Consider convective cooling of a two-dimensional streamlined strut. Rather than conducting expensive experiments involving pressurized hydrogen, an engineer proposes to take advantage of similarity by performing wind tunnel experiments using air at atmospheric pressure with T∞=23°C. The rate of heat loss per unit object length is ???? ′ =50 ?

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.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.15P

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3.9 The heat transfer coefficients for the flow of 26.6°C air over a sphere of 1.25 cm in diameter are measured by observing the temperature-time history of a copper ball the same dimension. The temperature of the copper ball was measured by two thermocouples, one located in the center and the other near the surface. The two thermocouples registered, within the accuracy of the recording instruments, the same temperature at any given instant. In one test run, the initial temperature of the ball was 66°C, and the temperature decreased by 7°C in 1.15 min. Calculate the heat transfer coefficient for this case.
Air at 22˚C and at atmospheric pressure flows over a flat plate at a velocity of 1.65 m/s. If the length of the plate is 2.179 m and its temperature is 98 ˚C, Calculate Heat rate by using exact and approximate methods both. What is the %age difference of the heat transfer rate values by these methods? Take width of the plate as unity. Properties given at 60˚C are as follows: Density: 1.058 kg/m3 , cp = 1.005 kJ/kg˚C, k= 0.02897 w/m˚C, Kinematic viscosity is 18.97 × 10-6 m2 /s
A fluid (Prandtl number, Pr = 1) at 500 K flows over a flat plate of 1.5 m length, maintained at 300 K. The velocity of the fluid is 10 m/s. Assuming kinetic viscosity, v = 30 x 10-6 m²/s, the thermal boundary layer thickness (in mm) at 0.5 m from the leading edge is (up to three decimal)?
The following equation may be used to estimate the take-off ground run for an aircraft: Equation has been attached as an image. Calculate the take-off ground run, from a runway at ISA-SL conditions, for a twin engine aircraft for which the following data may be assumed Aircraft lift-off speed 155 knots Max take-off gross weight 220 tonnes Wing planform area (S) 358 m Wing CL (t/o flaps deployed, a = 0) 1.1 Wing span 53.18 m Oswald efficiency factor, e 0.7 KGE = CD(IGE) / Co(OGE) 0.4 Co sum (fuselage, wing, tailplane and nacelle) 0.015 Co for undercarriage 0.021 Co for flaps at taking-off setting 0.0073 Coefficient of rolling friction, u 0.02 Engine thrust (assumed constant) 310 kN per engine It may be assumed that 1knot = 0.51444 m/s It may be assumed that 1knot = 0.51444 m/s
An air flow with velocity u∞ = 2m/s and T∞ = 300K is used to cool the surface of a flat metal plate that is L = 0.5m long, W = 0.5m wide, and H = 0.1m thick. The plate receives a uniform heat flux input of q′′ = 500W/m^2 from the bottom. Assume the plate reaches the steady state and has a uniform surface temperature Ts and bottom temperature Tb. Assume one-dimensional conduction across the plate. For the air flow, the Prandtl number is Pr = 0.7, the kinematic viscosity is ν = 2 × 10^(−5) m^2/s, and the thermal conductivity is kf = 0.03 W/m · K. The solid material of the plate has a uniform thermal conductivity ks = 10 W/m · K.Given correlations for convection heat transfer over flat plate:• For the laminar flow region, the local Nusselt number is Nu = 0.332Re^(1/2)*Pr(1/3) • For the turbulent flow region, the local Nusselt number is Nu = 0.0296Re^(4/5)*Pr(1/3) Questions:(1) Determine the local convection heat transfer coefficient h(x) and the averaged con- vection heat transfer…
SOLVE STEP BY STEP DONT USE CHATGPT Through a metal pipe (k=25 J/s m °C) with an internal diameter of 2.5 cm and a wall thickness equal to 2.5 mm, water flows with a speed of 0.25 kg/s entering at 25 °C. The pipe passes through a furnace where the air is at 125 °C and the path is 2.5 m. Outside, convection develops with (he =35 J/s.m^2.°C), while inside convection occurs with (hi= 958 W/m^2.°C). Determine the outlet temperature of the water.
