In a paper-drying process, the paper moves on a conveyor belt at 0.2 m/s, while dry air from an in-line array of round jets (Figure 7.18b) impinges normal to its surface. The nozzle diameter and pitch are
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- Air at 1000C flows at an inlet velocity of 2 m/s between two parallel flat plates spaced 1 cm apart. Estimate the distance from the entrance to the point where the boundary layers meet.arrow_forwardConsider two cases involving the parallel flow of dry air at V= 1.5 m/s, T∞=45°C, and atmospheric pressure over an isothermal plate at Ts=20°C. In the first case, Rex,c=R5 × 105, while in the second case the flow is tripped to a turbulent state at x=0 m. At what x‐location, in m, are the thermal boundary layer thicknesses of the two cases equal? What are the local heat fluxes, in W/m2, at this location for the two cases?arrow_forwardA 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 = 0.71arrow_forward
- Sketch the velocity gradients that arise from pressure-driven flow for a Newtonian liquid and a shear thinning liquid.arrow_forwardA solid ball is dropped into a water container for cooling. The ball has a diameter of D = 4 mm and sinks at a constant terminal velocity of Ut = 0.01 m/s. The thermophysical properties of the solid ball are: density ρ = 8000 kg/m3, thermal conductivity k = 200 W/m · K, and specific heat c = 1000 J/kg · K. The thermophysical properties of the water are: density ρw = 1000 kg/m3, kinematic viscosity νw = 10^(−6) m^(2)/s, thermal conductivity kw = 0.6 W/m · K, and Prandtl number Pr = 7. The vertical distance for the ball to sink from the initial fully submerged depth to the bottom of the container is H = 0.1 m. The initial temperature of the ball is T0 = 800 K, and the water temperature is T∞ = 300 K.Given correlations: For the convection heat transfer caused by flow past a sphere, the averaged Nusselt number is NuD = 2 + 0.6*(Re^(1/2))*(Pr^(1/3)) Questions:(1) Determine the averaged convection heat transfer coefficient h, and check if the LumpedCapacitance Method can be used to solve…arrow_forwardAssuming that the velocity profile in a laminar boundary layer of thickness δ is given by where u is the velocity at distance y from the surface and Ue is the freestream velocity (as shown in Figure P9.23), demonstrate that where θ is the momentum thickness, τw is the viscous stress at the wall, Cf is the local skin friction coefficient at a distance x from the leading edge of the plate, ρ is the density and ν is the kinematic viscosity.arrow_forward
- Water at 10°C flows over a 4.8-m-long flat plate with a velocity of 1.15 m/s. If the width of the plate is 6.5 m, calculate the average friction coefficient over the entire plate. (Water properties at 10°C are: ? = 999.7 kg/m3, ? = 1.307 × 10−3 kg/m·s.) (a) 0.00288 (b) 0.00295 (c) 0.00309 (d ) 0.00302 (e) 0.00315arrow_forwardWhat are the physical and quantitative evidence of turbulence in fluid flow?arrow_forwardAtmospheric air with free flow velocity U_∞= 30 m/s flows through a circular cylinder at T_∞= 250 K and D = 2.5 cm diameter. The surface of the circular cylinder is kept at a uniform temperature T_w = 350 K.The CD drag coefficient is 1.1. (D=1 cm- 3 cm and U_∞= 10 m/sec 30 m/s)(a) Calculate the average heat transfer coefficient ( h ̅_m,W/m2K)(b) Determine the amount of heat transfer (Q, W) per 1 m length of the cylinder(c) Calculate the drag force (FD, N) acting on the 1 m length of the cylinder FD=0.1 A=0.34 D=2.9 cd=1.2arrow_forward
- Atmospheric air with free flow velocity U_∞= 30 m/s flows through a circular cylinder at T_∞= 250 K and D = 2.5 cm diameter. The surface of the circular cylinder is kept at a uniform temperature T_w = 350 K. The CD drag coefficient is 1.1. (D=1 cm- 3 cm and U_∞= 10 m/sec 30 m/s)(a) Calculate the average heat transfer coefficient ( h ̅_m,W/m2K)(b) Determine the amount of heat transfer (Q, W) per 1 m length of the cylinder(c) Calculate the drag force (FD, N) acting on the 1 m length of the cylinderarrow_forwardWater at 20°C is pumped at a constant rate of 9 m3/h from a large reservoir resting on the floor to the open top of an experimental absorption tower. The point of discharge is 5 m above the floor, and friction losses in the 50-mm pipe from the reservoir to the tower amount to 2.5 J/kg. At what height in the reservoir must the water level be kept if the pump can deliver only 0.1 kW?In this problem, we can assume that the surface of the large reservoir and the absorption tower is at atmospheric pressure, show the complete mechanical energy balance describing the flow system? Take the floor to be at 0 height.arrow_forwardThe velocity and temperature of the flow ahead of a normal shock wave are 1215 m/s and 300 K, respectively. Calculate the velocity of the flow behind the shock.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning