Abstract
Optimizing of laminar viscous flow through a pipe by two dimensionless values is investigated analytically. Dimensionless entropy generation and pumping power to heat transfer rate ratio are used as basis for constant viscous and the temperature dependence on the viscosity. For this matter we calculate entropy generation and pumping power for a fully developed in a pipe subjected to constant wall temperature for either constant viscosity and the variable viscosity. The variation entropy generation increase along the pipe length for viscous fluid is drawn, either the variation summation dimensionless entropy generation and the pumping power to heat transfer rate ratio are varying the fluid inlet temperature for fixed pipe length and are varying pipe length for fixed fluid inlet temperature are drawn. For low heat transfer conditions the entropy generation due to viscosity friction becomes dominant and the dependence of viscosity with the temperature becomes essentially important to be considered.
Similar content being viewed by others
Abbreviations
- C p :
-
specific heat capacity (J/kg K)
- D :
-
diameter (m)
- Ec :
-
Eckert number \([\overline {U}^2/[C_p(T_{\rm w}-T_0)]]\)
- f :
-
friction factor
- \(\bar {h}\) :
-
average heat transfer coefficient (W/m2 K)
- \(\bar {h}_{c\cdot p}\) :
-
constant property average heat transfer coefficient (W/m2 K)
- k :
-
thermal conductivity (W/m K)
- l :
-
length of the pipe (m)
- \(\dot{m}\) :
-
mass flow rate (kg/s)
- P :
-
pressure (N/m2)
- P r :
-
pumping power to heat transfer rate ratio
- \(\dot{Q}\) :
-
total heat transfer rate (W)
- Re :
-
Reynolds number [ \(\rho\bar {U}D/\mu\)]
- s :
-
entropy (J/kg K)
- \(\dot{S}_{\rm gen}\) :
-
entropy generation (W/K)
- St :
-
Stanton number [ \(\bar {h}/(\rho\overline {U}(C_p)\)]
- T :
-
temperature (K)
- T 0 :
-
inlet fluid temperature (K)
- T ref :
-
reference temperature (=293 K)
- T w :
-
wall temperature the pipe (K)
- \(\overline {U}\) :
-
fluid bulk velocity (m/s)
- x :
-
axial distance (m)
- ΔT :
-
increase of fluid temperature (K)
- μ:
-
viscosity (N/s m2)
- μb :
-
viscosity of fluid at bulk temperature (N/s m2)
- μw :
-
viscosity of fluid at wall temperature (N/s m2)
- λ:
-
dimensionless axial distance [l/D]
- Π1 :
-
modified Stanton number [St λ]
- Π2 :
-
dimensionless group [Ec/(St Re)]
- Ψ:
-
dimensionless entropy generation [ \(\dot {S}_{\rm gen}/\)[ \(\dot {Q}\)/(T w − T 0)]
- Ψ′:
-
modified dimensionless entropy generation [ \(\dot {S}_{\rm gen}/\)[ \(\dot {Q}\)/(ΔT)]
- ρ:
-
density (kg/m3)
- τ:
-
dimensionless inlet wall-to-fluid temperature difference [(T w − T 0)/T w]
- θ:
-
dimensionless temperature [(T − T w)/(T 0 − T w)]]
References
Bejan A. (1980) Energy 5:721–732
Bejan A. (1982) Adv. Heat Transfer 15:1–58
Nag P. K., Mukherjee P. (1987) Int. J. Heat Mass Transfer 30(2):401–405
H. Perez-Blanco, in Second Law Aspects of Thermal Design. HTD, Vol. 33. ASME. NY, pp. 19–26; also presented at The 22nd National Heat Transfer Conference and Exhibition, Niagara Falls, New York. August 5–8 (1984)
Bejan A. (1988) Advanced Engineering Thermodynamics (John Wiley & Sons Inc., New York, 1988), pp. 594–602
A. Z. Sahin, Int. J. Heat Mass Transfer, ASME, 120, 76–83 (1998)
Kays W. M., Perkins H. C. (1973) In: Rohsenow W. M., Hartnett J. P. (eds.), Handbook of Heat Transfer. McGraw-Hill Co., New York, pp. 7–157
Kreith F., Bohn M.S. (1993) Principles of Heat Transfer, 5th edn. West Publ Co., New York, p. 386
Sherman, 1990
Cengel Y. A., Boles M. A. (1994) Thermodynamics, An Engineering Approach. McGraw-Hill Co., New York, p. 388
Saad M. A. (1997) Thermodynamics. Principles and Prentice Hall, New Jersey, p. 309
Moran M. J., Shapiro H. N. (1995) Fundamentals of Engineering Thermodynamics. John Wiley & Sons Inc., New York, p. 277
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Langeroudi, H.G., Aghanajafi, C. Analysis and Optimization Laminar Viscous Flow Through a Channel. J Fusion Energ 25, 155–164 (2006). https://doi.org/10.1007/s10894-006-9012-y
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10894-006-9012-y