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Re: Carbon Dioxide Refrigeration
Quote:
Originally Posted by
Andy P
The expander developed at Dresden University compresses at one end by expanding the gascooler outlet at the other. This device would sit "on top of" a lower stage compressor driven by a motor because the power recovered from full expansion is only enough to drive a portion of the compression path, due to losses in the expander and the second stage compressor. Its a neat device, and can give useful heat recovery too.
I've never tried it - they are a bit small for our stuff:D
cheers
Andy P
Neat principle:) uses waste energy to improve system effeciency.
Heat recovery with a transcritical system would be the way to go, kind of like CHP, but instead combined refrieration and heating. Most applicable to supermarkets:)
Kind Regards Andy:)
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Re: Carbon Dioxide Refrigeration
I was trying to locate some literatures and informations on NH3/CO2 cascading, when I cam accross an article the link to which I am providing.
http://www.hvacindia.com/journals/20...article02.html
I am sure that you will find it useful.
With best wishes,
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Re: Carbon Dioxide Refrigeration
Please only post the information in one thread.
Thank you.
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Re: Carbon Dioxide Refrigeration
Dear US Iceman,
I was not aware of this. I thought that others may read it also. Anyway I am sorry for my mistake.
With best wishes,
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Re: Carbon Dioxide Refrigeration
We try to maintain an unwritten rule for single posts only to prevent accumulation of multiple posts in different areas.
I do thank you for posting the link to the article, it was useful and I think worthwhile for others to review.
Best Regards,
US Iceman
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Re: Carbon Dioxide Refrigeration
I have some basic flow charts for CO2/Nh3 applications, but due to them being larger than this site will accept I can not post them, if you are interested let me know and Ill email them to you.:D
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Re: Carbon Dioxide Refrigeration
Dear nh3wizard,
Could you please mail the flow charts for CO2/NH3 applications to me at samarjitsen@rediffmail.com .
Thank you,
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Re: Carbon Dioxide Refrigeration
Hi, Andy P :)
Quote:
Originally Posted by
Andy P
Hi Josip,
Why not - it's just a compressor? The CO2 compressors developed by J&E Hall in the 1880s which dominated the marine market for about 30 years were two stage. "The first CO2 machine made by J&E Hall was a two-stage compressor in which the first stage of compression was effected in the orthodox way by the action of a piston in a horizontal cylinder, and the second stage completed in a vertical cylinder containing a column of glycerine....A machine of this type was installed on 16 August 1889 in a frozen meat store in Smithfield and set to work. At 2am the pipe conveying the gas from the first to the second stage compressor burst because of a mechanical fault. 'The pipe was literally blown to ribbons' said Everard Hesketh [company chairman and designer of the compressor] 'and had it not been for the sides of the water tank surrounding the compressor...my head which was only a yard away would have been the target for some of the pieces.'"
Fortunately compressors have improved since then!!
Cheers
Andy P
PS Quotation is from "Halls of Dartford 1785-1985" by Harry Miller
I think answer to your question is in your quotation. It is not impossible but then you are coming into high pressure area - what is dangerous, then big power consumption and so on...but as Andy said, why not to try;)
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Hi, all :)
Quote:
Originally Posted by
Samarjit Sen
Reading this journal and some other I came to one question: Why a lot of (but not all) smart people writing similar journals about CO2/NH3 cascade systems presume to have NH3 condensing temp at +40C, why not at +35C
Is there maybe some explanation for that which I do not know or maybe.........
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Hi Josip,
A good question you ask.
My guess is these people have done a lot of air conditioning work with water-cooled condensers. 40C (105F) is the normal design temperature for condensing with water-cooled condensers.
I have also seen something similar to this. Designing systems that use evaporative condensers based on 48.8C (120F) condensing, or higher.:D
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Re: Carbon Dioxide Refrigeration
Since I am not much aware of the CO2/NH3 system and I am yet to come accross one which has been and in operation in our country, I would like to ask a (maybe a stupid) question. But as I have said earlier, that I have no experience in these systems as I have been handling mostly halocarbons.
My question is that could the CO2 in the lower stage be used as a DX system with suitable TEV and Air Cooling Unit for maintaining the desired temperature in the rooms or we have to chill the brine solution and circulate the same through Coils?
From the Forum it appears that a lot of work in this field are being done in Europe and USA.
