The Driving Force For The Stack Effect
There is a pressure difference between the outside air and the air inside the building caused by the difference in temperature between the outside air and the inside air. That pressure difference ( ΔP ) is the driving force for the stack effect and it can be calculated with the equations presented below. The equations apply only to buildings where air is both inside and outside the buildings. For buildings with one or two floors, h is the height of the building. For multi-floor, high-rise buildings, h is the distance from the openings at the neutral pressure level (NPL) of the building to either the topmost openings or the lowest openings. Reference explains how the NPL affects the stack effect in high-rise buildings.
For flue gas stacks and chimneys, where air is on the outside and combustion flue gases are on the inside, the equations will only provide an approximation and h is the height of the flue gas stack or chimney.
- SI units:
-
where: ΔP = available pressure difference, in Pa C = 0.0342 a = atmospheric pressure, in Pa h = height or distance, in m To = absolute outside temperature, in K Ti = absolute inside temperature, in K
- U.S. customary units:
-
where: ΔP = available pressure difference, in psi C = 0.0188 a = atmospheric pressure, in psi h = height or distance, in ft To = absolute outside temperature, in °R Ti = absolute inside temperature, in °R
Read more about this topic: Stack Effect
Famous quotes containing the words driving, force, stack and/or effect:
“When you take a light perspective, it’s easier to step back and relax when your child doesn’t walk until fifteen months, . . . is not interested in playing ball, wants to be a cheerleader, doesn’t want to be a cheerleader, has clothes strewn in the bedroom, has difficulty making friends, hates piano lessons, is awkward and shy, reads books while you are driving through the Grand Canyon, gets caught shoplifting, flunks Spanish, has orange and purple hair, or is lesbian or gay.”
—Charlotte Davis Kasl (20th century)
“Mediocrity would always win by force of numbers, but it would win only more mediocrity.”
—Ellen Glasgow (1873–1945)
““Farewell to barn and stack and tree,
Farewell to Severn shore.
Terence, look your last at me,
For I come home no more.”
—A.E. (Alfred Edward)
“The second [of Zeno’s arguments about motion] is the one called “Achilles.” This is to the effect that the slowest as it runs will never be caught by the quickest. For the pursuer must first reach the point from which the pursued departed, so that the slower must always be some distance in front.”
—Zeno Of Elea (c. 490–430 B.C.)