u00edch ch\u1ea5p nh\u1eadn c\u00e1c \u0111\u1ecbnh ngh\u0129a v\u1ec1 nhi\u1ec7t \u0111\u1ed9 b\u00ean trong, nhi\u1ec7t \u0111\u1ed9 b\u00ean ngo\u00e0i, th\u1ec3 t\u00edch v\u00e0 c\u00e1c t\u00e1c \u0111\u1ed9ng nhi\u1ec7t kh\u00e1c g\u00e2y ra l\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t .<\/em><\/td>\n

      		FV<\/td>\nW\/(m3.K)<\/td>\n<\/tr>\n
      3.2 H\u1ec7 s\u1ed1 t\u1ed5n th\u1ea5t nhi\u1ec7t theo di\u1ec7n t\u00edch:<\/strong> L\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t t\u1eeb c\u00f4ng tr\u00ecnh chia cho t\u00edch s\u1ed1 di\u1ec7n t\u00edch v\u00e0 ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 gi\u1eefa m\u00f4i tr\u01b0\u1eddng b\u00ean trong v\u00e0 b\u00ean ngo\u00e0i:<\/p>\n

       <\/p>\n

      GHI CH\u00da: L\u01afU L\u01af\u1ee2NG D\u00d2NG NHI\u1ec6T C\u00d3 TH\u1ec2 BAO G\u1ed2M C\u00c1C T\u00c1C \u0110\u1ed8NG TRUY\u1ec0N NHI\u1ec6T QUA V\u1ece BAO CHE C\u1ee6A C\u00d4NG TR\u00ccNH, H\u1ec6 TH\u1ed0NG TH\u00d4NG GI\u00d3, B\u1ee8C X\u1ea0 M\u1eb6T TR\u1edcI,V.V…DI\u1ec6N T\u00cdCH C\u00d3 TH\u1ec2 L\u00c0 DI\u1ec6N T\u00cdCH V\u1ece BAO CHE, DI\u1ec6N T\u00cdCH S\u00c0N…<\/strong><\/em><\/p>\n

      Khi \u00e1p d\u1ee5ng h\u1ec7 s\u1ed1 t\u1ed5n th\u1ea5t nhi\u1ec7t theo th\u1ec3 t\u00edch ch\u1ea5p nh\u1eadn c\u00e1c \u0111\u1ecbnh ngh\u0129a v\u1ec1 nhi\u1ec7t \u0111\u1ed9 b\u00ean trong, nhi\u1ec7t \u0111\u1ed9 b\u00ean ngo\u00e0i, th\u1ec3 t\u00edch v\u00e0 c\u00e1c t\u00e1c \u0111\u1ed9ng nhi\u1ec7t kh\u00e1c g\u00e2y ra l\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t.<\/em><\/td>\n

      		FS<\/td>\nW\/(m2<\/sup>.K)<\/td>\n<\/tr>\n
      3.3 B\u1ed9i s\u1ed1 trao \u0111\u1ed5i kh\u00f4ng kh\u00ed:<\/strong> S\u1ed1 l\u1ea7n thay \u0111\u1ed5i kh\u00f4ng kh\u00ed trong m\u1ed9t th\u1ec3 t\u00edch x\u00e1c \u0111\u1ecbnh chia cho th\u1eddi gian:<\/p>\n

      Ghi ch\u00fa: <\/em><\/strong>\u0110\u01a1n v\u1ecb c\u1ee7a b\u1ed9i s\u1ed1 trao \u0111\u1ed5i kh\u00f4ng kh\u00ed (h-1) kh\u00f4ng ph\u1ea3i l\u00e0 \u0111\u01a1n v\u1ecb \u0111o trong h\u1ec7 SI. Tuy v\u1eady, s\u1ed1 l\u1ea7n thay \u0111\u1ed5i kh\u00f4ng kh\u00ed trong m\u1ed9t gi\u1edd n\u00f3i chung \u0111\u01b0\u1ee3c ch\u1ea5p nh\u1eadn \u0111\u1ec3 th\u1ec3 hi\u1ec7n b\u1ed9i s\u1ed1 trao \u0111\u1ed5i kh\u00f4ng kh\u00ed<\/em><\/td>\n

