GPS-X Technical Reference

103 Suspended Growth Models
The SOTR is calculated as follows:
Equation 6.21
The mechanical power is calculated using the SOTR:
Equation 6.22
where:
P mechanical
= mechanical power (kW)
η = mechanical aerator oxygen transfer rate (1.75 kg O2/kW h)
CF 2 = conversion factor (24,000)
The default α value for mechanical aeration in GPS-X is 0.9.
Entering Airflow
The airflow can be entered at either standard or field conditions. At standard conditions,
the user has three options:
1. U.S. Standard Conditions:
a. Temperature = 20°C
b. Pressure = 1 atm
c. Relative humidity = 36%
2. European Standard Conditions:
a. Temperature = 0°C
b. Pressure = 1 atm
c. Relative humidity = 0%
3. User-Defined Standard Conditions:
The user must specify the properties (mole fraction of O2 in air, density,
molecular weight, and exponent in blower power equation). When using the
user-defined standard conditions option, GPS-X uses a Henry’s law
correction to adjust the value of C * st.
GPS-X Technical Reference