Compact Heat Exchangers for Ammonia

[Darshi]

Hi,

I have a few suggestions on evaporative condensing for ammonia refrigeration based cold storage installations. The so called evaporative condensers are nothing but a set of bare MS tube on which water falls from another tube having holes. Many of these holes get blocked after some time due to poor water quality.

A cost effective and more efficient alternative will be use aluminium multiport tube and fin Heat exchangers, often used in automotive and industrial application.. Aluminium is a compatible material with ammonia and the tubes pass the pressure test .The multiport tube heat exchangers reduce the refrigerant charge ,offer compactness and rigidity of construction as the fins are brazed.

For evaporative condensing use Direct Evaporative Cooling (DEC) using high surface area cellulose matrix or newly available plastic matrix. One can get still lower condensing temperatures by using Indirect /Direct Evaporative Cooling IDEC) matrix. This scheme uses a plastic air to air plate heat exchanger in regenerative mode in addition to the direct evaporative cooling media.


These Ice and cold storage plants in India are perfect candidates for Hall of Shame. The viability of operating the installations was directly proportional to the use of stolen electrical power. Most of these installations are in shambles today because the power theft has become difficult and poor design makes them unprofitable to operate on today’s power tariffs.

[Darshi]

I understand many new compact ammonia refrigeration packages with screw compressors use plate heat exchangers for evaporator and condenser.
In many countries water quality may not allow use of plate heat exchangers .

In the last post, I tried to present a solution to eliminate bare pipe MS tube condenser by a suitable low refrigerant volume, evaporative condensing alternative.
My intention was to bring low cost multi port aluminium flat tube heat exchangers into focus in place of outdated evaporative condensers or expensive water cooled plate heat exchangers.

I would like to know if any one has used the multiport aluminium heat exchangers in the ammonia refrigeration jobs or has any view for their use.

[US Iceman]

Can you provide some background information and links to websites for this please? Thank you.

[Samarjit Sen]

Dear Darshi,

Could you please provide with more details of the condensers which you are suggesting as an alternative to the Evaprative Condensers. If possible please provide a drawing of the same.

[Josip]

Hi, Darshi

My intention was to bring low cost multi port aluminium flat tube heat exchangers into focus in place of outdated evaporative condensers or expensive water cooled plate heat exchangers.

Do you mean here aluminum flat plate heat exchangers?
Like Jackston flat plate freezers, sounds similar.

Can you provide some link, drawing or photo about?
I found this:
http://www.energy.kth.se/index.asp?pnr=9&ID=37&lang=0
http://www.hydro.com/precisiontubing...n_white_goods/


Best regards, Josip

[Andy]

My intention was to bring low cost multi port aluminium flat tube heat exchangers into focus in place of outdated evaporative condensers or expensive water cooled plate heat exchangers.

I would like to know if any one has used the multiport aluminium heat exchangers in the ammonia refrigeration jobs or has any view for their use.

Darshi

out of date evaporative condensers I recently specified cooling towers instead of evaporative condenser on a large job, there was no energy saving going from evaporative to water cooled, in fact the energy used by the cooling tower and pumps was higher.

You wouldn't be the guy selling aluminium plates and condensers at the IKK

Kind Regards Andy

[US Iceman]

If the heat exchanger looks like one of the pictures in the links Josip provided, it's a radiator for autos. That's how they are built.

Using this with water spraying over the top of it (on an ammonia system) would make "concrete" (calcium carbonate) in short order.

I would not recommend this approach at all...

The high surface area and small passages would generate fouling extremely quickly if the water quality was not absolutely perfect all of the time.

I'll stick to using plain old prime surface tubing and evaporative condensers myself. I would not even recommend some of the finned tubes you can get on some evap. condensers for the same reason as above.

Andy, I'm a little curious about your project. Why did you use a cooling tower instead of an evap. condenser?

[winfred.dela]

In many countries water quality may not allow use of plate heat exchangers.

You may mean brazed plate heat exchanger (BPHE) where you cannot easily clean the water side.

For very hard condensing water medium or sea water for condenser cooling medium you just need to use Titanium Semi Welded Plate Heat Exchanger (SWPHE).

[Darshi]

Dear samarjit,Andy,Josip and USIceman and winfred
I am attaching a world file .
Hope it is usefull to some friends like samarjit
here is a good link

http://www.news.uiuc.edu/scitips/01/08ammonia.html

[winfred.dela]

Hi Darshi,

Thanks for the link and the file.

If i may ask, have you used some of these CME?

