3 replies to this topic

[visir]

Dear colleagues,

just few words to introduce myself. I'm an engineer working in the refrigeration and air conditioning branches. I worked with different fluids (R22, R404A, R407C, R134a, propane and CO2) but never with NH3. I'm interested in many technical aspects and I've read often the posts on several matters published in this site, mainly the chemical ones to try to find some interesting suggestion.

Now I'm studying an ammonia chiller with screw compressors and I'm looking for some references to design a flash tank economizer. In my career I never used this kind of vessel but I've read that is often used on chemical plants so I suppose someone can suggest me a good book or an article I can consult.

I'd like t have to improve the compressor efficiency using this vessel to cool the liquid ammonia making a little portion of refrigerant to evaporate. The vapour returns back to screw compressor economizer port.

My main concer is to size the vessel so it can operate at compressor full and partial load.

Many thanks in advance

[Art Montemayor]

Visir:

What engineering profession do you belong to and where are you located? When you say you want to “design” the economizer vessel, what type of design do you mean – process or mechanical? Do you have a thorough thermodynamic training in your background – preferably at the university level? You will need a thorough thermo calculation experience to start in on an economizer process design and proceed on to a mechanical design. I’ve done both I have also uploaded in the past a lot of sample calculations and process diagrams on how the ammonia 2-stage economizer process works, complete with detailed explanations on the process. If you do a SEARCH on our forums you should find a lot of this information.

In your post you say you have a concern, but you fail to specifically ask for help in a specific area or on a specific subject or material. Could you please be specific in your query – if your intention is to obtain help or guidance in generating a process or a mechanical design for an ammonia economizer. If so, you will have to upload a lot of necessary basic data in order to get down to your specific case.

If you are simply looking for recommendations on a text book, I can tell you that just about every university text book has a chapter or section on this subject.

Await your reply.

[visir]

I'm really sorry and for your reaction to my inquiry. Probably my English doesn't allow me to explain clearly. It wasn't absolutely in my intention to make other people waste their precious time. First of opening the thread I've searched the forum but unfortunately I didn't find the answer. Evidently I didn't use the proper key words.

However I try to be more clear. To calculate the thermodynamic properties I can make a balance of mass and energy and this is not a problem. I have a liquid that expands to a lower pressure so a pert of it evaporates. For the mechanical side it's a pressure vessel and I can design it.

What I was searching to undestand if there's something peculiar bound to the use of ammonia that I must consider, something that makes the calculation different. In every field there are some tricks that are known to this sector people. For this reason I've asked a suggestion of reference books/articles specific for ammonia.....if they exist. My main reference is the Industrial Refrigeration Handbook of Stocker but it doesn't provide many details on this topic.

I hope the misunderstanding now has been cleared. Sorry again Montemayor.

[Art Montemayor]

Visir:

There is no need to be apologetic. My reaction to any inquiry is the same: to offer help and explain how I can furnish it better, accurately, and efficiently. That is what our Forums are for and why I have asked specific questions of you. However, you haven’t answered any of them. However, I will try to offer my help one more time.

I presume that you want to generate a process design – and I also assume that you know what I mean by that. I can tell you from actual, personal, 50 years of experience in the field that there are no “secrets” in generating a professional process design for a 2-stage ammonia refrigeration cycle.

I am not familiar with Stocker’s book. I believe you mean “W. F. Stoecker” instead. Am I correct?
I have various thermodynamic books as well as refrigeration books (including ASHRAE) and they cover the subject in detail. Again, you are not specific and prefer to write in general terms, so I can’t be specific in order to help you. Sorry; but if you give specifics I know I can help you if you need that assistance.