Two large plates are maintained at a temperature of 910 K and 500 K respectively. Each plate has area of 100 cm2. Compare thenet heat exchange between the plates for the following cases.Match each item to a choice:Both plates are blackPlates have an emissivity of 0.5Choices:i none of these: 353.3825 W: 176.6913 W: 362.4602 W181.2301 W

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Answered: Two large plates are maintained at a…

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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It is desired to heat the workshop with a stove made of falling cylindrical sheet material with an outer diameter of 400 mm and a height of 1600 mm. The surface temperature of the stove is 217 oC and the radiation emission coefficient is 0.92, the temperature of the workshop surfaces is 12 oC and the ambient temperature of the workshop is 17 oC. Next to the stove, the workshop surface area is very large. From the side surface of the stove to the workshop; a) By transport,b) with radiation Calculate the heat transfer.
A surface gains 500 W/m2 heat at an equilibrium temperature of 30 °C and it is subjected to a simultaneous heat loss to environment by convection and to surroundings by radiation. The convection conditions are 10 °C and 20 W/m2 K. If the surface assumed to be black what should be the surrounding temperature to sustain this physical condition?
An astronaut performing an extra-vehicular activity(space walk) shaded from the Sun is wearing a spacesuitthat can be approximated as perfectly white (e = 0) exceptfor a 5 cm × 8 cm patch in the form of the astronaut’snational flag. The patch has emissivity 0.300. The spacesuitunder the patch is 0.500 cm thick, with a thermalconductivity k = 0.0600 W/m °C , and its inner surface isat a temperature of 20.0 °C . What is the temperature of thepatch, and what is the rate of heat loss through it? Assumethe patch is so thin that its outer surface is at the sametemperature as the outer surface of the spacesuit under it.Also assume the temperature of outer space is 0 K. You willget an equation that is very hard to solve in closed form,so you can solve it numerically with a graphing calculator,with software, or even by trial and error with a calculator.
2. Consider steady heat transfer between two large parallel plates at constant temperatures of T1 = 295 K and T2 = 155 K that are L = 2 cm apart. Assuming the surfaces to be black, determine the rate of heat transfer between the plates per unit surface area assuming the gap between the plates is (a) filled with atmospheric air,(k = 0.01979 W/m- o C) (b) evacuated,(c) filled with superinsulation having an apparent thermal conductivity of 0.00015 W/m · °C.
Consider steady heat transfer between two large parallel plates at constant temperatures T1 = 300 K and T2 = 200 K that are L = 1 cm apart, as shown below. Assuming the surface to be black, determine the rate of heat transfer between the plates per unit surface area assuming the gap between the plates is a) filled with still air with k = 0.0219 W/m°C, b) free flowing air with h = 7.5 W/m2°C, c) evacuated, d) filled with urethane insulation with k = 0.026 W/m°C, and e) filled with superinsulation that has an apparent thermal conductivity k = 0.00002 W/m°C PLEASE ANSWER LETTER D AND E, THANK YOU
A 30 x 30 cm door in a brick kiln is at a distance of 3.5 m from a wall 12 m wide and 5 m high. The door is so located that a normal from the center of the door strikes the wall midway from the ends and 1.5 m above the floor. The opening into the kiln may be considered a black body; the wall is painted flat paint (Ɛ = 0.46). The temperature inside the kiln is 1 400 C and the wall temperature is 60 C. Determine (a) the configuration factor F12 and (b) the net radiant heat exchange between the opening and the wall when the fire door is open?
A plate that is exposed to the outside environment at 30 ° C, gets airradiation of 2000 W / m2. The plate, which absorbs 80% of the irradiationand it has an emissivity of 0.5, it is always at a uniform temperature.An external air flow at 20 ° C and 15 W / m2-K go through the plate. Calculatethe temperature of the plate if it is in thermal equilibrium and insteady state conditions.
A composite wall is comprised of two large plates separated by sheets of refractory insulation. In the installation process, the sheets of thickness L = 50 mm and thermal conductivity k = 0.05 W/mK are separated at 1-m intervals by gaps of width w = 10 mm. The hot and cold plates have temperatures and emissivities of T1 = 400 deg C, emissivity1 = 0.85 and T2 = 35 deg C, emissivity2 = 0.5, respectively. Assume that the plates and insulation are diffuse-gray surfaces. %3D Determine the heat loss by radiation through the gap per unit length of the composite wall (normal to the page). Recognizing that the gaps are located on a 1-m spacing, determine what fraction of the total heat loss through the composite wall is due to transfer by radiation through the insulation gap. Hot side Gap w = 10 mm A. 47 W/m, 9.2% T1 = 400°C B. 47 W/m, 10.2% L = 50 mm C. 37 W/m, 10.2% D. 37 W/m, 9.2% T2 = 35°C Cold side 1 m Insulation, k = 0.05 W/m-K
This experiment is conducted to determine the emissivity of a certain material. A long cylindrical rod of diameter D₁ = 0.01 m is coated with this new material and is placed in an evacuated long cylindrical enclosure of diameter D₂ = 0.1 m and emissivity 2 = 0.95, which is cooled externally and maintained at a temperature of 200 K at all times. The rod is heated by passing the electric current through it. When steady operating conditions are reached, it is observed that the rod is dissipating electric power at a rate of 16 W per unit of its length, and its surface temperature is 600 K. Based on these measurements, determine the emissivity of the coating on the rod. The emissivity of the coating on the rod is 0.1165
A tube pipe is heated to a temperature of 150°C with an outside diameter of 12cm and it’s enclosed in a large room of 20°C. Calculate the radiant heat loss per unit length, if the surface emissivity is 0.65.
A one-dimensional plane wall is exposed to convective and radiative conditions at x = 0. The ambient and surrounding temperatures are T. exposed surface is a = 0.78. Determine the convective and radiative heat fluxes to the wall at x = 0, both in W/m2, if the wall surface = 20°C and Tsur = 40°C, respectively. The convection heat transfer coefficient is h = 20 W/m²-K, and the absorptivity of the temperature is T, = 30°C. Assume the exposed wall surface is gray, and the surroundings are large. gbonv i W/m? Tad i W/m2
Determine the heat flow between the roof and floor of 4 x 3 m size of a furnace of 4 m x 4 m x 3 m size when the roof is at 1200 K and the floor is maintained at 600 K, with the other surfaces non absorbing and reradiating. The surface emissivity of the hotter surface is 0.8 and that of the cooler surface 0.6.

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