With best wishes.
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Re: Carbon Dioxide Refrigeration
Quote:
Originally Posted by Samarjit Sen
My question is that could the CO2 in the lower stage be used as a DX system with suitable TEV and Air Cooling Unit for maintaining the desired temperature in the rooms or we have to chill the brine solution and circulate the same through Coils?
Hi, you need to be careful with the application of CO2 due to it's inherently higher pressures. I can't think of reason why you could not use CO2 for DX, flooded, or liquid overfeed. It's just another refrigerant.
However, like any other refrigerant you can only apply it within the guidelines of safety and equipment limitations.
If you tried to use CO2 at normal refrigeration or AC conditions of say, -30C to +4.4C you would expect to see very high pressures. These higher pressures have to be contained by the components and piping.
On the other hand, if you were to use CO2 as we normally use common refrigerants you would find very low temperatures until you get to the triple point of CO2, which is about -67F (-55C).
Using air or liquid depends on the cooling process. In either case, air or liquid/brine are secondary refrigerants. The primary refrigerant would be CO2.
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Re: Carbon Dioxide Refrigeration
Thank you US Iceman. We propose to use CO2 in the lower stage and NH3 in the higher stage. The CO2 temperatures required are to be -45 Deg. C Te and -5 Deg. C Tc. There shall be three rooms. One to be maintained at - 40 Deg. C, and the other two at - 30 Deg. C. I would prefer to use a DX system as I am more aquainted with this . If you advice flooded we can also go for it.
Further you and Andy has been repeatedly emphasising on the maintaing the safety norms and controlling the pressure and temperatures. Could you please elaborate on this point, and as to how does one control the temperature of CO2 at the initial stage of commissioning and also at the idle stage.
With best wishes and thanks a lot for the guidance.
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Re: Carbon Dioxide Refrigeration
Quote:
Originally Posted by Samarjit Sen
as to how does one control the temperature of CO2 at the initial stage of commissioning and also at the idle stage
When the CO2 system is shut down (but still containing CO2) you have two options that I know of.
1) You can use a smaller, separate refrigeration to coil the main CO2 vessel. This is verysimilar to the CO2 storage tanks commonly found. A small heat exchanger is installed in the CO2 tank. As this little refrigeration system operates it keeps the CO2 pressure down by condensing the CO2 vapor in this vessel.
2) You can use what we call fade-out vessels (sometimes called an expansion tank). In this example you have to provide sufficient additional volume in the CO2 system. When the system is idle, the liquid CO2 will evaporate. This causes th epressure to increase. By adding sufficient volume to the CO2 system you can limit the pressure rise so that it stays within acceptable limits (of the pressure vessels and safety relief valves).
For start up or initial commisioning you have to have the high stage system in operation first. This is the same on a two-stage compression system. You have to pull the temperature down before starting the low stage.
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Re: Carbon Dioxide Refrigeration
Dear US Iceman,
Thank you for advice. What now I understand that as in a R 404A/R 23 cascade system we provide an expansion tank the same process has to be adopted.
I have been enquiring in our country, and it appears that there are no CO2/NH3 Cascade plants installed as yet. Now what I would like to know that cost wise if you compare with a two stage reciprocating compressor using R 404A, what would be the position. The running cost will be lower but one must have an expert technician who has handled such plant available, which unfortunately there are none. It is the capital cost that matters. Will it be worth while to install CO2/NH3 cascade system of 130 Kw capacity in our country considering the points that I have stated above.
With best wishes,
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Re: Carbon Dioxide Refrigeration
Hi, Samarjit Sen :)
Quote:
Originally Posted by
Samarjit Sen
Dear US Iceman,
Thank you for advice. What now I understand that as in a R 404A/R 23 cascade system we provide an expansion tank the same process has to be adopted.
I have been enquiring in our country, and it appears that there are no CO2/NH3 Cascade plants installed as yet. Now what I would like to know that cost wise if you compare with a two stage reciprocating compressor using R 404A, what would be the position. The running cost will be lower but one must have an expert technician who has handled such plant available, which unfortunately there are none. It is the capital cost that matters. Will it be worth while to install CO2/NH3 cascade system of 130 Kw capacity in our country considering the points that I have stated above.
With best wishes,
In your case I will go to your proposal (R404a) or to use 2 stage ammonia.
