4. The inner wall of a thermos bottle is at 32°F while the outer at 102.0°F. The space between the walls is evacuated and the walls are silvered so the emissivity is reduced to 0.10. If each wall has an area of 700cm2, how much energy (BTU/s) is transformed by radiation between the walls each second?

4. The inner wall of a thermos bottle is at 32°F while the outer at 102.0°F. The space between the walls is evacuated and the walls are silvered so the emissivity is reduced to 0.10. If each wall has an area of 700cm2, how much energy (BTU/s) is transformed by radiation between the walls each second?

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 1.25P: 1.25 A spherical vessel, 0.3 m in diameter, is located in a large room whose walls are at 27°C (see...

See similar textbooks

Similar questions

1.25 A spherical vessel, 0.3 m in diameter, is located in a large room whose walls are at 27°C (see sketch). If the vessel is used to store liquid oxygen at –183°C and both the surface of the storage vessel and the walls of the room are black, calculate the rate of heat transfer by radiation to the liquid oxygen in watts and in Btu/h.
1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (equal to the emittance) of 0.1. Then determine the rate of evaporation of the liquid oxygen in kilograms per second and pounds per hour, assuming that convection can be neglected. The heat of vaporization of oxygen at –183°C is .
Determine the rate of radiant heat emission in watts per square meter from a blackbody at (a) 15C, (b) 600C, and (c) 5700C.
1.47 A flat roof is modeled as a flat plate insulated on the bottom and placed in the sunlight. If the radiant heat that the roof receives from the sun is , the convection heat transfer coefficient between the roof and the air is 12 W/m2 K, and the air temperature is , determine the roof temperature for the following two cases: (a) Radiative heat loss to space is negligible, (b) The roof is black and radiates to space, which is assumed to be a black- body at 0 K.
Molten metal at 2000 C is poured using crucible. The liquid metal jet has a diameter of 3 mm with an insulation shield of 5 cm diameter. There is a slit of 30 degrees around the insulation shield. The temperature inside the room is 30 C and the shield is 700 C. Assuming black bodies, find the net heat transfer between jet and shield, jet and room, shield and the room. One of the steps is wrong A) Resistance network is required to be built B) To find the view factor between metal and shield , ratio of the angles is used C) View factors are one of the most important steps to solve the problem D) None of the above E) Slit doesnot participate in radiation
b) Two parallel square plates having 5 mm separation with each plate having 2 m2 area. One of the plates has a surface temperature of 800 K and surface emissivity of 0.6, while the other has a temperature of 300 K and surface emissivity of 0.9. Find the net energy exchange by radiations between the plates
A 3x3m plate at 500 degC is suspended vertically in a very large room. The plate has an emissivity of 0.13, The room is at 25degC. What is the net heat transfer from the plate?
A spherical radiator has a radius of 3ft and emissivity of 0.5. If radiates 6000 Btu/hr of heat at 3000R, what is the temperature of a surface affected by its radiation?
Give step-by-step calculation and explanation Consider a person sitting nude on a beach in Florida. On a sunny day, visible radiation energy from the sun is absorbed by the person at a rate of 30 kcal/h or 34.9 W. The air temperature is a warm 30 °C and the individual’s skin temperature is 32 °C. The effective body surface exposed to the sun is 0.9 m². (Assume this same area for sun absorption, radiative transfer, and convective loss. Is this a good assumption?) a. Find the net energy gain or loss from thermal radiation each hour. (Assume thermal radiative gain and loss according to the equation 6.51 in Herman and an emissivity of 1.) -(4). Equalion (6.51) - (40Tin)Eskin Aşkin (Tskin – Troom) dt = (4 x 5.67 x 10¬8 w/m²–K* x (307 K)')€skin Askin (Tskin – Troom). (6.52) b. If there is a 4 m/s breeze, find the energy lost by convection each hour. (Use Eq. 6.61 with eq. 6.63.) 1 Equation he(Tskin – Tair), (6.61) A dt he 10.45 – w + 10w0.5 (6.63) - c. If the individual’s metabolic rate is…
The inner wall of thermos bottle is at 0°C while the outer at 37°C. The space between the walls is evacuated and the walls are silvered so the emissivity is reduced to 0.10. If each wall has an area of 700 cm2, how much energy is transformed by radiation between the walls each second?
ueveiopeu vaiue. 1.5) Fill in the blanks: A body whose surface properties are independent of is . The emissivity of a wavelength is said to be a one for all wavelengths, the emissivity of a is between zero and one.
Liquefied natural gas (LNG) is transported around the globe using ships similar to thatshown in Figure QA3. This ship has four pressurised cylindrical steel tanks each ofradius of 20 m. The tanks are internally insulated with 30 cm of polyurethane foamwhich keeps the LNG at a constant -162 ºC. Take the effective sky temperature is 265K and the net radiative thermal energy exchange with the sky as 1x106 W. Calculate the surface temperature of the end (facing the sun) of a tank. Calculate the conductive heat transfer through the end (facing the sun)of a tank.