A 300 mm thick wall (k= 1.5 W/mK, p = 2600 kg/m³, cp = 1000 J/kg⚫K) has a uniform originaltemperature of 900 °C. At the time t = 0, its both surfaces are suddenly exposed to air (T∞ = 25 °C,h = 30 W/m²K).(a) Calculate the Biot number of the wall. Does it have a uniform temperature?(b) After 3 hours, what is the temperature at the middle plane (@x = 0)?Symmetry½L= 300 mmh = 30 W/m² KwallT∞ = 25°Ch = 30 W/m² KTo=25°C9. Ah (T-ToG=eptHot airxp = 2600 kg/m³k=1.5 W/m K900cHot airTr= 96warrume teNow.

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Answered: A 300 mm thick wall (k= 1.5 W/mK, p =…

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

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t = 30 + 0.9563 (62.2- 30) = 60.79°C (Ans.) Example 4.14. A very thin glass walled 3 mm diameter mercury thermometer is placed in a stream of air, where heat transfer coefficient is 55 W/m2°C, for measuring the unsteady temperature of air. Consider cylindrical thermometer bulb to consist of mercury only for which k and a = 0.0166 m2/h. Calculate the time required for the temperature change to reach half its final or, %3D 8.8 W/m C %3D value.
Q.3) The two sides of a large plan wall are maintained at constant temperatures of T₁ = 120°C and T₂ = 50°C, respectively. If you know that the wall thickness L = 0.2 m, thermal conductivity k = 1.2 W/m.K, and surface area A = 15 m². Determine (a) the variation of temperature within the wall and the value of temperature at x = 0.1 m and (b) the rate of heat conduction through the wall under steady conditions. (10 Pts)
(B) A cylinder made of aluminum has a mass of 7 Kg and initially at a temperature of 250 C is suddenly placed in a controlled environment in which the temperature is maintained at 15 'C. The convection heat transfer coefficient is 90 W/(m2. C ). Calculate the time required to cool the cylinder to 100 °C. Use the lumped capacity method. Take p=2707 kg/m³, C=896 J/kg°C, L=15cm.
I need the answer as soon as possible
3 Brass cube "p = 8530 kg/m , c= side length =9 mm, are annealed by heating them first to 813°C in a furnace and then allowing them to cool slowly to 130°C in ambient air at 28°C. If the average heat transfer coefficient is 19.9 W/m .°C, If 2204 balls are to be annealed per hour, what is the total rate of heat transfer (watts) from the balls to the ambient air? 380 J/kg.°C, k = 110 W/m.°C, a = 33.9E-6 W/m.°C",
A long rod with a thermal conductivity of 1 W/m K subject to the given boundary conditions. in the permanent regime temperature distribution with the energy balance method for ∆x=∆y= 0.2m find it. In addition, the unit of heat transfer between the rod and the fluid. Calculate for length.
Steaks (2 cm thick, k = 0.45 W/m - °C, « = 0.91 x 107 m2/s) usually have an original temperature of 25 °C. They will be cooled in a refrigeration room. The said room has a temperature of -11 °C. The heat transfer coefficient on both sides of the steak is 9 W/m2 - °C. How long will it take for both surfaces of the meat to be cooled to 2 °C? Assume the geometry of steaks to be a flat slab.
A 1800-W iron plate has a thickness of 4 mm, cross-sectional area of 340 cm^2. The room convection heat transfer coefficient is 20 W/(m^2K) with a temperature of 20 C. Determine the time required for the iron plate to drop from 850 C to 250 C? Density, specific heat value and conductivity of the plate are 2750 kg/m^3, 900 J/(kgK) and 180 W/(mK), respectively. 500 seconds 635 seconds O none 450 seconds 800 seconds
The temperature distribution in a wall (conductivity k=6-W/m2C, thickness L=10-cm) is given as T(x)=(-454 x2+53 x+ 17) (in °C) Assuming unit wall surface area, calculate the rate of heat loss from both sides of the wall in Watt.
Steel cubes 10 mm in width are annealed by heating to 1,377 K and then slowly cooling to 469 K in an air environment for which T∞ = 301 K and h = 24 W/m2-K. Assuming the properties of the steel to be k = 24 W/m · K, ρ = 7,047 kg/m3, and c = 916 J/kg · K, estimate the time required for the cooling process.
The initial temperature of a 50 cm long silver wire is 50 °C. The circumference of the wire in question is completely insulated, but both ends are kept at a temperature of 0 °C (zero degrees Celsius). Obtain the heat conduction along the wire as a function of time and position and, taking a single term in the solution, determine how many degrees Celsius the temperature in the middle of the rod will be after 7 minutes. (For silver wire, α=1.70 cm2/s.)

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