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The concrete slab of a basement is 11 in long. 8 in wide,and 0.20 m thick. During the winter, temperatures arenominally 17°C and 10°C at the top and bottom surfaces, respectively. If the concrete has a thermal conductivityof
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Fundamentals of Heat and Mass Transfer
- On a multi-layered rectangular wall, the thermal resistance of the first layer is 0.005 ° C / W, the resistance of the second layer is 0.2 ° C / W, and the third layer is 0.1 ° C / W.The overall temperature gradient in the wall is multilayered from one side. to the other side is 50 ° C. a. Determine the heat flux through the walls. = Answer watts / m2. b. If the thermal resistance of the second layer is changed to 0.3 ° C / W, what is the effect in% on heat flux, assuming the temperature gradient remains the same? = AnswerAnswer %.arrow_forwardIn a multilayered rectangular wall, the thermal resistance of the first layer is 0.005 °C/W, the resistance of the second layer is 0.2° C/W, and for the third layer it is 0.1 ° C/W. The overall temperature gradient in the multilayered wall from one side to another is 70° C. a. Determine the heat flux through the wall. b. If the thermal resistance of the second layer is doubled to 0.4° C/W, what will be its influence in % on the heat flux, assuming the temperature gradient remains the same?arrow_forwardA 15 mm diameter cylindrical nuclear fuel rod is housed in a hollow ceramic cylinder concentric to the rod with an inner diameter of 35 mm and an outer diameter of 110 mm. This creates an air gap between the fuel rod and the hollow ceramic cylinder with a convective heat transfer coefficient of 10 W/m²·K. The hollow ceramic cylinder has a thermal conductivity of 0.07 W/m·K and its outer surface maintains a constant temperature of 30 °C. If the fuel rod generates heat at a rate of 1 MW/m³. Solving, the temperature at the surface of the fuel rod is 1026°C. I need the solution with fundamental concepts (Textically with definitions) of how the heat flow behaves in the system. NOT THE MATHEMATICAL RESOLUTION. I already know how to solve it.arrow_forward
- A 15 mm diameter cylindrical nuclear fuel rod is housed in a hollow ceramic cylinder concentric to the rod with an inner diameter of 35 mm and an outer diameter of 110 mm. This creates an air gap between the fuel rod and the hollow ceramic cylinder with a convective heat transfer coefficient of 10 W/m²·K. The hollow ceramic cylinder has a thermal conductivity of 0.07 W/m·K and its outer surface maintains a constant temperature of 30 °C. If the fuel rod generates heat at a rate of 1 MW/m³. Solving, the temperature at the surface of the fuel rod is 1026°C. Explain how the heat flow behaves in the system, using the fundamental concepts.arrow_forwardA 15 mm diameter cylindrical nuclear fuel rod is housed in a hollow ceramic cylinder concentric to the rod with an inner diameter of 35 mm and an outer diameter of 110 mm. This creates an air gap between the fuel rod and the hollow ceramic cylinder with a convective heat transfer coefficient of 10 W/m²·K. The hollow ceramic cylinder has a thermal conductivity of 0.07 W/m·K and its outer surface maintains a constant temperature of 30 °C. If the fuel rod generates heat at a rate of 1 MW/m³. Solving, the temperature at the surface of the fuel rod is 1026°C. Give the solution from fundamental concepts of how the heat flow behaves in the system.arrow_forwardA 15 mm diameter cylindrical nuclear fuel rod is housed in a hollow ceramic cylinder concentric to the rod with an inner diameter of 35 mm and an outer diameter of 110 mm. This creates an air gap between the fuel rod and the hollow ceramic cylinder with a convective heat transfer coefficient of 10 W/m²·K. The hollow ceramic cylinder has a thermal conductivity of 0.07 W/m·K and its outer surface maintains a constant temperature of 30 °C. If the fuel rod generates heat at a rate of 1 MW/m³. Determine the temperature at the surface of the fuel rod. Note: Give the solution from fundamental concepts of how the heat flow behaves in the systemarrow_forward
- A 2.5-cm-thick sheet of plastic initially at 20oC is placed between two heated steel plates that are maintained at 140oC. The plastic is to be heated just long enough for its mid-plane temperature to reach 130oC. If the thermal conductivity of the plastic is 1.2 x 10 -3 W/m/K, the thermal diffusivity is 2.7 x 10 -6 m2/s, and the thermal resistance at the interface between the plates and the plastic is negligible, determine a) the required heating time, b) the temperature at a plane 0.6 cm from the steel plate at the moment the heating is discontinued, and c) the time required of the plastic to reach the temperature of 130oC at 0.6 cm from the steel plate.arrow_forwardConvective heat transfer coefficient is 15 W/(m*K), surface area of the fin is 2 m^2, the temperature at the base is 70 C and the ambient temperature is 20 C. Determine the fin efficiency if the actual heat transfer rate from the fin is 500 W?arrow_forwardConsider a 2-m-wide 1.5-m-high wood-framed window with 3-mm-thick single-panel glass covering 85 percent of the area (k = 0.7 W/m °C). Pine wood (k = 0.12 W/m °C) is used for the frame, which is 5 cm thick. Inside, the heat transfer coefficient is 7 W/m2 °C, while outside, it is 13 W/m2 °C. The temperature in the room is kept at 24°C, while the outside temperature is 40°C. Considering and stating the necessary assumptions. calculate the percent inaccuracy in heat transfer when the window is supposed to be made entirely of glass. (b) Consider the continuous heat flow through a room's wall in the winter. As a result of the winds, the convection heat transfer coefficient at the outer surface of the wall is three times that of the inner surface. Which side of the wall do you believe the temperature will be closest to the temperature of the surrounding air? Explain.arrow_forward
- Q1 / A5 - cm - diameter steel pipe is covered with a 1 - cm layer of insulating material having k = 0.22 W / m . ° C followed by a 3 - cm - thick layer of another insulating material having k = 0.06 W / m . ° C . The system is exposed to a convection surrounding condition of h = 60 W / m² . ° C and T -15 ° C . The outside surface temperature of the steel pipe is 400 ° C . Calculate the heat lost by the pipe - insulation assembly for a pipe length of 20 m . Express in Watts .arrow_forwardA 12-m-long and 5-m-high wall is constructed of two layers of 1-cm-thick sheetrock (k = 0.17 W/m·K) spaced 16 cm by wood studs (k = 0.11 W/m·K) whose cross section is 16 cm * 5 cm. The studs are placed vertically 60 cm apart, and the space between them is filled with fiberglass insulation (k = 0.034 W/m·K). The house is maintained at 20°C and the ambient temperature outside is 29°C. Taking the heat transfer coefficients at the inner and outer surfaces of the house to be 8.3 and 34 W/m2·K, respectively, determine (a) the thermal resistance of the wall considering a representative section of it and (b) the rate of heat transfer through the wall.arrow_forwardA 2-m x 1.8-m section of wall of an industrial furnace burning natural gas is not insulated, and the temperature at the outer surface of this section is measured to be 80°C. The temperature of the furnace room is 30°C, and the combined convection and radiation heat transfer coefficient at the surface of the outer furnace is 10 W/m² • °C. It is proposed to insulate this section of the furnace wall with expanded perlite insulation (k = 0.052 W/m • °C) in order to reduce the heat loss by 90%. Assuming the outer surface temperature of the metal section still remains at about 80°C, determine the thickness of the insulation that needs to be used. ANSWER:_______cmarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning