Humidification with heating, Using Thermo Utilities, MS Excel Add-ins

In an air conditioning plant, airflow rate of 2 kg/s passes through a spray water humidifier with a contact factor 0.7. The calorifier provides 40 kW. Determine the moisture content and temperature of the air leaving the humidifier and the amount of make-up water needed. The dry and wet-bulb temperatures of the inlet air are 9 C and 3 C respectively.


Inputs

Units

Inlet air, DBT

9,00

C

Inlet air, WBT

3,00

C

Inlet air, mass flow rate

2,00

kg/s

Contact factor of the humidifier

0,70

.

Heat provided by the calorifier

40,00

kW

Atmospheric pressure

1,01

bar


The contact factor of a humidifier is defined as the efficiency for humidification. A 100% efficient humidifier will bring the moisture content of the air to the saturation moisture content at the apparatus dew-point, mcC. The contact factor of the humidifier can be defined by the moisture content differences:

cf = (mcB - mcA)/(mcC - mcA)

or

cf = (hB - hA)/(hC - hA)


Output

moisture content of inlet air

0,0022

.

Spec. enthalpy at inlet

14,5

kJ/kg

Spec. enthalpy at outlet

34,4999

kJ/kg

Spec. enthalpy at ADP

43,0713

kJ/kg

Temperature at ADP

15,3825

C

Assumed

moisture content at ADP

0,0109

.

Estimate spec. enthalpy at ADP

43,0712

kJ/kg

Diff = Estimated(h) - h = 0

0,0001

.

Goal

Use solver to reach the goal

.

.

moisture content of outlet air

0,0083

.

make-up water req.

0,0122

kg/s

Dry-bulb temp at outlet

13,50

C


Copyright © 1998 Taftan Data. All Rights Reserved