# 比贊數

（重定向自Bejan数

## 熱力學

${\displaystyle \mathrm {Be} ={\frac {{\dot {S}}'_{\mathrm {gen} ,\,\Delta T}}{{\dot {S}}'_{\mathrm {gen} ,\,\Delta T}+{\dot {S}}'_{\mathrm {gen} ,\,\Delta p}}}}$

${\displaystyle {\dot {S}}'_{\mathrm {gen} ,\,\Delta T}}$ 是因為热传產生的
${\displaystyle {\dot {S}}'_{\mathrm {gen} ,\,\Delta p}}$ 是因為流體摩擦力產生的熵

## 流體力學、熱傳學及質傳學

${\displaystyle \mathrm {Be} ={\frac {\Delta PL^{2}}{\mu \nu }}}$

${\displaystyle \mu }$ 粘度
${\displaystyle \nu }$ 是動量扩散率（運動粘度）

${\displaystyle \mathrm {Be} ={\frac {\Delta PL^{2}}{\mu \alpha }}}$

${\displaystyle \mu }$ 是粘度
${\displaystyle \alpha }$ 熱扩散率

${\displaystyle \mathrm {Be} ={\frac {\Delta PL^{2}}{\mu D}}}$

${\displaystyle \mu }$ 是粘度
${\displaystyle \alpha }$ 質傳擴散率

${\displaystyle \mathrm {Be} ={\frac {\Delta PL^{2}}{\rho \delta ^{2}}}}$

${\displaystyle \rho }$ 流體密度
${\displaystyle \delta }$ 為要考慮過程的擴散係數

${\displaystyle \mathrm {Be} ={{32ReL^{3}} \over {d^{3}}}}$

${\displaystyle Re}$ 雷諾數
${\displaystyle L}$ 為流體長度
${\displaystyle d}$ 為管路直徑

## 參考資料

1. ^ Paoletti, S.; Rispoli, F.; Sciubba, E. Calculation of exergetic losses in compact heat exchanger passager. ASME AES-Vol. 1989, 10 (2): 21–29.
2. ^ Bhattacharjee, S.; Grosshandler, W. L. The formation of wall jet near a high temperature wall under microgravity environment. ASME 1988 National Heat Transfer Conference. 1988, 96: 711–716. Bibcode:1988nht.....1..711B.
3. ^ Petrescu, S. Comments on ‘The optimal spacing of parallel plates cooled by forced convection’. Int. J. Heat Mass Transfer. 1994, 37 (8): 1283. doi:10.1016/0017-9310(94)90213-5.
4. ^ Awad, M.M. A new definition of Bejan number. Thermal Science. 2012, 16 (4): 1251. doi:10.2298/TSCI12041251A.
5. ^ Awad, M.M.; Lage, J. L. Extending the Bejan number to a general form. Thermal Science. 2013, 17 (2): 631. doi:10.2298/TSCI130211032A.
6. ^ Awad, M.M. Hagen number versus Bejan number. Thermal Science. 2013, 17 (4): 1245. doi:10.2298/TSCI1304245A.