Question 1 The exterior wall of a building consists of 100 mm thick face brick (k = 0.9 W/m-K), 40 mm thick polystyrene insulating board (k = 0.036 W/m-K), 125 mm thick concrete block (k = 1.8 W/m-K) and 15 mm thick interior gypsum board (k = 0.18 W/m-K). The inside and outside convective heat transfer coefficients are 6.5 W/m2-K and 22.5 W/m2-K, respectively. The outside air temperature is -5°C and the inside air temperature is 20°C. The wall is 3 m high and 15 m long. Calculate the rate of heat loss (in W) through the wall. Round your answer to 2 decimal places. Add your answer Follow-up question to Question 1, calculate the temperature (in °C) of the interior surface of the wall. Round your answer to 2 decimal places. Add your answer Follow-up question to Question 1, calculate the temperature (in °C) of the exterior surface of the wall. Round your answer to 2 decimal places. Add your answer

Question 1 The exterior wall of a building consists of 100 mm thick face brick (k = 0.9 W/m-K), 40 mm thick polystyrene insulating board (k = 0.036 W/m-K), 125 mm thick concrete block (k = 1.8 W/m-K) and 15 mm thick interior gypsum board (k = 0.18 W/m-K). The inside and outside convective heat transfer coefficients are 6.5 W/m2-K and 22.5 W/m2-K, respectively. The outside air temperature is -5°C and the inside air temperature is 20°C. The wall is 3 m high and 15 m long. Calculate the rate of heat loss (in W) through the wall. Round your answer to 2 decimal places. Add your answer Follow-up question to Question 1, calculate the temperature (in °C) of the interior surface of the wall. Round your answer to 2 decimal places. Add your answer Follow-up question to Question 1, calculate the temperature (in °C) of the exterior surface of the wall. Round your answer to 2 decimal places. Add your answer

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 1.3P: 1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of...

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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.
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?
What is the rate of 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. Pls determine the temperature gradient and the direction of the heat transfer as well.
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.
A wall consists of a layer of wood and a layer of cork insulation of the same thickness. The temperature inside is 34.0°C, and the temperature outside is 0.0°C. The thermal conductivity of wood is 0.130 W/(m·K) and the thermal conductivity of cork is 0.0460 W/(m·K). A) What is the temperature at the interface between the wood and the cork if the cork is on the inside and the wood on the outside? in C B) What is the temperature at the interface if the wood is on the inside and the cork is on the outside? in C C) It doesn’t matter whether the cork is placed on the inside or the outside of the wooden wall because the temperature at the interface differs for the two cases.the temperature at the interface differs for the two cases. the temperature at the interface is the same for the two cases.the temperature at the interface is the same for the two cases. the total thermal resistance is the same for the two cases.the total thermal resistance is the same for the two cases.…
X Your answer is incorrect. A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal conductivity of k, = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L; = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/m-K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are T = 22°C and To = O°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m?-Kand h, 00, 25 W/m2-K, respectively. The heat flux through the original walls is 1.46 W/m?. The heat flux through the retrofitted walls is 0.92 W/m?.
The interior-wall temperature of an annealing oven constructed of firebrick (Missouri) is2552°F, and the exterior-wall temperature is 392°F. If the heat loss is 3600 Btu/(hr)(sq ft),determine the thickness of the wall, in inches. (answer 5.67”)
3.6 Heat losses through windows in buildings are substantial. What would be the percentage reduction in heat loss that would be mitigated by replacing a window containing a single pane of glass with (a) double-pane low-E insulating glass or (b) a 3-inch-thick sheet of expanded polystyrene sheet? The quoted R values for these items are: • single pane of glass: 0.90 ft 2 hr ° F/Btu, • double pane of low-E insulating glass: 2.3 ft 2 hr ° F/Btu, • 1-inch-thick sheet of polystyrene sheet: 4.0 ft 2 hr ° F/Btu.
Required info: There is a 2.00 cm thick stagnant air pocket. a) What thickness of cork would have the same R-factor as the stagnant air pocket? The thermal conductivity of air is 0.0230 W/m-K and of cork is 0.0460 W/m-K. b) What thickness of tin would be required for the same R-factor as a 2.00-cm-thick stagnant air pocket? The thermal conductivity of air is 0.0230 W/m:K and of tin is 66.8 W/m-K. THANK U
1. A 140 mm thick wall of 5 m x 3 m size is made of red brick (k = 0.6 W/m-K). It is covered on both sides by layers of plaster, 2 cm thick (k = 0.71 W/m-K). The wall has a double pane window size of 120 cm x 120 cm. The double pane window consists of 2 sheets of glass 6 mm thick (k = 0.96 W/m-K) separated by 138.8 mm thick air gap (k = 0.025 W/m- K). If the inner and outer surface temperatures are 18°C and 37°C, determine the total rate of heat transfer (W) through the composite wall and glass window. Express your final answer in five significant figures.
Bebang owns a 830-mm-thick concrete brick table top that has an area of 10,000,000 mm^2 and a 0.750-cm-thick glass plate that has an area of 20,000 cm^2. Assuming the same temperature difference across each, what is the ratio of the rate of heat conduction through the plate with respect to the rate of heat conduction through the table top? Use Table 10.1(given below) for the value of Thermal Conductivity k. Table 10.1 Thermat Conductivities of Common Substances Values are given for temperatures near o °C. Substance Thermal Conductivity k (W/m-O Diamond 2000 Silver 420 Copper 390 Gold 318 Aluminum 220 Steel iron Steel (stainless) 14 Ice 2.2 Glass (average) 0.84 Concrete brick O.84 water 0.6 Fatty tissue (without blood) 0.2 Asbestos 0.16 Plasterboard 0.16 wood 0.08-0.16 Snow (dry) 0.10 Cork 0.042 Glass wool 0.042 wool 0.04 Down feathers 0.025 Air 0.023 Polystyrene foam 0.010
To 8. Ti 1. 2. 3. 4" Common Brick 1/2" OSB Sheathing 3-1/2" x 1-1/2" (2x4) Yellow Pine Studding placed on 16" center 4. 5. 3-1/2" Figerglass Insulation 1/2" Drywall A wall of a house as shown in the accompanying sketch is 10 ft. high and 30 ft. long and has no windows. The outside heat transfer coefficient, h., is 6.0 Btu/hr ft2°F and the inside convective heat transfer coefficient hi is 1.45 Btu/hr ft2°F. 6. Calculate the heat loss through the wall if the house is heated such that the room air temperature, Ti, is 70°F on a day when the outside air temperature, T., is 0°F. State all assumptions and list the thermal resistances and thermal conductivities for 3 each selection of the wall. 7. For this problem, what would be the value of the overall heat transfer coefficient, U? Ans: U = 0.056 Btu/hr ft2ºF You are asked to design a metal hot dog holder for roasting hot dogs over an open campfire. The holder is to be designed such that while the end holding the hot dog becomes cherry red…