Exhaust Gas Re-circulation Heat Exchanger (mixed/unmixed): Heat Transfer Examples for Mechanical Eng

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In this problem, we design a crossflow heat exchanger by finding the area of an exhaust gas recirculation heat exchanger.
Heat exchanger problems typically have one of two potential main goals: (a) find the heat transferred between two fluids, OR (b) find the area needed to achieve a required target heat transfer between two fluids. In this example, we go through a systematic process to find the area required for a cross flow heat exchanger where one flow is mixed and the other is unmixed. I believe that understanding this process will allow you to solve any heat exchanger problem.

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6 окт 2024

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Комментарии : 16

@ghaliabintouq429 2 месяца назад

Your videos are so clear and easy to comprehend,thank you so much for this!

@diyaazaghloul756 3 года назад

Amazing video thank you

@eng.hawraz7100 3 года назад

thanks for your video, please do you have any video about two-pass cross-flow.

@mikeschertzer941 3 года назад

I think this is the only other video I have with cross flow: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VaVKYIgbNUU.html There is also this one with multiple passes in a shell and tube heat exchanger: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8nazSlO-e9o.html

@thedecisions8681 Год назад

That was amazing sir, I have problem to solve a calculating of heat exchanger cross flow. This heat exchanger is used for heating the brine before entering the desalination flash evaporator Chamber. We are usually called this heat exchanger as a brine heater. The tube side is containing by a brine and the Shell side is containing by a steam. I'm so confused to solve this problem because i don't know how much is outlet steam temperature, and my lecture ask me to find LMTD and the efficient of this heat exchanger. Perhaps if u want help me, I'm so grateful for it. But, i have one wishes. Could you send the LMTD and NTU matrix to US? I think that matrix can help me Thanks for your education in this video

@mikeschertzer941 Год назад

Sounds like there is one side of the Heat Exchanger where the change in temperature is unknown and another side where it's known? If you know how much heat is added / removed from one side, you can assume no losses and find how much heat is removed / added from the other side. Sounds like you have phase change, so you have to remember that once you hit the saturation temperature for a given pressure (i.e. phase boiling starts), you account for the extra energy by increasing the quality (i.e. more vapor formation). While you are "under the vapor dome" you can use latent heat.

@thedecisions8681 Год назад

@@mikeschertzer941 thank you very much sir, let my try your advice 🙏🏼 and maybe I'll be back again to asking if Im still confuse with this problem

@yukselkarabulut1203 4 года назад

Hello, My pipe diameters are Ri = 0.045 m and Ro = 0.05 m. The pipe metal I use is aluminum. How do I calculate the total heat transfer coefficient if we calculate it similarly to your question? Thank you.

@yukselkarabulut1203 4 года назад

Actually, here's my problem. I want to design a simple recuperator. Exhaust gas temperature 610 degrees and room temperature 20 degrees. I'd like to increase the room temperature to 250 degrees using the exhaust gas. I wonder how long I should use pipes. And what should be the surface area of these pipes ? Actually, the problem you solved was very helpful, but I couldn't calculate the total heat transfer coefficient. I'd be very happy if you could help me. Thanks.

@mikeschertzer941 4 года назад

You don't calculate the total HTC directly. You'll need h on both sides of the heat exchanger. If your heat exchanger looks like the one in this problem, one side is internal convection in a pipe, and the other is external convection over a cylinder (at least as a first approximation). I have videos for both of these cases in the same Playlist as this one. The resistance of the wall may or may not be important depending on its relative resistance.

@paulmayorga7611 2 года назад

Hello sir, one question, in the case of cooler grate cross flow heat exchange. What will be the case for NTU calculation ?

@mikeschertzer941 2 года назад

I think you want to follow the same 2x2 matrix as in this video. You will use effectiveness NTU. Then figure out if you are solving for heat transfer (known size) or size (known heat transfer). Go through the checklists on the 2x2 for these cases. You might benefit from watching a couple of my heat exchanger videos to see examples solving for heat and solving for size. Good luck!

@alish5598 2 года назад

Sir if there is phase changement in flue gas side (hot) what will change in calculation . Thanks

@mikeschertzer941 2 года назад

Having a two phase fluid in the system will change the heat transfer coefficient (h). So you'd likely need a chance different correlation.

@alish5598 2 года назад

@@mikeschertzer941 thanks sir if you have any refrence for that situation plz?

@mikeschertzer941 2 года назад

@@alish5598 Sally I don't. It will be specific to your situation. Try a heat textbook (maybe an advanced one). Or you can hunt around in the literature. Google scholar maybe. I'm not sure how common this situation is. Perhaps you could try to discuss with someone that works with a device similar to what you are thinking of.