ammonia refrigeration system

[Lc_shi]

Hi Sir
Ammonia refrigeration system is new to me ,who like to give me a brief about it:
# how about the normal working pressure and temp;
# the compressor and other components is different from ***** system?
# the advantage and disadvantage in comparison with ***** system
# application scope: if it possible to apply in AC area
# others

thx in advance

regards
LC

[Peter_1]

Hi Sir
Ammonia refrigeration system is new to me ,who like to give me a brief about it:
# how about the normal working pressure and temp;
# the compressor and other components is different from ***** system?
# the advantage and disadvantage in comparison with ***** system
# application scope: if it possible to apply in AC area
# others

Some quick answers before starting to work:
Pressure and temperatures can be compared +/- to those of R12 (remember the good old times)

Compressor is always an open type (copper windings can't withstand NH3) mostly economically used starting at 250 to 300 kW, pistons or screws.

Steel lines you can't solder yourself unless you're qualified (at least in Belgium)

All the regulation devices are made out of steel, condensers and evaporators also.
Condensers mainly evaporating condensers....water threatening systems for these.

Seen never another system then a pump system with LP receivers, mostly 2 pumps/receiver.

System is necessary to provide oil return.

If NH3 is used for freezing systems, an air purger is often used.

For AC....?? If a secondary brine is used because you can't let flow NH3 through copper lines.

With the Bitzer software (German compressors), you can compare same compressors for different refrigerants and play a Little bit with same evaporating pressures and condensing pressures and compare once the different COP's.

[Brian_UK]

LC, also have a look at www.robur.com for a gas fired system, they have manuals for download if required.

Brian

[deepakrbhat]

Also there is a huge thread with regards to construction of a small capacity ammonia system....around 1.5years back
Definitely it has got a lot of insight....i guess it is in the refrigerants fourm
Regards

[US Iceman]

LC,

Copper or copper alloys cannot be used with ammonia. The usual materials of construction are: carbon steel (for valves, vessels, & piping), cast iron (for compressors), stainless steel (for vessels or piping).

All piping connections are either: flanged, threaded, or welded.

Insulation and vapor barriers are a critical aspect of ammonia systems since most of the components are carbon steel and rust very easy. The installation of the insulation must include vapor barriers to prevent moisture from reaching the cold pipes. Most of the corrosion found on ammonia vessels and piping is due to badly installed insulation systems.

The normal design condensing temperature is 35C (maximum). Slightly lower design condensing temperature help to reduce the required input power.

Instead of cap tubes to feed the evaporator in an ammonia system we use: thermal expansion valves (TXV's), hand expansion valves.

The evaporators can be designed for: flooded, liquid overfeed (liquid recirculation), or TXV's.

The condensers are almost always evaporative type or water-cooled.

Ammonia is normally less expensive than the other refrigerants.

Ammonia stinks and this creates a lot of panic. Ammonia liquid is very dangerous, since it absorbs a lot of heat. The liquid also produces a caustic chemical burn to skin. Ammonia is bio-degradable with no ozone depletion factor.

Leak checking is very easy.

Ammonia reacts with chlorine so these should never be mixed together.

Water will absorb large quantities of ammonia.

I have attached a vapor pressure curve for ammonia (also called NH3 or R-717).

To compare mass flow and volume flow rates you can easily develop these to see the differences.

For purgers I recommend these on all ammonia systems. As Peter said, when the system uses ammonia for freezing, the refrigerant vapor pressures are below atmospheric pressure (below -33.3C).

Air can leak into the system and increase the discharge pressure. Air can also get into the system during service and charging. I recommend purgers for any ammonia system to reduce the air in the system.

If you have the ASHRAE Refrigeration Handbook look in the chapter for ammonia systems for additional information.

I have also included a typical information sheet about ammonia as a refrigerant.

Hope this is helpful.

Regards,
US Iceman

[Lc_shi]

Thanks for all your input-
It seems ammonia system is not suitable in AC area, the discharge temp is much higher than R22 at similar pressure.

regards
LC　

[Cofreth]

Thought Ammonia refrigeration system was already outdated??

