Show that the fin effectiveness is related to the fin efficiency by the equation
For a fin and a base area between succeeding fins, the fin effectiveness is
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Process of Science: Explain the varied ways in which we continue to explore the Solar System
What will be an ideal response?
What is the simplest way we might detect life on an extrasolar planet?
A) listen for radio signals coming from an advanced civilization on the planet B) wait for aliens from the planet to visit us C) analyze the spectrum of reflected light from the planet D) send an interstellar probe to the planetary system
To reduce the home heating requirements, modern building codes in many parts of the country require the use of double-glazed or double-pane windows, i.e., windows with two panes of glass. Some of these so called thermopane windows have an evacuated space between the two glass panes while others trap stagnant air in the space. (a) Consider a double-pane window with the dimensions shown in the sketch given below. If this window has stagnant air trapped between the two panes and the convective heat transfer coefficients on the inside and outside surfaces are 4 W/(m2 K) and 15 W/(m2 K), respectively, calculate the overall heat transfer coefficient for the system. (b) If the inside air temperature is 22°C and the outside air temperature is –5°C, compare the heat loss through a 4 m2
double-pane window with the heat loss through a single-pane window. Comment on the effect of the window frame on this result. (c) If the total window area of a home heated by electric resistance heaters at a cost of $.10/kWh is 80 m2 how much more cost can you justify for the double-pane windows if the average temperature difference during the six winter months when heating is required is about 15°C?
GIVEN
- Double-pane window with stagnant air in gap
- Convective heat transfer coefficients
- Air temperatures
FIND
(a) The overall heat transfer coefficient
(b) Compare heat loss of double- and single-pane window
(c) Cost to justify for the use of double-pane window.
ASSUMPTIONS
- Steady state conditions prevail
- Radiative heat transfer is negligible
SKETCH
A 400-W computer (including its monitor) is turned on for 8.0 hours per day. If electricity costs 10¢ per kWh, how much does it cost to run the computer annually for a 365-day year?
A) $120 B) $1200 C) $15 D) $150