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In this post I’ll list a few resources to find fouling factors for your heat exchanger designs. But first, let’s take a step back and review the definition and purpose of fouling factors in heat exchanger design.
Recall that in the heat exchanger sizing equation Q = U * A * LTMD, the “U” factor was a representation of all the resistances of heat exchange between the two sides. “U” was influenced by the types of fluids in the exchanger and also to a lesser degree by the material of construction of the heat exchanger. The fouling factor helps us add some additional detail, by representing the extra resistances that appear on the inside and outside of tubes after an exchanger has been operating awhile: the caked on products of fouling. There are different types of fouling, from crystalline scale to literal pieces of gunk. Fouling introduces a wrinkle into our simple equation, because now the resistance to heat exchange varies over time. But we still have to pick one exchanger design and one “A” value for the entire cycle of operation.
A properly chosen fouling factor will inform the detailed design of heat exchangers by vendors and/or software. As always, the best values to use are real-world values based on experience or tests in your own plant. Nevertheless, it’s helpful to have literature values for a starting point.
Some Literature Sources for Fouling Factors
Note that some of these links are PDF files: Continue reading
After a little downtime we are back! I have added a new category, Cost Estimation, to our store of suggested books. The collection of books by John Page, also called “Page and Nation” by some, are a great way to get manhour requirements for installing piping, HVAC systems, cable trays, and other items.
With the growing opportunities in Latin America, I’ve found myself having to deal with the occasional document in Spanish, despite never having taken so much as a high school class in Español. (I ended up with another language instead.) In some cases I’ve had to sift through getting everything in Spanish: the process description, P&IDs, you name it. Of course “you’ll need to start learning the process before we’ve hired the translator.” How to cope with a language you’ve never studied?
- Get electronic versions of the original documents. Get everything you can in text you can copy and paste. The less familiar you are with the characters of the language, the less able you are to type the words yourself, the more important this step is
- Piece by piece, run small parts of the process description and other text-heavy documents through the best translator I can find
- Research key words, tricky terms and language rules on a case-by-case basis it comes up.
- If at all possible, find someone who speaks the language (or even a related language) who can help you puzzle over the few remaining intractable issues. Or beg your boss to let you hire a translator for a few choice passages.
- Using your new understanding of the words and process, make sense of the P&IDs and other drawing
Here are some tools and tricks for steps 2 and 3: Continue reading