1. BAE4400 Topics in Processing
Fall 2006
August 22 through September 21
1 hour credit
Dr. C. L. Jones
Biosystems and Ag. Engineering

2. Psychrometrics – Lectures 5, 6, & 7
Assignment:
Read Chapter 9 in Henderson/Perry
HW #4 Due 9/14/06
GO TO THE CAREER FAIRS!!!!!
Dr. C. L. Jones
Biosystems and Ag. Engineering

3. Psychrometric Processes: Adiabatic Process
Adiabatic: a procedure whereby there is a change from one state to another without heat exchange between system and surroundings
Follows the wet bulb line, H changes, h stays the same
Examples: evap. cooling, dehumidification by absorption
Dr. C. L. Jones
Biosystems and Ag. Engineering

4. Psychrometric Processes: Adiabatic Process Example
Moisture content of a large container of coconut must be reduced by removing moisture from the container.
Air at 40°C, 25% rh will be passed through the container at 13 m^3/s.
What is the maximum rate of moisture removal?
Dr. C. L. Jones
Biosystems and Ag. Engineering

5. Psychrometric Processes: Adiabatic Process Example
If the original weight and moisture content of the coconut was 500 kg at 75% (wb), what will be the moisture content after 15 minutes of aeration?
Dr. C. L. Jones
Biosystems and Ag. Engineering

6. Psychrometric Processes: Addition of Water at any state
Changes enthalpy and humidity ratio
Mass of water: (eqtn 9.100)
Energy balance: (eqtn 9.101)
Dr. C. L. Jones
Biosystems and Ag. Engineering

7. Psychrometric Processes: Addition of Water at any state
Greenhouse plants like to be kept at 30°C and 95% rh.
To achieve this condition, steam at 160°C is injected into the ventilation air stream (20°C, 30% rh).
Mass flow rate of the air stream is 1800 kg/min and the mass flow rate of the steam is 5 kg/min.
Will this system achieve the ideal conditions for the plants?
Dr. C. L. Jones
Biosystems and Ag. Engineering