ammonia refrigeration

[Mark C]

hi andy,

dont ammonia attacks aluminium?

chemi

Yes, and no. Certain Aluminum Alloys are more prone to corrosion than others, but mostly it is a function of the fabrication properties of that alloy which determines what one is used. Aluminum tubes are frequently used for Ammonia systems. Care must be taken of course to use dielectric couplings where transitioning to a steel piping system.

[Peter_1]

More and more shrill words to condemn, yet nothing is actually accomplished! ....

What has the US lost in Afghanistan? Only the fact that you need the country to install a huge oil -pipeline from Turkmenistan to Pakistan. The other route was via Russia which they didn't of course not preferred.

Don't forget also that they created there Bin Laden, they funded him with billions of dollars. Or was this not in your news?

What have they lost in Iraq now? Mass destructions weapons? The troupes didn't found any Gas weapons? Nuclear weapons? Zero decimal zero?
The only thing they wanted was a complete control of the oil.
The reasons why they attacked Iraq were seen afterwards all been false.

That's what Richard Clarke, anti-terror expert since 30 years 'Against all enemies' also said 2 weeks ago in his new book (was it in your bookstores or Bush bought them all at once?)
The whole state was shaking man.
Clarke know his job I think, otherwise they shouldn't let him there for so many yeras.

Exact same story for Kuwait? Such a small country. Why didn't they interfered in Rwanda where hundred thousands were killed, why they didn' t helped in the Sahel... One simple answer.

What have they lost in Israel?

I wonder if, Marc, you actually watched the entirety of what Bush says, or just the edited sound bites the press wishes to show to massage your views?

The speeches he gives is what other has written for him. Those who fund him, he's only a puppet on a string and has to do what his fund raisers advise him (if he wants to be elected in June)

Your press, it is my conclusion, manipulates your opinion through what they choose to show, and most Europeans, and Britons, do not get the entire truth. Like I said, don't live an unexamined life

It's the world upside down, you don't have a clue what we ares seeing here and what they tell us here. That's clear now.

It's your media which is so hypocrite. They beep the words f**k and s**t and some other obscene ( are they anyway?) out in every ting on the television but on the same time when they say f**k, they shoot somebody or put a knife in someone's stomach, completely unsecured and if they let show a breast, they fade it out. (what a pity) What's the logic in this.
What will frighten a kid more? Do you think kid never saw a breast before? It was the first he saw when he was born.

We dare to say for what we stand for, even if it's not the opinion of the US. And sometimes with great consequences. Look what happened with the Iraq crisis in Belgium. Belgium refused to cooperate without a UN resolution which was fair.
And that's why they have installed the UN: to prevent peoples like Bush doing stupid things in the world. Beut he was so egocentric when he said "well, i will attack, even without a UN approval"
He thinks he is God himself.

What was Bush' reaction to this: we will move the NATO headquarters in Brussels. Bush forgot that NATO not stands for US, he thinks that this building is a US building.

Thats the reaction of a child. I you don't do what I' saying, then I will take your candy.

I didn't turned my head when Janet Jackson showed her breast. And in the US it was big news, it even overwhelmed the Iraq news.

[Mark C]

What has the US lost in Afghanistan? ....

Hey Peter, you Euro-boob. Get back to the topic at hand... Refrigerants, specifically in this thread ammonia. I tire of your diatribe of stupidity and blathering.

[Mark C]

Hey, Peter, did I tell you what they call Americans around here these days? Lol, seems I did

Oh, Marc?? If you cannot keep topics "on topic", in a professional refrigeration fourm, and cannot resist delving into that trashing of members and participating in such.... Well, you are not much of a "Moderator".

[Andy]

Hi
we Irish are slowly learning to keep our politics to ourselves, it has been a painfull slow lesson played with peoples lives
I suggest you guys keep your politics to yourselves, for fear you end up like we did in the North of Ireland

On a lighter note why do we even bother using ***** Ahh now I remember so we can charge the customer for endless hours leak testing

Kind Regards. Andy.