[Lc_shi]

I don't think it's outdated. Ammonia is more environment-friendly. It should have more application.

[US Iceman]

Ammonia is still a viable refrigerant. Some of the issues relate to the safety aspects for it's use. Ammonia stinks, so anytime some leaks from a system instant panic occurs for persons unfamiliar with this refrigerant.

In almost all large refrigeration systems, ammonia is the refrigerant to use. There have been some occasions where large R-22 systems were used. This happens when the system is near a large population and the idea of a large ammonia system scares the population.

Ammonia can be used for AC systems. I have seen large central chilled water (and glycol) systems used for commercial buildings. When I worked for a manufacturer we had an ammonia water chiller for the office air conditioning. (In the center of town!)

I have also seen large thermal storage projects where ammonia is used. These have been located in cities also.

The higher discharge temperatures are due to the higher specific heat ratio of the ammonia vapor. This is not the reason why ammonia is not used for AC.

Ammonia can not be used as a direct refrigerant. Let's say you have an air handler that has a refrigerant coil for cooling. R-22 can be used for cooling, but not ammonia.

Indirectly, ammonia can be used to cool water or glycol. The water or glycol can be circulated through the coil for cooling.

This is part of the safety code for refrigeration systems here in the US.

Anytime ammonia leaks from a tank or system, the news reporters try to tell everyone that the gas is poisonous and the people will die.

Ammonia is dangerous, but then so are all of the refrigerants.

[US Iceman]

Found something you guys may be interested in reading...

On the continent, ammonia air-conditioning systems are already commonplace. The SAS Radisson Hotel in Denmark, a high occupancy building in the heart of Aarhus town centre, has been successfully guaranteeing its guests’ comfort through the operation of water-cooled ammonia chillers for over five years. In the UK, four 6.6 MW ammonia chillers have been installed in the energy centre at Heathrow Airport to provide chilled water for the air conditioning system in the new Terminal 5 building.

There is no doubt that ammonia has now been firmly re-born into air conditioning. Its future-proof potential and environmental advantages will ensure this is not just a passing vogue but represents a long term, viable alternative to HCFCs and, even, HFCs.

This was taken from this link:
http://www.modbs.co.uk/news/fullstor..._chillers.html

You may be seeing more ammonia equipment as the trend catches on!

[Lc_shi]

very interesting topic--ammonia water chiller for AC area.
i know there is absorption ammonia chiller or heat pump but i'm not sure if there is compression type ammonia water chiller or heat pump. need do some research-
thx for all your valuable comment--it's a free lesson-

rgds
LC

[willie]

if you are not experienced or have'nt worked on ammonia leave it to those that are experienced, that way no one gets hurt or system gets damaged

[US Iceman]

A refrigerant is a refrigerant. Ammonia, R-22, or CO2.

The use of any refrigerant for a particular application must be carefully selected for the desired operating conditions, type of equipment, and equipment limitations.

Compression systems for ammonia are only limited to imagination and in some cases, local safety codes. I have heard of ammonia heat pumps up to about 100C, and ammonia compression for chilled water production.

One of the biggest differences between a commercial "*****" system and an industrial ammonia system is the type of equipment and how the equipment is used.

Persons working on an ammonia system must be familiar with the technology and components. Processes done in an ammonia system might be totally different from what may be expected in a "*****" system.

willie raises a good point! If someone does not fully understand the system, walk away from it.

Sulphur dioxide was also used as a refrigerant. This smells worse than ammonia. Since most of the "new" refrigerants do not exhibit a strong smell, does not mean they are totally safe.

All refrigerants can cause death. Treat all of them with respect and understanding.

[frank]

i know there is absorption ammonia chiller or heat pump

Not a type of installation I've heard of

But I would be interested in reading any info available.

Ammonia is not something I have worked with so I'm up for being educated, although I have seen ammonia plant working.