      		n<\/td>\nh-1<\/sup><\/td>\n<\/tr>\n
      4. K\u00fd hi\u1ec7u v\u00e0 \u0111\u01a1n v\u1ecb \u0111o c\u1ee7a c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng kh\u00e1c:<\/strong><\/td>\n<\/td>\n<\/td>\n<\/tr>\n
      4.1 Nhi\u1ec7t \u0111\u1ed9 nhi\u1ec7t \u0111\u1ed9ng l\u1ef1c<\/td>\nT<\/td>\nK<\/td>\n<\/tr>\n
      4.2 Nhi\u1ec7t \u0111\u1ed9 b\u00e1ch ph\u00e2n<\/td>\nq<\/td>\n0<\/sup>C<\/td>\n<\/tr>\n
      4.3 Chi\u1ec1u d\u00e0y<\/td>\nd<\/td>\nM<\/td>\n<\/tr>\n
      4.4 Chi\u1ec1u d\u00e0i<\/td>\nl<\/td>\nM<\/td>\n<\/tr>\n
      4.5 Chi\u1ec1u r\u1ed9ng<\/td>\nb<\/td>\nM<\/td>\n<\/tr>\n
      4.6 Di\u1ec7n t\u00edch<\/td>\nA<\/td>\nm2<\/sup><\/td>\n<\/tr>\n
      4.7 Th\u1ec3 t\u00edch<\/td>\nV<\/td>\nm3<\/sup><\/td>\n<\/tr>\n
      4.8 \u0110\u01b0\u1eddng k\u00ednh<\/td>\nD<\/td>\nM<\/td>\n<\/tr>\n
      4.9 Th\u1eddi gian<\/td>\nt<\/td>\nS<\/td>\n<\/tr>\n
      4.10 Kh\u1ed1i l\u01b0\u1ee3ng<\/td>\nM<\/td>\nKg<\/td>\n<\/tr>\n
      4.11 Kh\u1ed1i l\u01b0\u1ee3ng ri\u00eang<\/td>\nr<\/td>\nkg\/m3<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
        \n
      1. C\u00e1c k\u00fd hi\u1ec7u ph\u1ee5:<\/strong><\/li>\n<\/ol>\n

        \u0110\u1ec3 tr\u00e1nh nh\u1ea7m l\u1eabn c\u1ea7n ph\u1ea3i s\u1eed d\u1ee5ng nh\u1eefng k\u00fd hi\u1ec7u ph\u1ee5 ho\u1eb7c c\u00e1c d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft kh\u00e1c. Trong c\u00e1c tr\u01b0\u1eddng h\u1ee3p \u0111\u00f3 \u00fd ngh\u0129a c\u1ee7a ch\u00fang c\u1ea7n ph\u1ea3i r\u00f5 r\u00e0ng.<\/p>\n

        Nh\u1eefng k\u00fd hi\u1ec7u ph\u1ee5 d\u01b0\u1edbi \u0111\u00e2y khuy\u1ebfn c\u00e1o s\u1eed d\u1ee5ng:<\/p>\n

        – b\u00ean trong (interior).\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 i<\/p>\n

        – b\u00ean ngo\u00e0i (exterior)\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 e<\/p>\n

        – b\u1ec1 m\u1eb7t (surface)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 s<\/p>\n

        – m\u1eb7t trong (interior surface)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 si<\/p>\n

        – m\u1eb7t ngo\u00e0i (exterior surface)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 se<\/p>\n

        – d\u1eabn truy\u1ec1n (conduction)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 cd<\/p>\n

        – \u0111\u1ed1i l\u01b0u (convection)\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 cv<\/p>\n

        – b\u1ee9c x\u1ea1 (radiation)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 r<\/p>\n

        – ti\u1ebfp x\u00fac (contact)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c<\/p>\n

        – kh\u00f4ng gian kh\u00ed (kh\u00f4ng kh\u00ed) (gas (air) space)\u00a0\u00a0\u00a0\u00a0\u00a0 g<\/p>\n

        – m\u00f4i tr\u01b0\u1eddng xung quanh (ambient)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 a<\/p>\n