[Mark C]

"....On a lighter note why do we even bother using *****

Hold that thought!! I like that idea....

[baker]

I wonder how much of ammonia's success is due to it not being miscible with oil. Lack of oil in the evaporator must surely make it more efficient.

It has been reported that R410A is inferior to R22 theoretically (thermodynamic calculations) but better in practice. With oilless compressors now becoming available, it will be interesting to see if they are ever used with NH3.

[jg/oz]

Friends,
if this is the way we are going to correspond to each other than I am
out of this conversation. I think we have an ethical Code of Conduct
to behave on this Forum
jg/oz

[RogGoetsch]

In scientific circles, there is a testing procedure known as "double-blind testing" in which neither the test subjects nor the professionally-trained observer knows which subject received the real drug and which received an inert compound.

It has been discovered that this procedure is essential because even a professionally-trained observer trying only to be unbiased is unable to do so if he knows which drug is real. His beliefs about the test affect his observations.

Since our biases affect our very observations themselves, how can we possibly hope to know the truth if we can only perceive what we already believe to be true? We can't. We tend to accept evidence that supports our beliefs and discount evidence that does not.

Moreover we identify with our beliefs and feel that anyone attacking those is attacking us personally.

The scientist recognizes that everything rests on assumptions, fallible observations and fallible processes. So to think rationally means we must doubt our own conclusions and seek the errors in our own thinking all the time.

The opposite of this is certainty. This is the hallmark of those who have closed their minds. If you are certain you are right, you are not operating in the domain of rational thought but in that of emotional "rationalizing" thought. This is natural because our experience is more powerful than our thinking. If you experience a feeling, the rationalizing brain has the relatively simple task of rationalizing the feeling rather than reasoning towards the truth. Evidence which contradicts the feeling can be ignored since it is obviously in error.

So the first clue that you are not really thinking is that you have a strong feeling about the subject. The second clue is that you are convinced you are right. The third clue is that your thinking is simplified: you think in categories (liberal vs conservatives, evil vs. good), generalizations (those people are all jerks, inferior), and other simplifications. The fourth clue is that you don't refute ideas, you attack the holder of the idea (ad hominem attacks).

My own technique for trying to approach the truth is to assume that human nature is pretty much the same everywhere. Self interest tends to bias perception for everyone about the same. I think most people are sincere in believing what they are about is in the best interests of humanity.

The men who piloted the airliners into the World Trade Center believed they were doing God's work and striking a blow against Satan. The men who called for a bunker-busting bomb to be dropped on a residential Baghdad neighborhood because they thought Sadaam was there believed they were waging a war against "evildoers" and the loss of innocent lives would prevent larger losses later.

I suspect what we are seeing is a stage in the evolution of humankind. We have evolved to a point where we are altering our entire environment by using our rational minds, but we have not yet learned to act rationally. Will we make it?

Rog

[Andy]

jg/oz
don,t take these guys seriously, they are all piss and wind I don't think any of them are entirely serious about the political ideals they are coming out with.
I know for a fact that Marc is taking part in a little known past time called Yank bating, which to date has been quite sucessful.
I fear our friends accross the Atlantic take critisim from europeans much too much to heart. If the same debate was to go on between two europeans, the needling would not be taking anyway near as seriously.
Kind Regards. Andy

[Mark C]

Says who?

Says, me, you twit. "Pouncing" ... "tearing apart"??? Get a life and get real. You came to a battle of wits unarmed. You are not much of a moderator in a professional forum in which you take part in this O/T baiting game. You are a "Euro-boob" yourself.

GET BACK ON TOPIC, or go elsewhere. This is the absolute last time I will respond to anything you ever say that is not refrigeration related. You are a failure.... GOODBYE!

[Mark C]

I wonder how much of ammonia's success is due to it not being miscible with oil. Lack of oil in the evaporator must surely make it more efficient.