Sincerely,
Winfredy

[Darshi]

Winfred ,
Yes
I have used them for many applications such as comfort cooling, IC engine inlet air cooling , Compressor inlet cooling and indirecr evaporatiev airconditiong.
Many of you may have used a similar matrix as cooling tower fill

[winfred.dela]

Winfred ,
Yes
I have used them for many applications such as comfort cooling, IC engine inlet air cooling , Compressor inlet cooling and indirecr evaporatiev airconditiong.

Thanks for your immediate reply.

I have been absent in the aircon design & build for quite a while.
Very active lately as a fridge guy.

[Josip]

Hi, Darshi

Winfred ,
Yes
I have used them for many applications such as comfort cooling, IC engine inlet air cooling , Compressor inlet cooling and indirecr evaporatiev airconditiong.
Many of you may have used a similar matrix as cooling tower fill

All what you wrote (and sent link) is OK but I have to admit I still do not follow you idea completely. Please can you provide some scheme about (we are engineers and we can better speak and understand each other via drawings and numbers) industrial or heavy commercial application. One picture (drawing) can say thousand words....

Prof. Predrag Hrnjak published his invention in 2001 but still until today it is not widely accepted in industrial refrigeration (maybe I am not informed well) due to some problems not seen in the beginning like cost, installation, maintenance, or...

Best regards, Josip

[winfred.dela]

I have a few suggestions on evaporative condensing for ammonia refrigeration based cold storage
installations.
. . . .
A cost effective and more efficient alternative will be use aluminium multiport tube and fin Heat exchangers, often used in automotive and industrial application.. Aluminium is a compatible material with ammonia and the tubes pass the pressure test .The multiport tube heat exchangers reduce the refrigerant charge ,offer compactness and rigidity of construction as the fins are brazed.

I have used them for many applications such as comfort cooling, IC engine inlet air cooling , Compressor inlet cooling and indirecr evaporatiev airconditiong.

Hi Darshi,

Have you applied, installed or seen these particular component in Ammonia Refrigeration System?

Regards,
Winfredy

[US Iceman]

I suggest a new thread be started on the heat exchanger topic as this is off track of the original thread.

Thanks.

[Josip]

Hi, US Iceman

I suggest a new thread be started on the heat exchanger topic as this is off track of the original thread.

Thanks.

Agree, maybe named...Aluminum CME/MPFT heat exchangers for ammonia or .....

BTW, maybe is not bad idea to do similar with some other topics (some of them are too long with lot of "off track" replays

Best regards, Josip

[US Iceman]

Here is a new thread for the subject.

[US Iceman]

Since we have a new subject, let's add some material for everyones review. If others find some interesting material, please go ahead and post it.

http://www.eng.hawaii.edu/ME/Weilin%...due/P-C-03.pdf

http://www.xpedio.carrier.com/idc/gr...f?SMSESSION=NO

I believe if this technology is to be used for refrigeration (especially industrial refrigeration) we have to be aware of certain limitations, i.e., surface fouling and low temperature oil circulation.

Under the topic of surface fouling I can see two distinct problems with this; ice/frost when used as an evaporator, and, mineral precipitation if used in an atmosphere containing dissolved minerals (such as an evaporative condensing function).

Secondary surface such as fins are cheap heat transfer surface, but the use of fins also includes the awareness that restriction of air flow will rapidly decrease the exchanger capacity. For this reason, wide fin spacing is a requirement for frost forming surfaces.

If the fin spacing is increased to compensate for this continous requirement of potential fin bridging, what would the expected performance increase be for a microchannel exchanger when compared to tube & fin exchangers?

An additional similar problem also relates to the fins. It can be difficult enough to keep prime surface tubes clean in an evaporator condenser. Adding secondary surface to evaporative condensers would make for some interesting maintenance issues I believe.

I'm not trying to say we should not be investigating new technologies. Only that we should be prudent in the application of those.

I have a feeling this thread will generate some interesting observations and comments.

Best Regards,
US Iceman

[winfred.dela]

Since we have a new subject, let's add some material for everyones review. If others find some interesting material, please go ahead and post it.

http://www.eng.hawaii.edu/ME/Weilin%...due/P-C-03.pdf

http://www.xpedio.carrier.com/idc/gr...f?SMSESSION=NO

Thanks a lot for above reading materials.

I believe if this technology is to be used for refrigeration (especially industrial refrigeration) we have to be aware of certain limitations, i.e., surface fouling and low temperature oil circulation.
. . . . .
I'm not trying to say we should not be investigating new technologies. Only that we should be prudent in the application of those.

