Q2) Consider a 150-W incandescent lamp. The filament of the lamp is 5-cm long and has a diameter of 0.5 mm. The diameter of the glass bulb of the lamp is 8 cm. Determine the heat flux, in W/m2, (a) on the surface of the filament and (b) on the surface of the glass bulb, and (c) calculate how much it will cost per year to keep that lamp on for eight hours a day every day if the unit cost of electricity is $0.08/kWh.

Q2) Consider a 150-W incandescent lamp. The filament of the lamp is 5-cm long and has a diameter of 0.5 mm. The diameter of the glass bulb of the lamp is 8 cm. Determine the heat flux, in W/m2, (a) on the surface of the filament and (b) on the surface of the glass bulb, and (c) calculate how much it will cost per year to keep that lamp on for eight hours a day every day if the unit cost of electricity is $0.08/kWh.

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 1.29P: 1.29 A spherical interplanetary probe with a 30-cm diameter contains electronic equipment that...

See similar textbooks

Similar questions

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.
Required information Consider a person whose exposed surface area is 21 m4, emissivity is 0.5, and surface temperature is 32°C. Given: 0 = 5.67×10-8 W/m2.K4 Determine the rate of heat loss from that person by radiation in a large room having walls at a temperature of 300 K (upto 3 decimal places). You must provide an answer before moving to the next part. The rate of heat loss from the person at 300K is W.
Heat is lost through the glass pane of a window. The thickness of the glass is 3 mm, and the window is 0.9 m by 1.8 m. The thermal conductivity of glass is 0.8 W/mK. If the temperature difference across the glass is 17 K, what is the total heat transfer through the pane of glass? Give your answer in Watts to the nearest integer.
What are the equations for heat transfer from conductions, convection, and radiation?
What happens to heat transfer per unit time in conduction heat transfer as thermal conductivity decreases?
A wood stove is used to heat a single room. The stove is cylindrical in shape, with a diameter of 26 cm and a length of 52 cm, and operates at a temperature of 490°F. If the temperature of the room is 60°F, and if the emissivity is 0.844, then Calculate, the amount of radiant energy delivered to the room by the stove each second (KW) Answer
In a lab testing material samples to determine the thermal conductivity of the material. Now, the test specimens are 18.5 cm long by 14.4 cm wide and 0.26 cm thick. The sample is placed in a test device so that one of the large sides is maintained at 13, while the other large side is kept at -7. The heat transfer through the sample is measured to be 287 Watts. Determine the thermal conductivity. Give your answer to 2 decimal places.
A furnace must be built with an inner layer of refractory brick (conductivity 1.27 Kcal/h mºC). This layer must be coated with a layer of insulating brick (conductivity 0.134 Kcal/hm ºC) 22 cm thick, in turn covered with a 15 cm layer of building brick (conductivity 0.75 Kcal/ hm°C). The inner surface of the refractory wall will operate at 1150ºC and the outside at 65ºC. How many centimeters of refractory brick would be required for the insulation not to exceed 930ºC (safety limit of the material in question).
We often think of pollution in terms of smog or trash in the ocean. Give an example of thermal pollution, discuss its impact and possible mitigation.
Consider steady heat transfer between two large parallel plates at constant temperatures T1 = 300 K and T2 = 200 K that are L = 1 cm apart, as shown below. Assuming the surface to be black, 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/moC, b) free flowing air with h = 7.5 W/m2oC, c) evacuated, d) filled with urethane insulation with k = 0.026 W/moC, and e) filled with superinsulation that has an apparent thermal conductivity k = 0.00002 W/moC
2.The owner of the house in number 1 is thinking that heat of 1.2 kW coming from the wall is too high, he then decides to add a layer of 5 cm of expanded polystyrene in order to insulate the building. The rest of the wall is still be made of bricks. Bricks have a conductivity of 0.8 W/m/K and are 15 cm wide. Expanded polystyrene has a thermal conductivity of 0.04W/m/K The wall is 6 m long per 3 m high. He measures now 35 degrees on the outside surface and 22 degrees on the surface of the wall inside. Calculate the heat transferred.
The interior-wall temperature of an annealing oven constructed of firebrick (Missouri) is2552°F, and the exterior-wall temperature is 392°F. If the heat loss is 3600 Btu/(hr)(sq ft),determine the thickness of the wall, in inches. (answer 5.67”)