         <\/p>\n

        PH\u1ee4 L\u1ee4C<\/strong><\/p>\n

        KH\u00c1I NI\u1ec6M V\u1ec0 \u0110\u1ed8 D\u1eaaN NHI\u1ec6T<\/p>\n

        A.0. Gi\u1edbi thi\u1ec7u<\/strong><\/p>\n

        \u0110\u1ec3 hi\u1ec3u r\u00f5 th\u00eam kh\u00e1i ni\u1ec7m \u0111\u1ed9 d\u1eabn nhi\u1ec7t khi \u00e1p d\u1ee5ng, ph\u1ee5 l\u1ee5c n\u00e0y \u0111\u01b0a ra c\u00e1ch gi\u1ea3i th\u00edch theo to\u00e1n h\u1ecdc ch\u00ednh x\u00e1c h\u01a1n.<\/p>\n

        A.1. Gradian nhi\u1ec7t (grad T) t\u1ea1i \u0111i\u1ec3m P<\/strong><\/p>\n

        \u0110\u00c2Y L\u00c0 M\u1ed8T V\u00c9CT\u01a0 THEO H\u01af\u1edaNG PH\u00c1P TUY\u1ebeN N V\u1edaI M\u1eb6T \u0110\u1eb2NG NHI\u1ec6T CH\u1ee8A \u0110I\u1ec2M P. \u0110\u1ed8 L\u1edaN C\u1ee6A N\u00d3 B\u1eb0NG \u0110\u1ea0O H\u00c0M C\u1ee6A NHI\u1ec6T \u0110\u1ed8 T THEO KHO\u1ea2NG C\u00c1CH T\u1eea P D\u1eccC THEO PH\u01af\u01a0NG PH\u00c1P TUY\u1ebeN N, V\u00c9CT\u01a0 \u0110\u01a0N V\u1eca L\u00c0 EN<\/p>\n

        T\u1eeb \u0111\u1ecbnh ngh\u0129a n\u00e0y c\u00f3:<\/p>\n

        grad T.en = \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (1)<\/p>\n

        A.2. C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t b\u1ec1 m\u1eb7t, q, \u1edf \u0111i\u1ec3m P (b\u1ec1 m\u1eb7t c\u00f3 d\u00f2ng nhi\u1ec7t \u0111\u01b0\u1ee3c truy\u1ec1n qua)<\/strong><\/p>\n

        \u0110\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh nh\u01b0 sau:<\/p>\n

        (2)<\/p>\n

        Khi \u0111\u1ec1 c\u1eadp \u0111\u1ebfn s\u1ef1 trao \u0111\u1ed5i nhi\u1ec7t do d\u1eabn nhi\u1ec7t \u1edf m\u1ed7i \u0111i\u1ec3m c\u1ee7a v\u1eadt th\u1ec3 n\u01a1i t\u1ed3n t\u1ea1i s\u1ef1 d\u1eabn nhi\u1ec7t th\u00ec \u0111\u1ea1i l\u01b0\u1ee3ng q ph\u1ee5 thu\u1ed9c v\u00e0o h\u01b0\u1edbng c\u1ee7a b\u1ec1 m\u1eb7t (t\u1ee9c l\u00e0 ph\u1ee5 thu\u1ed9c v\u00e0o h\u01b0\u1edbng ph\u00e1p tuy\u1ebfn \u1edf \u0111i\u1ec3m P t\u1edbi b\u1ec1 m\u1eb7t di\u1ec7n t\u00edch A) v\u00e0 c\u00f3 th\u1ec3 t\u00ecm \u0111\u01b0\u1ee3c h\u01b0\u1edbng ph\u00e1p tuy\u1ebfn n v\u1edbi b\u1ec1 m\u1eb7t di\u1ec7n t\u00edch An ch\u1ee9a \u0111i\u1ec3m P, n\u01a1i m\u00e0 tr\u1ecb s\u1ed1 q c\u00f3 gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t v\u00e0 \u0111\u01b0\u1ee3c k\u00fd hi\u1ec7u b\u1eb1ng v\u00e9ct\u01a1 q:<\/p>\n

        \u0110\u1ed1i v\u1edbi b\u1ec1 m\u1eb7t b\u1ea5t k\u1ef3 di\u1ec7n t\u00edch AS \u0111i qua \u0111i\u1ec3m P, c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t b\u1ec1 m\u1eb7t q l\u00e0 m\u1ed9t th\u00e0nh ph\u1ea7n c\u1ee7a v\u00e9c t\u01a1 q theo h\u01b0\u1edbng ph\u00e1p tuy\u1ebfn t\u1edbi b\u1ec1 m\u1eb7t \u0111\u00f3 t\u1ea1i \u0111i\u1ec3m P.<\/p>\n

