Ammonia Heat Pumps

I found this link and though it may be of interest to those looking for different heat pump or ammonia applications.

http://www.ntnu.no/gemini/1994-02E/sog_side_38a.html

One more reason why you can do something different! :cool:

Hey US iceman

i have Workede on a test Heatpump on Ammonia,this were fitede on at Nuclear test site in denmark, som basic numbers

Pe = 29 C
Pc= 69 C
COP 5,05

Hi kasperDK,

Did these heat pumps use the Sabroe high pressure recip. compressors? I cannot remember the model numbers, but it was something like HPC I believe.

I have a friend who saw one of these heat pumps in New Zealand. He was very impressed with the whole system.

Yes the names are HPO (for the CMO type mark 2)and HPC for (The SMC mark 3) it is the same comp.they use for R744-CO2

only one problem it is very hard for the comp,alot of rep, pistons, valves, shafts ect

Hello,

I have one plant here with Stal screw S57E 26F working like ammonia heat pump to heat the cherry juice and then with vacuum pump extract some quantity of water. The rest is natural cherry juice very good one, believe me ;)

It was installed around 1985 or before. Still working becuse they use this unit only couple of month per year.

ammonia is getting more attention as it is a environemnt friendly refrigerant

Quote:

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I have Workede on a test Heatpump on Ammonia,this were fitede on at Nuclear test site in denmark, som basic numbers

Pe = 29 C
Pc= 69 C
COP 5,05

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I'm not clear what Pe and Pc ,you mean the Te and Tc.pls give more detail. COP looks not too bad:)

rgds
LC

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Originally Posted by kasperDK

only one problem it is very hard for the comp,alot of rep, pistons, valves, shafts ect

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Were the problems related to low oil viscosity due to the high temperatures? Or, heat and higher pressures?

Thanks.

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Originally Posted by US Iceman

Were the problems related to low oil viscosity due to the high temperatures? Or, heat and higher pressures?

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Heat and high pressure

Defect(broken) shaft
broken dis/suc vavles- rings plats springs
defect berings in pistonsrods

normaly we overhall Heat pumps at 6000-8000 h

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Defect(broken) shaft
broken dis/suc valves- rings plates springs
defect bearings in piston rods

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This sounds a lot like the compressor was hit with liquid refrigerant. Or, the oil viscosity was being lowered by the combination of high temperature and pressures.

I'm not sure if the scroll and screw can apply for ammonia. How about the advantage of ammonia heat pump comparing with R22 system? initial cost/COP/operation fee etc. It's a good topic,i really hope it can go further:)
Pro and con's for ammonia system:
pro's as above mentioned by Iceman

I've heard con's as :
low mass volume /not enough cooling decide it's no good to apply ammonia in hermetic compressor

pls input yours and keep the topic continuing:)

regards
LC

I believe the problem with ammonia and hermetic compressors is that ammonia reacts with copper, so the windings would have to be made of something else.

All should be made from aluminium if I not wrong.Regarding the compressor defect I go with usiceman.Dgust one question did that compressor have unloader piston or something similar?

Renato

Most, if not all of the ammonia systems are open driven compressors; screws and reciprocating. Hermetic ammonia systems are not something I am familiar with.

Mycom may have something for ammonia hermetic systems if I remember some advertising correctly.

Ammonia heat pumps should be very good. All of the ones I have heard of are industrial systems.

Copper bearing alloys or copper should not be used with ammonia. The copper will dissolve.

Ammonia has higher discharge temp. Does it need any ways to prevent it?

regards
LC

Quote:

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Originally Posted by LC

Ammonia has higher discharge temp. Does it need any ways to prevent it?

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It depends on how you are using the heat. It could be possible to use the high pressure gas from the discharge of one compressor, then desuperheat the gas, then compress the vapor once more to reach really high temperatures.

One ammonia heat pump I am aware of does this very thing.

I've read some Chinese article about ammonia system,there are some comments as follows:
#***** system is more efficient than ammonia system and more and more used in cold storage
#***** system initial cost is higher than ammonia system
#***** system has better automatic control than ammonia system
#***** system has lower operation and maintenance cost because ammonia system need air purge /charge makeup /oil adding more often
Hope experienced people give your comment. thx!

rgds
LC

Quote:

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Originally Posted by lc_shi

#***** system is more efficient than ammonia system and more and more used in cold storage
#***** system initial cost is higher than ammonia system
#***** system has better automatic control than ammonia system
#***** system has lower operation and maintenance cost because ammonia system need air purge /charge makeup /oil adding more often

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I'm not such an expert but ca add this:
***** systems are not more energy efficient, it depends somehow at the working conditions.
The initial cost for ***** is much lower then ammonia.
The market for automatic control systems for ***** systems is much bigger then that of ammonia so I think there is more money invested in control systems. Ammonia systems function many times the way it was done 30 years ago.
You only need an air purger when there's a change that evaporating pressure can go below atmospheric pressure.

