Problem 7A clay brick is heated in an oven to 1330°C and then cooled in air at 315 K with a convection coefficient of50 W/m2 · K. If the dimensions of the brick are 0.06 m x 0.09 m × 0.20 m, determine the temperature atthe center after 50 minutes of cooling.Assume a thermal conductivity of k = 1.0 W/m · K, a c, = 960 K/kg · K, a thermal diffusivity of a =0.51 x 10-6 m²/s, and a density of 2050 kg/m³.Problem 8For the same conditions as problem 7, determine the temperature at the corners of the brick.

Answered: Image /qna-images/answer/12b70b16-cabe-482a-b941-efc55ccbe776.jpg

Answered: 50 W/m2 . K. If the dimensions of the…

50 W/m2 . K. If the dimensions of the brick are 0.06 m × 0.09 m × 0.20 m, determine the temperature at the center after 50 minutes of cooling.

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.55P: 2.55 A long, 1-cm-diameter electric copper cable is embedded in the center of a 25-cm-square...

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The handle of a ladle used for pouring molten lead is 30 cm long. Originally the handle was made of 1.9cm1.25cm mild steel bar stock. To reduce the grip temperature, it is proposed to form the handle of tubing 0.15 cm thick to the same rectangular shape. If the average heat transfer coefficient over the handle surface is 14 W/m K, estimate the reduction of the temperature at the grip in air at 21C.
2.55 A long, 1-cm-diameter electric copper cable is embedded in the center of a 25-cm-square concrete block. If the outside temperature of the concrete is 25oC and the rate of electrical energy dissipation in the cable is 150 W per meter length, determine temperatures at the outer surface and at the center of the cable.
3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.
The 8-mm-thick bottom of a 220-mm-diameter pan may be made from aluminum (k = 240 W/m · K) or copper (k = 390 W/m · K). When used to boil water, the surface of the bottom exposed to the water is nominally at 110°C. If heat is transferred from the stove to the pan at a rate of 600 W, what is the temperature of the surface in contact with the stove for each of the two materials?
The 5-mm-thick bottom of a 200-mm-diameter pan may be made from aluminum (k= 240 W/m·K) or copper (k= 390 W/m·K). When used to boil water, the surface of the bottom exposed to the water is nominally at 110°C and heat is transferred from the stove to the pan at a rate of 1200 W. What is the temperature of the surface in contact with the stove for each of the two materials?Aluminum:T= _____ °CCopper:T= _____ °C
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 9oC 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.
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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.
It is required to perform a heat treatment for gas turbine applications, for them it is required to analyze a sample of the material to be used. The analysis will be performed using the method of a semi-infinite cylinder of stainless steel 12Awith the following thermal properties; (ρ=8700 kg/m3, Cp = 897 J/kg. °C and k = 242 W/m. °C. Of diameter D=12 cm is initially at a uniform temperature of 120 °C. Then the cylinder is placed in a furnace at a constant heat flux of 3800 W/m2, a temperature of 60 °C andh= 170 W/m2. Determine the temperature at the center of the cylinder 3.5 cm from the end surface 6 minutes after placing it in the furnace.
Question 3: A house has a composite wall of wood, fiberglass insulation, and plaster board, as indicated in the sketch. On a cold winter day the convection heat transfer coefficients are ho 60 W/m2 K and hi 30 W/m2 K. The total wall surface area is 350 m2. (a)Determine the total heat loss through the wall. (b) If the wind were blowing violently, raising ho to 300 W/m2 K, determine the percentage increase in the heat loss.
Example 2: The roof of an electrically heated home is 6 m long, 8 m wide, and 0.25 m thick, and is made of a flat layer of concrete whose thermal conductivity is k=0.8 W/m·°C. The temperatures of the inner and the outer surfaces of the roof one night are measured to be 15°C and 4°C, respectively, for a period of 10 hours. Determine the rate of heat loss through the roof that night
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