Down to -40C ammonia is the best one for sure even as 2 stage system, for capacity less then 750 kW!
Quote:
Originally Posted by Web page
Why CO2?
Advantages:
Quote:
1. CO2 is a natural gas. Compared to the other new refrigerants it has a friendly global environmental character. The ozone deletion potential (ODP) is zero and the global warming potential (GWP) is one.
2. CO2 is a class 1 refrigerant (non toxic, non flammable)
3. CO2 has a very large volumetric refrigeration capacity (it means small compressors, small pipe dimensions)
4. CO2 has very good heat transfer characteristics.
5. It is not foreseen that law in the future will limit CO2.
Disadvantages:
Quote:
1. Large operation pressures inside the evaporator and the condenser, for defrosting a pressure of 40 bar is required (condensing temperature of CO2 +5 °C at this pressure)
2. Pressure limitation is required when the plant stops.
3. Reaction of CO2 and NH3 generates solid particles.
4. CO2 could be a local danger due to its absence of smell and higher density than air.
5. Limitation of evaporation temperature of –54 °C caused by the triple point at –56,6 °C.
CO2 has been investigated as a refrigerant in non-critical refrigeration processes for a long time especially for mobile car air conditioning plants.
Due to the thermodynamic characteristic and huge volumetric refrigeration capacity of CO2 a cascade plant has small compressor and small pipe diameters at the low temperature side. One has to accept that the use of CO2 with evaporation temperatures below the triple point is not yet possible. Therefore the application field of a CO2-cascade refrigeration plant is limited within an evaporation temperature range of –40 °C and –54 °C.
Quote:
Above –40 °C evaporation temperature the use of CO2 is not so interesting since efficiency becomes less when compared to a two-stage ammonia plant.
The CO2/NH3-cascade refrigeration plant offers reduced refrigerant charges, higher efficiency and a contribution for environment protection by the use of natural substances without ozone depletion potential and possibly without direct greenhouse potential. The ammonia charge being reduced to a minimum is located only in the machine room.
Based on our own investigations with two different refrigeration systems with refrigeration capacities of 750 kW and 1500 kW and an evaporation temperature range of between –40°C and –54°C, it is clear that the cascade refrigeration plant is more efficient than a two stage refrigeration plant with ammonia in this evaporation temperature range. Therefore the application focuses on freeze drying of coffee, freezing of fish and meat, low temperature storage and quick-freezing processes.
You mentioned 3 rooms (one at -40C, and 2 at -30C) and all is 130kW.
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
I'm going to agree with Josip and suggest the R-404a or two-stage ammonia system. Yes, there are some trade-offs between efficiencies and installed costs.
However, if the system is more complicated than the service people have experience with an efficienct cascade system does the owner no good. It's also probably much safer to provide a system close the experience level of the service technicians.
Josip, where did you find that web page?
Thanks my friend.
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Re: Carbon Dioxide Refrigeration
Dear Josip,
Thank you for the clear picture put up by you . The total refrigeration load of the system for all the three rooms is 130 kw.
Regarding the comparison of cost of the two system, it is still not clear. Could you please let me know as to the cost of whish system would be cheaper.
With best wishes,
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Re: Carbon Dioxide Refrigeration
Hi, US Iceman :)
Quote:
Originally Posted by
US Iceman
Hi Josip,
A good question you ask.
My guess is these people have done a lot of air conditioning work with water-cooled condensers. 40C (105F) is the normal design temperature for condensing with water-cooled condensers.
I have also seen something similar to this. Designing systems that use evaporative condensers based on 48.8C (120F) condensing, or higher.:D
I can agree for ***** plants, but for ammonia!?
Check this standard:
http://www.ari.org/NR/rdonlyres/193A...18/0/51093.pdf
maybe is too old, or...
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Hi, Samarjit Sen :)
Quote:
Originally Posted by
Samarjit Sen
Dear Josip,
Thank you for the clear picture put up by you . The total refrigeration load of the system for all the three rooms is 130 kw.
Regarding the comparison of cost of the two system, it is still not clear. Could you please let me know as to the cost of whish system would be cheaper.
With best wishes,
It is not clear for me either, but coming into new field with so many safety units, electronic devices, and so on; for me is clear: CO2/NH3 must be more expensive then the good old way: double stage R404a or ammonia.