Quote:

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Originally Posted by lc_shi

I've read some Chinese article about ammonia system,there are some comments as follows:
#***** system is more efficient than ammonia system and more and more used in cold storage
#***** system initial cost is higher than ammonia system
#***** system has better automatic control than ammonia system
#***** system has lower operation and maintenance cost because ammonia system need air purge /charge makeup /oil adding more often
Hope experienced people give your comment. thx!

rgds
LC

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Bollocks:eek:

Ammonia plant has a higher initial cost, and when properly applyed is more effecient.

However large screw compressors with capcity reduction will not run as effeciently as say a larger number of recips, sized to meet the same load.

Effeciency is all down to good design, good maintenance and a good clean installation.

What about the leaks on *****:eek: will this not effect your effeciency.

Kind Regards Andy:)

Hi LC,

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#***** system is more efficient than ammonia system and more and more used in cold storage

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If the system were designed identically using the same components and same operating conditions, ammonia is still better than the other refrigerants.

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#***** system initial cost is higher than ammonia system

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Again, using the same example, the ammonia system may be slightly higher. If steel pipe is used, the R-22 would probably be higher cost due to larger pipe sizes required.

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#***** system has better automatic control than ammonia system

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No. Ammonia systems are starting to get some very "smart" control systems. PLC control is essentially ON/Off control. It is the control algorithms that make the control system work. I have personally seen a "*****" control system used on an ammonia system. The controls were junk...

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Originally Posted by Peter_1

The market for automatic control systems for ***** systems is much bigger then that of ammonia so I think there is more money invested in control systems.

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Very true, but it is beginning to change.

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#***** system has lower operation and maintenance cost because ammonia system need air purge /charge makeup /oil adding more often

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On an industrial system using R-22 you would still need a purger. The industrial compressors all have shaft seals, which can admit non-condensable vapors into the system.

Even if the system pressures are above atmospheric pressure, air can still get into a system during service and charging. I would recommend a purger for any industrial system.

I agree with Peter and Andy (although I'm not sure what a Bollocks is, or means. I suspect it is not very complimentary!)

You really got me excited with this one LC. :D

All your input are very good. I know nothing about ammonia sytem. So the Bollocks is not for me:) ,for the kind experts :p

If anyone can give some related articles of the comparison between ***** and Ammonia ，it should be better.

thanks anyway

rgds
LC

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#***** system is more efficient than ammonia.....

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False, ammonia is more efficient.

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#***** system is more efficient than ammoniasystem and more and more used in cold storage

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Right, ***** systems coming more and more into this field for many argumented and non argumented reasons. We have to understand, in many industry fields, profit is on the very first place, this one is not exception....:( more like promised land...for non scrupulous people.

Definitely we have to use ammonia, CO2 and water for large industrial plants.

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#***** system initial cost is higher than ammonia system

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False, ammonia is always more expensive due to much more installed components (liquid receiver, pumps, surge drums, more valves, installation cost due to higher welding costs (X-ray).

Quote:

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#***** system has better automatic control than ammonia system

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False, automatic control complete depends on design and knowledge...but more often it is related to budget :)

Quote:

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#***** system has lower operation and maintenance cost because ammonia system need air purge /charge makeup /oil adding more often

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False, installation of air purger you need always with open compressors working below atmospheric pressure, charge make up you need always due to leaks and ammonia is cheaper, you can say free :)
Installing good oil recovery system there is no need to add oil more often.

Hi Ic shi, you asked for some info on comparison of Ammonia to *****. See if you can get a copy of the Bitzer international Refrigerant Report 10th. edition.
You can try www.iiar.org web site for mone information as a member of the Institute I can use the all the site. But you should get to the info you want to see.

Hi aawood1,i'll check your mentioned website,thx!

Josip,good comment,It seems all what I read are false:( . I'll go further into it while I get time.

best wishes
LC

who can give a link for ammonia heat pump's manufacturer if available? thx!

regards
LC

Hi LC,

Try this for some information.

http://www.sabroe.com/Products/Recip...HPC/index.html

Sabroe builds a very nice high pressure compressor that has been used on ammonia heat pumps.

Regards,
US Iceman

Thanks for your link.
Sabroe is affiliated with York? I don't know.

regards
LC

I've heard that there 's one China manufacturer build ammonia heat pump with plate heat exchanger and a patented expansion tech,it's said very compact.
Do you know any similar products?

welcome any input

regards
LC

Hi LC,

I have not heard of this. Is the unit for home use or commercial use?

I would be very surprised if the unit is for an area where people would be present?

Although not exactly a heat pump the work that Star refrigeration in Scotland does with ammonia reverse cycle for low temp is very interesting

After seeing a presentation at IIAR I built a small unit in the usa for testing. We still need a little work but it was basically a two pipe heat pump for low temp refrigeration.

