I am looking for a heat exchanger type that can be use to extract heat from exhaust gas @200-300 degree celsius. Kindly suggest some heat exchanger types.Currently i ma planning to use Finned Tube heat exchanger. Is there a more efficient heat exchanger type that can be used.
Thanking you
I think a finned heat exchanger is a good option but you need to determine what kind of fins will be used to extend the heat transfer area. Probably an interrupted fin like slit fins or louvers fins will be an option. The gas side of the heat exchanger is the limiting part and a higher heat transfer reduce the size of the device. On the other hand consider the cleaning process because normally the exhaust gas are dirty and contain particulates, then the fouling reduce the heat exchanger effectiveness.
These conditions (exhaust gas 200-300C) are typical of the tail end of a heat recovery steam generator (HRSG). A lot of money and effort has gone into the design and testing of such heat exchangers. I suggest you consider that configuration. There are a lot of pictures on line as well as discussion of the performance and maintenance issues. There are also design details available that you can use to size the fins, tubes, surface area, and select materials. I know of one particular system that sits on the roof of a building and is supposed to supply heat for air conditioning and heating of an adjacent hospital. That particular design is a complete flop, but it doesn't mean that you couldn't do it right and derive real benefits.
Due to the low heat transfer coefficients for gases, extended surfaces is an obvious selection. However, as mentioned by Ruben Borrajo, flue gases are often polluted by soot/particles, condensables etc, that may foul up the heat transfer surface. Luckily, the fin efficiency will tend to increase when fouling occurs, reducing the negative effect of the fouling. You may want to check out the available fin-tube designs used in economisers for biomass, coal or municipal waste fired steam generators to get an idea of designs that work in such conditions. If your exhaust gas is clean (e.g. gas-fired system), then fouling is a non-issue, and you have a wider range of parameters to choose from.
To choose the recommended heat exchanger, you need to know "how much heat" does your process need to remove from this gas? Whether it is an open or closed circuit? How fast are these gases through the exchanger? What is the fluid? The space available for heat exchanger design? What coolant do you want to use? What if the application is industrial or laboratory? I am asking these questions, because depending on the requirement, resources and methods available, even plain pipes can be used.
Good morning Mr. Jatin Prasath, how are you? The type of heat exchanger will depend on a few factors: -What is the flow of these exhaust gases? Is it constant? Are these gases corrosive? Would you like to reuse this heat to generate some form of energy? Or simply cooling? Do you have a boiler so that energy reuse can be done? What is the desirable outlet temperature? What is the easiest way to make exchanger for companies in your region?
The interesting thing is to reuse this energy. If you are going to take advantage of this energy and your energy matrix has it is by a thermal oil system it is a type of exchanger. If it is by boiler it will be another type. If it is just gas cooling you can use a system that injects compressed air with water to work with convection cooling, I have already done this, but it works well only above 180 ° C. If you want to cool to temperatures below 180 ° C, it will be another system. And so on.
It is also important to check the fact that the coils are available in your region, start there. There is no point in considering a copper and aluminum parallel plate exchanger if companies in your region manufacture only carbon steel and smooth tube exchangers.
I hope I helped you.
ummeed hai kee yah madad karega.
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