Consider a person standing in a room maintained at
Want to see the full answer?
Check out a sample textbook solutionChapter 1 Solutions
HEAT+MASS TRANSFER FUNDAMENTALS
- 1.29 A spherical interplanetary probe with a 30-cm diameter contains electronic equipment that dissipates 100 W. If the probe surface has an emissivity of 0.8, what is its surface temperature in outer space? State your assumptions in the calculations.arrow_forward1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 , the temperature of the air is 27°C, and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.arrow_forward7.Consider a person standing in a room maintained at 20°C at all times. The inner surfaces of the walls, floors, and ceiling of the house are observed to be at an average temperature of 12°C in winter and 23°C in summer. Determine the rates of radiation heat transfer between this person and the surrounding surfaces in both summer and winter if the exposed surface area, emissivity, and the average outer surface temperature of the person are 1.6 m2, 0.95, and 32°C, respectively.arrow_forward
- Consider a person standing in a room maintained at 20°C at all times. The inner surfaces of the walls, floors, and the ceiling of the house are observed to be at an average temperature of 15°C in winter and 30°C in summer. Determine the rate of radiation heat transfer between this person and the surrounding surfaces if the exposed surface area and the average outer surface temperature of the person are 1.2 m2 and 34°C, respectively. Given: εskin = 0.95, σ = 5.67x10^(-8) W/(m^2∙K^4 ). Heat Radiation in Winter (W) = Heat Radiation in Summer (W) =arrow_forwardDetermine the net heat transferred by radiation from a 9-ft square hot plate to a cold plate of equal size that are parallel to one another, and 20 ft apart if the hot plate is oxidized steel at 700°F and the cold plate is dull brass at 175°F.Ans: 2,863 Btu/hrarrow_forwardConsider a person standing in a room. The inner surfaces of the walls, floors, and ceiling of the house are observed to be at an average temperature of 22.21°C in summer. Determine the rate of radiation heat transfer (Watts) between this person and the surrounding in summer if the exposed surface area, emissivity, and the average outer surface temperature of the person are 1.54 m2, 0.95, and 30.49°C, respectively. (Use 2 decimal places for the final answer.)arrow_forward
- An electronic box that consumes 200 W of power is cooled by a fan blowing air into the box enclosure. The dimensions of the electronic box are 15 cm * 50 cm * 50 cm, and all surfaces of the box are exposed to the ambient except the base surface. Temperature measurements indicate that the box is at an average temperature of 32°C when the ambient temperature and the temperature of the surrounding walls are 25°C. If the emissivity of the outer surface of the box is 0.75, determine the fraction of the heat lost from the outer surfaces of the electronic box.arrow_forwardas a researcher in the field of heat transfer explain how you will distinguish between radiation by black body and a real bodyarrow_forwardA 1000-W iron is left on the iron board with its base exposed to the air at 20°C. The convection heat transfer coefficient between the base surface and the surrounding air is 35 W/m2. C. If the base has an emissivity of 0.6 and a surface area of 0.02 m2, determine the temperature of the base of the iron.arrow_forward
- Does any of the energy of the sun reach the earth by conduction or convection?arrow_forwardConsider steady heat transfer between two large parallel plates at constant temperatures of T1 = 300 K and T2 = 200 K that are L = 1 cm apart, as shown in Fig. 1–44. Assuming the surfaces to be black (emissivity ε = 1), determine the rate of heat transfer between the plates per unit surface area assuming the gap between the plates is (a) filled with still air with k= 0.0219 W/m°C, (b) free flowing air with h= 7.5 W/m^2°C, (c) evacuatedarrow_forwardQuestion 4:Consider a person standing in a room maintained at20°C at all times. The inner surfaces of the walls, floors, and ceiling of the house are observed to be at an average temperature of 12°C in winter and 23°C in summer. Determine threats of radiation heat transfer between this person and the surrounding surfaces in both summer and winter if the exposed surface area, emissivity, and the average outer surface temperature of the person are 1.6 m2, 0.95, and 32°C, respectively.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning