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Writer's pictureTaliya Mammadhasanzada
Aug 25, 20206 min read

Introduction to Heat Exchangers 🚀

Warm greetings to all 🤩in the 21th post and in the new series 🚀on #Day21 ! Today, we will give introduction to Heat Exchangers.

  • What is Heat Exchanger?

  • What are types of HE?

  • Design Requirements

  • What are HE's used for?

  • What are the best materials for HE?

🚨P.S: In the future's posts, we will learn about each type of heat exchangers with more details. Here we go,


What is a Heat Exchanger?🐢

A heat exchanger is a device which transfers heat from one medium to another, a Hydraulic Oil Cooler or example will remove heat from hot oil by using cold water or air. Alternatively, a Swimming Pool Heat Exchanger uses hot water from a boiler or solar heated water circuit to heat the pool water. Heat is transferred by conduction through the exchanger materials which separate the mediums being used. A shell and tube heat exchanger passes fluids through and over tubes, where as an air cooled heat exchanger passes cool air through a core of fins to cool a liquid.


What types of Heat Exchanger are available?🧐

There are many different types of heat exchanger available, the three main types are:

  • Shell and tube

  • Plate

  • Air cooled


🧚🏻Shell and Tube Heat Exchangers

They consist of a large number of small tubes which are located within a cylindrical shell. The tubes are positioned into the cylinder using a tube bundle or "tube stack" which can either have fixed tube plates (permanently fixed to the body).


🧚🏻Plate Type

Plate Heat Exchangers operate in very much the same way as a shell and tube heat exchanger, using a series of stacked plates rather than tubes. Plate heat exchangers are usually brazed or gasketed depending on the application and fluids being used. Their compact stainless steel construction makes them an ideal choice for use with refrigerants or in food and beverage processing.



🧚🏻Air Cooled types

Air Cooled Heat Exchangers are commonly used in vehicles or other mobile applications where no permanent cool water source is available. Some companies design and supply combination cooling packs (or combi-coolers) which combine an engine jacket water cooler, oil cooler and charge air cooler into a single unit reducing space requirements and improving efficiency. Cool air is provided either by a fan or by air flow caused by the movement of the vehicle.


Designing a Heat Exchanger🎛

To be able to select a heat exchanger, we need to know;

  • Primary circuit fluid type, temperature and flow rate (usually the hot fluid)

  • What you want to take out of the primary circuit (Heat dissipation or a target outlet temperature)

  • Secondary circuit fluid type, temperature and flow rate (usually the coolant)

The fields above are only the basics. When putting an inquiry together you should also make company aware of any pressure loss limitations and any other special requirements.

What are heat exchangers used for?🔌

You can see heat exchangers in all kinds of places, usually working to heat or cool buildings or helping engines and machines to work more efficiently. Refrigerators and air-conditioners, for example, use heat exchangers in the opposite way from central heating systems: they remove heat from a compartment or room where it's not wanted and pump it away in a fluid to some other place where it can be dumped out of the way. The cooling fluid is completely sealed inside a network of pipes, so it never actually comes into contact with the air: it takes heat energy from the air inside and dumps it in the air outside, but it never mixes directly with that air.


 

In power plants or engines, exhaust gases often contain heat that's heading uselessly away into the open air. That's a waste of energy and something a heat exchanger can certainly reduce (though not eliminate entirely—some heat is always going to be lost). The way to solve this problem is with heat exchangers positioned inside the exhaust tail pipes or smokestacks. As the hot exhaust gases drift upward, they brush past copper fins with water flowing through them. The water carries the heat away, back into the plant. There, it might be recycled directly, maybe warming the cold gases that feed into the engine or furnace, saving the energy that would otherwise be needed to heat them up. Or it could be put to some other good use, for example, heating an office near the smokestack.


 

In buses, fluid used to cool down the diesel engine is often passed through a heat exchanger and the heat it reclaims is used to warm cold air from outside that is pumped up from the floor of the passenger compartment. That saves the need for having additional, wasteful electric heaters inside the bus. A car radiator is another kind of heat exchanger. Water that cools the engine flows through the radiator, which has lots of parallel, aluminum fins open to the air. As the car drives along, cold air blowing past the radiator removes some of the heat, cooling the water and heating the air and keeping the engine working efficiently. The radiator's waste heat is used to heat the passenger compartment, just like on a bus.