I have learned early in life that we need to ask lots of questions to be able to learn more. Also, the shortest way to learn is asking guys that have the experience to share.

I hope somebody who have experimented, applied & installed these products will come forward and share their knowledge.

[Samarjit Sen]

Good afternoon Darshi,

Thank you for the link. I would be grateful if you could let me know the name of the manufacturers so that I may contact them and try using them in my future projects.

With best wishes,

[Samarjit Sen]

Thank you US Iceman for the link. I shall be thankful if you could kindly elaborate on the constructional features of these heat exchangers.

I was planning to use Gasketted Type PHEs as ammonia condensers. But now with Darshi coming up with this type, I would like to learn more about it.

As Fredy as has said it that if some one who has used these could please come forward and explain more in detail, it would be helpful.

With best wishes,

[US Iceman]

Well, to be honest I do not have any first hand knowledge of these exchanger types (other than my vehicles radiator).

I tend to approach new technology cautiously and lean on my background doing weird applications for various refrigeration systems.

The first thing I always look for is; "what can go wrong"? That helps to keep happy customers as no one wants to be used for experimentation purposes.

I've used the gasketed PHE's before with good success and also the brazed PHE's. Both are a good product.

Obviously, Darshi does have some exerience with these and I do not mean to prevent him from offering comments. That is certainly not my intention. I'm only suggesting we need to carefully review the application parameters to make sure we do not create other problems, that might not have been recognized.

[Josip]

Hi,

The first thing I always look for is; "what can go wrong"? That helps to keep happy customers as no one wants to be used for experimentation purposes.

I've used the gasketed PHE's before with good success and also the brazed PHE's. Both are a good product.

Obviously, Darshi does have some exerience with these and I do not mean to prevent him from offering comments. That is certainly not my intention. I'm only suggesting we need to carefully review the application parameters to make sure we do not create other problems, that might not have been recognized.

Yes, it is better to use known HE instead to make very expensive mistakes

Best regards, Josip

[Handyman-1]

Good afternoon Darshi,

Thank you for the link. I would be grateful if you could let me know the name of the manufacturers so that I may contact them and try using them in my future projects.

With best wishes,

Hi Samarjit,

is this the link you need?

w . idalex. com / applications / Mcondenser. htm


regards

[Samarjit Sen]

Thank you Handyman 1. I have visited the idalex web site and gone through the details.

It appears that as far as of now there has not been many users of this system. The gasketed PHEs would be a better deal in our country, as generally the water is pretty hard and they have to be treated to make it useful. With gasketed types, we can clean it if required.

However it would be nice if some users of the condensers which Drashi has said provides us with his experience with such type of units.

[Darshi]

Dear Darshi,

Could you please provide with more details of the condensers which you are suggesting as an alternative to the Evaprative Condensers. If possible please provide a drawing of the same.

I am sure you will find the link useful

http://www.epsltd.co.uk/
They manufacture evap condensors for HCFCs it is question of changing heat exchanger type from al fin copper tube to MPFT/ MS tube integral fin . If you need further help please post your questions on the fourm

[winfred.dela]

If you need further help please post your questions on the fourm

In this thread, I have posted this question:

Hi Darshi,

Have you applied, installed or seen these particular component in Ammonia Refrigeration System?

Regards,
Winfredy

Hi Darshi,

Components that are new in the market should be tested by the manufacturer. We will be comfortable to use if there will be some referral projects and contact persons.

I remember more than 10 years ago when Alfa Laval Engineers started visiting our City selling the semi welded plate heat exchanger (SWPHE) as replacement for Shell & Tube (S&T) condensers.
It need a few customers and few years before most consider the product.
Now, the Alfa Laval Titanium SWPHE is alwats considered as replacement for most of the old S&T with titanium tubes.

An answer for my previous question would be very helpful.

Regards
Winfredy

[Darshi]

Dear Winfredy ,

The answer to your question is NO , I have not seen or tried.
There is always the first time.
Being a fellow Techi , I expected you to tell me why the suggested heat exchanger technique cannot be used .

I have heard this question many a time from purchase guys, the pen pushing engineers who did not care to apply the knowledge they acquired in the engineering study.

It is more useful to question concepts than to kill them.
The forum is a place to put the ideas up for good technical questioning.

I have provided a link in the previous post and please go to page 4 of the brochure. You will find Evaporative condensing used for Ammonia air cooled condensers in UK.Now let us substitute the integral fin steel tube in this condenser with Multiport flat tube (MPFT) aluminium tubes.