        V\u00e9ct\u01a1 q \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 \u201cm\u1eadt \u0111\u1ed9 d\u00f2ng nhi\u1ec7t\u201d (kh\u00f4ng ph\u1ea3i c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t). Thu\u1eadt ng\u1eef \u201cd\u00f2ng nhi\u1ec7t\u201d v\u00e0 \u201cl\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t\u201d l\u00e0 c\u00e1ch n\u00f3i t\u01b0\u01a1ng \u0111\u01b0\u01a1ng khi \u0111\u1ec1 c\u1eadp t\u1edbi d\u1eabn nhi\u1ec7t. B\u1ea5t k\u1ef3 khi n\u00e0o v\u00e9ct\u01a1 q kh\u00f4ng th\u1ec3 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c (\u0111\u1ed1i v\u1edbi truy\u1ec1n nhi\u1ec7t \u0111\u1ed1i l\u01b0u v\u00e0 h\u1ea7u h\u1ebft c\u00e1c tr\u01b0\u1eddng h\u1ee3p truy\u1ec1n nhi\u1ec7t b\u1ee9c x\u1ea1), th\u00ec ch\u1ec9 s\u1eed d\u1ee5ng thu\u1eadt ng\u1eef \u201cl\u01b0u l\u01b0\u1ee3ng d\u00f2ng nhi\u1ec7t\u201d v\u00e0 \u201cc\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng nhi\u1ec7t b\u1ec1 m\u1eb7t\u201d<\/p>\n

        A.3. Nhi\u1ec7t tr\u1edf su\u1ea5t r t\u1ea1i \u0111i\u1ec3m P<\/strong><\/p>\n

        \u0110\u00e2y l\u00e0 \u0111\u1ea1i l\u01b0\u1ee3ng cho ph\u00e9p t\u00ednh to\u00e1n v\u00e9ct\u01a1 grad T t\u1ea1i \u0111i\u1ec3m P t\u1eeb v\u00e9ct\u01a1 q t\u1ea1i \u0111i\u1ec3m P b\u1eb1ng \u0111\u1ecbnh lu\u1eadt Fourier. Tr\u01b0\u1eddng h\u1ee3p \u0111\u01a1n gi\u1ea3n nh\u1ea5t (v\u1eadt li\u1ec7u \u0111\u1eb3ng nhi\u1ec7t) l\u00e0 khi grad T v\u00e0 q song song v\u00e0 ng\u01b0\u1ee3c chi\u1ec1u, l\u00fac \u0111\u00f3 r \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh \u1edf m\u1ed7i \u0111i\u1ec3m nh\u01b0 h\u1ec7 s\u1ed1 t\u1ef7 l\u1ec7 gi\u1eefa c\u00e1c v\u00e9ct\u01a1 grad T v\u00e0 q:<\/p>\n

        grad T = – rq\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (4)<\/p>\n

        Trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y r c\u0169ng l\u00e0 h\u1ec7 s\u1ed1 t\u1ef7 l\u1ec7 ngh\u1ecbch gi\u1eefa c\u00e1c th\u00e0nh ph\u1ea7n c\u1ee7a grad T v\u00e0 q t\u1ea1i c\u00f9ng m\u1ed9t \u0111i\u1ec3m d\u1ecdc theo h\u01b0\u1edbng s b\u1ea5t k\u1ef3 v\u00e0 kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o h\u01b0\u1edbng s \u0111\u00e3 ch\u1ecdn.<\/p>\n

        Trong tr\u01b0\u1eddng h\u1ee3p chung (v\u1eadt li\u1ec7u \u0111\u1eb3ng h\u01b0\u1edbng ho\u1eb7c d\u1ecb h\u01b0\u1edbng), m\u1ed9t trong ba th\u00e0nh ph\u1ea7n x\u00e1c \u0111\u1ecbnh grad T l\u00e0 \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ef7 l\u1ec7 tuy\u1ebfn t\u00ednh c\u1ee7a c\u00e1c th\u00e0nh ph\u1ea7n c\u1ee7a v\u00e9ct\u01a1 q. Do \u0111\u00f3 nhi\u1ec7t tr\u1edf su\u1ea5t \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh th\u00f4ng qua tenx\u01a1 [r] c\u1ee7a ch\u00edn h\u1ec7 s\u1ed1 c\u1ee7a c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ef7 l\u1ec7 tuy\u1ebfn t\u00ednh \u0111\u00f3 theo h\u1ec7 th\u1ee9c d\u01b0\u1edbi \u0111\u00e2y :<\/p>\n

        grad T = – [r] q \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (5)<\/p>\n

