3 replies to this topic

[Engineers Are The Best]

hello every one well I am new in this forum and I want a very basic help from you people.My question is that I want to know that if a fluid is to be cooled from 200 to 150 degree fahrenheit by using cooler fluid at 100 degree fahrenheit in a concentric tube heat exchanger than i want to ask will the final temperature of the exit of cold fluid would be the same for the parallel and countercurrent arrangement.Please explain how and give some reference if you have some.I am actually regarding to problem 11.3 of the fifth edition of Unit Operations Of Chemical Engineering by McCabe and Smith

[latexman]

The best help I can give you is - read chapter 11. When you come to an equation you think you need to solve the problem, write it down as your basis on a sheet of paper. After reading the chapter, use the equations you wrote down to solve the problem and obtain all the answers. Then, turn this in as your homework.

No pain, no gain! ?

Do, or do not! There is no try. Yoda

[Padmakar Katre]

Dear,

If the problem is given there so it means its feasible but I would like to bring it your notice that Students forum is not for to solve your this kind of queries.What you want from us? That we should go through this problem and give the complete solution of it.....hummmm........

My dear whenever you are asking any query it should be specific.If you would have asked with giving the data and the exact problem where you had confusion probably somebody would have helped you but in this case no hopes.

My kind suggestion to you is just go through the topic thorougly and solve the problem you will get the right answer.
All the best.

Regards,

Padmakar katre

[Art Montemayor]

Your English and communicating skills are horrible! I got a headache just trying to understand your grammar, composition, spelling, and thought organization. I hope your engineering aptitude is just the contrary. Since you are a student, I am hoping that you’ll do some tremendous improvement on this handicap this school year. You will need all the communicating skills you can beg, borrow, and steal when (& “if”) you graduate as a Chemical Engineer.

Again, since you are a student, I believe you are having trouble understanding the possible difference that might exist between the approach temperature obtained in a parallel flow heat exchanger as opposed to that in a counter-flow unit. Am I correct? Here I assume that you know that the approach temperature is the temperature achieved by the one of the fluids in the exchanger as it reaches the exit nozzle of the unit with respect to the temperature of the other fluid that is entering the same unit. For the sake of simplicity and good engineering communications, please refer to the attached sketch in the Excel Workbook.

Note that in the first case of counter flow, the heat transferred is maximized. The approach temperature is maximized as well (since the heat transferred is maximized). However, in the parallel flow unit, the temperatures T2 and t2 start to get “close” to each other – the approach is closer and minimized.

I hope that is what you wanted to find out. If not, please explain in clear, concise terms and in good English.
 Heat_Exchange_Temperatures.xls   36KB   78 downloads