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Air exchange through doorways. The effect of temperature difference, turbulence and ventilation flow

Published online by Cambridge University Press:  15 May 2009

O. M. Lidwell
O. M. Lidwell
Affiliation:
Central Public Health Laboratory, Colindale Avenue, London NW9 5HT
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Summary

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Analytical expressions have been derived for the exchange of air across doorways or similar apertures, in terms of the temperature difference between the spaces on both sides of the opening and the net volume of air flowing through this as a result of unbalanced air supply or extract. A simple allowance for turbulence which gives reasonable correspondence with observation is included. The formulae, which assume complete air mixing on both sides of the doorway up to the plane of the aperture, predict outflows from the warmer side, when there is an excess air supply to this side, which are progressively smaller than those observed as the temperature difference rises above 2–3 °C and the volume of excess air supply increases to produce an averaged outflow velocity greater than 0·1–0·15m/s. This seems to be due to lack of mixing of the warm outflowing air with the cooler air mass. A correction factor for this can be deduced as a function of the pressure difference due to the excess air supply. The limiting magnitude and general form of this function are compatible with a simple theoretical model of the air flow patterns involved.

Type
Research Article
Information
Journal of Hygiene , Volume 79 , Issue 1 , August 1977 , pp. 141 - 154
Copyright
Copyright © Cambridge University Press 1977

References

REFERENCES

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