Air at 305 K flows at 4 m/s over a flat plate at 350 K. The air properties are as follows: density =1.1 kg/m3, viscosity =18.1×10−6 Pa.s, specific heat capacity =1005 J/kgK, and thermal conductivity =0.024 W/mK. The velocity and temperature profiles are assumed to be linear, giving the local Nusselt number to be Nux = 0.289 Rex1/ 2Pr1/3. The flow will become turbulent at a Reynolds number of 5×105. Assume the width of the plate perpendicular to the air flow is 1 m. At what distance from the leading edge does the flow become turbulent? ________m What is the heat transfer at the point of transition? ___________W What is the total heat transfer along the length of the plate where the flow is laminar? __________W
Over the ocean surface, the Bowen ratio is estimated to be about 0.2. Estimate the sensible heat and latent heat fluxes to the atmosphere, as well as the rate of evaporation, in millimeters per day, from the ocean surface, when the net radiation received just above the surface is 800W per m^2 , the heat flux to the water below 55 m is negligible, the rate of warming of the 55 m deep oceanic mixed layer is 0.12 deg. Celsius per day, and the sea surface temperature is 27deg. Celsius.
5. The wind variation for a typical site is described using Weibull distribution. Consider a case where the annual mean wind speed is 6 meters/second at 30 meters in height, and the Weibull distribution factor k=2. Discretize this in 1.5 m/s increments and predict the number of hours per year for the range of wind speeds that would be expected. For a 1.5MW wind turbine with Cp=0.40, density of air=1.225kg/m^3, and rotor diameter of 60 meters, determine the energy captured by this wind turbine over the course of a year.
Consider the vertical heat sink (see the figure) used to cool a surface at 70 0C. The room temperature is 30 0C. The dimensions are given as (H=2 cm, L=5 cm, t=1 mm, W=15 cm). If the space between the fins is arranged so that the heat transfer rate is maximum, what is the heat transfer rate from the heat sink? Properties of air: ρ=1 kg/m3, k=0.03 W/mK, ν=1.5x10-5 m2/s, cp=1 kJ/kg0C, Pr=0.7
A jacketed reactor heats a stream of water from 10°C to 54°C as an initial part of sauce production to increase production.To increase the heat transfer to the water, a rotary agitator (turbine flow) is placed and thus increase the average heat transfer coefficient on the inner wall of the reactor by 32%, by generating more turbulence in the water (from 1.00 to 1.32).After improvement, this coefficient can be estimated with Nu=0.76Re2/3Pr1/3. To heat the water, saturated steam at 100°C is condensed on the jacket, whose average heat transfer coefficient is h0=13.3(Tgas-Twater) -0,25kW/m²•K. The dimensions of the reactor are Dt=0.6m (reactor tank internally), H=0.6m and Da=0.2m (agitator). The agitator speed is 60rpm.Determine the mass flow rate of water that can be heated steadily under the given reactor conditions if the wall thickness is 3 mm of food-grade steel. Mainly, I also need the solution from concepts of how the heat flow behaves in the system, it can be with a diagram.
Fluid flows over a flat plate, 1.2 m long. The direction of flow is along the length of the plate and parallel to the surface of the plate. The plate is held at a constant temperature of 283 K. Velocity and temperature profiles are assumed to be linear inside the boundary layers. The free stream temperature of the fluid is 340 K and it travels at 5 m/s. The fluid properties are as follows: thermal conductivity = 0.029 W/mK, density = 0.92 kg/m3, viscosity = 12.9 x 10-6 Pa.s, and specific heat capacity = 1003 J/kgK. The value of the Nusselt number at the tailing edge of the flat plate is: [ans1] The convective heat transfer from the middle of the flat plate is: [ans2] W/m2 step by step working out piease, hit final answer is 145, -281 respectively