        N\u1ebfu nhi\u1ec7t tr\u1edf su\u1ea5t r ho\u1eb7c [r] kh\u00f4ng \u0111\u1ed5i theo to\u1ea1 \u0111\u1ed9 v\u00e0 th\u1eddi gian, c\u00f3 th\u1ec3 xem n\u00f3 nh\u01b0 l\u00e0 m\u1ed9t \u0111\u1eb7c t\u00ednh nhi\u1ec7t \u1edf nhi\u1ec7t \u0111\u1ed9 \u0111\u00e3 cho.<\/p>\n

        A.4. \u0110\u1ed9 d\u1eabn nhi\u1ec7t <\/strong>l \u1edf \u0111i\u1ec3m P<\/strong><\/p>\n

        \u0110\u00e2y l\u00e0 \u0111\u1ea1i l\u01b0\u1ee3ng cho ph\u00e9p \u0111\u1ec3 t\u00ednh to\u00e1n v\u00e9ct\u01a1 q t\u1ea1i \u0111i\u1ec3m P t\u1eeb v\u00e9ct\u01a1 grad T t\u1ea1i \u0111i\u1ec3m P, c\u00f3 ngh\u0129a l\u00e0 b\u1eb1ng t\u00edch s\u1ed1 c\u1ee7a \u0111\u1ed9 d\u1eabn nhi\u1ec7t v\u1edbi nhi\u1ec7t tr\u1edf su\u1ea5t b\u1eb1ng m\u1ed9t ho\u1eb7c b\u1eb1ng m\u1ed9t \u0111\u01a1n v\u1ecb tenx\u01a1.<\/p>\n

        N\u1ebfu q v\u00e0 grad T song song v\u00e0 ng\u01b0\u1ee3c chi\u1ec1u th\u00ec:<\/p>\n

        q = – l grad T\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (6)<\/p>\n

        lr = 1<\/p>\n

        Gi\u1ed1ng nh\u01b0 nhi\u1ec7t tr\u1edf su\u1ea5t, \u0111\u1ed9 d\u1eabn nhi\u1ec7t trong h\u1ea7u h\u1ebft c\u00e1c tr\u01b0\u1eddng h\u1ee3p l\u00e0 m\u1ed9t tenx\u01a1 [l ] c\u1ee7a ch\u00edn h\u1ec7 s\u1ed1 c\u1ee7a c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ef7 l\u1ec7 tuy\u1ebfn t\u00ednh thu\u1ed9c c\u00e1c th\u00e0nh ph\u1ea7n c\u1ee7a grad T m\u00e0 c\u00e1c h\u1ec7 s\u1ed1 n\u00e0y x\u00e1c \u0111\u1ecbnh m\u1ed7i th\u00e0nh ph\u1ea7n c\u1ee7a q theo h\u1ec7 th\u1ee9c d\u01b0\u1edbi \u0111\u00e2y:<\/p>\n

        q = – lgrad T\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (7)<\/p>\n

        Nh\u01b0 v\u1eady [l ] c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c b\u1eb1ng c\u00e1ch \u0111\u1ea3o ng\u01b0\u1ee3c [r ] v\u00e0 ng\u01b0\u1ee3c l\u1ea1i. N\u1ebfu \u0111\u1ed9 d\u1eabn nhi\u1ec7t l ho\u1eb7c [l ] kh\u00f4ng \u0111\u1ed5i theo to\u1ea1 \u0111\u1ed9 v\u00e0 th\u1eddi gian, n\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c xem nh\u01b0 l\u00e0 m\u1ed9t \u0111\u1eb7c t\u00ednh nhi\u1ec7t \u1edf nhi\u1ec7t \u0111\u1ed9 \u0111\u00e3 cho.<\/p>\n

