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| There are two different '''Bejan numbers''' ('''Be''') named after [[Duke University]] professor [[Adrian Bejan]] which are used in the scientific domains of [[thermodynamics]] and [[fluid mechanics]].
| | == Feng Luo they are not making money fast == |
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| ==Thermodynamics==
| | Speed, Feng Luo they are not making money fast!<br><br>a junior-level monster beast will be an important material generally sell 500 million to 15 million.<br><br>Intermediate level monster beast will be an important material, generally can be sold for 10 million - more than one hundred [http://www.nrcil.net/fancybox/lib/rakuten_LV_110.html ルイヴィトン 財布 メンズ タイガ] million.<br><br>senior level monster beast will be an important material, generally can be sold for about 50 million - six or seven million.<br><br>course, occasionally there are some exceptions, such as some extremely special monster, beast or some [http://www.nrcil.net/fancybox/lib/rakuten_LV_77.html ルイヴィトン ケース] although the [http://www.nrcil.net/fancybox/lib/rakuten_LV_111.html ルイヴィトン バッグ 価格] senior level, can in itself was almost lords grade, naturally the price [http://www.nrcil.net/fancybox/lib/rakuten_LV_102.html 大阪 ルイヴィトン] to rise. But the vast majority, are above this price position.<br><br>fire hammer squad hunted almost every day ten heads as the level! Of course, almost all of the beast will be the primary level! That efficiency is simply [http://www.nrcil.net/fancybox/lib/rakuten_LV_101.html ルイヴィトン 六本木] to make money very scary!<br><br>......<br><br>struggle [http://www.nrcil.net/fancybox/lib/rakuten_LV_40.html 新作ルイヴィトン] after another ten days, Luo Feng beast they will kill 92 primary level, three intermediate beast will [http://www.nrcil.net/fancybox/lib/rakuten_LV_18.html ルイヴィトン ライン] level. Estimated total price [http://www.nrcil.net/fancybox/lib/rakuten_LV_55.html 中古ルイヴィトン] Geyue Mo ten one hundred million! Ten consecutive days of high-intensity combat, |
| In the context of [[thermodynamics]], the Bejan number is the ratio of [[heat transfer]] [[irreversibility]] to total irreversibility due to heat transfer and [[fluid friction]]:<ref>{{cite paper |first=S. |last=Paoletti |first2=F. |last2=Rispoli |first3=E. |last3=Sciubba |title=Calculation of exergetic losses in compact heat exchanger passager |work=ASME AES-Vol. |volume=10 |issue=2 |year=1989 |pages=21–29 }}</ref>
| | 相关的主题文章： |
| | | <ul> |
| : <math>\mathrm{Be} = \frac{\dot S'_{\mathrm{gen},\, \Delta T}}{\dot S'_{\mathrm{gen},\, \Delta T}+ \dot S'_{\mathrm{gen},\, \Delta p}}</math>
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| | | <li>[http://028zypx.com/plus/feedback.php?aid=1 http://028zypx.com/plus/feedback.php?aid=1]</li> |
| where
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| | | <li>[http://www.lindicateur.com/calanthe/blog.cgi http://www.lindicateur.com/calanthe/blog.cgi]</li> |
| : <math>\dot S'_{\mathrm{gen},\, \Delta T}</math> is the entropy generation contributed by heat transfer
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| : <math>\dot S'_{\mathrm{gen},\, \Delta p}</math> is the entropy generation contributed by fluid friction.
| | <li>[http://www.trustchinese.com/plus/feedback.php?aid=17 http://www.trustchinese.com/plus/feedback.php?aid=17]</li> |
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| ==Fluid mechanics, heat transfer and mass transfer==
| | </ul> |
| In the context of [[fluid mechanics]]. the Bejan number is the [[Dimensionless quantity|dimensionless]] pressure drop along a channel of length <math>L</math>:<ref>{{cite paper |first=S. |last=Bhattacharjee |first2=W. L. |last2=Grosshandler |title=The formation of wall jet near a high temperature wall under microgravity environment |work=ASME 1988 National Heat Transfer Conference |volume=96 |issue= |year=1988 |pages=711–716 |bibcode=1988nht.....1..711B }}</ref>
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| : <math>\mathrm{Be} = \frac{\Delta P L^2} {\mu \nu}</math>
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| where
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| : <math>\mu</math> is the dynamic viscosity
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| : <math>\nu</math> is the momentum diffusivity
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| In the context of [[heat transfer]]. the Bejan number is the [[Dimensionless quantity|dimensionless]] pressure drop along a channel of length <math>L</math>:<ref>{{cite journal |first=S. |last=Petrescu |title=Comments on ‘The optimal spacing of parallel plates cooled by forced convection’ |journal=[[International Journal of Heat Transfer and Mass Transfer|Int. J. Heat Mass Transfer]] |volume=37 |issue=8 |year=1994 |pages=1283 |doi=10.1016/0017-9310(94)90213-5 }}</ref>
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| : <math>\mathrm{Be} = \frac{\Delta P L^2} {\mu \alpha}</math>
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| where
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| : <math>\mu</math> is the dynamic viscosity
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| : <math>\alpha</math> is the thermal diffusivity
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| The '''Be number''' plays in forced convection the same role that the [[Rayleigh number]] plays in natural convection.
