Introduction to Food Engineering

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Single Effect Evaporator - Heat and Mass Balance

Learning Outcomes

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

  1. describe the flow of steam and liquid food in a single effect evaporator
  2. conduct a mass and energy balance on an evaporator
  3. determine steam economy for a single effect evaporator

The evaporation process is commonly used in the food industry to concentrate liquid foods such as milk, orange juice, and apple juice. This process is carried out either in a single-effect evaporator or multiple-effect evaporator. In this module, you will learn how to determine the operating conditions of a single-effect evaporator by conducting heat and mass balances. In the following video, you will view the movement of steam and liquid food streams through a single-effect evaporator.

As you noted in the above video, the liquid food stream is heated by steam under low-pressure conditions. The low pressure causes the liquid to boil at a low boiling point. Steam and the liquid food stream do not come into direct contact with each other; the heat exchanger wall separates them. In the next video, we will conduct a mass and energy balance for a single-effect evaporator. This analysis will provide expressions to determine flow rates, rate of heat transfer, and steam economy.


In this module, you learned how steam and product flow inside a single effect heat exchanger. We conducted a mass and energy balance on an evaporator to obtain information required for designing the process.