7An electric heater is made of thin conducting wires forming a mesh. The diameter of the wire is0.5 mm and the total length of all the wires is 2 m. The temperature of the wire is 1,000 K. Theheat from the wire is dissipated to the air at 300 K flowing through the wire mesh at a velocity of5 m/s. Ignore radiation of the heater and assume it has a uniform temperature. T Const=(a) Calculate the convection heat transfer coefficient(h) between the air and the heater.(b) If the total electrical resistance of the heater is 10 2, what is the electrical current?(c) Calculate the Biot number of the heater. V=IR(d) The electrical current is suddenly cut off. How long does it take for the heatertemperature to drop to 500 K?Properties of the air: pa = 0.7 kg/m³, Cp,a= 1030 J/kg K, va = 38.8×106 m²/s, ka=0.041 W/m•K,aa =56.7×106 m²/s, and Pra = 0.684.Properties of the heater: ph = 8900 kg/m³, Cp,h= 380 J/kg K, and kn = 400 W/m.K.

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Answered: 7 An electric heater is made of thin…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

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A house, for cooling purposes, consists of two zones: the atric area zone A and the living area zone B (see below figure). The living area is cooled by a 2 -ton air conditioning unit that removes 23,000 Btu/hr. The heat capacity of zone B is 1/6 °F per thousand Btu. The time constant for heat transfer between zone A and the outside is 3ℎr, between zone B and the outside is 6ℎr, and between the two zones is 6ℎr. If the outside temperature stays at 90°F, how warm does it eventually get in the attic zone A ?
Solve with thermal resistance and conduction/convection. Specifically account for the V= 9 ft/s The wall of a furnace has an inner temperature of 500 F. The wall has a thickness of 2 inches and has a thermal conductivity of 0.02 Btu/(h·ft·F). On the outside, air at 30 F flows over the 10 ft x 10 ft wall at a speed of 9 ft/s. Determine the rate of heat loss from the furnace to the environment.
IMPORTANT!!! ONLY ANSWER PART D Parts A, B, and C are solved and the answers are in the picture.
A long, bare, 0.20 mm diameter nichrome wire experiences the cross flow of 300 K nitrogen at a velocity of 6.0 m/s. The wire carries 2 A of current, and its resistance per unit length is 30 Q/m. Estimate the temperature of the wire. (Recall that P = I² R).
* Energy Equation : (First law of thermodynamics) + (8-1). M? du u dT T =。
Problem 6. Suppose we want to cool an object of temperature A to a temperature of B by submerging it in an environment of temperature To. Use Newton's Law of Cooling to show the time needed to cool the object from temperature A to temperature B is 1 А - То t = In k В -То where k is the cooling constant.
n electric generator at a power plant produces energy by passing superheated steam from a high temperature container (reservoir), through a pipe connected to a series of fans, and then into a low temperature reservoir. As the steam passes across the blades of the fans some of the heat energy of the steam is transformed into mechanical energy, which turns the fans which in turn are connected to a generator, which in turn converts the mechanical energy into electrical energy. If the high temperature steam has a temperature of 412.1 K and the low temperature reservoir has a temperature of 105.4 K, what is the Carnot efficiency of this process?

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