Rithmware Technologies

Example 1 - Drying Gas Stream

Problem 1

Moist air has the following conditions:

Pressure = 1 atm

Dry-bulb Temperature = 25 ^oC

Absolute Humidity = 0.009 kg/kg dry air

Calculate wet-bulb temperature, dew point temperature, relative humidity, humid heat, humid volume, specific enthalpy and density.

Solution Steps:

1. Start ProcesSimO. By default, a new empty flowsheet is created with the default material of the software.

2. Go to File | Application Preferences | Unit Systems tab. Select SI-3 and click “Set Current” button to set SI-3 unit system as the current unit system. Then close the dialog.

3. Create a drying gas stream on the flowsheet and double click the icon of the stream to bring up the stream’s editor.

4. Input 1.0 atm at the Pressure field.

5. Input 25 ^oC at the Dry-bulb Temperature field.

6. Input 0.009 kg/kg in the Absolute Humidity field

7. After the enter key of last input is hit, wet-bulb temperature, dew point temperature, relative humidity, humid heat, humid volume and specific enthalpy are automatically calculated and displayed on the stream editor as in Figure 1.1.

Figure 1.1

Problem 2

Moist air has the following conditions:

Pressure = 1 atm.

Temperature = 25 ^oC.

Absolute Humidity = 0.009 kg/kg.

Mass Flow Rate (wet basis) = 1000 kg/hr.

Calculate the wet-bulb temperature, dew point temperature, relative humidity, humid heat, humid volume, specific enthalpy, density, mass flow rate (dry basis) and volume flow rate.

Solution Steps:

1. Follow the solution steps 1 through 6 in problem 1.

2. Input 1000 kg/hr in Mass Flow Rate (wet basis) field

3. After the enter key of the last input is hit, the stream is completely solved and the result is as shown in Figure 1.2.

Figure 1.2

Summary

1. When pressure, one of the temperatures (either Dry-bulb Temperature, or Wet-bulb Temperature or Dew Point Temperature), and one of the humidities (either Absolute Humidity or Relative Humidity) are know, the state of the moist air is determined and can be calculated, and therefore all the thermal physical properties at this state can also be calculated and automatically displayed on the stream’s editor.

2. When one of the flow rates (either Mass Flow Rate (wet basis), or Mass Flow Rate (dry basis), or Volume Flow Rate) is know and the state of the moist air is determined, the other flow rates are automatically calculated and displayed on the stream editor.