A

Area of opening, in.2, or duct cross section, ft2

A, B

Factors used in Q5.26

BD

Blowdown, fraction

BHP

Boiler horsepower

C

Corrosion allowance, in.

Cc

Initial investment, $

Cd

Coefficient of discharge

Ce

Cost of electricity, $/kWh

Cp

Specific heat, Btu/lb °F

Dp

Tube or outer diameter, in.

Di

Tube or pipe inner diameter, in.

E

Escalation factor

E

Sealing efficiency, %; ligament efficiency, fraction

F

Factor defined in Eq. (33)

G

Gas mass velocity, lb/ft2 h

H

Enthalpy, Btu/lb

H

Height of liquid column, in.

Hg, hf

Enthalpy of saturated vapor and liquid, Btu/lb

Hg

Head of gas column, ft

H

Head of liquid, ft

Hw

Differential pressure across damper, in. WC

I

Interest rate

L

Distance, ft

LCC

Life-cycle cost, $

M

Moisture in air, lb/lb

MW

Molecular weight

N

Annual period of operation, h

Pw

Partial pressure of water vapor, psia

P

Gas pressure, psia; design pressure, psig

DP

Differential pressure, psi

PWL

Sound power level

Q

Volumetric flow, gpm or cfm

Q

Energy, Btu/h

R

Radius of drum, in.

RH

Relative humidity

S

Specific gravity

Sa

Allowable stress, psi

SBV

Steam by volume

SPL

Sound pressure level, dB

SVP

Saturated vapor pressure, psia