From my previous post you can see they made comparison with two plants 750kW and 1500kW, what is about 6 to 12 times bigger then your plant i.e. under 750kW it is maybe too expensive, even to start to think about;) .
You can ask for an budget offer from Sabroe (http://www.sabroe.com/Information/CO2/index.html), or Gea-Grasso (http://www.grasso-global.com/Applications.14.0.html) or ask Andy for some help.
Maybe I am not right;) , but other guys will come with some better info...
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Quote:
Originally Posted by
Josip
The evaporative condenser project I saw was used on ***** systems for condensing temperatures about 48.8C (120F). From what I was able to learn Carrier tried this back in the 1950's & 60's. Unfortunately the condensers were never maintained and in a short time the condenser was converted into a solid block of concrete.:D Needless to say the condensers did not work well when that happened.
The 40C condensing for the NH3/CO2 system may have been due to higher supply water temperatures for some reason.
Or then again, someone may have tried to save money on the water cooling system with regard to the impact to the refrigeration system power use.
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Re: Carbon Dioxide Refrigeration
Hi Josip,
I just looked at the ARI standard you posted. This standard applies to the actual process used for rating the compressor performance and the tolerance for capacity & power deviation from published to test data.
It is not an actual design document for ammonia refrigeration systems.
You might see some ammonia systems using air-cooled condensers on some facilities such as atmospheric ammonia storage. In those examples, the condensing temperature are quite higher than 35C.
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Re: Carbon Dioxide Refrigeration
Hi, US Iceman :)
Quote:
Originally Posted by
US Iceman
Hi Josip,
I just looked at the ARI standard you posted. This standard applies to the actual process used for rating the compressor performance and the tolerance for capacity & power deviation from published to test data.
It is not an actual design document for ammonia refrigeration systems.
You might see some ammonia systems using air-cooled condensers on some facilities such as atmospheric ammonia storage. In those examples, the condensing temperature are quite higher than 35C.
Agree 100%, it is not actual design document, what I was trying to said, it is possible to start design with CT at 35C, 13.5Bar i.e. lower energy consumption. If we have too hot water or too high temp with high humidty (some part of the year, in some part of the world) we will have, for short time higher CT.
With design of EC to work with CT at 35C, there should be more capacity in hard weather condition, then if design is for CT at 40C.
In another hand I was working with ammonia air condensers (CT=50C, 20Bar) in Saudi Arabia (still in use because there is not water available) but it is very hard for compressors and you need a lot of money for el.power ;).
To design a low energy consumption plant for sure is not to start with high condensing temp/press.
Of course there were and there are some facilities with condensing temp higher of 35C, due to process request but that is another story.
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Hi Josip,
I agree 100% with what you mentioned.
I would like to know the reasoning behind th euse of 40C CT on ammonia for the NH3/CO2 system you posted earlier.
I normally use 35C CT as the starting point in the design, but also include greater allowances for higher entering wet bulb temperatures.
Most of the weather data I've seen for the US is of course based on the ASHRAE data. Then we have to select the percentage factors for the actual design conditions.
I prefer to use the accumulated weather data that shows the actual values. As you know, the weather is always hotter or more humid for some period of the year than what the weather data suggests.
For HVAC purposes this data is probably OK. However, for process requirements I would rather have the equipment sized to run in the extreme cases.
If we save money on the installation and equipment costs, this is a small portion of what the "real costs" are for production cooling.
The way I look at this is... It might be cheaper to use the "design conditions", but if the refrigeration system has to run at partial capacity due to high discharge pressures, who looses?
I can certainly understand the logic in using AC condensers in Saudia Arabia at first glance. But, is the quantity of water that might be needed for the evaporative condensers really that limited?
What do they do for all of those large HVAC chillers? Are they AC also?
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Re: Carbon Dioxide Refrigeration
Hi, US Iceman :)
Quote:
Originally Posted by
US Iceman
Hi Josip,
I agree 100% with what you mentioned.
I would like to know the reasoning behind th euse of 40C CT on ammonia for the NH3/CO2 system you posted earlier.
I normally use 35C CT as the starting point in the design, but also include greater allowances for higher entering wet bulb temperatures.
Most of the weather data I've seen for the US is of course based on the ASHRAE data. Then we have to select the percentage factors for the actual design conditions.
