Document xznJD2rva42ndNKKNMjB4ORDg
American Society of Heating and Ventilating Engineers Guide, 1932
Chapter 15--Draft and Chimneys
T0 = absolute temperature of atmosphere, degrees Fahrenheit. To = absolute temperature of chimney gases, degrees Fahrenheit. W = amount of gases generated in the combustion chamber of the boiler and passing
through the chimney, pounds per second. / = coefficient of friction. L = length of friction duct of the chimney, feet. D -- minimum diameter of chimney, feet.
lU93 J9d 'fcU3pyJ3
>
Id
Z
a3MOd 3SBOH 3MVUS O < TM . O
The first term of the right hand expression of Equation 1 represents the theoretical draft intensity and the second term, the loss due tojfriction.
Example 1. Determine the available draft of a natural draft chimney 200 ft in height and 10 ft in diameter operating under the following conditions: atmospheric temperature, 62 F; chimney gas temperature, 500 F; sea level atmospheric pressure, B0 = 29.92 in. of mercury; atmospheric and chimney gas density, 0.0863 and 0.09, respectively; coefficient of friction; 0.016; length of friction duct, 200 ft; and discharging 100 lb of gases per second.
234 235 /