Comparison of surface area between corrugated tubes and ordinary heat exchange tubes
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Wave tubular heat exchangers are being used more and more these days. How is the surface area of wave tubes calculated? Are there any empirical formulas for comparing them with ordinary shell-and-tube heat exchangers? I would appreciate some guidance
For ordinary coiled tubes, that is, circular tubes, there is a formula available for calculating their surface area, making it quite easy to do so. The formula is πxRXL – it’s simply the product of pi, the outer diameter, and the tube length. There are also many different specifications for corrugated tubes, and manufacturers provide the heat exchange area per meter of length for the most common specifications; in other words, it’s the surface area of such tubes over a length of one meter under specific conditions. For example, for our company’s corrugated tube with a pitch of 25 and a wave count of 32, with dimensions of Φ32xΦ25, the heat exchange area per meter of length is 0.0966 m2. If you need the surface area for other specifications of corrugated tubes, please send me a message and I’ll provide you with that information.
Thank you, moderator. We would like to replace the heat exchanger with a corrugated tube type heat exchanger; the heat exchange area should be 600 square meters, and the tube material should be 304. The original wall thickness was 0.8 mm, but we want it to be 1.2 mm this time. What is the approximate cost of such tubes? The manufacturers’ quote is 37,000–38,000 yuan – is that a reasonable price? Moderators, do you deal with pipes or equipment? How are the troughs and peaks of corrugated tubes fixed to the holes in the baffle plates?
The price seems reasonable; however, steel prices have been falling recently, so I’m not sure whether the current price has gone up or down. Overall, the price appears acceptable and not excessively high. For us in the equipment manufacturing industry, each corrugated tube doesn’t have corrugations and valleys throughout its entire length – rather, there are straight sections of varying lengths at both ends and in the middle, which makes it easier to fix and process. So, the issue of fixation can be resolved in this way.
May I ask how the surface area per meter of length for a corrugated tube is determined – is it measured through experiments? Empirical formula?
Our corrugated tube data is generally provided by the manufacturers of such tubes.
Moderator, I still don’t understand the issue of fixing the corrugated tube to the baffle plates. The tube sheets at both ends are understandable, but for multiple baffle plates, I think the dimensions of the holes in those plates should be larger than the peak values of the corrugated tube; as for the valley values, it’s even larger, so sleeves are needed for fixation. How is this usually implemented? I’d appreciate some guidance
I’m sorry, I’m not too sure either. Although we have pressure vessels, I generally don’t get involved in that area. The reason I know a bit about corrugated tubes is that they are widely used in evaporative cooling. Let’s take a look at everyone’s answers.
The conversion parameters should vary depending on the manufacturer; what we commonly use is the nominal heat exchange area
There are two methods for inserting tubes into heat exchangers. One is external insertion, where the tubes are inserted after the shell has been assembled; the other is internal insertion, where the tube sheet and shell are fixed first before the tubes are inserted. Bellows heat exchangers use the external insertion method, which involves fixing some straight tube sections on the baffle first and then inserting the tubes.
The corrugated tubes mentioned above are of the expansion-type; generally, the thickness of such heat exchange tubes is less than 1.0 mm. The manufacturing process for these corrugated tubes is relatively complex. Currently, there is a type of rolled corrugated tube available on the market, also known as an arc-shaped tube. Its heat transfer efficiency is similar to that of conventional corrugated tubes, but the thickness of this new type of tube can reach 2.0 mm. Moreover, the connection between the tube, the tube sheet, and the baffle plates is simpler, as no additional fixing sleeves are required. It is formed by rolling inward starting from the outer diameter. Generally, its area is calculated based on the area of the light tube. If you increase the wall thickness, it still has to be this new type of corrugated tube.