I prefer to use the accumulated weather data that shows the actual values. As you know, the weather is always hotter or more humid for some period of the year than what the weather data suggests.
For HVAC purposes this data is probably OK. However, for process requirements I would rather have the equipment sized to run in the extreme cases.
If we save money on the installation and equipment costs, this is a small portion of what the "real costs" are for production cooling.
The way I look at this is... It might be cheaper to use the "design conditions", but if the refrigeration system has to run at partial capacity due to high discharge pressures, who looses?
I can certainly understand the logic in using AC condensers in Saudia Arabia at first glance. But, is the quantity of water that might be needed for the evaporative condensers really that limited?
What do they do for all of those large HVAC chillers? Are they AC also?
It seems we are coming back to another question again:
-first cost or running cost;)
Agree with you to use design conditions for HVAC units but for refrigeration we have to use extreme conditions and try to design refrigeration plant to work with max COP even with partial load in extreme conditions.
All AC in SA are quite old and nowdays they start to change them with EC for ammonia plants.
HVAC chillers still today are with AC, because EC is more expensive. ***** is another story because we cannot beat them with the prices but you know that very well.
They approach with; we have green *****, not harmful, extra effective:eek: :mad: almost good as clear air you need for breathing and all that story to make a profit (and they are good in that). Another problem is a lack of knowledge about ammonia
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Hi Josip,
Here is some information you can use with your next discussion of R-22 with the HVAC people.
This information comes from the Material Safety Data Sheets (MSDS) for R-22. I found this for another discussion taking place with some other gentlemen.
“Flash Point: Will not burn
Auto-decomposition: 632 C (1170 F)
Other burning materials may cause "*****" 22 to burn weakly. Chlorodifluoromethane is not flammable at ambient temperatures and atmospheric pressure. However, chlorodifluoromethane has been shown in tests to be combustible at pressures as low as 60 psig at ambient temperature when mixed with air at concentrations of 65 volume % air. Experimental data have also been reported which indicate combustibility of "*****" 22 in the presence of certain concentrations of chlorine.”
This does not even include the comments about disrupting the heart rate, potenital oxygen deprivation, or other fun things that can happen.
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Re: Carbon Dioxide Refrigeration
Dear Freinds,
Although I have hardly done any projects with NH3 and none involving CO2, but after seeing the datas that you all have provided and the details taught to me, I am really facinated with this refrigerant. You people have been a tremendous help to me and I wish some of my coleagues in our country could take advantage and learn a lot of things from this thread. I am now very keen to execute some contracts in CO2/NH3, and would request you all to please provide me some more technical details on the same.
Regarding the Condensing temperature of 40 Deg. C, we use it at places where the ambient are very high which are generally in the part of Northern side of our country. There are a number of projects where Condensing is taken as 35 deg. C. The ambient conditions in our country vary very much.
With all the best,
Samarjit
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Re: Carbon Dioxide Refrigeration
One of the items I tend to use for designing systems is an upper limit for condensing temperature on ammonia systems of 33.8C (93F).
35C (95F) is the normal "design" temperature commonly used, but I seem to remember some factors that can be minimized by a slightly lower condensing temperature when evaporative condenser are used.
It has to do with water quality and the chemical treatment of the recirculated water. It has nothing to do with Legionella bacteria, only scale formation.
I'll have to do a little research to refresh my memory. I will add these comments later.
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Re: Carbon Dioxide Refrigeration
Hi, US Iceman :)
Quote:
Originally Posted by
US Iceman
One of the items I tend to use for designing systems is an upper limit for condensing temperature on ammonia systems of 33.8C (93F).
35C (95F) is the normal "design" temperature commonly used, but I seem to remember some factors that can be minimized by a slightly lower condensing temperature when evaporative condenser are used.
It has to do with water quality and the chemical treatment of the recirculated water. It has nothing to do with Legionella bacteria, only scale formation.
I'll have to do a little research to refresh my memory. I will add these comments later.
You are right, I remember the past time when we design EC with desuperheater section (above water eliminator) where the inlet gas temperature were reduced to prevent extraction of calcium carbonate from cooling water. In that time water was treated only with NaCl to be soft, no other chemicals were added.
Best regards, Josip :)
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Re: Carbon Dioxide Refrigeration
Quote:
Originally Posted by Josip
You are right, I remember the past time when we design EC with desuperheater section (above water eliminator) where the inlet gas temperature were reduced to prevent extraction of calcium carbonate from cooling water. In that time water was treated only with NaCl to be soft, no other chemicals were added.
