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A leading manufacturer of household appliances is proposing a self-cleaning oven design that involves use of a composite window separating the oven cavity from the room air (Figure 2a). The composite is to consist of two high-temperature plastics (A and B) of thicknesses LA = 2LB and thermal conductivities ka = 0.15 W/m·K and kB = 0.08 W/m K. During the self-cleaning process, the oven wall and air temperatures, Tw and Ta, are 400°C, while the room air temperature T is 25°C. The inside convection and radiation heat transfer coefficients h; and hr, as well as the outside convection coefficient ho, are each approximately 25 W/m2.K. What is the minimum window thickness, L = La + LB, needed to ensure a temperature that is 50°C or less at the outer surface of the window? This temperature must not be exceeded for safety reasons.

A leading manufacturer of household appliances is proposing a self-cleaning oven design that involves use of a composite window separating the oven cavity from the room air (Figure 2a). The composite is to consist of two high-temperature plastics (A and B) of thicknesses LA = 2LB and thermal conductivities ka = 0.15 W/m·K and kB = 0.08 W/m K. During the self-cleaning process, the oven wall and air temperatures, Tw and Ta, are 400°C, while the room air temperature T is 25°C. The inside convection and radiation heat transfer coefficients h; and hr, as well as the outside convection coefficient ho, are each approximately 25 W/m2.K. What is the minimum window thickness, L = La + LB, needed to ensure a temperature that is 50°C or less at the outer surface of the window? This temperature must not be exceeded for safety reasons.

Elements Of Electromagnetics
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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Composite window, LA = 2L6 LA %3D Oven cavity Ti 250 °C s,0 T = 400 °C h, = 25 W/m2-K Air B, kg = 0.08 W/m-K A, ka = 0.15 W/m-K T= 400 °C h; = 25 W/m?-K %3D = 25 °C Air h, = 25 W/m2-K Figure 2a
Transcribed Image Text:Composite window, LA = 2L6 LA %3D Oven cavity Ti 250 °C s,0 T = 400 °C h, = 25 W/m2-K Air B, kg = 0.08 W/m-K A, ka = 0.15 W/m-K T= 400 °C h; = 25 W/m?-K %3D = 25 °C Air h, = 25 W/m2-K Figure 2a
A leading manufacturer of household appliances is proposing a self-cleaning oven design that involves use of a composite window separating the oven cavity from the room air (Figure 2a). The composite is to consist of two high-temperature plastics (A and B) of thicknesses LA = 2LB and thermal conductivities ka = 0.15 W/m K and KB = 0.08 W/m K. During the self-cleaning process, the oven wall and air temperatures, Tw and Ta, are 400°C, while the room air temperature To is 25°C. The inside convection and radiation heat transfer coefficients h; and hr, as well as the 2 a) outside convection coefficient ho, are each approximately 25 W/m².K. What is the minimum window thickness, L = LA + LB, needed to ensure a temperature that is 50°C or less at the outer surface of the window? This temperature must not be exceeded for safety reasons.
Transcribed Image Text:A leading manufacturer of household appliances is proposing a self-cleaning oven design that involves use of a composite window separating the oven cavity from the room air (Figure 2a). The composite is to consist of two high-temperature plastics (A and B) of thicknesses LA = 2LB and thermal conductivities ka = 0.15 W/m K and KB = 0.08 W/m K. During the self-cleaning process, the oven wall and air temperatures, Tw and Ta, are 400°C, while the room air temperature To is 25°C. The inside convection and radiation heat transfer coefficients h; and hr, as well as the 2 a) outside convection coefficient ho, are each approximately 25 W/m².K. What is the minimum window thickness, L = LA + LB, needed to ensure a temperature that is 50°C or less at the outer surface of the window? This temperature must not be exceeded for safety reasons.
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