1. In flow over a surface, velocity and temperature profiles are of the forms u(y)=Ay+By²-Cy³ and T(y)=D+Ey+Fy²+Gy³ where the coefficients A through G are constants. Obtain expressions for the friction coefficient Cf and the convection coefficient h in terms of u∞, T∞, and appropriate profile coefficients and fluid properties. Answer: h= -k[E D To

1. In flow over a surface, velocity and temperature profiles are of the forms u(y)=Ay+By²-Cy³ and T(y)=D+Ey+Fy²+Gy³ where the coefficients A through G are constants. Obtain expressions for the friction coefficient Cf and the convection coefficient h in terms of u∞, T∞, and appropriate profile coefficients and fluid properties. Answer: h= -k[E D To

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.35P

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Q2) In flow over a surface, velocity and temperature profiles are of the forms u(y) = Ay + By² + Cy3 and T(y) = D+ Ey + Fy? - Gy3 where the coefficients A through G are constants. Obtain expressions for the friction coefficient C, and the convection coefficient h in terms of uo, To, and appropriate profile coefficients and fluid properties. Q3) Water at a temperature of T = 25°C flows over one of the surfaces of a steel wall (AISI 1010) whose temperature is Ts1 = 40°C. The wall is 0.35 m thick, and its other surface temperature is Ts,2 = 100°C. For steady state conditions what is the convection coefficient associated with the water flow? What is the temperature gradient in the wall and in the water that is in contact with the wall? Sketch the temperature distribution in the wall and in the adjoining water.
Cooling water for a power plant is stored in a pond 900 m in length and 400 m wide. A dry wind at 300 K blows in a horizontal direction parallel to the 900 m side of the pond at a velocity of 2 m/s. The cooling water is at 300 K. Known the air dynamic viscosity v= 1.67 x10m?/s.; the Re transition from laminar flow to turbulent flow is 500,000; and the saturated water vapor pressure at 300 K is 3580 Pa; gas constant R= 8.3144 J/mole.K. 1.) At what position across the pond is the air flow no longer laminar? Would it reasonable to assume that the mean gas-film mass transfer coefficient for water vapor in air is dominated by turbulent flow mass transfer? 2.) As part of an engineering analysis to predict the evaporation rate of water from the pond, determine the mean gas film mass transfer co-efficient. 3.) Calculate the rate of water evaporation from the pond.
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A nuclear reactor is cooled by liquid sodium. The liquid sodium has the following properties: dynamic viscosity = 0.41 mPa·s, specific heat capacity = 1.2 kJ/kgK, thermal conductivity 82 W/mK. Which of the following statements is correct for this scenario? please explain A The thermal boundary layer is thicker than the hydraulic boundary layer. B Heat is transferred through the fluid more easily than momentum. C The velocity varies significantly from the surface to the thickness of the thermal boundary layer. D The hydraulic boundary layer is thicker than the thermal boundary layer.
Conduct thorough a research on Boundary layer and viscous sub layer, Shear stress in circular pipe as it relates to mechanics of fluids
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You are designing an IC heatsink which uses round pins in cross-flow. The heatsink must dissipate 3000W. The heatsink has 10 rows of 8 columns of round pins with a diameter of 1mm. The pins have longitudinal and transverse pitch of 6mm. The incoming air is at 25oC with a velocity of 3 m/s. Assume fluid properties are constant. If the pins are arranged in-line: a) Find the Reynold’s Number b) Find the Nusselt Number c) If the pins are 30mm tall, how hot must the pin surface be (average) to dissipate the proper amount of heat?