WOLFRAM|DEMONSTRATIONS PROJECT

Concentration of Sugar Solution in a Bubble Column

inlet air conditions:

temperature (°C)

dew point temparature (°C)

sugar content (weight %):

dilute solution

0.05

concentrated solution

0.2

diagram

psychrometric data

inlet air

outlet air

A bubble column is used to concentrate a dilute sugar solution in water. Set the dry-bulb and wet-bulb temperature of the inlet air stream (labeled

and

in the diagram). The humidification of the air is assumed to be an adiabatic process. The air exiting the column is saturated (i.e. its relative humidity

is 100%). You can vary the weight fraction of the sugar in the dilute and concentrated liquid solutions. This Demonstration enables you to compute how many kilograms of air must enter the column to achieve the target exit concentration. To do this, assume as a basis 1 kg of sugar solution in the column. The volume of the inlet air is also calculated. Finally, selecting the "psychrometric data" tab lists all relevant thermal parameters for the two air streams:

1. the dry-bulb temperature

2. the wet-bulb temperature

3. the dew point temperature

4. the relative humidity

5. the absolute humidity or moisture content

6. the humid volume

7. the specific enthalpy

Things to try out or check:

1. For fixed values of

and

of the inlet air stream as well as the inlet weight fraction of sugar in the dilute solution, increase the value of the target concentration of the sugar solution. As expected, you will observe an increase in the computed mass of inlet air.

2. The values of the wet-bulb temperature and specific heat of both the inlet and outlet air streams are identical. This is expected because we assume adiabatic humidification. We move along a constant wet-bulb line on the psychrometric chart.

3. Keep all variables constant and decrease the dry-bulb temperature of the inlet air. As expected, more inlet air will be needed.