1.0-mm-diameter wire is maintained at a temperature of 400°C and exposed to a convection environment at 40"C with h=120 W/m. "C. Calculate the thermal conductivity that will just cause an insulation thickness of 0.2 mm to produce a critical radius." How much of this insulation must be added to reduce the heat transfer by 75 percent from that which would be experienced by the bare wire

1.0-mm-diameter wire is maintained at a temperature of 400°C and exposed to a convection environment at 40"C with h=120 W/m. "C. Calculate the thermal conductivity that will just cause an insulation thickness of 0.2 mm to produce a critical radius." How much of this insulation must be added to reduce the heat transfer by 75 percent from that which would be experienced by the bare wire

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.1P: 1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed...

See similar textbooks

Similar questions

A 1 in. o.d. (outer diameter) tube reactor is insulated with a 3 inch layer of asbestos. If the temperature of the outer surface of the insulation is 100 °F and the rate of heat loss per foot of reactor length is 50 BTU/hr, what must the temperature of the inside of the reactor be? [for asbestos, k = 0.105 BTU/hr ft °F]
A hot steam pipe having an inside surface temperature of 250°C has an inside diameter of 8 cm and a wall thickness of 5.5 mm. It is covered with a 9-cm layer of insulation having k =0.5 W/m-°C, followed by a 4-cm layer of insulation having k =0.25W/m-°C. The outside temperature of the insulation is 20°C. Calculate the heat lost per meter of length. Assume k =47 W/m-°C for the pipe.
A wall 2 cm thick is to be constructed from material that has an average thermal conductivity of 1.3 W/m. °C . The wall is to be insulated with material having an average thermal conductivity of 0.35 W/m. °C, so that the heat loss per square meter will not exceed 1830 W. Assuming that the inner and outer surface temperatures of the insulated wall are 1300 and 30 degrees * C , calculate the thickness of insulation required.
A brick wall, plastered on one face, has a thermal conductance of 0.36 m2 K/W, an inside surface resistance of 0.4 m2K/W, and an outside surface resistance of 0.075 m2K/W. Calculate the total heat resistance.
The heat conducts through the shape below. The temperature of the right face is 93 °C, while the left face is at 23 °C. If the top and bottom faces are completely insulated, and the thermal conductivity of the material decreases with decreasing temperature. * Assume that the thermal conductivity is 100 at 23, decreased to 10 at 93. A) Sketch the temperature profile inside the plate. B) If both sides of the plate in the above problem is exposed to air: Left side (h = 20 W/m2K, TL = 20 °C) and right side (h = 90 W/m2K). Calculate the temperature of the air on the right side.
A 1.0-mm-diameter wire is maintained at a temperature of 400°C and exposed to aconvection environment at 40·C with h=120 W/㎡2.C. Calculate the thermal conductivitythat will just cause an insulation thickness of 0.2 mm to produce a “critical radius."How much of this insulation must be added to reduce the heat transfer by 75 percent from thatwhich would be experienced by the bare wire?
Question 1: A glass window of width W = 1 m and height H = 2 m is 5 mm thick and has a thermal conductivity of kg =1.4 W/m.K. If the inner and outer surface temperatures of the glass are 15 oC and -20 oC, respectively, on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through windows, it is customary to use a double pane construction in which adjoining panes are separated by an air space. If the spacing is 10 mm and the glass surfaces in contact with the air have temperatures of 20 oC and -15 oC, what is the rate of heat loss from a 1 m x 2 m window? The thermal conductivity of air is ka = 0.024 W/m.K.
What is thermal conductivity? How the thermal conductivity of Solid, liquid and gases are varying with temperatures and pressure? Explain the variation of thermal conductivity of metals and non-metals with temperatures?
Question 1: A glass window of width W = 1 m and height H = 2m is 5 mm thick and has a thermal conductivity of kg =1.4 W/m.K. If the inner and outer surface temperatures of the glass are 15 °C and -20 C, respectively, on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through windows, it is customary to use a double pane construction in which adjoining panes are separated by an air space. If the spacing is 10 mm and the glass surfaces in contact with the air have temperatures of (last two digit of your Registration number) °C and -15 °C, what is the rate of heat loss from a 1 mx2mwindow? The thermal conductivity of air is ka = 0.024 W/m.K.
In order to reduce the heat loss through a large furnace wall, the decision has been made to add external insulation. Calculate the thickness of insulation required to reduce the heat loss by 75%. Before the change is made, no outer steel shell is used.Data: Refractory brick and wall brick:k = 0.87 W m-1 K-1Insulation: k = 0.090 W m-1 K-1•Steel: k = 43 W m-1 K-1h = 55 W m-1 K-1 (inside furnace).h = 11 W m-1 K-1 (outside furnace).
A 1.0-mm-diameter wire is maintained at a temperature of 400 •C and exposed to a convection environment at 40 •C with h = 120 W/m2 • -C. Calculate the thermal conductivity in BTU/hr-ft-deg F that will just cause an insulation thickness of 0.2 mm to produce a "critical radius."
What is the rate of heat transfer, temperature gradient, and the direction of the heat transfer through a piece of Celotex 3 ft by 8 ft by 1 in. in thickness, if the temp of one surface is 80°F and of the other side is 60°F? - thermal conductivity of Celotex in AES = 0.028.