Heat exchangers are most suitable for medium and low pressure fluids as the speed of the process is achieved through the surface area. The two alternating chambers are separated by a plate which is usually corrugated metal. Stainless steel is commonly used as it is a durable metal with a high temperature tolerance rate which is ideal for transferring heat. These plates are connected to each other in a frame, usually with a thin space between each plate forming a parallel channel for the different temperature liquids to flow through.
A plate heat exchanger is a device used to transfer heat from one fluid to another. It consists of a series of thin, corrugated metal plates stacked together and clamped between two end frames. The plates create a series of channels through which the two fluids flow, allowing for heat transfer through the thin metal walls of the plates. The two fluids can flow either in parallel or in a cross-flow configuration. In a parallel-flow arrangement, both fluids enter at the same end and flow in the same direction through alternating channels, with heat transfer occurring through the plates. In a cross-flow configuration, the two fluids flow at right angles to each other, with one fluid flowing through the channels formed by one set of plates and the other fluid flowing through the channels formed by another set of plates. Plate heat exchangers are commonly used in a wide range of applications, including heating and cooling systems, refrigeration, chemical processing, and food and beverage processing. They are highly efficient due to their large surface area, compact size, and ability to handle high flow rates with low pressure drops.
Heat exchangers help control fluid temperatures in food, beverage, and pharmaceutical processing for pasteurization, sterilization, clean-in-place and other hygienic operations. In this post, we discuss how three types of heat exchangers work: plate and frame, shell and tube, and scraped surface. The purpose of heat exchangers is to transfer heat between two or more fluids to regulate temperatures during food, beverage, and pharmaceutical processing.
1. Food and Beverage Industry: heat exchangers make products safe for consumption and extend shelf life by preventing growth of harmful microbes.
2. Milk processing: heat exchangers pasteurize milk by raising milk temperatures.
3. Pharmaceutical processing: ingredients in cosmetics and pharmaceuticals must be mixed at specific temperatures to ensure safe use and product quality.
Heat exchangers vary according to the attributes of the processed fluids, such as viscosity, particle size, temperature, and flow.
Plate Heat Exchanger Components
Gaskets and plates are used to separate the flowing mediums and prevent them mixing; gaskets are adhered to one side of each plate only. The plates hang upon a carry bar and are pressed together using clamping bolts. When the plates are compressed together, they are referred to as a ‘plate stack’. A guide bar ensures the plates are aligned correctly when the plate stack is opened and closed. The final components of interest are the two covers at opposite ends of the plate stack. One cover is movable whilst the other is fixed. The movable cover and fixed cover are also sometimes referred to as the frame plate and pressure plate. Note that the inlets and outlets are mounted to the fixed cover only.
Notice that the two flowing mediums are always adjacent to each other throughout the heat exchanger. The flowing mediums thus have a hot, cold, hot, cold, flow pattern, as they flow through the heat exchanger. Both flowing mediums are completely separated from each other by the gaskets and plates, they do not mix.
