5. Psychrometric Properties of Air

Try these first

1. 1.

   What does DBT stand for and what does it measure?

   Hint

   Think about the standard thermometer.

2. 2.

   What is Relative Humidity?

   Hint

   Consider how much moisture air can hold at a given temperature.

3. 3.

   What does Relative Humidity indicate?

   • The weight of dry air
   • Moisture content relative to saturation
   • Air temperature

   Hint

   Think of it as a percentage of how full the air is with moisture.

4. 4.

   True or False: Dew Point Temperature is the same as Wet Bulb Temperature.

   • True
   • False

   Hint

   Consider their definitions carefully.

5. 5.

   Using a psychrometric chart, illustrate the process of cooling and dehumidifying air from a DBT of 30°C and RH of 60% to a target DBT of 20°C. Explain what changes occur.

   Hint

   Track the curvature on your chart.

6. 6.

   Calculate the enthalpy of air if you have a DBT of 25°C, a WBT of 20°C, and a humidity ratio of 0.008 kg/kg.

   Hint

   Ensure you convert values properly first.