It has been reported that R410A is inferior to R22 theoretically (thermodynamic calculations) but better in practice. With oilless compressors now becoming available, it will be interesting to see if they are ever used with NH3.

Oil management is indeed quite different with ammonia. It does require a different mindset. I sure would not say that there is a complete lack of oil in the evaporators and throughout the system! The immisicibility of oil in ammonia is one of its attributes!

It is quite possible to completely log an avaporator with oil, and, like all oil in a refrigeration system, it acts like an insulator. It is not an uncommon experience for me to have shown up on a service call that a room will not cool to find an oil-logged evap! Usually, this is at a time when the hot gas has not kept pressure high enough to blow the oil through on defrost. (As in winter or other low ambient conditions) Sometimes, it is just an accident of piping or valving (disrepair) that allows this to happen.

Make no mistake, oil needs to be managed in the ammonia system.... It needs to be recognized that it settles in and needs to be removed!! I have one client who lets it accumulate for the entire grape cooling season in California. When all the grapes are shipped after that season, it is their time to drain oil.... hundreds of gallons of it! Per coil. Mind you, these are huge pressure cooling systems that have huge coils in a bunker-coil setup.

I have not played with the newer replacement "*****s" to have any opinion on them. However, I do not believe that any design consideration will call for the ammonia industry to attempt the use of "oil free" compressors. It just is not a big deal to go drain oil once in a while!

[Mark C]

In scientific circles, there is a testing procedure....

Rog

<<<Scratching head>>> Ever the diplomat, Roger! (All while holding a club that the other fails to notice.) You never change, and I like that! Rog and I went to the same school, and have worked at the same company.... we go "way back".

[WebRam]

Gentlemen.

I do believe you have went "off Topic"

Please return to topic, thanks

[chemi-cool]

hi mark,

dont you use oil separators in ammonia based systems?

chemi

[Mark C]

hi mark,

dont you use oil separators in ammonia based systems?

chemi

Yes, chemi... These are typically coalescing filter elements that are installed post compression. (It is rare today to use a central vessel to do this.) However, these are not 100% effective, and They pass about .05% of the oil anyway if they are in good condition. So the oil circulates freely in the system and winds up in the low spots, which are typically at the bottom of liquid recircualtors, and Oil distallation Pots are used to remove it from the system.

[chemi-cool]

hi mark,

the reason I asked is that some years ago I was asked to look at a condensing unit ( a miniture in your respect) 20 HP that was feading 100% fresh air 25 meters below and the oil presure controls triped every week.
the tech that was looking after it said he had added some 40L per month!!!!!
of oil.

there was no oil separator used!! strange design.

left them an offer to fix the unit and after two weeks they called back- now it is not cooling either!

what I did was recover all the gas, install an oil separator and.... at the bottom of the evaporator brazed 3/8 tube and an SV controlled by compressor's contactor that opened for 30 sec 5 min. after unit came on.

the end of this tube went int the suction line just before the condensing unit.

because of the presure dif. it pushed the oil that left inside the evaporator up.

after recovering the system, 45L of oil came out!

chemi

[Mark C]

I'll bet!! Yikes!

[chemi-cool]

so why not use it in ammonia systems?


chemi

[Mark C]

so why not use it in ammonia systems?


chemi

I guess the best response would be that it just doesn't matter all that much. The oil in an ammonia system gets trapped mostly in the oil coalescing filters at the compressor oil seperator. The small amount that gets by that gets trapped in the oil distallation pots. The small amount that gets past both of those generally gets blown about until it settles back into the oil pots.... We simply drain it when it is there.

Only on the oldest of systems where there is no coalescing oil filter at the oil seperators do we see quite a bit of oil to be distilled. It's just a part of the normal "things to do".