🗽If you have an energy-efficient shower, it might have a heat exchanger installed in the wastewater outlet. As the water drips past your body and down the plug, it runs through the copper coils of a heat exchanger. Meanwhile, cold water that's feeding into the shower to be heated pumps up past the same coils, not mixing with the dirty water but picking up some of its waste heat and warming slightly—so the shower doesn't need to heat it so much.



What are the best materials for a heat exchanger?⛵️

Heat exchangers would always need to be made of metals, which quickly absorb and conduct heat—and many of them are. But heat exchangers can also be made of ceramics, composites (based on either metals or ceramics), and even plastics (polymers).


🗼All these materials have their advantages. Ceramics are a particularly good choice for the kind of high-temperature applications (over 1000°C or 2000°F) that would melt metals like copper, iron, and steel, though they're also popular for use with corrosive and abrasive fluids at either high or low temperatures. Plastics generally weigh and cost less than metals, resist corrosion and fouling, and can be engineered to have good thermal conductivity, though they tend to be mechanically weak and may degrade over time. Although not generally suitable for high-temperature applications, plastic exchangers could be a good choice for something like a swimming pool or shower, operating at everyday, room-temperatures. Composite heat exchangers combine the best features of their parent materials—say, the high thermal conductivity of a metal with the reduced weight and better corrosion resistance of a plastic.


 

🚛In the future, it's distinctly possible we'll be using even more interesting materials in heat sinks. 💡Carbon nanotubes, for example (thin hexagonal sheets of carbon wrapped around to make "pipes"), have amazing heat conducting properties and are already being used in heat sinks (heat removal devices used mainly in electronics). Lots of research is currently being done to see how they can be deployed in heat exchangers.

References📖
Additional Resources 🧪🔑

You can get deep insight about Process/Chemical Engineering from these sources😉:

  1. https://www.youtube.com/watch?v=NCvYPclQNWM- Heat Exchangers Explanation

  2. https://t.me/ebookstorage/210-Introduction to Process Engineering and Design (2015)

  3. https://t.me/ebookstorage/211-Elementary Principles of Chemical Processes

  4. https://t.me/OilAndGas/18122- Valve Sizing Sheet

  5. https://t.me/ebookgate/1127- Engineering Fluid Mechanics Book

  6. https://coursemania.xyz/course.html?id=433291- Free course on Fundamentals of Fluid Mechanics

  7. https://t.me/ebookstorage/178- Engineering Heat Transfer

  8. https://t.me/ebookstorage/159- Fundamentals of Engineering Thermodynamics (9th Edition) (2018)

  9. https://t.me/ebookstorage/183-Heat Transfer applications and principles

  10. https://t.me/ebookstorage/171-Design and Operation of Heat Exchangers and their Networks (2020)

  11. https://t.me/ebookstorage/215- Industrial Separation Processes (book)

  12. https://t.me/ebookstorage/214- Advanced Process Engineering Control (book)

  13. https://t.me/OilAndGas- Information about Oil&Gas (mainly arabic lang)

  14. https://t.me/chemical_worlds- Chemical Engineering Books, Quizzes and GATE Study Group

  15. https://t.me/chemical_environmental- Discussion group related to Chemical Engineering Problems

  16. https://t.me/chemicalengineeringworld_cew- Everything related to Chemical Engineering

  17. https://t.me/ebookgate- Chemical Engineering E-books (Telegram Channel)

  18. https://www.youtube.com/channel/UCqioh32NOJc8P7cPo3jHrbg- Piping Analysis

  19. https://www.youtube.com/channel/UCQfMyugsjrVUWU0v_ZxQs2Q -Mechanics of engineered devices

  20. http://chemicalengineeringguy.com/- suggests a wide range of courses in Chemical engineering (you can find free courses on topic of Aspen HYSYS, Aspen Plus)

  21. https://www.youtube.com/user/LearnEngineeringTeam- suggests working principles of every engineered devices, equipment and etch.

  22. https://www.youtube.com/channel/UCR0EfsRZIwA5TVDaQbTqwEQ- suggests great information about pumps, compressors with animation.


Today we have started learning about Heat Exchangers. Now, time to say goodbye👋🏻 until tomorrow and Stay tuned for more content 😉🌝✨!



✏️Note: If you need one of those books or links, you can contact me via my email or LinkedIn profile.



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