This is the same thing. Desuperheaters are very seldom used anymore on recip. plants, but they should be. They do make a difference on scale formation on the top row of tubes.
The desuperheaters do accumulate some very small amounts of scale. But since they are in a humid air, rather than complete liquid water this makes a big difference.
I think it is a combination of discharge temperature in the tubes and the actual water temperature. Where both are high, the scale formation is much worse.
This makes another good example of why we should keep condensing temperatures/discharge pressures lower.:D
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Re: Carbon Dioxide Refrigeration
hi,everyone
i am a new engineer, and now working on designing co2 liquifier, could someone help me especially on calculating the co2 condensation heat transfer coefficients in-tube? and more information on the shell and tube exchanger design? thanks a lot!
best regards
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Re: Carbon Dioxide Refrigeration
Another plus for desuperheaters is that in winter the airflow leaving the condenser is slightly heated away from the saturation curve so that when mixed with the lower temperature ambient air it is kept clear of fogging conditions. Hence reducing the annoying (to some) plume of steam.
mick
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Re: Carbon Dioxide Refrigeration
hi i'm new at this forum but i was sent to a co2/r410a system becase of high pressure alarm in the r410a system.After 3,5 hours of checking i got a bit frustated and opened a liquid service valve for 2 seconds and all i saw was snow:mad: .Reason was a leaking heat exchanger(co2 condensor/r410a evaperator).Now when you try to recover 2500 kg r410a when it's mixed with co2 you will find enorm pressure in the tank All in all all the oil changed cleaned the inst. with n2 new ***** and co2(4000kg) and 60 hours later with 3 engineers inst. was up and running.
Just to point out one of the riscs
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Re: Carbon Dioxide Refrigeration
Quote:
Originally Posted by
ART KUHN
hi i'm new at this forum but i was sent to a co2/r410a system becase of high pressure alarm in the r410a system.After 3,5 hours of checking i got a bit frustated and opened a liquid service valve for 2 seconds and all i saw was snow:mad: .Reason was a leaking heat exchanger(co2 condensor/r410a evaperator).Now when you try to recover 2500 kg r410a when it's mixed with co2 you will find enorm pressure in the tank All in all all the oil changed cleaned the inst. with n2 new ***** and co2(4000kg) and 60 hours later with 3 engineers inst. was up and running.
Just to point out one of the riscs
Hi Art:)
good job it was R404a not an ammonia job;) now that would be fun:D
Kind Regards Andy:)
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Re: Carbon Dioxide Refrigeration
hi,all.
Long long long time no see!
I am missing in the nh3/co2.
sagittarius
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Re: Carbon Dioxide Refrigeration
HAI, iam refrigeration engineer in uae .please send me a
drawing digrem in co2 and ammonia pumping
"xxxxxxxxxxxxxxx".
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Re: Carbon Dioxide Refrigeration
Hi fellows
I am interested for Co2 / NH4 Cacade Refrigeration cycle. If any body have a case study with system details for any existing refrigeration plant please let me know.
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Re: Carbon Dioxide Refrigeration
Hi Kawaljeet Singh,
It is very difficult much information on CO2/NH3 at present. However for your information a portal has been opened in Germany very recently. You may visit the same at www.co2refrigeration.com . Further Danfoss and Bock have done and are still working on this application. Just for your information the cascade system is just like anyothe cascade system. Here the NH3 is used in the High Stage and CO2 is used in Low Stage. CO2 has the pressure of building up a very high pressure at a higher temperature and as such to control the pressure is important. If you study this thread from the begining you will get a lot of reply to your questions.
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Re: Carbon Dioxide Refrigeration
I would be interested in the drawings for the cascade system. Please send them to me. I do not know how to email you directly. Can you find me?
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Re: Carbon Dioxide Refrigeration
Our plant manager is terrified of NH3, he says it all has to go. he wants all co2. I surmise that in the long run, more deaths will be attributed to co2 deaths than ammonia. (due to sensory properties.)
So he asked me, can we put smell in it like they do natural gas? I don't have a clue if it can be or is done or if anyone ever tried. I suggested maybe we should try color, then when you see purple haze you vacate.
WM