[iceman007]

Ammonia is the most efficient refrigerant. 3% more than R22 and 10% or so more than R134a. Like any refrigerant it has it's good and bad points, on the plus side it's thermodynamically stable and will condense and evaporate pretty much at constant temperatures, the valves and other componenets are usually smaller than standard CFC HCFC systems because of the high latent heat capacity and thermal transfer characteristics. Moisture if it gets in has to be removed because it usually gets to the coldest part (evaporator) and needs to be removed, but on the whole the components are reliable, and less refrigerant is necessary to achieve the same degree of heat transfer than halocarbons. The plant is different and it sometimes in the past has intimidated some of our guys, but like anything else it's knowledge of how it all works. My opinion is that you need to know what you're doing with it, but a good refrigeration technician can learn it with time. I think ASDA have used ammonia/CO2 systems in one or two of their sites.

James
(PS I might be able to forward something on to you Frank-if I find it I'll send you a message)

[botrous]

Not a type of installation I've heard of

But I would be interested in reading any info available.

Ammonia is not something I have worked with so I'm up for being educated, although I have seen ammonia plant working.

A hotel here have an ammonia chiller that have the heat source comming from an oil burner (fuel oil # 2 ) and i think it's the only one in the country as an ammonia chiller . . . went to see it once with a fellow friend but never worked on it myself . . . so if there is more information about this subject i will be glad to see it

Regards

[Frosty]

Hello US Iceman

'Ammonia can not be used as a direct refrigerant. Let's say you have an air handler that has a refrigerant coil for cooling. R-22 can be used for cooling, but not ammonia.'
Is that really the case in the US? Over the pond (UK) NH3 is frequently used as a direct refrigerant - coldstores, distribution centres etc. It's also being used as the high stage refrigerant in CO2 cascade systems more and more frequently. Take a look at the following web site
www.star-ref.co.uk I think the hyperlink has gone pear-shaped! Type it in manually, there's lots of interesting stuff in here.

[US Iceman]

Hi Frosty,

Ammonia can not be used as a direct refrigerant. Let's say you have an air handler that has a refrigerant coil for cooling. R-22 can be used for cooling, but not ammonia.

You are correct also.

The ASHRAE safety code for refrigeration lists both direct and indirect systems. A direct system would be an air handler for comfort cooling with people. You can use chilled water (indirect, & cooled by ammonia, if you follow the safety codes and the correct guidelines), but you cannot use an ammonia coil in the air handler (direct).

For cold storage or food processing, etc. the use of ammonia is OK. The difference is the type of occupancy, and the refrigerant type.

Ammonia can be used for industrial occupancy, but not commercial (more people).

Everything you have written I agree with. What I should have said in my earlier post was, " Ammonia can not be used as a direct refrigerant in some types of applications".

It is a safety issue.

When I was talking about air handlers, I meant the very large sizes you see in commercial office buildings. Not ceiling hung cooling units.

Nice catch on a subtle point.

US Iceman

[TXiceman]

The only place I have seen ammonia absorption used is in process cooling. While is is similar to Li-Br absorption, it is totally different. Where a Li-Br sytem used the water as the refrigerant and the Li-Br as a transport agent, the NH3 absorption system uses the ammonia as a refrigernat and the water as a transport agent. Since the NH3 is the refrigerant, you run run much colder evaporator temps (double and triple effect systems) and not limited to the freeze point of water.

The last time I saw a NH3 absortion unit here in the states was for a project in California for a refinery. These things are huge built up process plants and typically cost 5 to 10 times the cost of a mechanical plant of equivalent capacity.

As for mechanical units, I have built several NH3 screw water chillers for chemical plants with capacites ranging from 100 HP up to 2500 HP, both electric drive and steam turbine drive. Personally I prefer to use ammonia in the larger systems over the "*****s".

In the states, if you are interested in NH3 systems, two excellent organizations to coantact are IIAR and RETA. RETA offers a PSM accepted Ammonia Operator training courses .

As noted above, if you are not familar with NH3 and it safety practices, you need to get someone that is familar with NH3 to take care of the problem. Likewise, propane (R-290) is a good refrigerant. It is a safe refrigerant and can be used in a lot of applications. It is all in knowing how to handle it.