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| In the context of [[mass transfer]]. the Bejan number is the [[Dimensionless quantity|dimensionless]] pressure drop along a channel of length <math>L</math>:<ref>{{cite journal |first=M.M. |last=Awad |title=A new definition of Bejan number |journal=[[Thermal Science]] |volume=16 |issue=4 |year=2012 |pages=1251 |doi=10.2298/TSCI12041251A }}</ref>
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| : <math>\mathrm{Be} = \frac{\Delta P L^2} {\mu D} </math>
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| where
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| : <math>\mu</math> is the dynamic viscosity | |
| : <math>D</math> is the mass diffusivity
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| For the case of Reynolds analogy (Le = Pr = Sc = 1), it is clear that all three definitions of Bejan number are the same.
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| Also, Awad and Lage:<ref>{{cite journal |first=M.M. |last=Awad |first2=J. L. |last2=Lage |title=Extending the Bejan number to a general form |journal=[[Thermal Science]] |volume=17 |issue=2 |year=2013 |pages=631 |doi=10.2298/TSCI130211032A }}</ref> obtained a modified form of the Bejan number, originally proposed by Bhattacharjee and Grosshandler for momentum processes, by replacing the dynamic viscosity appearing in the original proposition with the equivalent product of the fluid density and the momentum diffusivity of the fluid. This modified form is not only more akin to the physics it represents but it also has the advantage of being dependent on only one viscosity coefficient. Moreover, this simple modification allows for a much simpler extension of Bejan number to other diffusion processes, such as a heat or a species transfer process, by simply replacing the diffusivity coefficient. Consequently, a general Bejan number representation for any process involving pressure-drop and diffusion becomes possible. It is shown that this general representation yields analogous results for any process satisfying the Reynolds analogy (i. e., when Pr = Sc = 1), in which case the momentum, energy, and species concentration representations of Bejan number turn out to be the same.
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| Therefore, it would be more natural and broad to define Be in general, simply as:
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| : <math>\mathrm{Be} = \frac{\Delta P L^2} {\rho \delta^2}</math>
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| where
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| : <math>\rho</math> is the fluid density
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| : <math>\delta</math> is the corresponding diffusivity of the process in consideration
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| In addition, Awad:<ref>{{cite journal |first=M.M. |last=Awad |title=Hagen number versus Bejan number |journal=[[Thermal Science]] |volume=17 |issue=4 |year=2013 |pages=1245 |doi=10.2298/TSCI1304245A }}</ref> presented Hagen number vs. Bejan number. Although their physical meaning is not the same because the former represents the dimensionless pressure
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| gradient while the latter represents the dimensionless pressure drop, it will be
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| shown that Hagen number coincides with Bejan number in cases where the characteristic
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| length (l) is equal to the flow length (L). Also, a new expression of Bejan
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| number in the Hagen-Poiseuille flow will be introduced. This expression is
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| :<math> \mathrm{Be} = {{32 Re L^3} \over {d^3}}</math>
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| where
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| : <math>Re</math> is the Reynolds number
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| : <math>L</math> is the flow length | |
| : <math>d</math> is the pipe diameter
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| The above expression shows that the Bejan number in the Hagen-Poiseuille flow is indeed a
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| dimensionless group, not recognized previously.
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| ==See also==
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| * [[Adrian Bejan]]
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| * [[Entropy]]
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| * [[Exergy]]
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| * [[Thermodynamics]]
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| * [[Constructal theory]]
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| ==References==
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| {{reflist}}
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| ==Further reading==
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| *{{cite journal |first=S. |last=Petrescu |title=Comments on ‘The optimal spacing of parallel plates cooled by forced convection’ |journal=[[International Journal of Heat Transfer and Mass Transfer|Int. J. Heat Mass Transfer]] |volume=37 |issue=8 |year=1994 |pages=1283 |doi=10.1016/0017-9310(94)90213-5 }}
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| *{{cite journal |first=M.M. |last=Awad |title=A new definition of Bejan number’ |journal=[[Thermal Science]] |volume=16 |issue=4 |year=2012 |pages=1251 |doi=10.2298/TSCI12041251A }}
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| *{{cite journal |first=M.M. |last=Awad |first2=J. L. |last2=Lage |title=Extending the Bejan number to a general form |journal=[[Thermal Science]] |volume=17 |issue=2 |year=2013 |pages=631 |doi=10.2298/TSCI130211032A }}
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| *{{cite journal |first=M.M. |last=Awad |title=Hagen number versus Bejan number |journal=[[Thermal Science]] |volume=17 |issue=4 |year=2013 |pages=1245 |doi=10.2298/TSCI1304245A }}
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| {{NonDimFluMech}}
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| [[Category:Dimensionless numbers of thermodynamics]]
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| [[Category:Dimensionless numbers of fluid mechanics]]
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| [[Category:Convection]]
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Feng Luo they are not making money fast
Speed, Feng Luo they are not making money fast!
a junior-level monster beast will be an important material generally sell 500 million to 15 million.
Intermediate level monster beast will be an important material, generally can be sold for 10 million - more than one hundred ルイヴィトン 財布 メンズ タイガ million.
senior level monster beast will be an important material, generally can be sold for about 50 million - six or seven million.
course, occasionally there are some exceptions, such as some extremely special monster, beast or some ルイヴィトン ケース although the ルイヴィトン バッグ 価格 senior level, can in itself was almost lords grade, naturally the price 大阪 ルイヴィトン to rise. But the vast majority, are above this price position.
fire hammer squad hunted almost every day ten heads as the level! Of course, almost all of the beast will be the primary level! That efficiency is simply ルイヴィトン 六本木 to make money very scary!
......
struggle 新作ルイヴィトン after another ten days, Luo Feng beast they will kill 92 primary level, three intermediate beast will ルイヴィトン ライン level. Estimated total price 中古ルイヴィトン Geyue Mo ten one hundred million! Ten consecutive days of high-intensity combat,
相关的主题文章：