        \u0110\u1ed9 d\u1eabn nhi\u1ec7t c\u00f3 th\u1ec3 l\u00e0 m\u1ed9t h\u00e0m s\u1ed1 c\u1ee7a nhi\u1ec7t \u0111\u1ed9 v\u00e0 c\u1ee7a h\u01b0\u1edbng (v\u1eadt li\u1ec7u d\u1ecb h\u01b0\u1edbng). Do \u0111\u00f3 c\u1ea7n bi\u1ebft m\u1ed1i quan h\u1ec7 c\u1ee7a c\u00e1c th\u00f4ng s\u1ed1 n\u00e0y.<\/p>\n

        H\u00e3y xem x\u00e9t m\u1ed9t v\u1eadt th\u1ec3 c\u00f3 chi\u1ec1u d\u00e0y d \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n b\u1eb1ng hai m\u1eb7t ph\u1eb3ng song song v\u00e0 \u0111\u1eb3ng nhi\u1ec7t, c\u00f3 nhi\u1ec7t \u0111\u1ed9 T1<\/sub> v\u00e0 T2<\/sub> , m\u1ed7i m\u1eb7t c\u00f3 di\u1ec7n t\u00edch A.<\/p>\n

        C\u00e1c m\u00e9p b\u00ean bao quanh c\u00e1c m\u1eb7t ch\u00ednh c\u1ee7a v\u1eadt th\u1ec3 n\u00e0y \u0111\u01b0\u1ee3c gi\u1ea3 thi\u1ebft l\u00e0 \u0111o\u1ea1n nhi\u1ec7t v\u00e0 th\u1eb3ng g\u00f3c v\u1edbi ch\u00fang. Gi\u1ea3 thi\u1ebft r\u1eb1ng v\u1eadt th\u1ec3 \u0111\u01b0\u1ee3c t\u1ea1o b\u1edfi v\u1eadt li\u1ec7u \u1ed5n \u0111\u1ecbnh, \u0111\u1ed3ng nh\u1ea5t v\u00e0 \u0111\u1eb3ng h\u01b0\u1edbng (ho\u1eb7c kh\u00f4ng \u0111\u1eb3ng h\u01b0\u1edbng -d\u1ecb h\u01b0\u1edbng- v\u1edbi m\u1ed9t tr\u1ee5c \u0111\u1ed1i x\u1ee9ng vu\u00f4ng g\u00f3c v\u1edbi c\u00e1c m\u1eb7t ch\u00ednh). Trong \u0111i\u1ec1u ki\u1ec7n nh\u01b0 v\u1eady c\u00e1c h\u1ec7 th\u1ee9c d\u01b0\u1edbi \u0111\u00e2y = \u0111\u1ea1o h\u00e0m t\u1eeb \u0111\u1ecbnh lu\u1eadt Fourier trong c\u00e1c tr\u1ea1ng th\u00e1i \u1ed5n \u0111\u1ecbnh s\u1ebd \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng n\u1ebfu h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t l ho\u1eb7c [l ], ho\u1eb7c nhi\u1ec7t tr\u1edf su\u1ea5t r ho\u1eb7c [r] kh\u00f4ng ph\u1ee5 thu\u1ed9c nhi\u1ec7t \u0111\u1ed9:<\/p>\n

        (8)<\/p>\n

        (9)<\/p>\n

        N\u1ebfu t\u1ea5t c\u1ea3 c\u00e1c \u0111i\u1ec1u ki\u1ec7n tr\u00ean \u0111\u01b0\u1ee3c \u0111\u00e1p \u1ee9ng (ngo\u1ea1i tr\u1eeb h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t l ho\u1eb7c [l] l\u00e0 h\u00e0m s\u1ed1 tuy\u1ebfn t\u00ednh c\u1ee7a nhi\u1ec7t \u0111\u1ed9 th\u00ec v\u1eabn \u00e1p d\u1ee5ng c\u00e1c h\u1ec7 th\u1ee9c tr\u00ean nh\u01b0ng h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t \u0111\u01b0\u1ee3c t\u00ednh \u1edf nhi\u1ec7t \u0111\u1ed9 trung b\u00ecnh<\/p>\n

