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[hydrobromic acid]

hi

we have to formulate a design of heating ethanol using extended surface heat exchanger. what procedure will i use? what kind of material will i use if i was given a mass flowrate of 100 kilogram per hour and an inlet temperature of 25 degree Celcius?

thank you

[Art Montemayor]

Hydro:

I don't know the exact or specific reason you were instructed "to formulate a design of heating ethanol using extended surface heat exchanger". There may be a specific reason for doing this. However, I believe that it is important - in case you don't already know it - that you know that an extended surface (external fins on the heat exchanger tubes, for example) doesn't do any effective improvement on the unit operation of heat transfer for liquids. Plain tubes will do a much better job --- process-wise and from a cost-effectively. I state this because you might have mis-interpreted the instructions of your assignment. If not, then your instructor is probably trying to point out something important in the exercise. It could be that you are employing hot air or gases to heat the alcohol. Am I correct? If so, then state so. It is very important to explain all the important basic data up front. Otherwise you fail to describe your problem and the responses will be flawed and erroneous - just as much as your explanation/description.

The ethanol flow rate has no value in selecting the material of construction (MOC). The ambient-level temperature of 25 ^oC indicates you can apply ordinary carbon steel. This is assuming that the terminal alcohol temperature is not too high (around 125 ^oC, max.). If the alcohol is used in an industrial process, carbon steel is OK. If the alcohol is used in a human food-based process, then stainless steel is the material of choice.

You ask for a procedure - but you don't explain what type of design you are asked to do: process or mechanical design? Learn here and now that you must be specific and accurate in describing what it is that you are trying to do. You waste a lot of your time and other peoples' time when you fail to specify exactly what it is that you intend to do and what your problem is. I have to assume that you also have already taken a process heat transfer course - or lectures. If so, then simply apply what you have been taught or have been told to read and study. It's as simple as that. We are not here to do your homework for you. If you have taken the related courses and have failed to understand and study the material given you, then you will fail the course and probably never graduate as a Chemical Engineer. It's as simple as that. However, if you try to solve the problem and come to a part that you don't understand, then perhaps we can help you out --- but only if you specifically and accurately explain exactly what it is that confronts and baffles you.

Await your reply - if you have a pertinent one.