Consider flow over a flat plate for which it is desired to determine the average heat transfer coefficient over the short span
Provide three different expressions that can be used to evaluate
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Fundamentals of Heat and Mass Transfer
- 5.7 The average Reynolds number for air passing in turbulent flow over a 2-m-long, flat plate is . Under these conditions, the average Nusselt number was found to be equal to 4150. Determine the average heat transfer coefficient for an oil having thermal properties similar to those in Appendix 2, Table 18, at at the same Reynolds number and flowing over the same plate.arrow_forwardEthylene glycol at 40°C flows over a heated plate very wide, 6 m long, at velocity of 0.04 m/s. For a temperature = 90°C, determine: 1- the thickness of the hydrodynamic boundary layer at the end of the plate2- the thickness of the thermal boundary layer at the end of the plate3- the local and average heat transfer coefficient at the end of the plate4- the total heat flux transferred from the heated surface.arrow_forwardCalculate the rate at which the average friction coefficient, friction force and heat transfer rate will change if the free flow rate of the turbulent air flowing parallel to the plate over a smooth plate is doubled. Does the result change for constant temperature and constant heat flux conditions; Please evaluate.arrow_forward
- Air stream at 1 atm flows with a velocity of 2 m/s, in parallel over a 3 m long square flat plate, placed on ground, where there is an unheated starting length of 1 m. The air stream has a temperature of 20 °C and the heated section of the flat plate is maintained at a constant temperature of 80 °C. Determine the local heat transfer coefficient at trailing edge and average convection heat transfer coefficient for the heated section. Also calculate the heat loss by convection. Determine the average friction coefficient and wall shear stress and drag force.arrow_forwardWater at 45.0oC flows over a large plate at a velocity of 30.0 cm/s. The plate is 1.0 m long (in the flow direction), and its surface is maintained at a uniform temperature of 5.0oC. Calculate the steady rate of heat transfer per unit width of the plate. Properties The properties of air at 1 atm and the film temperature of (Ts+T∞)/2 = (5+45)/2 = 25°C are: ρ = 996.6 kg/m3, k = 0.610 W/m.oC, μ = 0.854x10-3 kg/m.s, Pr = 5.85arrow_forwardA 20 °C water flows to 50cmx60cm flat plate with velocity of 6m/s . The flat plate surface temperature is maintained at 40 °C . The air flows parallel to the 50cm side of the plate. If the kinematic viscosity of water is 78x10-8 m2/s, at what length the flow become turbulent? If the average laminar heat transfer coefficient of water is 7740W/m2 °C , what is the overall heat transfer at the laminar section?arrow_forward
- Air at 200C and at a pressure of 1 bar is flowing over a flat plate at a velocity of 3 m/s. If the plate is 280 mm wide and at 560C, calculate the following quantities at x = 280 mm given that properties of air at the bulk mean temperature 20 + 56/2= 380C are: (i) Boundary layer thickness,(ii) Local friction coefficient,(iii) Average friction coefficient,(iv) Shearing stress due to friction(v) Thickness of the boundary layer,(vi) Local convective heat transfer coefficient,(vii) Average convective heat transfer coefficient,(viii) Rate of heat transfer by convection(ix) Total drag force on the plate, and(x) Total mass flow rate through the boundaryarrow_forwardAir at atmospheric pressure and a temperature of 25 degrees C is in parallel flow at a velocity of 5 m/s over a 1-m-long flat plate that is heated from below with a uniform heat flux of 1250 W/m2 . Assume the flow is fully turbulent over the length of the plate. Take ν = 18.76 × 10−6 m2/s, k = 0.0284 W/m·K and Pr =0.703. (a) Calculate the plate surface temperature, Ts(L), and the local convection coefficient, hx(L), at the trailing edge, x = L. (b) Calculate the average temperature of the plate surface.arrow_forwardAir at standard conditions of 1 atm and 27°C flows over a flat plate at 20 m/s. The plate is 60 cm square and is maintained at 97°C. Calculate the heat transfer from the plate.arrow_forward
- Air at 60°F flows over a 10-ft-long flat plate at 7 ft/s. Determine the local friction and heat transfer coefficients at intervals of 1 ft, and plot the results against the distance from the leading edge.arrow_forwardHeat Transfer from a Flat Plate.Air at a pressure of 101.3 kPa and a temperature of 288.8 K is flowing over a thin, smooth, flat plate at 3.05 m/s. The plate length in the direction of flow is 0.305 m and its temperature is 333.2 K. Calculate the heat-transfer coefficient assuming laminar flow.arrow_forwardWater at 1500 kg/h and 10°C enters a 10-mmdiameter smooth tube whose wall temperature is maintained at 49°C. Calculate (a) the tube length necessary to heat the water to 40°C, and (b) the water outlet temperature if the tube length is doubled. Assume average water properties to be the same as in (a).arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning