Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN: 9781305387102
Author: Kreith, Frank; Manglik, Raj M.
Publisher: Cengage Learning
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Chapter 2, Problem 2.51P
Determine by means of a flux plot the temperatures and heat flow per unit depth in the ribbed insulation shown in the accompanying sketch.
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In order to reduce the heat loss through a large
furnace wall, the decision has been made to add
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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).
Determine the heat flux through the composite walls as shown in Figure. The frontal area (normal to heat flow) for the layers of Fir brick and Brick is 1 sq.m. The frontal area for Asbestos and Earth layers are equal and the summation of the frontal areas of them is 1 sq.m. as shown required to answer.
OPTIONS:
1.Heat flux is around 487.3 Watt
2.Heat flux is around 742.7 Watt
3.Heat flux is around 305.4 Watt
4.None
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brick and air space, which are fiberglass and firebrick. Calculate the minimum thickness
required for the both fiberglass and firebrick. Which option do you recommend?
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Based on your recommendation, calculate the temperature at each interface throughout the
wall and draw a temperature variation diagram from inside wall surface to outside wall
surface.
* Refractory
brick
Fiberglass or
firebrick?
0.5" Plaster
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4 Concrete block
Figure 2
Chapter 2 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 2 - A plane wall, 7.5 cm thick, generates heat...Ch. 2 -
2.2 A small dam, which is idealized by a large...Ch. 2 - 2.3 The shield of a nuclear reactor is idealized...Ch. 2 - A plane wall 15 cm thick has a thermal...Ch. 2 - 2.5 Derive an expression for the temperature...Ch. 2 - A plane wall of thickness 2L has internal heat...Ch. 2 - 2.7 A very thin silicon chip is bonded to a 6-mm...Ch. 2 - 2.9 In a large chemical factory, hot gases at 2273...Ch. 2 - 2.14 Calculate the rate of heat loss per foot and...Ch. 2 - 2.15 Suppose that a pipe carrying a hot fluid with...
Ch. 2 - Prob. 2.16PCh. 2 - Estimate the rate of heat loss per unit length...Ch. 2 - The rate of heat flow per unit length q/L through...Ch. 2 - A 2.5-cm-OD, 2-cm-ID copper pipe carries liquid...Ch. 2 - A cylindrical liquid oxygen (LOX) tank has a...Ch. 2 - Show that the rate of heat conduction per unit...Ch. 2 - Derive an expression for the temperature...Ch. 2 - Heat is generated uniformly in the fuel rod of a...Ch. 2 - 2.29 In a cylindrical fuel rod of a nuclear...Ch. 2 - 2.30 An electrical heater capable of generating...Ch. 2 - A hollow sphere with inner and outer radii of R1...Ch. 2 - 2.34 Show that the temperature distribution in a...Ch. 2 -
2.38 The addition of aluminum fins has been...Ch. 2 - The tip of a soldering iron consists of a 0.6-cm-...Ch. 2 - One end of a 0.3-m-long steel rod is connected to...Ch. 2 - Both ends of a 0.6-cm copper U-shaped rod are...Ch. 2 - 2.42 A circumferential fin of rectangular cross...Ch. 2 - 2.43 A turbine blade 6.3 cm long, with...Ch. 2 - 2.44 To determine the thermal conductivity of a...Ch. 2 - 2.45 Heat is transferred from water to air through...Ch. 2 - 2.46 The wall of a liquid-to-gas heat exchanger...Ch. 2 - Prob. 2.47PCh. 2 - The handle of a ladle used for pouring molten lead...Ch. 2 - 2.50 Compare the rate of heat flow from the bottom...Ch. 2 - 2.51 Determine by means of a flux plot the...Ch. 2 - Prob. 2.52PCh. 2 - Determine the rate of heat transfer per meter...Ch. 2 - Prob. 2.54PCh. 2 - 2.55 A long, 1-cm-diameter electric copper cable...Ch. 2 - Prob. 2.56PCh. 2 - Prob. 2.57PCh. 2 - Prob. 2.58P
