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6 Steady state evaporation rate kg/s
7 Steady state specific humidity in the chamber In decimal
8 Steady state air temperature in the chamber °C
9 Steady state airflow velocity in HADT m/s
10
Average of fluctuating airflow velocities in HADT
and the connecting duct
The average velocities of airflow in HADT and the connecting duct are used to calculate
the flow rate in the chamber.
4.3.1.1 Whole chamber steady state subsystem
The Whole chamber steady state subsystem consists of 5 subsystems.
Fluid dynamic section subsystem (for steady flow)
Temperature of chamber inlet from ADU subsystem
Water thermal balance subsystem
Chamber-air steady state thermal balance subsystem
Chamber air specific humidity subsystem
The “Fluid dynamic section subsystem (for steady flow)” is basically the same as the
one in “Fluid dynamic and exhaled air re-breath model”. The only difference is that the
breath load input to it is always zero thus makes this subsystem always provide steady
flow velocity and steady pressures. The inputs are listed in Table 4.15 below.
Table 4.15 Inputs to the whole chamber steady state subsystem
Input port number Input Unit
1 Heat element temperature setting °C
94
m/s
2 Ambient air specific humidity In decimal
3 CPAP pressure setting cmH2O
4 Mask capacity m 3
5 Ambient air temperature °C
6
Portion of direct impact area to total
water surface area
In decimal