The emissivity of galvanized steel sheet, a commonroofing material, is
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Fundamentals of Heat and Mass Transfer
- The jet plane is flying upward such that its wings make an angle of attack of 15∘∘ with the horizontal. The plane is traveling at V� = 750 m/sm/s , in air having a temperature of 8∘C∘C and absolute pressure of 95 kPakPa . The leading edge of the wing has an angle of 8∘∘. (Figure 1) Express your answer to three significant figures and include the appropriate units. Determine the temperature of the air just in front or to the right of the expansion waves. Express your answer using three significant figures.arrow_forwardIn addition , the space between the upper cap, the lower cap, and the cylindrical wall is filled with linear insulating material of permeability u.arrow_forwardA greenhouse 20m long and 15m wide has a nearly flat roof 3m above the floor level. When the sun is directly overhead the solar flux is 1,000 W/m^2. If the glass roof has an emissivity of 0.9 and the convective losses are 0.8 times the radiation losses, what is the temperature in the greenhouse?arrow_forward
- The interior of a refrigerator whose dimensions are 0.05 x 0.05 dam base area and 1.25 m high, must be kept at 4 °C. The refrigerator walls are constructed of two steel sheets (k= 35 kcal/h.m.°C) 3 mm thick, with 65 mm of material insulation (k=0.213 kcal/h.m.°C) between them. The film coefficient of the inner surface is 10 kcal/h.m².°C, while on the external surface it varies from 8 to 12.5 kcal/h.m².°C. Calculate: a) The power (in HP) of the refrigerator motor so that the heat flux removed from the inside the refrigerator maintain the specified temperature, in a kitchen whose temperature can vary from 21 to 36 °C; b) The temperatures of the inner and outer surfaces of the wall. Given 1 HP = 641.2 Kcal/harrow_forwardShape factor for a cylinder whose length equals its diameter is 1.5 B. 0.5 1.0 D. 2.0arrow_forwardCalculate the resistive force acting on the disk, with the error level not less than h^4, according to the pressure distribution on a circular disk of 0.5 m diameter held against the air flow, given in the table below.arrow_forward
- When the submarine is on the surface, its ballast tanks are filled with air. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine. The submarine descends from sea level and holds at a constant depth of 3,500m. Background Information Submarine Volume is 450 m3 Mass (excluding weight in ballast tank) is 400 tons Outer haul Mass is 40 tons Thickness is 15 cm Exterior surface area is 200 m2 Specific heat capacity is 420 J/kg/K Latent heat of fusion is 250 kJ/kg Temperature at surface (depth of 0 m) is 25°C depth of 3,500 m internal of the outer haul (next to ballast tank) is 10 30°C (Refer to diagram) external of the outer haul is 10°C (Refer to diagram) Thermal conductivity is 80 kW/m/K Emissivity of 0.9 Ballast Tank at a depth of 3,500 m Temperature at is 30°C Seawater Specific gravity of 1.05 Surrounding temperature at a depth of 3,500 m is 4°C Convective heat transfer coefficient for free…arrow_forwardWhen the submarine is on the surface, its ballast tanks are filled with air. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine. The submarine descends from sea level and holds at a constant depth of 3,500m. Background Information Submarine Volume is 450 m3 Mass (excluding weight in ballast tank) is 400 tons Outer haul Mass is 40 tons Thickness is 15 cm Exterior surface area is 200 m2 Specific heat capacity is 420 J/kg/K Latent heat of fusion is 250 kJ/kg Temperature at surface (depth of 0 m) is 25°C depth of 3,500 m internal of the outer haul (next to ballast tank) is 10 30°C (Refer to diagram) external of the outer haul is 10°C (Refer to diagram) Thermal conductivity is 80 kW/m/K Emissivity of 0.9 Ballast Tank at a depth of 3,500 m Temperature at is 30°C Seawater Specific gravity of 1.05 Surrounding temperature at a depth of 3,500 m is 4°C Convective heat transfer coefficient for free…arrow_forwardWhen the submarine is on the surface, its ballast tanks are filled with air. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine. The submarine descends from sea level and holds at a constant depth of 3,500m. Background Information Submarine Volume is 450 m3 Mass (excluding weight in ballast tank) is 400 tons Outer haul Mass is 40 tons Thickness is 15 cm Exterior surface area is 200 m2 Specific heat capacity is 420 J/kg/K Latent heat of fusion is 250 kJ/kg Temperature at surface (depth of 0 m) is 25°C depth of 3,500 m internal of the outer haul (next to ballast tank) is 10 30°C (Refer to diagram) external of the outer haul is 10°C (Refer to diagram) Thermal conductivity is 80 kW/m/K Emissivity of 0.9 Ballast Tank at a depth of 3,500 m Temperature at is 30°C Seawater Specific gravity of 1.05 Surrounding temperature at a depth of 3,500 m is 4°C Convective heat transfer coefficient for free…arrow_forward
- The solar power striking Earth every day averages 168watts per square meter. The highest ever recorded electricalpower usage in New York City was 13,200 MW. A recordestablished in July of 2013. Considering that present technologyfor solar energy conversion is about 10% efficient,from how many square meters of land must sunlight becollected in order to provide this peak power? (For comparison,the total area of New York City is 830 km2.)arrow_forwardFind the minimum amount of diameter for the insulation of a spherical water tank? Radius of the tank is 10 m, thermal conductivity is 25 W/(m^2*K) and convective coefficient is 5 W/(m*K)arrow_forwarddetermine the thermal resistance of three concentric cylinders of radious r1, r2, r3arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning