The Chesy's formulaa1 is generally used to determine the friction loss in
inches of water for chimneys. This is
| where | Dc | = friction loss in in. of H20 |
| K | = coefficient including friction and reduction factors | |
| V | = velocity of air in ft/sec. | |
| H | = height of stack above intake in ft. | |
| D | = mean diameter of stack | |
| Tc | = mean absolute temperature of gas |
The value of K is about 0.008 for air and a brick lined chimney. This
is the algebraic mean of the values assumed by various authorities.
In the proposed building for the
must be removed. The temperature of the air can be assumed to be about 78°F
so as to give an effective working temperature in the building of about 72°F.
A table below gives Dc as a function of the stack diameter at a stack height
of 100 ft.
| Diameter of Stack in Feet | Friction Loss in Inches of H20 |
| 4 | 0.41 |
| 5 | 0.130 |
| 6 | 0.054 |
| 7 | 0.025 |
| 8 | 0.013 |
The friction loss for any height can be obtained from this table by
multiplying by 0.01H. It can be seen that the losses arc small in general
and after the losses in the ducts have been estimated it will be possible
to choose a blower to do the job. If the stack is assumed to be 110 feet
with a 6 foot diameter than the loss will only be 0.059 inches of water,
Blowers develop with ease in the capacity needed pressure differences of
2" of H20. The difference between this and the loss in stack is certainly
suffIcient for duct losses.
CC: Reactor Committee
a1Steampower Plant Engineering