Introduction to Food Engineering

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Multiple Effect Evaporator - Mass and Energy Balance

Learning Outcomes

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

  1. describe the flow of liquid food, steam and vapors in a multiple effect evaporator
  2. determine the steam economy of a multiple effect evaporator
  3. describe different types of evaporators used in concentrating liquid foods

Multiple-effect evaporators combine two or more single-effect evaporators to obtain improved energy efficiency. The vapors produced from one effect become the heating medium in the following evaporator. In this module, you will learn the flow of steam and product in multiple effects, set up a heat and mass balance on a multiple-effect evaporator, and examine various types of evaporator designs to handle different product requirements. In the next video, you will learn about the flow of steam and product in a multiple-effect evaporator.

In the next video, you will learn how to conduct heat and mass balance of a multiple-effect evaporator. As you will observe, the mathematical analysis yields multiple equations that are solved simultaneously.

In the next series of short videos, you will observe the characteristics of different types of evaporator designs. Many of these designs address unique product requirements. In most cases, the objective is to create a sufficient rate of product flow on the heated surface to obtain a high heat transfer coefficient.

Batch type evaporator

Natural Circulation Evaporator

Forced Circulation Evaporator

Rising Film Evaporator

Falling Film Evaporator

Agitated Film Evaporator


In this module, you learned about product and steam flow through multiple effect evaporators. We conducted heat and mass balance to determine process conditions. You also learned different designs of evaporators to accommodate unique product requirements.