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- Calculate the overall heat loss and the temperature profile for each interface if the length of the cylinder is 50 m.Please write your answers legibly.arrow_forwardProblem 1 A hot water pipe is used for domestic applications is insulated with a layer of calcium silicate. If the insulation is 25 mm thick and its inner and outer surfaces are maintained at Ts,1 = 800 K and Ts,2 = 400 K, respectively. The outside diameter is 0.12 m. Given the thermal conductivity calcium silicate insulation equals to 0.09 W/m.K. A. Define the difference between lagged and unlagged pipes. B. Calculate the heat loss per unit length for this pipe.arrow_forward(5) 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. Page | 1 Inside Furnace Insulation Refractory Brick, 250 mm Wall Brick, 50 mm Outer Steel Shell, 25 mm Data: Refractory brick and wall brick: k = 0.87 W/m K Insulation: k= 0.090 W/m K k = 43 W/m K h = 55 W/m K (inside furnace) h = 11 W/m K (outside furnace) Steel:arrow_forward
- A composite wall is formed of a 2.5 cm copper plate, a 3.2 mm layer of asbestos,and a 5 cm layer of fiberglass. The wall is subjected to an overall temperaturedifference of 560oC. Calculate the heat flux through the composite structure.arrow_forwardCalculate the thermal resistance of a copper tube with diameter1=0.153 mm diameter2= 0.157 mm and thermal conductivity of 310 W/m.K insulated with a layer of Styrofoam diameter = 0.09 mmarrow_forwardc) A steel pipe of 100 mm bore, and 10 mm bore thickness, carrying dry saturated steam at 28 bars, is insulated with a 40 mm layer of moulded insulation. This insulation in turn is insulated with a 60 mm layer of felt. The atmospheric temperature is 15 °C. Calculate: (i) the rate of heat loss by the steam per metre pipe length. (ii) the temperature of the outside Dimensions in mm surface.zzzzzzz h₂-15 W/m²K Steel k₁=50 W/mK AVALEHT Ø100 1₂ " Steam 28 bar h-550 W/m²K, Inner heat transfer coefficient = 550 W/m² K Outer heat transfer coefficient = 15 W/m² K Thermal conductivity of steel = 50 W/m K Thermal conductivity of felt = 0.07 W/m K Moulded insulation Felt Moulded insulation K₂=0.09 W/mK Thermal conductivity of moulded insulation = 0.09 W/m 40 10. A 60 15°C Felt K₁=0.07 W/mK zzzzzzzzarrow_forward
- Write the expression for critical radius of insulation for a cylindrical pipe. Consider aninsulated pipe exposed to the atmosphere. Will the critical radius of insulation begreater on calm days or on windy days? Why?arrow_forwardcomposite protective wall is formed of a 1 in copper plate, a 1/8 in layer of asbestos, a 2 in layer of fiberglass. The thermal conductivities of the materials in units of BTU/hr-ft-F are 240, 0.048 and 0.022 respectively. The overall temperature difference across the wall is 500 F. Calculate the heat transfer per unit area through the composite structure.arrow_forwardThe Diamond Ring Solution. The processing chip on the computer that controls the navigation equipment on your spacecraft is overheating. Unless you fix the problem, the chip will be damaged and the navigation system will shut down. You open the panel and find that the small copper disk that was supposed to bridge the gap between the smooth top of the chip and the cooling plate is missing, leaving a 2.0 mm gap between them. In this configuration, the heat cannot escape the chip at the required rate. You notice by the thin smudge of thermal grease (a highly thermally conductive material used to promote good thermal contact between surfaces) that the missing copper disk was 2.0 mm thick and had a díameter of 1.2 cm. You know that the chip is designed to run below 65 °C, and the copper cooling plate is held at a constant 5.0 °C. (a) What was the rate of heat flow from the chip to the copper plate when the original copper disk was in place and the chip was at its maximum operating…arrow_forward
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