Hydrodynamics and heat transfer in turbulent pipe flow of liquid under conditions of monotonic time variation of the flow rate

2005 ◽  
Vol 43 (2) ◽  
pp. 203-213 ◽  
Author(s):  
E. P. Valueva
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Time Variation ◽  
Pipe Flow ◽  
Turbulent Pipe Flow

Heat Transfer in Turbulent Pipe Flow for Liquids Having a Temperature-Dependent Viscosity

1978 ◽  
Vol 100 (2) ◽  
pp. 224-229 ◽  
Author(s):  
O. T. Hanna ◽  
O. C. Sandall
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Pipe Flow ◽  
Turbulent Pipe Flow ◽  
Fluid Viscosity ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Analytical Approximations ◽  
Constant Viscosity ◽  
Dependent Viscosity

Analytical approximations are developed to predict the effect of a temperature-dependent viscosity on convective heat transfer through liquids in fully developed turbulent pipe flow. The analysis expresses the heat transfer coefficient ratio for variable to constant viscosity in terms of the friction factor ratio for variable to constant viscosity, Tw, Tb, and a fluid viscosity-temperature parameter β. The results are independent of any particular eddy diffusivity distribution. The formulas developed here represent an analytical approximation to the model developed by Goldmann. These approximations are in good agreement with numerical solutions of the model nonlinear differential equation. To compare the results of these calculations with experimental data, a knowledge of the effect of variable viscosity on the friction factor is required. When available correlations for the friction factor are used, the results given here are seen to agree well with experimental heat transfer coefficients over a considerable range of μw/μb.

Effects of Nanoparticles and Polymer Additives in Turbulent Pipe Flow

2010 ◽  
Author(s):  
Alparslan Oztekin ◽  
Sudhakar Neti ◽  
Ananchai Ukaew
Keyword(s):  
Heat Transfer ◽  
Drag Reduction ◽  
Pipe Flow ◽  
Turbulent Pipe Flow ◽  
Polymer Additives ◽  
Turbulent Structures ◽  
Heat Transfer Fluids ◽  
Pressure And Velocity Measurements ◽  
Nanosilica Particles ◽  
Elongated Nanoparticles

Spatial and temporal characteristics of turbulent pipe flows using nanofluids and dilute polymer solutions are examined by means of instantaneous differential pressure and velocity measurements. Spherical and elongated nanosilica particles (SiO2) are mixed into water to make nanofluid and polyacrylamide (PAC) is dissolved into water to make PAC solution. The effects of nanofluid on the drag reduction and turbulent structure are determined and compared with the effects of polymer additives on the turbulent structures and drag reduction. Suppression of turbulence near pipe wall was observed with the introduction of both spherical and elongated nanoparticles. Although experimental results show that nanofluids are not candidates for drag reduction unlike polymer additives, they do not increase pressure drop. Hence addition of nanoparticles into heat transfer fluids could have the potential for heat transfer enhancement in pipe flow without paying the penalty of increasing pumping power.

Application of a Simplified Velocity Profile to the Prediction of Pipe-Flow Heat Transfer

1968 ◽  
Vol 90 (2) ◽  
pp. 191-198 ◽  
Author(s):  
R. D. Haberstroh ◽  
L. V. Baldwin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Velocity Profile ◽  
Pipe Flow ◽  
Energy Equation ◽  
Momentum Equation ◽  
Turbulent Pipe Flow ◽  
Transfer Coefficients ◽  
Constant Property ◽  
Wide Range

The temperature profiles and heat-transfer coefficients are predicted for fully developed turbulent pipe flow with constant wall heat flux for a wide range of Prandtl and Reynolds numbers. The basis for integrating the energy equation comes from a continuously differentiable velocity profile which fits the physical boundary conditions and is a rigorous (though not necessarily unique) solution of the Reynolds equations. This velocity profile is the semiempirical relation proposed by S. I. Pai, reference [12]. The assumptions are those of steady, incompressible, constant-property, fully developed, turbulent flow of Newtonian fluids in smooth, circular pipes with constant heat flux at the wall. The ratio of the turbulent thermal diffusivity to the turbulent momentum diffusivity is taken to be unity. The thermal quantities are obtained by numerical integration of the energy equation, and they are presented as curves and tables. A compact formula for the Nusselt number is given for a wide range of Reynolds and Prandtl numbers. The results degenerate identically to the case of laminar flow. The heat-transfer calculation requires neither adjustable factors nor data-fitting beyond the empirical constants in the momentum equation; thus this analysis constitutes a heat-transfer prediction to be tested against heat-transfer data.

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