ammonia refrigerant 1

[joeywpittman]

has anyone here ever worked with ammonia as a refrigerant?
what training is needed?
where do you get the training?
where do you purchase ammonia equipment and refrigerant?

How much more efficient is ammonia over R-22?

 

[rgoulet]

I would suggest you go to the International Association of Ammonia Refrigeration (

http://www.iiar.org).

They can help a lot with information and training. In terms of efficiency it is from 4 to 10 times more efficient than R22, depending on temperatures. This can result in smaller pipe sizes, smaller evaps etc.

It takes some time to develop a reputation with NH3 but it can be a good part of any mechanical contractor's bag of tricks.

 

[tombmech]

I am certainly no expert, but have dealt with a couple of major proposals for ammonia refrigeration plants. (Unfortunately, they all failed, but as a consequence of initial cost, not ammonia.)

As rgoulet notes, efficiencies can be 10 times as much as with "normal" refrigerants. Imagine if you will, a chiller not much bigger than a kitchen table with a 5000+ ton capacity. They are an attractive solution for high capacity chiller plants. However, certain traits have limited their application in typical commercial/light industrial environments.

Saturation temperatures are very close to desired water temperatures for HVAC applications - with delta T's on the order of 3 degrees F. That is not enough of a temperature gradient to leverage good heat transfer with typical construction. Moreover, copper and ammonia don't mix.

Those two factors have inhibited ammonia's use for HVAC water chillers. The requisite stainless steel/steel heat exchanger materials (often plate & frame) are difficult to rifle or combine with numerous fins as in typical water chillers or DX coils. So, heat exchanger efficiencies suffer at small sizes. These factors diminish in larger sizes due to the comparative investment, and the super-high refrigerant efficiency. There is a great deal of work going on to mitigate these issues for commercial applications, and we should see the numbers of ammonia-based machines grow.

The ammonia handling issues are not as great as one might imagine. The human nose is literally the best defense against exposure. The nose can detect ammonia smells at magnitudes less than dangerous concentrations. The greatest issue is the dispersion path in case of catastrophic ruptures.

 

[TXiceman]

I have been in the industrial refrigeration field for over 35 years now and never have found ammonia to be 4 to 10 times more efficient than R-22. At certain temperatures it is a bit more efficient...just a few percent. It generally has better heat transfer cofficients than do the "Freon" refrigerants and had a much higher latent heat, almost 3 times that of R-22, so you mass flow of refrigerant is about 1/3 of R-22.

It is a much misunderstood refigerant, main;y due to the local news media and the bad press given to the slightest leak. WHne trated properly, like any refrigerant, ammonia or NH3 is a very good refrigerant. It is advertised as "The Self-Alarming Refrigerant" by IIAR. You best source of training and material on Amonia will be IIAR and RETA (Refrigeration engineers and technicians assoc).

Ken

TXiceman

http://www.rae-corp.com

 

[tombmech]

Strictly speaking, you are correct. However, "efficiency" is a loosely-used term, especially since refrigerant equipment is typically measured by COP, not by %eff.

The broader point, though is its usefulness as a refrigerant. A refrigerant is selected on the basis of its properties, and the advantages those properties have with regard to the refrigerant process. One of the most important properties (if not the) is the Heat of Vaporization. This is the measure of the potential cooling leverage (heat rejection) obtained when a change in phase is forced through an expansion valve.

At typical HVAC refrigeration values - for example, 40 deg.F., R-717 (Ammonia) has an Enthalpy difference between liquid and vapor states of 536 Btuh/lb. R-22, on the other hand, is 87 Btuh/lb, R-134a is 84 Btuh/lb, and R-123 is 77 Btuh/lb. R-12 was as little as 65 Btuh/lb.

Now, there are a lot of other attributes: specific heat, pressure, specific volume, and thermal conductivity. They are all important to the suitability of the overall process. However, the refrigerant process is ultimately defined by how much heat is removed.

In that regard, Ammonia has up to 8 times (not quite 10) more heat removal potential than other commonly used refrigerants.

 

[TXiceman]

"In that regard, Ammonia has up to 8 times (not quite 10) more heat removal potential than other commonly used refrigerants"

Tom, your assumption is based on mass flow. But what a PD (positive displacment) compressor in the systems sees is CFM (volume displacment). So you also have to consider the specific volume of the gas.

So many food plants use ammonia as the refrigerant for several reasons....
-smaller liquid lines due to the higher heat of vaporization.(less mas of refrigerant is circulated for a given heat capacity)
-slightly better heat transfer properties.
-easier to handle the oil (oil return) that is in the system.
-it is a relatively inexpensive refrigerant compared to the "Freon" family.
-it is also an enviromentally friendly refrigerant as it appears in nature.

Ken

TXiceman

http://www.rae-corp.com

 

[mxstar]

As far as the What training is required ? goes - In the UK service technicians or those responsible for ammonia refrigeration plant should have received City & Guilds 2078 Ammonia or Construction Industry Training Board (CITB) training on Safe Handling of ammonia. Contact BES Publications Sales, CITB, tel: 01485 577704, email: bes.enquiry@citb.co.uk. There are a few trainers in the UK who deliver th training. The CITB referance manual is
ISBN 1 857 51022 4

 

[sterl]

R-717 systems are characterized by Low Mass Flows (because the latent heat is so high) Open Drive arrangements because the low mass flow and corrosivity to copper makes hermetic arrangements pretty special; and "bulletproof" piping, as most field built systems are completely welded steel pipe installations...
The rest of the system advantages are consequential of the liquid delivery and control arrangements, most evaporators are deliberately overfed and have accumulators for a volume of liquid. Both will help carry the system through short term high load conditions; there are none of the handicaps of TXV-type control so temperature approaches can be very low. The other substantial advantage has already been indicated: Modern systems have virtually no oil carryover from the compressors and a sprawling system can be built up with minimal detailing applied to oil management and return...And the tolerance of the refrigerant for minor proportions of water or air in the system permits many applications where the compressor suction pressure is well into the vacuum range.