Ken

[frank]

Hi frosty

Long time no speak - what brings you back to the forum

If you still need some one to one training in Fridge give me a ring

Frank

[Lc_shi]

TXiceman,
propane(R-290) is a safe refrigerant? It is ignitible.How about its application?

rgds
LC-

[US Iceman]

Hi LC,

R-290 is very similar to R-22 performance. Yes, the propane is flammable and requires the use of explosion proof electrical components.

All electrical components must be "spark-proof". The control panels are usually made from cast aluminum enclosures, or use water-tight control panels that are purged at a positive pressure with dry nitrogen.

The facilities where a propane refrigeration is used will be familiar with these requirements.

Like R-22, propane has some oil solubility issues and the oil used must be carefully selected for the operating conditions.

I'm sure TXiceman will have some good information to share also.

[TXiceman]

Any refrigerant can be unsafe if not handled properly. A lot of chemical plants and refineries use propane as they have it on hand as a feed stock. They usually have a propane grade that is lower than refrigerant grade and contains some light end and heavy end hydrocarbons.

It is fairly comparable to R-22 in properties and efficencies, but does have the requirement of a Class 1, Group D, Division 2 area in the states. I believe in Europe requires an IP54 area. All sparking devices have to be contained in a cast NEMA 7 box or in a purged enviroment.

There are oil solubility problems with the hydrocarbon refrigerants and nearly everyone uses a snythhtic based oil now. The one use most of the time is a polyglycol based oil.

With the oil and it's affinity for the refrigerant, it is very critical to keep the oil warm during operation and during all off cycles.

Propane does not have a large tendency toward high discharge superheat and therefore does not produce very high discharge temsp and can create problems with oil injected screw compressors and over cooling of the oil.

Some companies and local authorities require the use of a cast steel compressor case inlieu of the more common cast iron compressor case. This feature alone can double or triple the cost of the compressor. Most plants will want B-31.3 piping as a minimum and all steel body valves for the propane service. Generally when comparing an R-22 system to a propane system, the initial cosr will be a minimum of 20% higher on the larger systems and it can approach 50% more on a smaller system.

Ken

[frank]

Hi Ken

This may be of interest http://www.protectingpeople.co.uk/fi..._explained.htm

[knudo]

Could you elaboarate on the different type of evaporator designs. How does each work ???
Regards - Kevin

[bigtwin]

Hi guys, my first post here so let me introduce myself. My name is Bob and the nic' "bigtwin" thats cos I ried and build hogs. It is important to consider that the carbon foot print created per / ton refrigeration is approximately 20% less using ammonia when compared with R507 etc.....

[TXiceman]

Could you elaboarate on the different type of evaporator designs. How does each work ???
Regards - Kevin

Which type of evaporator designs?
Flooded
Thermosiphon
DX
Spray
Shell and tube
plate and frame or brazed plate?

Ken

[Sridhar1312]

Germany has sealed compressors for refrigerators commercially available.Even in India I happen to see the NH3 Ammonia Refrigeration system at "SAFAL" cold rooms and there is no trace of ammonia smell any where near the plant also.

[nejatde]

Hi friends,
I am looking for a comprehensişve Ammonia refrigeration e-book...Any information on it?
Thank you

[James priyono]

wanted to give the idea to the producer of the AC to make the split AC that his evaporator not fast leaked because of the refrigerant pressure.

Must be known by you damage that often happened in the split AC was baldness in the evaporator part, was caused by the refrigerant pressure that was so high when the split AC was not operated on.

When the split AC was not operated on by the pressure on the cooling system that is compressor, condenser, installasi the ac pipe and the evaporator was in the high pressure/high pressure.
So as to make the evaporator so susceptible to the pressure because this part was always irrigated because of the process of condensation that made pipes in the fast evaporator corrosion.

Apparently from the producer's side of any ac did not make an innovation so that the not fast evaporator leaks from the pressure ***** when the split AC was not operated on.

Was not possible for the producer of the split AC to increase the thickness of the pipe to the evaporator, because of increasing the refrigeration capacity also became high.

