In an air conditioning plant, airflow rate of 2 kg/s passes through a pan steam humidifier. Determine the load on the humidifier and the steam supplied. The dry and wet-bulb temperatures of the inlet air are 9 C and 3 C respectively. Air leaves the humidifier with moisture content of 0.008
| Inputs |
Units |
|
|
Inlet air, DBT |
9,00 |
C |
|
Inlet air, WBT |
3,00 |
C |
|
Inlet air, mass flow rate |
2,00 |
kg/s |
|
Outlet air, moisture content |
0,008 |
. |
|
Atmospheric pressure |
1,01 |
bar |
A pan steam humidifier uses a heating element inside a water tank. The tank is mounted at the bottom of the air duct. The air flowing over the water surface will cause some evaporative cooling which results in drop of air dry-bulb temperature. The ratio of sensible heat to total heat is approximately 0.2
Load on the humidifier is:
Q = mA * (hB - hA)
and the steam supplied by humidifier is:
mSteam = mA * (mcB - mcA)
| Output | |||
|
moisture content of inlet air |
0,0022 |
. |
|
|
Outlet air, DBT |
12,66 |
C |
Assumed |
|
Spec. enthalpy at inlet |
14,5 |
kJ/kg |
|
|
Spec. enthalpy at outlet |
32,9 |
kJ/kg |
|
|
Load on the humidifier = total heat |
36,8061 |
kW |
|
|
Sensible heat |
7,3591 |
kJ/kg |
|
|
Qs / Q = 0.2 |
0,1999 |
. |
Goal |
|
Use the solver to reach the goal |
. |
. |
|
|
steam supplied |
0,0117 |
kg/s |