There are two Bejan numbers (Be) in use, named after Duke University professor Adrian Bejan in two scientific domains: thermodynamics and fluid mechanics. Duke University is a private coeducational research university located in Durham, North Carolina, USA. The school, founded by Methodists and Quakers in the present-day town of Trinity in 1838, moved to Durham in 1892. ... Adrian Bejan (born September 24, 1948), Ph. ...

Thermodynamics

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: Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... In thermal physics, heat transfer is the passage of thermal energy from a hot to a cold object. ... Fluid friction is the friction between a solid object and a fluid (a liquid or gas) it is moving through. ...

where

is the entropy generation contributed by heat transfer

is the entropy generation contributed by fluid friction.

This definition was introduced by Paoletti et al. (see reference).

Fluid mechanics and heat transfer

In the context of fluid mechanics and heat transfer. the Bejan number is the dimensionless pressure drop along a channel of length L: The hydrogeology is study about of water-bearing formation. ... In thermal physics, heat transfer is the passage of thermal energy from a hot to a cold object. ...

where

μ < / 65454 > isthedynamicviscosity: < math > α is the thermal diffusivity

The Be number plays in convection the same role that the Rayleigh number plays in natural convection. The Be number was introduced by Bhattacharjee and Grosshandler (see references) In fluid mechanics, the Rayleigh number for a fluid is a dimensionless number associated with the heat transfer within the fluid. ...

See also

• Adrian Bejan
• Entropy
• Exergy
• Thermodynamics
• Constructal theory

Adrian Bejan (born September 24, 1948), Ph. ... Ice melting - classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... Constructal design of a cooling system The constructal theory of global optimization under local constraints explains in a simple manner the shapes that arise in nature. ...

References

• S. Paoletti, F. Rispoli, E. Schiubba, Calculation of exergetic losses in compact heat exchanger passager, ASME AES-Vol. 10-2, 1989, pp. 21-29.
• S. Bhattacharjee and W.L. Grosshandler, The formation of wall jet near a high temperature wall under microgravity environment, ASME MTD-Vol. 96, 1988, pp. 711-716.
• S. Petrescu, Comments on the optimal spacing of parallel plates cooled by forced convection, International Journal of Heat Transfert and Mass Transfer, Vol. 37, 1994, p. 1283.