A gas flows over a heated horizontal surface with a surface temperature that is uniform and higher in value than the temperature of the gas. The local convective coefficient in W/m².K of this flow with convective heat transfer can be given as a function of the distance x (in meters) from the beginning of the horizontal surface by: h = A xD + B x + C, where A = -2.4, B = 14.8, C = 9.3 and D = 2.7. Based on this information, calculate the average Nusselt number of the flow over the plate if it is three meters long. Consider: ρgas = 0.9950 kg/m³; kgas = 30 x 10-3 W/m.K. Note: Use the equations given in the book by Schmidt et al. for problem resolution.

A gas flows over a heated horizontal surface with a surface temperature that is uniform and higher in value than the temperature of the gas. The local convective coefficient in W/m².K of this flow with convective heat transfer can be given as a function of the distance x (in meters) from the beginning of the horizontal surface by: h = A xD + B x + C, where A = -2.4, B = 14.8, C = 9.3 and D = 2.7. Based on this information, calculate the average Nusselt number of the flow over the plate if it is three meters long. Consider: ρgas = 0.9950 kg/m³; kgas = 30 x 10-3 W/m.K. Note: Use the equations given in the book by Schmidt et al. for problem resolution.

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 7.22P

See similar textbooks

Similar questions

An average man has abody surface area of 1.8m2 and a skin temperature of 33degrees celcius .The convection heat transfer coefficient for a clothed person walking in still air is expressed as {h,8.6V^0.53}FOR 0.5<v<2m/s,where V is the walking velocityin m/s.Assuming the average surface temperature of the clothed person to be 30degrees celcius, determine the rate of heat loss from an average man walking in still air at 10degrees celcius by convectionat a walking velocity of (a)0.5m/s (b)1.0m/s (c)1.5m/s (d)2.0m/s
A long 8-cm diameter vertical steam pipe whose external surface temperature is 90oC passes through some open area that is not protected against the wind blows. Determine the rate of heat loss from the pipe per unit length when the air is at 1 atm, 7oC and the wind is blowing across the pipe at a velocity of 50 km/h. From Table A-1: Thermal conductivity, k = 0.0275 W/m oC , viscosity, v = 1.77 x 10-5 m2/s Prandtl no. Pr = 0.71
A long 8-cm diameter vertical steam pipe whose external surface temperature is 90 degrees C passes through some open area that is not protected against the wind blows. Determine the rate of heat loss from the pipe per unit length when the air is at 1 atm, 7 degrees Celsius and the wind is blowing across the pipe at a velocity of 50 km/h. From Table A-1:Thermal conductivity, k = 0.0275 W/m degrees Celsius ,viscosity, v = 1.77 x 10^-5 m^2/sPrandtl no. Pr = 0.71
Hot air at 1 bar and 80 degree Celcius enters a 8 m long uninsulated square duct of cross-section 20 cm x 20 cm that passes through the attic of a house at a rate of 150 L/s. The duct is observed to be constant surface temperature of 60 degrees Celcius. Determine (a) air film coefficient (b) the exit temperature of air (c) logarithmic mean temperature difference (d) the rate of heat loss from the duct to the attic space. From Table A-18, for air gives, density, ρ = 1.009 kg/m^3thermal conductivity, k = 0.0297 W/m degree celciusviscosity, v = 2.06 x 10^-5 m^2/sspecific heat, Cp = 1008 J/kg degree celciusPrandtl no., Pr = 0.706
Oil flow in journal bearing can be approximated as parallel flow between two large plates with one plate moving and the other stationary. Determine the velocity, temperature distributions, the maximum temperature, the rate of heat transfer and the mechanical power wasted in oil. Take properties of oil at 50°C are given to be, k=0.17W/m. K, and u=0.05N.s/m2.
A7 To a 5ft long ½” ID pipe that is maintained at a uniform temperature of 150ºF oil enters at 70ºF with an average speed of 2ft/s. Determine the temperature rise on leaving the tube. The properties of the fluid can be taken as:=0.015lb/ft.s at 70ºF, =0.0055lb/ft.s at 150ºF, ρ=55lb/ft3, Cp=0.45 BTU/lb.ºF,k=0.1 BTU/h.ft.ºF.
Water at 43.3°C flows over a large square plate at a velocity of 28 cm/s. The plate is 1.2 m long (in the flow direction) and its surface is maintained at a uniform temperature of 10.0°C. The width of the plate is 1.2 m. Calculate the steady rate of heat transfer for the entire width of the plate in watts (W). The properties of water at the film temperature of (Ts + T∞)/2 = (10 + 43.3)/2 = 27°C are ρ = 996.6 kg/m3, k = 0.610 W/m·°C, μ = 0.854 × 10–3 kg/m·s, and Pr = 5.85. The steady rate of heat transfer per unit width of the plate is ___ W.
Air at 10oC enters a 10-cm-diameter and 4-m-long pipe at a rate of 0.035 kg/s. The inner surface of the pipe has a roughness of 0.22 mm, and the pipe is nearly isothermal at 60o Determine the rate of heat transfer to air using the Nusselt number relation given by (a) Eq. 8–66 and (b) Eq. 8–71. Evaluate air properties at a bulk mean temperature of 20oC. Is this a good assumption?
A liquid metal flows at a mass rate of 3 kg/s through a constant heat flux 5-cm-i.d tube in a nuclear reactor. The fluid at 473 K is to be heated with the tube wall 30 K above the fluid temperature. Determine the length of the tube required for a 1-K rise in bulk fluid temperature, using the following properties: p = 7.7 x 10^3 kg/m^3v = 8.0 x 10^-8 m^2/sCp = 130 J/(kg K)k = 12 W/mKPr = 0.011 Kaufman's correlation: Nu = 0,625.(Re.Pr)0,4
In a thermal system, water enters a 25-mm-diameter and 23-m-long circular tube with a mass flow rate of 0.1 kg/s at 25°C. The heat transfer from the tube surface to the water can be expressed in terms of heat flux as qs(x) = ax. The coefficient a is 400 W/m3, and the axial distance from the tube inlet is x measured in meters. Determine (a) an expression for the mean temperature Tm(x) of the water, (b) the outlet mean temperature of the water, and (c) the value of a uniform heat flux qs on the tube surface that would result in the same outlet mean temperature calculated in part (b). Evaluate water properties at 35°C.
Air at 20°C, 1 atm flows with a velocity of 4.5 m/s over a flat plate having a sharp leading edge. The plate surface isisothermal at 60°C.(a)Find out the distance from leading edge at which the flow in the boundary layer changes from laminar to turbulent.(b)Using exact solution,determinethe following parameters at the location established at part (a):(i)Thickness of the hydrodynamic boundary layer(ii)Thickness of the thermalboundary layer(iii)Local convective heat transfer coefficient(iv)Average convective heat transfer coefficient(v)Heat transfer rate from both sides per unit width of the plate(vi)Mass entrainment in the boundary layer(vii)The skin friction coefficient
A 20-cm-square plate loses heat at a rate of 5000 W/m2. Air at 1 atm and 300 K flows across the lower surface of the plate at a free-stream velocity of 20 m/s. The lower surface of the plate has a uniform temperature of 350 K. Water flows across the upper surface of the plate. The temperature difference between the surface and free stream velocity of water is 10oC. Find the velocity of water when the properties of water are Pr = 4.929 , k = 0.6107 W/m oC and ν= 7.239×10-7 m2/s.