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:
“On a late-winter evening in 1983, while driving through fog along the Maine coast, recollections of old campfires began to drift into the March mist, and I thought of the Abnaki Indians of the Algonquin tribe who dwelt near Bangor a thousand years ago.”
—Norman Mailer (b. 1923)
“Awareness of the stars and their light pervades the Koran, which reflects the brightness of the heavenly bodies in many verses. The blossoming of mathematics and astronomy was a natural consequence of this awareness. Understanding the cosmos and the movements of the stars means understanding the marvels created by Allah. There would be no persecuted Galileo in Islam, because Islam, unlike Christianity, did not force people to believe in a “fixed” heaven.”
—Fatima Mernissi, Moroccan sociologist. Islam and Democracy, ch. 9, Addison-Wesley Publishing Co. (Trans. 1992)
““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)
“I have witnessed, and greatly enjoyed, the first act of everything which Wagner created, but the effect on me has always been so powerful that one act was quite sufficient; whenever I have witnessed two acts I have gone away physically exhausted; and whenever I have ventured an entire opera the result has been the next thing to suicide.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)