So I proposed that the producer of the ac made some product the AC that his evaporator kept by the refrigerant pressure , that is by means of adding one condenser that his measurement was the same as the evaporator in the part outdoor unit.

His function was to accommodate *****/refrigerant that ought to be dievaporator was moved be alloted condenser in addition at the time of the split AC was not operated on, so at the time of the split AC was not operated on by the pressure on the evaporator of becoming low/low pressure.

This method indeed like did pump down when wanting to overhaul the split AC that was different was at the time of did pump down all ***** entered in condenser, but when being added by one condenser and several the tap selenoid valve the burden of the pressure on the evaporator of becoming light at the time of the split AC was not operated on.

My idea, could maintain the evaporator from baldness? Please the answer from friends....thx and Sorry when my English was not so good.

[josei]

Hi friends,
I am looking for a comprehensişve Ammonia refrigeration e-book...Any information on it?
Thank you

Take a look at books.google.com and search for industrial refrigeration. In the 1st. page shown can see Stoecker´s Industrial Refrigeration Handbook link to more content included a complete toc.

[sterl]

Ammonia systems are expensive because they are built like industrial systems, in large increments of capacity, with very rugged and enduring pieces.
There are very few 1000 Hp compressors cooling their motors with refrigerant gas; so open drives are considered advantageous because they are more tolerant of electrical faults and can more readily be renewed.

The circuits are easily expanded, virtually indefinitely. We often run out of machine room footprint before we run out of vessel or pipe capacity.

Mineral oil is not normally considered immiscible in ammonia so the separation and return topic is addressed right at the compressor or centrally between the compressor of one stage and the interstage cooler, or alternatively the condensers.

Compressor cooling, liquid distribution, evaporator circuiting and so on is nowhere near as sensitive a topic for ammonia as it is for most of the halocarbons, so using a single evaporator to make 10-tons cooling at 15-deg F. with recirc glycol one day, and the same unit to make 50-tons of Minus 20 Deg. recirc glycol the next, is only problematic for the glycol side of the heat excahnger; the refrigerant side will accomodate it quite handily. Similary: multi stages of compression permit 5 or more suction pressures on the same condensing arrangement...Some equipment will operate at 4-suction conditions on One Motor.

Operation at Saturated Discharge Temperatures below 60-deg. F. is also no issue for a well designed system.

[mrfreezeit]

Wow! Ammonia was the first refrigerant and still the best as far as heat per pound.

First, a question has to be asked, what is the application. If talking about a 8x10 box, *****

If we are talking about a 1M cuft cold storage or food processing then yeah ammonia is ideal. Sometimes we get up in HP but I have never seen a 1000HP or even a 2000hp compressor that needed any cooling other than air cooling and it is extremely rare to see these outside of the petrochemical industry. Ammonia is used in all types of applications including direct cooling. I can name 20 locations with plate heat exchangers (not plate and frame). Most applications fall in the 1000hp-8000hp which is done with smaller compressors 100hp-750hp so you don't put all your eggs in one basket. The systems are far superior on energy efficiency. We removed 10 rack systems costing $200k per month in electric, to ammonia system now costing $60k per month in electric. Unless below -28F sst you show run positive pressure. -28F = 0bar or 0psig. The average condensing pressure is 130-180psig when running screw compressors 9-13bar. If your system is large central is the way to go, otherwise ***** packaged units might be better. If doing a beverage plant, reciprocating compressors are a must, otherwise screw compressors are great. Advantages: cheaper, self alarming, smaller equipment. Disadvantages: toxic in low concentrations. Yes you can and we have used on AC applications but with glycol as the secondary refrigerant.

17 years of doing 99% ammonia refrigeration work.
IIAR and RETA have lots of info on the subject.

[Miles Brennan]

Incidently Ammonium steel lines can be brazed - but not with conventional brazing alloys, the alloy must be copper free so the only proven product is a Silver Manganese alloy - IPM8515 - Please contact me if you need anymore info
miles.brennan@blueyonder.co.uk

[The Mennis]

Hi there. I'm interested in the absorbtion system using waste heat. Been searching for ages. Ive only found schematics, very good but no dimentions, volumes, pressures or temps. Any suggestions?