We just reversed the flows for defrost. works well but we need a good four way valve to reverse with.

It is great for small or medioum sized freezers and coolers

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Originally Posted by bruceboldy

We just reversed the flows for defrost. works well but we need a good four way valve to reverse with.

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This sounds like the old Kramer-Trenton Thermobank systems. It may not have the Thermobank, but otherwise seems similar from the description.

Hi bruce:)

the attached post has some pictures of a reverse cycle, Low Pressure Receiver system by Star Refrigeration, I used to work for them
http://www.refrigeration-engineer.co...read.php?t=821

I have since changed all the controls on this and added an inverter drive on the lead compressor.

Iceman,
on the Kramer system what is the thermo store, a low pressure receiver:confused:

Kind Regards. Andy:)

Andy,

You are forcing me to remember stuff from 25 years ago, but I raised the issue.:)

The Thermobank was a tank that contained some sort of solution that stored heat. The discharge line ran through the tank and heated it during normal operation. When the evaporator went into defrost (hot gas), the condensate was returned through this tank to boil off the liquid back to a gas.

The the gas returned to the compressor suction.

This way the a single compressor could be used for hot gas defrost with only one evaporator coil.

I will see if I can find some pictures to post.

Andy,

Here is a link for the Thermobank system described in an earlier post.

http://66.28.63.222/documents/Kramer..._844A_Full.pdf (0.67 meg file size)

Iceman,
thanks for this, there is something very similar in Dossats, interesting system.

Kind Regards. Andy:)

Hi Andy,

The systems I worked on were eventually fitted with suction accumulators to protect the compressor. The original design did not include these.

At the time I was working on these the systems were probably first or second generation. We did have occasional problems which always resulted in the compressor failure. Some of the problems were electrical to be fair to the manufacturer.

Hi Andy,

Since attaching the inverter drive of the lead compressor, have you had any problems with harmonics when the compressors are operating at different rpms??

I am familiar with a similar set up (two screw compressors one separator one with inverter drive) that has experienced numerous leaks. I am thinking they are coming from harmonics frequencies between the two compressors. There was a vibration analysis performed and the drive was programmed to avoid certain transient rpm ranges that created the harmonic frequencies, but there are still leakage problems.

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Originally Posted by refteach

Hi Andy,

Since attaching the inverter drive of the lead compressor, have you had any problems with harmonics when the compressors are operating at different rpms??

I am familiar with a similar set up (two screw compressors one separator one with inverter drive) that has experienced numerous leaks. I am thinking they are coming from harmonics frequencies between the two compressors. There was a vibration analysis performed and the drive was programmed to avoid certain transient rpm ranges that created the harmonic frequencies, but there are still leakage problems.

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Hi refteach:)

we were careful with the operating speeds. Inverter is only used between 35 and 55hz.

Rototunes have a very wide range of RPM, this gives a good capacity match but you tend to have this sort of problem.
Our unit is deep freeze, so it is easier to get a better capacity match, things happen a lot slower.

Kind Regards Andy:)

Hey Refteach,

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I am familiar with a similar set up (two screw compressors one separator one with inverter drive) that has experienced numerous leaks.

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Who sold that? That sounds like someone is asking for trouble. I would suspect one compressor is amplifying the vibration of the other one. Seems like the same problem with recip's next to each other on a mezzanine floor.

You hit a natural frequency and then start a resonance problem.

As you can probably guess, there is a reason why not too many of these (dual screw packages) are built. That is probably the reason right there.:o

I can say I was not the one to sell it, I just have to deal with the fall out now. Currently we have done some resonant frequency investigation and are going to do more to see what may all be happening when these units are operating.

Quote:

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Originally Posted by Josip

False, ammonia is more efficient.



Right, ***** systems coming more and more into this field for many argumented and non argumented reasons. We have to understand, in many industry fields, profit is on the very first place, this one is not exception....:( more like promised land...for non scrupulous people.

Definitely we have to use ammonia, CO2 and water for large industrial plants.



False, ammonia is always more expensive due to much more installed components (liquid receiver, pumps, surge drums, more valves, installation cost due to higher welding costs (X-ray).



False, automatic control complete depends on design and knowledge...but more often it is related to budget :)



False, installation of air purger you need always with open compressors working below atmospheric pressure, charge make up you need always due to leaks and ammonia is cheaper, you can say free :)
Installing good oil recovery system there is no need to add oil more often.

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Installing a good recovery oil system in amonia system isn't easy, mainly dueing to bad project and budget, also amonia sysyems are more expensive to maintain compared to a good***** system.Usualy you don´t use ***** on large industrial plants.About controls existe very good electonic equipment to control ***** amd amonia systems try looking for new generation of Danfoss adapkool, works very well.