[Andy]

Hi chemi
on our low pressure receiver systems, we would automatically drain the oil from the receiver, PAO oil is used in these systems. Doesn't really matter about a little carry over as it all makes it way back to the LPR and is rectified.
Mark/Chemi
before you ask an LPR system is a liquid over feed system, with usually one or two coolers on it. Liquid is fed into the evaporators by an expansion device, much like DX, the liquid comes out the cooler suction line and is trapped in the LPR and boiled off by indirect heat exchange using the haet available from the liquid off the condenser, subcooling the liquid in the process.
Nominal capacities are 100 to 400kW at -30 C evaporation.
Kind Regards. Andy

[Mark C]

Lol, what's there to arm myself for?

Back to the subject at hand.

[Mark C]

Hi chemi
on our low pressure receiver systems, we would automatically drain the oil from the receiver, PAO oil is used in these systems. Doesn't really matter about a little carry over as it all makes it way back to the LPR and is rectified.
Mark/Chemi
before you ask an LPR system is a liquid over feed system, with usually one or two coolers on it. Liquid is fed into the evaporators by an expansion device, much like DX, the liquid comes out the cooler suction line and is trapped in the LPR and boiled off by indirect heat exchange using the haet available from the liquid off the condenser, subcooling the liquid in the process.
Nominal capacities are 100 to 400kW at -30 C evaporation.
Kind Regards. Andy

Ummmmm, not really.... I'm well aware of the nomenclature of the ammonia system. However, these systems sometimes have sixty or more evaporators, ice makers and other heat exchangers on them. I would not limit them to "one or two coolers on it." I have designed, installed, and operated systems with 9,800 connected BHP operating at multiple temperature levels down to minus 60°F.

Liquid is fed to the evaporators through a hand expansion valve which is actually used as a balancing valve. The actual expansion to low temperature happens within the recirculator vessel, and not at the evaporator.

when heat is added at the evaporator, the liquid present then flashes to vapor, absorbing the heat. There is no DX evaporation, and certain not any superheat generated. There is no TXV or superheat to be "set" here, and two to five times the vapor weight (depending on temperatures and the needs of the circuiting) is returned to the recirculator vessel via gravity after exiting the evaporator and riser.

The returned liquid is then pumped out or "recirculated" to the evaporators again. The oil, usually heavier than the refrigerant liquid is traped in the recirculator vessel. What small amount does get out to the evaporators is returned with the liquid ammonia returning from the evaporators after a high load "blows it through the coil" or the coil is defrosted, and drained of all liquid.

Oh, and there is nothing "unreliable at best" regarding a properly designed and circuited ammonia refigeration system. As a matter of fact, there is nothing more reliable or efficient! Anybody that uses a TXV on an ammonia system really does not understand the proper design and use of an ammonia system. TXV should rarely be employed on an ammonia system.

[Andy]

Hi Mark
LPR systems may have only a few coolers on them, but they are not DX in nature but liquid overfeed. Charges are critical, and thus an LPR system allows Nh3 to be used where it would normally not be aceptable.
Pumped Nh3 has it's place, but that would not be on the roof of a building in London. LPR chillers are now quite common on government building in London.
The only DX Nh3 we use is for economisers on plate and shell heat exchangers
Kind Regards. Andy

[Andy]

Andy, surely the most widely seen application of ammonia is in the form of liquid overfeed, LPR or PLA, because overfeed assists oil return

I would say so. I did see a good aplication of DX Nh3 once. A compound compressor plant had an extra high stage compressor, to handle the a high temp side load at intermediate pressure. The rooms requiring high temp cooling were fed H.P liquid by DX valves and the subsequent dry return was fed into the interstage closed flash intercooler.
But that is the only one in 15 years
So DX Nh3 is not common.
Kind Regards. Andy.

[Andy]

Hi Mark
yep a loading bay also. Neat solution where only a small to medium sized HT load is required.
Kind Regards. Andy

[shogun7]

When I joined this forum It was with the express purpose of trying to help others in our industry with my 40+ years of experience, but it didn't take long to get bashed buy adolf and a few others with your chicken **** politics. Some of you have a real problem understanding us "Colonials" .

Admin note
this poster goes on to express his opinion in a rather forceful way.

[WebRam]

OK, I gave you all a chance to get back to the subject.