Posted 17 October 2010 - 12:28 PM
adi_6294:
Allow me to interject myself into this thread with only the intent of trying to fulfill what Ankur originally has tried to accomplish – to help you out in the best possible way.
Ankur is a very experienced and accomplished engineer who labors on our Forums with the honest and dedicated intention of helping Chemical Engineering Students. Sometimes student members fail to see and recognize what is being done with their (and only their) benefit in mind. They fail to identify the reality of the situation in dealing with a real, down-to-earth, experienced engineer and fail to take advantage of the opportunity that is seldom available to many students. By doing so, a grave error in judgment and a failure to capitalize on an opportunity and gain immeasurable experience and abilities has been lost. This is unfortunate for the student and leaves the professional engineer who wants to help in a position where he/she can only remain mute and regretful that the sound and practical advice being offered is rejected in ignorance or misunderstanding. The engineer goes on with his successful professional career; the student remains behind, with an excellent opportunity to increase his abilities and engineering awareness lost and un-exploited.
By cutting off the specific help and advice that Ankur offered, you have effectively cut off future communications with regards to your query – and consequently lost the link to what Ankur was preparing to offer as sound, experienced, and valuable advice and recommendations. You fail to recognize the specific manner in which you presented your query. That is why Ankur – being a polished and experienced engineer – immediately offered to get down to specifics, in order to guide you through a series of practical and detailed explanations of how a process engineer goes through that type of design. There are no "standard" heat exchangers nor "standard" parameters. Let me give you examples of some of the “general queries” you presented:
Change to salt (sea) water (one-side only)
You cannot “generalize” what is a specific detail. Are you referring to the tube side or the shell side? If seawater is applied to the shell side, it impacts on both the shell and the tube side! This is only common sense and is a lesson for all students to learn about analyzing and visualizing their design. If applied on the tube side, it only affects that side. As Ankur inferred, you must be specific if you want a practical, sound engineering answer.
Change to refrigerant(s)
This is a very specific-oriented query. As any experienced engineer knows, the employment of a refrigerant means that you will be evaporating that same refrigerant when you apply its latent heat. That means that from a practical (and common sense) point of view, you cannot expect to apply the refrigerant to the tube side. If a vaporizing refrigerant is to be applied, it must have the ability to free itself of the generated vapor and therefore, that leaves only the shell side as being available – and even then, it must be sized sufficiently large enough to ensure adequate vapor-liquid separation so that only the generated vapor is liberated for subsequent recompression in its refrigeration cycle. This, again, is common engineering sense. Therefore, you cannot apply the tube side and you must be specific about this.
Employ finned tube; inside only
What side are you referring to? Fins can be applied to either the shell or tube side – but the costs will be very different! You must be specific about what you intend to discuss. Generalities in this case only aggravate and confuse the entire issue and topic. Additionally, fins are only effective in vapor or gas service. They are totally inadequate in liquid service. Therefore, what are the specific fluids that you intend to discuss? I hope you see the futility of trying to be general and discuss these issues from only that position.
Students continue to believe they can apply “cook-book” or “standard”, “universal” equations or “Rules of Thumb” to resolve typical and general engineering problems and are frustrated to discover that they cannot expect to do so and gain any semblance of achieving professional engineering status in the future continuing to believe in a magical, easy, and convenient manner to resolve all engineering problems. They prefer to believe there is an “easy” way to become an engineer. There are no such things! There is only hard work, hard study, hard application, and the attainment of valuable experience and know-how with the application of the fore-mentioned. It takes a lot of hard work, risk, and opportunity to participate in important and complex engineering projects that leads to further knowledge and experience. And when you have an engineer who has “been there, and done that” who offers his/her kindly advice, you would be a very smart future engineer if you only open your ears, close your mouth, and heed what is said for your benefit. It is only common sense.
Forums
Blogs
Articles
File Library
FAQ
Search
FB