Inherent efficiencies are a few % better than R-22 for the "normal" suction pressure ranges, though the limitations of Air Cooled Condensers VS Evap condensers hands the efficiency advantage to R-717 when "normal" design practises are being matched head to head.

As to Training: Besides the process specific stuff, RETA and IIAR are the sources. Many plant also fall under OSHA - PSM and thus there is intensive training available from that avenue as well.

 

[MFranklin]

To answer your questions:
1) I've been involved with ammonia refrigeration since 1996, both as a design/build contractor and a year as an operator.

2)Ammonia is listed as a highly hazardous chemical due to its flammibility properties (which is rare) so in my book training is required. Legally very little is required in the United States at this time, and what is, is usually HAZWOPER training.

3)RETA,IIAR,Garden City Community College in Kansas?,Northwest Technical Institute in NW Arkansas,University of Wisconson, and the University of Ill. at Urbana had a course at one time. The schools offer a variety of courses, generally for system operators. IIAR and RETA offer books with RETA aimed more toward operation and IIAR toward design and installation. But these names give you a starting point for a web search.

4)Typically ammonia equipment manufacturers do not sell directly to the end users, they prefer to deal through ammonia refrigeration contactors. I will name off a few names:
Ammonia screw compressor packages are made by Frick Co.(part of York Intl) FES part of GEA, M & M Refrigeration, Mycom and Vilter. Mycom and Vilter also manufacture recip compressors. I've listed these alphabetically not out of my perferences. All of these companies maintain websites and market other components for ammonia refigeration systems.
Air cooling evaporators:Baltimoe Aircoil Co.(BAC), Evapco,Frick/Imeco,Frick/Frigidcoil,Krack
Valves(control and stop)Refrigerating Specialties part of Parker, Hansen,Danfoss/Danvalve,Sporlan

5)I don't know the actual numbers but in -40 degree(F) to +40 degree(F) with a load in excess of 100 tons in the poultry,pork,beef and a large number of storage freezers industry it will most likely be ammonia.
Most of the companies above have web site with information about their sales reps.,contractors and design firms they work with on a regular basis.

Ammonia refrigeration design and installation is a relatively narrow field, especially when compared to general mechanical contracting and HVAC work, and as rgoulet stated above "It takes some time to develop a reputation with NH3 but it can be a good part of any mechanical contractor's bag of tricks."

Unless you want to pay for someone's time to develop their reputation with your capital, in a specialized field use contractors that specialize in that field.

 

[superbee70]

Hello all,

First of all I am new and found this site by accident and this is my first post. However, after reading the postings by joeywpittman,TXiceman and the others well I found many of their comments interesting.

Please allow me to give my past related experinces(I can Just hear the moans now from the crowds). I have HVAC/R related career experices and education ranging from residential to commercial as well as I was an Assitant Eng. for an Ammonia desgind co. So, I have both the Freon back ground as well as the NH3 training and hands on exp. And, with all of that and $2.00 (used to be .50) I can get a cup a coffee at the quik shop. Joey, I can't express this strongly enough, if you don't understand the media of NH3 do yourself and others in the industry a favor, find an expert in the field that does and have them do the work. You are embarking into an area that can be very dangerous! I applaud your quest for knoweldge and NH3 can be intresting but, please do not play with your life and the lives of others if the reason your asking for this information is to attempt to enter into a project using NH3.

Now I would like to relate a quick story as why I say it is so dangerous and should not be taken lightly, as an example to support my comment of " what you don't know may kill you".

I worked with in a company, as I stated, that had several Engineers with a total combined experinces of nearly 200 years strictly in the NH3 industry. And even with all the countless safety training classes as well as all the "fail safe" procedures we put into play we had a horrific incedent happen. When it was all done and over we burnt a beef packing plant nearly to the ground, sent several people to the hospital with inhalation issues,had several of our own works severly burnt, had 7 fire depts trying to extiguish the fire and it cost our insurance company over $10 MILLI0N!! in damages!! All because of one little mistake made with a torch!!

And if I may quickly address the other questions you had yes I totaly agree you can contact any of the proffessionla associations and they will guide you to some of the best places known to man to get an education and will be able to answer any questions you have in a non bias mannor.

 

[grizzlyfish]

In answer to your query, there is a RETA approved class that is taught by Grant Golding at alliance industrial refrigeration services in walnut california on wenesday evenings.The cost of the class is not cheap $250, but the course consists of four sections it is a very informative class.One that has a large ephasis on ammonia and grant has some horrific tales to tell of the things he has seen. he has a strong safety backgroud. dont be too gung ho to start a career in ammonia untill you get the proper schooling.
oh....and to answer your question as to which refrigerant has a higher btu per pound rating. ammonia would win hands down. good luck.