[TXiceman]

Hi there. I'm interested in the absorbtion system using waste heat. Been searching for ages. Ive only found schematics, very good but no dimentions, volumes, pressures or temps. Any suggestions?

You won't find any "standard" ammonia absorption systems. They are all custom designed and the information is closely guarded. You can figure one will cost 5 to 8 times a custom mechanical system. The COP is low and they occupy a lot of space.

The only way I have seen one pay out was to use true waste heat. If you are generating steam for the express purpose of an absorption system, it is too costly.

There was a company in India building these systems.

Ken

[frank]

There was a company in India building these systems.

http://www.thermaxindia.com/v2/Divis...o=1&objectid=2

[717_dealler]

,
hi frank , I made search to get more information to understand how absorption chillers ( Robur , trade mark) work , & what it parts ‘s function & likeness .
I insure it was hard and long way ,even some time finished with closed end , specially when u looking for some thing u heard about it ,but u never see it
I would like ask some question I hope u could give me answers for it & other members kindly can do too .
* why the information that dealing about ammonia refrigeration is not much available like other refrigerants ? , despite its older in this field .
* did any one in the forum has experience on ( Robur ) absorption chillers or any other trade mark chillers works by NH3-WATER absorption ( small cooling capacity chillers ) could I bother him with my questions in this field of refrigeration ?
Thanks for your help and your time
de

[717_dealler]

hi all membs., dear frank,
did any one have any picture or photo explaine the internal components in pakage unit of Robur machine .
i saw a skiches & some flash movie show how it works , but i need to see it more clear on here natcure .

[Alfred85]

Hi, i m new guy here and i m a undergraduate student. i m doing a reserch abt absorption refrigeration system. the system that i use is Gas Absorption Refrigeration Unit (Model: RF 10) which consist of ammonia,water and a bit gas hydrogen. Do anyone know that wat is the pressure in this system? and hw i wan to calculate the exergy because i dont have the data of mass flow rate.. what i have is the temperature of boiler, condenser, evaporator and absorber..

[wangxiaomin]

ammonia is a dangerous refrigerant in fact. it can be compared by travelling on air to by railway,if any problem occures,the injured oputunity will be high.

[Alfred85]

Do anyone got idea about RF10?

[iceman007]

Do anyone got idea about RF10?

Absorption machines are not that common because they aren't efficient unless you can use heat that you would otherwise release.

My last post on this thread was over 4 years ago. I've had another 2 kids since then !!! Must be a record

[bhushanpande]

Hi all members,

I am studing Vapor compression refrigeration system for Ammonia R717 refrigerant.
I am going to use this system for Large volume non agitated tank cooling system. As we know for multiple evaporators Liquid overfeed system is effecient method.
But while designing the Heat Transfer area (HTA) for cooling the fluid inside tank why do we need to follow the Ammonia recirculation ratio ? What happens if we send the Liquid ammonia in jacket which will evaporate 100 % inside jacket and vapors will come back to L.P.(low pressure) receiver.
And If recirculation ration is very important then how do i correlate the recirculation ratio with Heat transfer area.
Basically how do i finalize the recirculation ratio ?

[PVA]

+1
I agry with you, ammonia system needs very very big attantion!

[charlie n]

Recirculation ration is governed by more than a requirement to wet all of the evaporator surface. Balanced liquid distribution throughout all of the evaporator circuits is a major design factor as is controllability. 1:1 will probably be difficult to control.

[bhushanpande]

Yes, but how to decide the recirculation ratio can you guide me on that ?

[charlie n]

For your tank jacket, I would use a recirculation ratio of at least 2:1.This should work OK if the circuits are upfed. Circuit design (length etc) is more complex than I would want to take on without help from an evaporator designer.

[garethjones10]

Hi

This is Gareth Jones

very interesting topic--ammonia water chiller for AC area.
i know there is absorption ammonia chiller or heat pump but i'm not sure if there is compression type ammonia water chiller or heat pump. need do some research-
thx for all your valuable comment--it's a free lesson-
Regards,

Gareth
CNM ONLINE