Completely solve and box the final answer. Write legibly 3. Determine the heat loss in KW of a vertical furnace made up of inner wall of firebrick 28 cm thick followed by insulating brick 18 cm thick and an outer wall of steel 1.5 cm thick. Surface temperature of the wall adjacent to the combustion chamber is 895ºC while that of the outer surface of steel is 42ºC. Use a thermal conductivity of wall in W/m-ºK for firebrick, insulating brick and steel to be 14, 0.92, and 52 respectively. The cross section is 2.5 m x 7.5 m.

Completely solve and box the final answer. Write legibly 3. Determine the heat loss in KW of a vertical furnace made up of inner wall of firebrick 28 cm thick followed by insulating brick 18 cm thick and an outer wall of steel 1.5 cm thick. Surface temperature of the wall adjacent to the combustion chamber is 895ºC while that of the outer surface of steel is 42ºC. Use a thermal conductivity of wall in W/m-ºK for firebrick, insulating brick and steel to be 14, 0.92, and 52 respectively. The cross section is 2.5 m x 7.5 m.

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.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.43P

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1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of material are available. One has a maximum usable temperature of 1040°C and a thermal conductivity of 1.7 W/(m K), and the other has a maximum temperature limit of 870°C and a thermal conductivity of 0.85 W/(m K). The bricks have the same cost and are laid in any manner, but we wish to design the most economical wall for a furnace with a temperature of 1040°C on the hot side and 200°C on the cold side. If the maximum amount of heat transfer permissible is 950 , determine the most economical arrangement using the available bricks.
1.77 Explain each in your own words. (a) What is the mode of heat transfer through a large steel plate that has its surfaces at specified temperatures? (b) What are the modes when the temperature on one surface of the steel plate is not specified, but the surface is exposed to a fluid at a specified temperature?
2.15 Suppose that a pipe carrying a hot fluid with an external temperature of and outer radius is to be insulated with an insulation material of thermal conductivity k and outer radius . Show that if the convection heat transfer coefficient on the outside of the insulation is and the environmental temperature is , the addition of insulation actually increases the rate of heat loss if , and the maximum heat loss occurs when . This radius, is often called the critical radius.
To determine the thermal conductivity of a structural material, a large 15-cm-thick slab of the material is subjected to a uniform heat flux of 2500 W/m2 while thermocouples embedded in the wall at 2.5 cm. intervals are read over a period of time. After the system had reached equilibrium, an operator recorded the thermocouple readings shown below for two different environmental conditions: Distance from the Surface (cm) Temperature (C) Test 1 0 40 5 65 10 97 15 132 Test 2 0 95 5 130 10 168 15 208 From these data, determine an approximate expression for the thermal conductivity as a function of temperature between 40 and 208C.
A plane wall of thickness 2L has internal heat sources whose strength varies according to qG=qocos(ax) Where qo is the heat generated per unit volume at the center of the wall (x=0) and a is a constant. If both sides of the wall are maintained at a constant temperature of Tw, derive an expression for the total heat loss from the wall per unit surface area.
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?
Completely solve and box the final answer. Write legibly 1. How much heat will be transferred in KW if a hot gas at 175ºC crosses a wall 100-mm thick and cross-sectional dimensions of 25 cm x 52 cm. It leaves the wall at 52ºC. The thermal conductivity of the wall is 12.4 W/m-ºK?
Completely solve and box the final answer. Write legibly. 3. An electrical wire with 0.4cm in diameter and 2.5m long extends across a room with 15deg C temperature. Heat is generated in the wire as a result of resistance heating, and the surface of the wire is measured to be 162degC. the voltage drop and electric current along the wire is 60V and 1.86 A, respectively. Determine the convection heat transfer coefficient for the heat transfer between the surface of the wire and the room air. Hint, electric power formula. Round your answer to 2 decimal places.
Completely solve and box the final answer. Write legibly. 9. A steam pipe having a surface temperature of 573 K passes through a room where the temperature is 25C. The outside diameter of pipe is 0.11 m and emissivity factor is 0.69 . Determine the radiated heat loss for a 5 m pipe length.
Completely solve and box the final answer. Write legibly 4. Compute the heat conducted in KW through a sheet of plate glass, k = 0.025 Cal/s-cm-ºC, which is 3.5 m x 4.8 m and 12.5mm thick. The temperature of the surfaces are 28ºC and negative 5.4ºC.
QUESTION-) 236 °C steam flows in a pipe which features are given below. Inner and outer diameters of pipe are 300 mm and 320 mm. Coefficient of heat transmission is 40 W/mK. It's external ambient is air and it's temperature is 20 °C. Take the temperature of the pipe's external surface 180 °C. It is known that the internal temp convection coefficient is 600 W/m^2K and external heat transfer coefficient is 5,9109 W/m^2K The pipe's length is 500 meter. You need to add the radiation in the calculation. The rate of the radiation emissivity is 0.85. You can take the environmental surface temp directly. Please calculate the heat loss of pipe.
QUESTION-) 236 °C steam flows in a pipe which features are given below. Inner and outer diameters of pipe are 300 mm and 320 mm. Coefficient of heat transmission is 40 W/mK. It's external ambient is air and it's temperature is 20 °C. Take the temperature of the pipe's external surface 180 °C. It is known that the internal temp convection coefficient is 600 W/m^2K and external heat transfer coefficient is 5,9109 W/m^2K The pipe's length is 500 meter. You need to add the radiation in the calculation. The rate of the radiation emissivity is 0.85. You can take the environmental surface temp directly. a-) Please draw this question on the resistance network. b-) Please calculate the heat loss of pipe. c-) By applying insulation to this pipe, it is desired to reduce the heat loss to 20% of the uninsulated loss (option a). Calculate the insulation thickness accordingly. Take glass wool as insulation material.(Conductivity of glass wool = 0.040 W/mK.) Given, The temperature of steam inside the…