FROM:

SUBJECT: Friction Loss in Stack

The Chesy's formula^{a1} 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

Notes:

^{a1}Steampower Plant Engineering