Consider conditions for which a fluid with a free stream velocity of
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- Air at 20 ◦ C flows inside a pipe 18-mm-ID having a uniform heat flux of 150 W/m 2 on the surface, the average flow velocity at entry being 1.0 m/s. The air pressure is 2 bar. Determine the value of convection coefficient. If the pipe is 2.5 m long, determine the air exit temperature and the wall temperature at the exit. Assume fully developed hydrodynamic boundary layer.arrow_forwardCold fluid flows at a velocity of 8 m/s over a hot flat plate. The flow is laminar, and the velocity and temperature profiles are assumed to be linear. The fluid properties are as follows: density ρ=1.14kg/m3, viscosity μ=18.2×10−6Pa s, specific heat capacity cp=1,008J/kgK, and thermal conductivity k=0.023W/mK. What is the thickness of the thermal boundary layer at the position x=2mm downstream of the leading edge? Give your numerical answer in mm to 1 decimal place.arrow_forwardA 2-cm diameter, 10-m long tube transports water at an average flow velocity of 8 m/s. The water enters at 20°C and leaves at 30°C. To compute for the Nusselt number of the water flow, what is the exact value of the temperature in °C on which the water properties should be based?arrow_forward
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- QUESTION 4 Cold air at 5 °C enters a 12-cm-diameter 20-m-long isothermal pipe at a velocity of 2.5 m/s and leaves at 19 °C as shown in Figure Q4. Take the pressure of air 1 atm, i. estimate the rate of heat transfer to the air, and ii. calculate the surface temperature of the pipe. T, Air 5°C 12 cm 19°C 2.5 m/s 20 m Figure Q4arrow_forwardAn oil preheater consists of a single tube of 10 mm diameter and 25 m length. The tube is heated by a heat rate per unit length of q' = ax2 [W/m], where a = 1.2 W/m³. Before entering the tube, the oil has a uniform temperature of 25 °C and a flow rate of 0.025 kg/s. The hydrodynamic boundary layer has been fully developed. (a) Determine the type of flow (laminar) or turbulent) inside the tube. Is it fully developed? (b) Calculate the mean fluid temperature and the surface temperature at the tube exit. Note: When determining the convection coefficient, use the correlation equation for constant heat flux. Properties of the oil: p = 865.8 kg/m³, cp=2035 J/kg K, μ= 8.36×102 N⚫s/m², k = 0.141 W/m K, and a = 0.8×107 m²/s. knowns: q' = ax² L: 25m D= 0.01m m = 0.025 kg/s Tm,i=25 C 0 x (Tm.o assumptions qwns! Steady flowarrow_forwardA rod of diameter 0,08 m and length 0,13 m is inside a concentric cylindrical casing. The rod and its casing are vertically located. A liquid of density 900 kg/m3 and viscosity 0.9 Pa.s is used as a lubrication medium between rod and its casing. The rod is rotated at a speed of 46 rad/s. Due to the narrow clearance 0,03 m between rod and casing gravitational effects and surface curvature effects are ignored . Assume liquid flow in clearance as laminar steady and incompressible and use pi number, π = 3.14 a) What is the magnitude of shearing stress over the rod (in Pa)? b) What is the magnitude of frictional torque on rod (in N m)? c) What is the magnitude of Reynolds Number of flow ? Use clearence as dimensional characteristics in Reynolds Number calculationarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning