Introduction to Food Engineering

Home Syllabus
Material Balances Energy Balances
Fluids Laminar and Turbulent Flow Volumetric Flow and Friction Bernoulli's Equation and Pump Power Flow Measurement
Thermodynamic Properties
Modes of heat transfer Conduction in walls Conduction in multilayered walls Convection heat transfer Forced Convection Free Convection Overall Heat Transfer Coefficient Heat Exchangers Unsteady State Heat Transfer Heisler Charts
Decimal Reduction Time F value General Method Improved General Method
Properties of Air and Water Vapor Psychrometric Chart
Moisture Content and Drying Rates Drying Time
Single Effect Evaporator Multiple Effect and Industrial Evaporators
Refrigerants Vapor Compression Refrigeration System Ideal and Non-Ideal Cycle
Ice Crystallization Freezing Time Freezer Selection
Instructions List of Experiments

Psychrometric Chart

Learning Outcomes

At the end of this module, you will be able to:

  1. explain how a psychrometric chart is constructed
  2. determine properties of an air and water vapor mixture from a psychrometric chart
  3. show air conditioning processes on a psychrometric chart and make design calculations

Psychrometric Chart is used widely as an easy to use nomogram to obtain numerical values of properties of air and water vapor mixtures. These values are useful in designing heating and cooling systems. In this module, we will first observe the salient features of a psychrometric chart. In the next video, we will identify the lines and curves on the chart and the properties they represent.

Now that you have seen how to construct a Psychrometric chart, in the next video, you will learn how to read the values of different properties from the chart. We will use illustrative examples and obtain numerical values.

In the following video, you will learn how to represent selected air conditioning processes on a psychrometric chart. The processes include heating, cooling, humidification, and adiabatic saturation. Once you draw a process on the chart, one can obtain numerical values for further calculations useful in the design of such systems.

Example 1 - A drying system involving a heater, a drier, and a dehumidifier

Example 2 - A drying system involving two heaters and two drying beds

Recap

In this module, you learned about a Psychrometric chart, how to draw it, how to read property values from the chart, and how to represent selected air conditioning processes on the chart. As you may have observed, this chart is a simple but useful tool in obtaining property data of air and water vapor mixtures.