There are some aspects of the design of shell-and-tube heat exchangers that are hard to understand

This post was last edited by wiseboy on 2015-6-4 19:05. Assuming a heat transfer coefficient is a poor algorithm and an unreliable approach. Almost no one does this. The correct approach is to assume a specific heat exchanger design, then accurately calculate the heat transfer coefficient and the amount of heat transferred; if the area is insufficient or the pressure drop is inappropriate, the design is adjusted accordingly. There are also several approaches to adjusting the structure; mathematically, this is referred to as multi-dimensional optimization. When doing it manually, the pipe length, the number of pipe passes, the shell diameter, and the pipe spacing – these four variables are adjusted one after another, which constitutes 4-dimensional optimization. Software algorithms (such as Heat Exchanger Master), as well as optimizations involving more than 4 dimensions such as tube arrangement patterns and tube specifications (outer diameter, wall thickness).

Still not quite understanding? If that’s the case, then without assuming a heat transfer coefficient, how can we know whether the subsequent heat transfer area is sufficient? Shouldn’t there be two sets of data for comparison?

It’s not necessary for them to be exactly the same; it’s sufficient if the heat transfer coefficient you calculate later falls within the range given in the manual. You should keep in mind that this is an estimate – performing calculations according to the book and retaining n decimal places is also an act of estimation. . .

My previous method. Q=AKT. First, design a heat exchanger arbitrarily, calculate K and T, etc., until you get A; then check whether this A is suitable for the heat exchanger ； It is not appropriate to adjust the heat exchanger parameters to match K, T, and A; of course, flow rate and pressure drop must also be taken into account.

Calculating heat exchangers is quite complicated; it is best to know the properties of the medium, etc., and use specialized software for the calculations.

This post was last edited by arpcd on 2015-6-5 15:30. Has the original poster obtained a driver’s license? ? Take the task of moving the vehicle and adjusting the rods (I don’t know which subject this falls under) as an example: at your current stage, the driving school instructor has already told you the key points for performing this task (you already know the process for calculating the heat exchanger), and your question now is how to actually complete this task. . There is only one way —— calculate it by yourself! To complete the course, you need to get in the car and give it a try! Without doing the calculations, those principles and steps are nothing but worthless details – things like how to choose K, what shape the heat exchange tubes should have, how many tubes are needed, and what arrangement to use, etc. All of this can only be understood gradually through the actual calculation process (which involves multiple calculations, repeated iterations), preferably with reference to real-world engineering data. . . Go and give it a try – can you successfully move the car into the garage? ? For questions as straightforward as this, you can only solve them by doing it yourself. . It seems the original poster hasn’t even calculated a single heat exchanger, whether manually or using software. What you lack is not the methods or tools, but rather the diligence to do the work yourself.

This post was last edited by wiseboy on 2015-6-5 18:47. If the specific structure is assumed, can its area A and heat transfer coefficient K be calculated accurately based on that structure? At this point, its actual heat transfer capacity Qr is given by: Qr = KA△T. Once again, it should be emphasized that Qr represents the actual heat transfer capacity of the structure as assumed by you. The required heat amount Qo is determined by the heat balance; it represents the required heat transfer capacity. If Qr