**33. ssm A solid cylinder is radiating power. It has a length that is ten timesits radius. It is cut into a number of smaller cylinders, each of which has thesame length. Each small cylinder has the same temperature as the originalcylinder. The total radiant power emitted by the pieces is twice that emittedby the original cylinder. How many smaller cylinders are there?

Given data: The radius of cylinder is, r. The length of the cylinder is, l = 10r. The initial…

Answered: **33. ssm A solid cylinder is radiating…

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.44P

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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 .
1.54 The soldering iron tip in Problem 1.53 becomes oxidized with age and its gray-body emittance increases to 0.8. Assuming that the surroundings are at 20°C, determine the power requirement for the soldering iron.
A long wire 0.7 mm in diameter with an emissivity of 0.9 is placed in a large quiescent air space at 270 K. If the wire is at 800 K, calculate the net rate of heat loss. Discuss your assumptions.
Describe and compare the modes of heat loss through the single-pane and double-pane window assemblies shown in the sketch below.
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.
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?
Radiators are used in most of the houses’ heating. If we happen to place a sofa justin front of our heating radiator, how will the heating of the room be affected? Explain.
a) b) Assume that the solar receiver has cooled to 600 K at some point during the night. What is the value of its overall emissivity when it is at this new temperature? (Assume the original coating is still on the receiver) c) At this instance in time during the night (when Gs =0 and the solar receiver has cooled to 600 K), what is the rate of change of the temperature of the receiver with respect to time (dTr/dt ) in K/s if the amount of electricity being produced by the receiver does not change.
3. How to use radiation in food preservation process. What is the health issue related consumption of radiated foods?. 4. Compare the rapid and slow freezing in details .
The last portion asks you for "net radiant heat flux to the surface", meaning that positive net radiative heat flux means in and negative net radiative heat flux means out. This is opposite the typical sign convention - be aware of this
A small sphere (emissivity =0.503 radius=r1) is located at the center of a spherical abestos shell ( thickness =1.74 cm, outer radius= r2; thermal conductivity of abestos is 0.090 J/ (sm c degrees) The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere is 695 degrees Celsius while the temperature of the inner surface of the shell is 352 degrees Celsius, both temperatures remaining constant. Assuming that r2/r1 =8.75 and ignoring any air inside the shell, find the temperature in degrees Celsius of the outer surface of the shell.
If you add heat of magnitude 800 kJ to a mass of 800g of water originally at a temperature 75 degrees C and the water eventually begins to boil. The latent heat of vaporization of water is 22.6 x 105 J/kg, and its specific heat capacity is 4186 J/kg · K. How much water is left in the container? How much heat does its take to get rid of all the water? How long would it take the water to boil away? Please do fast asap

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