You are asked to determine the heat loss from a very thin spherical cap containing a hot fluid at a temperature of 140.0°C. The outside diameter of the cap is 40.0 m and it is insulated by three layers of insulation of thickness 50.0 m each. The thermal conductivities of each layer are: k1 = 0.02 W/mK; k2 = 0.06 W/mK; k3 = 0.16 W/mK These thermal conductivities are indicated from the inside out in the spherical space coordinate. On the other hand, the external temperature of the system is 30.0°C. Additionally, you are asked to determine the temperatures at the contact interfaces between the different materials. Finally, you are asked to make a freehand diagram of the system, indicating the temperatures obtained by you for each interface and the heat flux.

You are asked to determine the heat loss from a very thin spherical cap containing a hot fluid at a temperature of 140.0°C. The outside diameter of the cap is 40.0 m and it is insulated by three layers of insulation of thickness 50.0 m each. The thermal conductivities of each layer are: k1 = 0.02 W/mK; k2 = 0.06 W/mK; k3 = 0.16 W/mK These thermal conductivities are indicated from the inside out in the spherical space coordinate. On the other hand, the external temperature of the system is 30.0°C. Additionally, you are asked to determine the temperatures at the contact interfaces between the different materials. Finally, you are asked to make a freehand diagram of the system, indicating the temperatures obtained by you for each interface and the heat flux.

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 1.10P: 1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss...

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1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
As a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed 40C when the temperature at the inside surface of the oven is 300C. Also, the air temperature in the kitchen varies from 15Cto33C, and the average heat transfer coefficient between the outer surface of the oven and air is estimated to be 12.0W/m2K. Determine the thickness of the fiberglass insulation that is required for these conditions. What would be the outer surface temperature when the inside surface of the oven is at 475C?
20-m pipe has an outside diameter of 50 mm. Pipe is insulated with a layer of asbestos, then followed by a layer of cork. Inside and outside diameter of the cork is 77 mm and 80 mm, respectively. If the temperature drop from pipe to cork is 1165°C, calculate the inside diameter of the pipe (mm). The rate of the heat transfer is 8778 W. The thermal conductivity of steam pipe, asbestos and cork are 0.045 kW/m-K, 0.058 W/m-K and 0.043 W/m-K respectively.
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Steel pipe (outer diameter 100 mm) is covered with two layers of insulation. The inner layer, 40 mm thick, has a thermal conductivity of 0.07 W / (m K). The outer layer, 20 mm thick, has a thermal conductivity of 0.15 W / (m K). Pipes are used to deliver steam with a pressure of 800 kPa. The temperature on the outer insulation surface is 24 ° C. If the pipe is 10 m long, determine the following: (assuming that the conduction heat transfer resistance of the steel pipe and the vapor convection resistance are negligible). a. Heat loss per hour. = AnswerkJ / hr. b. Temperature between insulation layers. = Answer ° C.
Steel pipe (outer diameter 100 mm) is covered with two layers of insulation. The inner layer, 40 mm thick, has a thermal conductivity of 0.07 W / (m K). The outer layer, 20 mm thick, has a thermal conductivity of 0.15 W / (m K). Pipes are used to deliver steam with a pressure of 800 kPa. The temperature on the outer insulation surface is 24 ° C. If the pipe is 10 m long, determine the following: (assuming that the conduction heat transfer resistance of the steel pipe and the vapor convection resistance are negligible). a. Heat loss per hour. = Answer kJ / hour. b. Temperature between insulation layers. = Answer ° C.
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A steel pipe (outside diameter 100 mm) is covered with two layers of insulation. The inside layer, 40 mm thick, has a thermal conductivity of 0.07 W/(m K). The outside layer, 20 mm thick, has a thermal conductivity of 0.15 W/(m K). The pipe is used to convey steam at a pressure of 600 kPa. The outside temperature of insulation is 24°C. If the pipe is 10 m long, determine the following, assuming the resistance to conductive heat transfer in steel pipe and convective resistance on the steam side are negligible: a. The heat loss per hour. b. The interface temperature of insulation.