The advantages are as follows.
1. The MPFT condensers are tested in more critical dynamic automotive application for decades.
2. Less wall thickness improves heat transfer.
3. MPFT offers more surface than a comparable tube of equivalent area.
4. Less refrigerant pressure drop.
5. Pressure tested for refrigeration duty even for CO2 Applications.

Now let us question the questionable and be the first one to bring about a change in the unquestioned practices followed by my grandpa, because he always wanted to know if some one else did it before.

Darshi

[Andy]

Hi

I would think finned surfaces cooled by evaporation would only work if the water treatment was perfect
otherwise scale would build.
The question is not where it is a more effective way of cooling, but whether water treatment is up to the task of looking after the heat exchanger in the long term.

Kind Regards Andy

[Darshi]

Hi

I would think finned surfaces cooled by evaporation would only work if the water treatment was perfect
otherwise scale would build.
The question is not where it is a more effective way of cooling, but whether water treatment is up to the task of looking after the heat exchanger in the long term.

Kind Regards Andy

Dear Andy ,
You are right about the water treament if one sprays the liquid water but not true for adiabatic evaporation.
I am attching a note ,I prepared for evaporative condensing .
It will be self explainatory

[Andy]

Dear Andy ,
You are right about the water treament if one sprays the liquid water but not true for adiabatic evaporation.
I am attching a note ,I prepared for evaporative condensing .
It will be self explainatory

Darshi

can you please explain the differance between Adiabatic cooling and the cooling we associate with evaporative bare tube condensers

Thank you

Andy

[Darshi]

Dear Andy
May be the attached document with my last post will explain the process, however a quick reply to your quarry is here:-
Bare tube evaporative condensing:
Water is sprayed on high temperature bare tube surface for heat exchange.
The pure water evaporates and cools the rubes and impurities (salts) remain stuck to the surface as scales ..The heat exchange takes place between water at wet bulb temperature of the location
Compact Mass Exchangers(CME):
These exchangers are made of large surface area matrixes like brass wire mesh., paper or plastic corrugated surfaces which are wetted with water . The simple example will be an evaporative cooler fill or cooling Tower fill.
Air for cooling the condenser is first passed over the wetted surface and cooled evaporativily to near the wet bulb temperature and this cooled air now passes over the finned condenser heat exchanger to transfer heat. The air touching the fins and tubes has water in vapour state and ca not carry salts like the liquid water. Hence there is very little chance for corrosion.

Generally, the wet bulb temperature never exceeds 300 C .In tropical climates, the coincident wet bulb may be often as low as 18 -230 C at temperatures exceeding 400 C.

[winfred.dela]

The answer to your question is NO , I have not seen or tried.

I expected you to tell me why the suggested heat exchanger technique cannot be used .

I have heard this question many a time from purchase guys, the pen pushing engineers who did not care to apply the knowledge they acquired in the engineering study.

Now let us question the questionable and be the first one to bring about a change in the unquestioned practices followed by my grandpa, because he always wanted to know if some one else did it before.

Dear Darshi,

I have done a lot of prototypes myself spending my own money. Being a practicing application engineer (not the pen pushing you are referring) with my own company, I always use the applied science that have been tested by others thus minimizing losses and expenses in experimental products.

The practice of doing for the sake of being the first is for the scientist that use people's money in the product development or in prototypes.

I hope to have offer my view which is the same line of thinking with your grandpa.

My question is:

- Have you also done prototypes or any product development using your own money?

- Or, just offering some questions and some comments like the obove in some forum like RE forum?

Regards
Winfredy

[US Iceman]

Now I have a better idea of what's being described as an evaporative condenser. The process shown in the brochures is not what we would typically refer to as an evaporative condenser.

The product is an evaporative process to pre-cool the air stream on an air-cooled condenser. If the micro-channel heat exchanger was used with this technology it might make for an interesting study or trial.

But I would emphasize I would not make the trial as part of a normal project, UNLESS, the client fully understood what was being attemped and agreed to bear the risks, in writing.

I still feel there might be some additional risk with using this type of heat exchanger in a potentially dirty service (and outdoor air is dirty with a high potential for air borne debris).

I know from past experience it is very difficult to keep air-cooled condensers clean, mostly due to the fin spacing and coil depth.

The new heat exchanger surface would not appear to correct any of those problems.

It's an interesting experiment, and I could see how it would have a lot of merit for high dry bulb/low wet bulb environments, such as the Middle East.