        T\u01b0\u01a1ng t\u1ef1, n\u1ebfu m\u1ed9t v\u1eadt th\u1ec3 c\u00f3 chi\u1ec1u d\u00e0i l \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n b\u1edfi hai m\u1eb7t \u0111\u1eb3ng nhi\u1ec7t, h\u00ecnh l\u0103ng tr\u1ee5, \u0111\u1ed3ng tr\u1ee5c c\u00f3 nhi\u1ec7t \u0111\u1ed9 T1<\/sub> v\u00e0 T2<\/sub> v\u00e0 \u0111\u01b0\u1eddng k\u00ednh D1<\/sub> v\u00e0 D2<\/sub> t\u01b0\u01a1ng \u1ee9ng, v\u00e0 n\u1ebfu hai \u0111\u1ea7u c\u1ee7a v\u1eadt th\u1ec3 l\u00e0 c\u00e1c m\u1eb7t \u0111o\u1ea1n nhi\u1ec7t ph\u1eb3ng vu\u00f4ng g\u00f3c v\u1edbi h\u00ecnh l\u0103ng tr\u1ee5, v\u00e0 c\u00e1c v\u1eadt li\u1ec7u l\u00e0 \u1ed5n \u0111\u1ecbnh, \u0111\u1ed3ng nh\u1ea5t v\u00e0 \u0111\u1eb3ng h\u01b0\u1edbng, th\u00ec c\u00e1c h\u1ec7 th\u1ee9c d\u01b0\u1edbi \u0111\u00e2y = \u0111\u1ea1o h\u00e0m t\u1eeb \u0111\u1ecbnh lu\u1eadt Fourier trong c\u00e1c \u0111i\u1ec1u ki\u1ec7n \u1ed5n \u0111\u1ecbnh s\u1ebd \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng n\u1ebfu \u0111\u1ed9 d\u1eabn nhi\u1ec7t l ho\u1eb7c nhi\u1ec7t tr\u1edf su\u1ea5t r kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o nhi\u1ec7t \u0111\u1ed9 :<\/p>\n

        (10)<\/p>\n

        (11)<\/p>\n

        Trong \u0111\u00f3 D c\u00f3 th\u1ec3 l\u00e0 \u0111\u01b0\u1eddng k\u00ednh b\u00ean ngo\u00e0i ho\u1eb7c b\u00ean trong ho\u1eb7c \u0111\u01b0\u1eddng k\u00ednh x\u00e1c \u0111\u1ecbnh kh\u00e1c.<\/p>\n

        N\u1ebfu t\u1ea5t c\u1ea3 c\u00e1c \u0111i\u1ec1u ki\u1ec7n tr\u00ean \u0111\u1ec1u \u0111\u01b0\u1ee3c \u0111\u00e1p \u1ee9ng ngo\u1ea1i tr\u1eeb h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t l l\u00e0 m\u1ed9t h\u00e0m s\u1ed1 tuy\u1ebfn t\u00ednh c\u1ee7a nhi\u1ec7t \u0111\u1ed9 th\u00ec c\u00e1c h\u1ec7 th\u1ee9c tr\u00ean v\u1eabn \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng nh\u01b0ng h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t \u0111\u01b0\u1ee3c t\u00ednh theo nhi\u1ec7t \u0111\u1ed9 trung b\u00ecnh qua bi\u1ec3u th\u1ee9c sau:<\/p>\n

        Tm =<\/p>\n

        V\u1edbi nh\u1eefng gi\u1edbi h\u1ea1n tr\u00ean, c\u00f4ng th\u1ee9c (8), (10) th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 d\u1eabn nhi\u1ec7t c\u1ee7a m\u00f4i tr\u01b0\u1eddng kh\u00f4ng trong su\u1ed1t, \u0111\u1ed3ng nh\u1ea5t t\u1eeb c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng \u0111\u00e3 \u0111o \u0111\u01b0\u1ee3c \u1edf nhi\u1ec7t \u0111\u1ed9 trung b\u00ecnh Tm.<\/p>\n

        T\u01b0\u01a1ng t\u1ef1, c\u00f4ng th\u1ee9c (8) v\u00e0 (10) c\u00f2n th\u01b0\u1eddng \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh \u0111\u1eb7c t\u00ednh nhi\u1ec7t c\u1ee7a c\u00e1c m\u00f4i tr\u01b0\u1eddng x\u1ed1p t\u1eeb c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng \u0111o \u0111\u01b0\u1ee3c m\u00e0 \u0111\u1ed1i v\u1edbi ch\u00fang qu\u00e1 tr\u00ecnh truy\u1ec1n nhi\u1ec7t t\u1ed5ng h\u1ee3p bao g\u1ed3m ba ph\u01b0\u01a1ng th\u1ee9c : b\u1ee9c x\u1ea1, d\u1eabn nhi\u1ec7t v\u00e0 \u0111\u00f4i khi c\u1ea3 \u0111\u1ed1i l\u01b0u nhi\u1ec7t.<\/p>\n

