Consider a rectangular fin that is used to cool a motor- cycle engine. The fin is 0.15 m long and at a tempera- ture of 250°C, while the motorcycle is moving at 80 km/h in air at 27°C. The air is in parallel flow over both surfaces of the fin, and turbulent flow conditions may be assumed to exist throughout. (a) What is the rate of heat removal per unit width of the fin? (b) Generate a plot of the heat removal rate per unit width of the fin for motorcycle speeds ranging from 10 to 100 km/h.

Consider a rectangular fin that is used to cool a motor- cycle engine. The fin is 0.15 m long and at a tempera- ture of 250°C, while the motorcycle is moving at 80 km/h in air at 27°C. The air is in parallel flow over both surfaces of the fin, and turbulent flow conditions may be assumed to exist throughout. (a) What is the rate of heat removal per unit width of the fin? (b) Generate a plot of the heat removal rate per unit width of the fin for motorcycle speeds ranging from 10 to 100 km/h.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Engine oil at 100°C and a velocity of 0.15 m/s flows over both surfaces of a 1.2-m-long flat plate maintained at 20°C. Determine: (a) The velocity and thermal boundary layer thicknesses at the trailing edge. (b) The local heat flux and surface shear stress at the trailing edge. (c) The total drag force and heat transfer per unit width of the plate. Determine the velocity boundary layer thickness & at the trailing edge, in m. 8 = i m Determine the thermal boundary layer thicknesses 8, at the trailing edge, in m. m Determine the magnitude of the local heat flux at the trailing edge, W/m?. q" x W/m2 i Determine the local surface shear stress at the trailing edge, in N/m?. Ts, L. = N/m2 Determine the total drag force per unit width of the plate, in N/m. D' = i N/m Determine the magnitude of the heat transfer per unit width of the plate, in W/m. W/m
A vertical pipe 90 mm diameter and 2.5 m height is maintained at a constant temperature of 125 o The pipe is surrounded by still atmospheric air at 25 oC. Find heat loss by natural convection. Properties of water at 75 oC: Density = 1.0145 kg/m3 Kinematic viscosity = 20.55 x10-6 m2/s Prandtl number (Pr) = 0.693 Thermal conductivity (k) = 30.06 x 10–3 W/m K
Example 1: Engine oil at 60°C flows over the upper surface of a 5-m-long flat plate whose temperature is 20°C with a velocity of 2 m/s (Figure). Determine the total drag force and the rate of heat transfer per unit width of the entire plate.
Water at 5°C is being used to cool apples from an initial temperature of 25° to 10°C. Thewater flow over the surface of the apple creates a convective heat-transfer coefficientof 15 W/(m2-K). Assume the apple can be described as a sphere with a 10 cm diameterand the geometric center is to be reduced to 10°C. The apple properties include thermalconductivity of 0.45 W/(m-K), specific heat of 3.950 kJ/(kg-K), and density of 940 kg/m3.a. Determine the time that the apples must be exposed to the water.b. If the apple is submerged only for 2 hours, what will be its center temperature?
Small potato balls of 0.5 cm radius (can be approximated as a sphere) baked in the oven and initially at a uniform temperature of 160°C. Assume, potatoes have a density of 650 kg/m, specific heat of 3400 J/kgK and conductivity of 1 W/mK. You want to eat potatoes quickly without burning your tongue so that you have decided to cool them down with forced convection. Air h, T. hot potato initially Air temperature is 20°C and the convective heat transfer coefficient is 140 W/m?K. Calculate the time (in seconds) required for its surface temperature to drop 90°C.
2.0 Engine oil at 100°C and a velocity of 0.25 m/s flows over both surfaces of a 0.8-m-long flat plate maintained at 20°C.Determine:(a) The velocity and thermal boundary layer thicknesses at the trailing edge.(b) The local heat flux and surface shear stress at the trailing edge.(c) The total drag force and heat transfer per unit width of the plate.
Engine oil at 100°C and a velocity of 0.20 m/s flows over both surfaces of a 1.1-m-long flat plate maintained at 20°C. Determine: (a) The velocity and thermal boundary layer thicknesses at the trailing edge. (b) The local heat flux and surface shear stress at the trailing edge. (c) The total drag force and heat transfer per unit width of the plate. Determine the velocity boundary layer thickness & at the trailing edge, in m. 8 = i m Determine the thermal boundary layer thicknesses &, at the trailing edge, in m. 8, = i m Determine the magnitude of the local heat flux at the trailing edge, W/m². q" x = i W/m² Determine the local surface shear stress at the trailing edge, in N/m². Ts, L i N/m² Determine the total drag force per unit width of the plate, in N/m. D' = i N/m Determine the magnitude of the heat transfer per unit width of the plate, in W/m. d' = W/m i
Thermal jackets are typically put on cryogenicstorage tanks to minimize the heat transfer gainsfrom the surroundings. Consider a cylindercontainer that is 1.5 m long made from steel (k = 750W/m.K) with an inner diameter of 0.5 m and outerdiameter of 0.7 m. If the liquefied natural gas (LNG)inside the cylinder is maintained at 90 K, ambientconditions are Tamb = 20 °C, h = 7 W/m2.K. What isthe required thermal jacket thickness to maintainthe outer temperature of that jacket of 15 °C? (Takea thermal conductivity of the insulation to be kins =0.015 W/m.K). Image credit: Okorder. Image forillustrative purposes only.
A printed circuit board with constant surface temperature dissipates 100 W from one side over an area (0.3 mx 0.2 m). A fan is use to cool this board with a flow speed of 12 m/s parallel to the longest dimension of the board. Calculate: 1. The surface temperature of the board for an air temperature of 30 C. 2. Thickness of hydrodynamic and thermal boundary layer. 3. Amount of change in heat transfer rate if the flow parallel to the short dimension. Cp-1000 J/kg.K, k-0.03 W/m.C, Pr-0.667, u = 2 x 105 kg/m.s, p=1.15 kg/m³ Laminar flow, Nu= 0.664Rel/2Pr1/3, Turbule flow, Nu= 0.037Re4/5Prl/3
Thermal jackets are typically put on cryogenicstorage tanks to minimize the heat transfer gainsfrom the surroundings. Consider a cylindercontainer that is 1.5 m long made from steel (k = 750W/m.K) with an inner diameter of 0.5 m and outerdiameter of 0.7 m. If the liquefied natural gas (LNG)inside the cylinder is maintained at 90 K, ambientconditions are Tamb = 20 °C, h = 7 W/m2.K. What is the required insulationmaterial to maintain the outer temperature of that jacket of 15 °C? Usethe end of the book and write your assumption with the right value.(Take a maximum allowed jacket thickness of Lins = 7 cm)
A long, cylindrical, electrical heating element of diameter D = 14 mm, thermal conductivity k = 251 W/m · K, density p= 2,805 kg/m3, and specific heat cp = 903 J/kg · K is installed in a duct for which air moves in cross flow over the heater at a temperature and velocity of 30°C and 9 m/s, respectively. (a) Neglecting radiation, estimate the steady-state surface temperature when, per unit length of the heater, electrical energy is being dissipated at a rate of 1,033 W/m.
6- Air at a pressure of 200 kPa and free-stream temperature of 27°C flows over a square flat plate at a velocity of 30 m/s. The Reynolds number is 10° at the edge of the plate. Calculate the heat transfer for an isothermal plate maintained at 57 C. v = 8,6x10 k = 0.0274; Pr = 0.7 V Nu = 1299 Answers: g = 676W