I have spent considerable time as an application engineer too, so I'm not too crazy about the pen pushing type mentioned. Although, I do know the type you are describing. These usually revolt at the first mention of thinking outside the box.

[winfred.dela]

I have spent considerable time as an application engineer too, so I'm not too crazy about the pen pushing type mentioned. Although, I do know the type you are describing. These usually revolt at the first mention of thinking outside the box.

Handyman-1:

is this the link you need?
http://www.idalex.com/applications/Mcondenser.htm

Hi US Iceman,

When this particular product was mentioned in this thread, i also inquired from idalex.com with the purpose of purchasing the Idalex Refrigerant Condenser. I intend to use it in my prototype unit for a marine application.

The product is not yet available. Am sharing here a portion of their email:

Thank you for your interest in Idalex. From your comments, it looks as though you are interested in HVAC applications of our technology, which for now is limited to Coolerado. The Idalex refrigerant condenser is at least a year away from commercialization.

There are always those that wanted to use new products but it always equate to giving the 3 Ts (Time, Treasure, Talent). Very few have the luxury of giving all those 3, especially the TIME.

As an application engineer, we always know that TIME (to make a prototype and gathering the test data) is the hardest one to find.
With RE forum, we can make the TIME somewhat shorter by asking some members to share their experiences.
For this, i am thanking those that share their experiences.

Of course, as we always know: giving ideas are great but then talk is cheap. . . .

That's why application engineers always loathe those pencil pushers. . . .

Regards & Thanks.
Winfredy

[Darshi]

Now I have a better idea of what's being described as an evaporative condenser. The process shown in the brochures is not what we would typically refer to as an evaporative condenser.

The product is an evaporative process to pre-cool the air stream on an air-cooled condenser. If the micro-channel heat exchanger was used with this technology it might make for an interesting study or trial.

But I would emphasize I would not make the trial as part of a normal project, UNLESS, the client fully understood what was being attemped and agreed to bear the risks, in writing.

I still feel there might be some additional risk with using this type of heat exchanger in a potentially dirty service (and outdoor air is dirty with a high potential for air borne debris).

I know from past experience it is very difficult to keep air-cooled condensers clean, mostly due to the fin spacing and coil depth.

The new heat exchanger surface would not appear to correct any of those problems.

It's an interesting experiment, and I could see how it would have a lot of merit for high dry bulb/low wet bulb environments, such as the Middle East.

I have spent considerable time as an application engineer too, so I'm not too crazy about the pen pushing type mentioned. Although, I do know the type you are describing. These usually revolt at the first mention of thinking outside the box.

US Iceman,
Yes, if I can sum up what you have said very rightly .
The different condensing processes used are as follows
1. Conventional Evap condensers use evaporativily cooled water
2. Shell and tube/shell and coil use water cooled in a cooling Tower or Pond or use river water once thru.
3. Conventional air cooled condensers having typically 9 to 11 fins per inch use hot and dirty ambient air at the dry bulb temperature. The result is often condensers clogged by debris and system tripping on high temperature.
4. The net result is increased power use / lowered COP
5. CME s cool the high temperature ambient air, closer to ambient wet bulb temperature depending on the effectiveness of the mass exchanger .The cooling is achieved by surface evaporation .
Additional advantages of CME cooled condenser are as under.
1. Air filtered down to 5 micron or better by the process known as air washing
2. Low parasitic pumping power use due to low head requirements of surface evaporation system when compared with high pressure pumping used in nozzle based system
3. No water carry over due to “low velocity over matrix” design
4. Nearly No corrosion
Multiport Flat tube heat exchangers use different fin design and need less fins per inch as the primary surface are is considerably more compared to round tube systems without addition cost burden.. Please see the car air con condenser for reference. You will notice the difference and the fouling in automotive application is more critical.

[Darshi]

Hi US Iceman,

When this particular product was mentioned in this thread, i also inquired from idalex.com with the purpose of purchasing the Idalex Refrigerant Condenser. I intend to use it in my prototype unit for a marine application.

The product is not yet available. Am sharing here a portion of their email:




There are always those that wanted to use new products but it always equate to giving the 3 Ts (Time, Treasure, Talent). Very few have the luxury of giving all those 3, especially the TIME.

As an application engineer, we always know that TIME (to make a prototype and gathering the test data) is the hardest one to find.
With RE forum, we can make the TIME somewhat shorter by asking some members to share their experiences.
For this, i am thanking those that share their experiences.