        \u0110\u1eb7c t\u00ednh nhi\u1ec7t \u0111o \u0111\u01b0\u1ee3c \u0111\u1ea1i di\u1ec7n cho t\u1ea5t c\u1ea3 c\u00e1c ph\u01b0\u01a1ng th\u1ee9c truy\u1ec1n nhi\u1ec7t n\u00eau tr\u00ean \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 \u0111\u1ed9 d\u1eabn nhi\u1ec7t (\u0111\u00f4i khi c\u00f2n g\u1ecdi l\u00e0 \u0111\u1ed9 d\u1eabn nhi\u1ec7t bi\u1ec3u ki\u1ebfn, t\u01b0\u01a1ng \u0111\u01b0\u01a1ng ho\u1eb7c hi\u1ec7u qu\u1ea3) c\u1ee7a m\u00f4i tr\u01b0\u1eddng x\u1ed1p \u0111\u1ed3ng nh\u1ea5t khi n\u00f3 kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o k\u00edch th\u01b0\u1edbc h\u00ecnh h\u1ecdc c\u1ee7a m\u1eabu \u0111o, t\u00ednh ch\u1ea5t b\u1ee9c x\u1ea1 nhi\u1ec7t c\u1ee7a c\u00e1c b\u1ec1 m\u1eb7t gi\u1edbi h\u1ea1n c\u1ee7a m\u1eabu \u0111o v\u00e0 ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 (T1<\/sub> – T2<\/sub>)<\/p>\n

        Khi c\u00e1c \u0111i\u1ec1u ki\u1ec7n \u0111\u00f3 kh\u00f4ng tho\u1ea3 m\u00e3n, nhi\u1ec7t tr\u1edf b\u1ec1 m\u1eb7t ph\u1ea3i \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 bi\u1ec3u th\u1ecb \u0111\u1eb7c t\u00ednh c\u1ee7a m\u1eabu \u0111o v\u1edbi c\u00e1c k\u00edch th\u01b0\u1edbc h\u00ecnh h\u1ecdc, ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 (T1<\/sub> -T2<\/sub> ) v\u00e0 v\u1edbi \u0111\u1ed9 b\u1ee9c x\u1ea1 nhi\u1ec7t \u0111\u00e3 cho c\u1ee7a c\u00e1c m\u1eb7t b\u00ean c\u1ee7a m\u1eabu \u0111o.<\/p>\n","protected":false},"excerpt":{"rendered":"

        TI\u00caU CHU\u1ea8N X\u00c2Y D\u1ef0NG VI\u1ec6T NAM TCXDVN 299: 2003 (ISO 7345: 1987) C\u00c1CH NHI\u1ec6T – C\u00c1C \u0110\u1ea0I L\u01af\u1ee2NG V\u1eacT L\u00dd V\u00c0 \u0110\u1ecaNH NGH\u0128A Thermal insulation- physical quantities and definitions L\u1eddi n\u00f3i \u0111\u1ea7u TCXDVN 299: 2003 (ISO 7345:1987)- C\u00e1ch nhi\u1ec7t- C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng v\u1eadt l\u00fd v\u00e0 \u0111\u1ecbnh ngh\u0129a \u0111\u01b0\u1ee3c ch\u1ea5p nh\u1eadn t\u1eeb ISO 7345:1987- C\u00e1ch nhi\u1ec7t-…<\/p>\n","protected":false},"author":1,"featured_media":2076,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42],"tags":[],"class_list":["post-2087","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tieu-chuan-xay-dung"],"_links":{"self":[{"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/posts\/2087","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2087"}],"version-history":[{"count":2,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/posts\/2087\/revisions"}],"predecessor-version":[{"id":2089,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/posts\/2087\/revisions\/2089"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=\/wp\/v2\/media\/2076"}],"wp:attachment":[{"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2087"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2087"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tailieuxaydung.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2087"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}