Types of Heat Exchangers
Selecting the right heat exchanger is crucial for achieving efficient heat transfer, minimizing costs, and ensuring easy maintenance in hygienic processing industries like food, beverage, dairy, and pharmaceuticals. Heat exchangers allow fluids to exchange heat without mixing, making them vital for various applications. Whether you’re a processor, production manager, or engineer, understanding different heat exchangers—such as plate, shell and tube, and scraped surface—will help you make the best choice for your specific processing requirements.
What Is A Heat Exchanger?
A heat exchanger is a device that transfers heat between two fluids without mixing them. There are many types of heat exchangers, each designed for different applications. When choosing a heat exchanger, it’s important to consider what type of fluid you need to heat or cool and the purpose it will serve in your process.
What Are The Different Types Of Heat Exchanger?
Finned Tube Heat Exchanger (Air Cooled Heat Exchanger)
Suitable for: air/gas to liquid
A finned tube heat exchanger, also known as an air-cooled heat exchanger (ACHE), works by circulating liquid through a series of tubes while gas or air flows around them to cool the fluid. The “fins” on the tubes increase the surface area, improving heat transfer. These exchangers can either be enclosed in ductwork or fully exposed, with air flowing directly over the fins.
Applications:
Finned tube heat exchangers are commonly used for heat recovery from processes that release hot gas. The heat from these gas is transferred to a liquid, such as water or thermal oil, which can then be used in other applications, reducing energy consumption.
ACHEs are widely used in industries like chemical processing, petrochemical cooling, steam cooling, textiles, grain drying, concrete curing, paper manufacturing, and food processing. With air being the most common process fluid, ACHEs have a broad range of applications across various sectors.
Shell and Tube Heat Exchanger
Suitable for: fluid to fluid / fluid to gas
A shell and tube heat exchanger works by passing a hot or cold fluid (or gas) through a set of tubes enclosed in a large metal shell. The other fluid or gas flows around the outside of these tubes, transferring heat between them.
Applications:
Shell and tube heat exchangers are ideal for high-pressure applications and situations requiring containment, such as handling hot, noxious, or harmful gas. These units are commonly used in the oil, gas, and chemical industries, where their ability to withstand extreme conditions and high stresses is crucial. They are also suitable for processes that require careful control to prevent the release of gas into the atmosphere.
Plate Heat Exchanger and Gasket Plate Heat Exchanger
Suitable for: fluid to fluid / vapor
A plate heat exchanger works by passing fluids through a series of compact, side-by-side plates. This setup allows for efficient heat transfer between the fluids.
Applications:
Plate heat exchangers are commonly used in liquid-to-liquid systems. For example, they can heat cold mains water by transferring heat from hot process water that may contain chemicals or contaminants. They are also used in district heating systems to supply homes with hot water from a central source. Additionally, plate heat exchangers are ideal for cooling oils using water when the two fluids must remain separate.
Typical Applications for Scraped Surface Heat Exchangers
Scraped surface heat exchangers are commonly used for:
Viscous Products: Ketchup, mayonnaise, hummus, peanut butter, puddings, salad dressings, bread dough, gelatine, baby food, skin lotions, and shampoos.
Heat-Sensitive Products: Egg products, fruit purées, cream cheeses, and fishmeal.
Crystallizing and Phase-Changing Products: Coffee/tea extracts, icings, sugar concentrates, margarine, shortening, spreads, gelatine broth, lard, and fondant.
Particulate Products: Meats, poultry, pet foods, jams, preserves, and rice puddings.
Sticky Products: Caramel, cheese sauces, processed cheese, gums, gelatin, mascara, and toothpaste.