Of course, as we always know: giving ideas are great but then talk is cheap. . . .

That's why application engineers always loathe those pencil pushers. . . .

Regards & Thanks.
Winfredy

Dear Winfredy,

I have always done prototypes myself spending my own money.
Winfredy, We seem to have a lot in common, having run our own companies and being application engineers, to start with.
(No offence intended, if you are an application engineer, you must have met your share of the pen pushing types, I referred),

Sure, we are not inventors but as application engineers, we are innovators.
Our job is to use the applied science in an innovative way. Otherwise what way are we different than any other practicing refrigeration engineer.

We use time tested components /techniques in an innovative manner to create either a new application or a new product.
During the design process we do not invent new processes but use the existing knowledge to leverage a commercial advantage.

Because in private industry it is never people s money (it is your own or you are accountable ) so we learn to minimize losses and expenses (including our professional reputation) to our own self/ our companies.

(The practice of doing for the sake of being the first is for the scientist that use people's money in the product development or in prototypes)

I wonder where our applied science will be without fundamentals,
The research painstakingly pursued by scientists. (Many good ones were paid salaries less than our assistants, so much for people‘s money)

I think let us not undermine the contribution of science in our profession.

I seem to have touched some raw nerve to make you respond like my Grandpa.

My answers to your questions are :

-Yes , I have done prototypes always with my own money and sold all of them to intelligent customers and Believe me they do exist .

- This second comment is a bit offensive, without knowing some one‘s capability.

Incidentally, Idalex does not make this product .The do Indirect/Direct Evaporative Cooling (IDEC)systems. These are also called Dew point coolers.
Which are commercially not viable for this application at the moment?

No doubt the talk is cheap. Unfortunately, Knowledge is exchanged only by discussing and asking questions but one must have the substance for that not merely semantics.

Any way, thanks for making me work overtime without paying

[winfred.dela]

- This second comment is a bit offensive, without knowing some one‘s capability.

Hi Darshi,

Sorry for the comment then, i apologized . . .
Just got a little off my regular tone, maybe because i had a not so good day.

Sincerely,
Winfred

[Darshi]

Winfred
It is fine .
Let us keep exchanging views.
We learn more from each other's mistakes.
Have a very nice day .

[US Iceman]

Multiport Flat tube heat exchangers use different fin design and need less fins per inch as the primary surface are is considerably more compared to round tube systems without addition cost burden.

The increase in primary surface makes sense. But, what's the surface ratio of the flat tube exchanger compared to a round tube and fin exchanger.

In the tube and fin exchanger the secondary to primary surface ratio is usually quite high. Fins make cheaper heat transfer surface than primary surface.

I could also see the flat tubes having slightly lower static pressure losses, since you would not have staggered tube banks (like in a tube & fin exchanger).

[Darshi]

Hi every one, It is long time !
Wish all of you a very Happy new year.
Let me share some thing new
have a look at www.torogreentech.com
A new pre cooler for air cooled condensers using recycled water!

[ismail]

Darshi

out of date evaporative condensers I recently specified cooling towers instead of evaporative condenser on a large job, there was no energy saving going from evaporative to water cooled, in fact the energy used by the cooling tower and pumps was higher.

You wouldn't be the guy selling aluminium plates and condensers at the IKK

Kind Regards Andy

Is there any chemicals to clean the plate type heat exchangers. PHE uses amonia and glycol and foriegn particles are milk fat about 65 %

[simplygold]

Darshi,

Interesting concept... How would the systems you are describing run in a med/low humidity environment? Say constant 40%-80% humidity levels.

Would this precooled air system be more efficient that current evaporative condensors? (For an NH3 system at a 9.3 bar condensing pressure)

[Darshi]

Darshi,

Interesting concept... How would the systems you are describing run in a med/low humidity environment? Say constant 40%-80% humidity levels.

Would this precooled air system be more efficient that current evaporative condensors? (For an NH3 system at a 9.3 bar condensing pressure)

Dear Simplygold,

Systems will be less efficient when the ambient humidity is high.I would consider 50 to 60% as the ideal band for the application of Indirect Direct Closed Cycle, Cooling Towers.

In any case the the condensing temperature will be lower than the evaporative condenser.These cooling towers have approach to dew point instead of wet bulb temperature applicable to evaporative condensing.

the systems can reduce the refrigerant charge/Tonne, as the heat exchangers used can be Aluminum(compatible with a NH3)Multi Port Flat Tube units, similar to automobile radiators.

[Darshi]

hi Andy,
I will check up and let you know.