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Vincent Yu
18-08-2005, 10:06 PM
Hello everyone,

I am trying to design a refrigeration system which has about 20 Watts cooling capacity at -140 degree Celsius. The ambient temperature is 25 degree Celsius. I think it should be a three-stage cascade system. What I am concerning is the last stage. Does someone have any experience on such a low temperature application? Which company provides suitable compressors for this application? What kind of refrigerant I should use? What kind of compressor oil I could use in such a low temperature?

Any comments and suggestions are appreciated.

Thanks
Vincent

vaidas_78
18-08-2005, 11:17 PM
Take a look here http://www.copeland-corp.com/cp_rf/prod_sol/cp_rf_products_scroll_cryo.htm
Copeland cryoscroll compressors operate with helium.

US Iceman
19-08-2005, 12:27 AM
Hi Vincent,

There is quite a bit to be concerned with on a cascade system. The lowest stage normally uses a very high-pressure refrigerant (at ambient temperatures) to allow the system to operate in a positive pressure at the ultra low temperatures.

Oil and refrigerant compatability and also solubility and miscibilty are some of the issues to be concerned with. The high-pressure refrigerants require a fade-out (expansion) drum so that the mass of refrigerant in the cascade system (low temp. system) can expand in volume without exceeding the system design pressure.

The suction gas coming from the low-temperature evaporator can contain a lot of suction superheat that increases the specific volume of the refrigerant. The superheat is a combination of the evaporator superheat (the normal expected) plus all of the parasitic heat gain through the suction line, etc.

Most of this superheat is not useful, therefore you need higher mass flows to produce the same capacity.

If the system is to be started and run continously at low temperature this one operational concern. If the system is required to do frequent hot starts and pulldowns that can be another issue (high suction pressure pull-down conditions and overloading).

If this is for a single use (medical storage, research test, etc.) I would recommend you look into buying one from a manufacturer who specializes in this type of work. If it is for a production item you are selling, the design and research effort may be worth your time.

I have seen more problems with cascade systems than any other type of system. Even those built by the manufacturers. This a highly specialized and engineered system. They are also very expensive.

It can be done however.

Some systems I have seen use ethane, ethylene, R-23, and others. Some of these refrigerants are flammable, so this raises another level of requirements (explosion-proof electrical design- NEMA 7, Group D, Div. 1 or 2). Sometimes you can use NEMA 4nitrogen purged panels, but only with the insurers blessing.

I hope this information is useful to you for your initial reviews.

Best Regards,
US Iceman

Lc_shi
19-08-2005, 04:08 AM
Hi Vincent
you can refer to http://www.helixtechnology.com. It's difficult to use normal vapor compression to reach to -140 Celius. pls share your progress .

rgds
LC

Peter_1
19-08-2005, 06:38 AM
We service some Polycold machines, those which Helix sells also I see.
There working principle is the autocascade system.
Theory is rather simple but to build it yourself is very difficult.
But a 3 cascade sytem, yes why not.
But like US Iceman said, be ware of the high pressures.
Do a serach on this forum, there were some posts in the past of it.

US Iceman
20-08-2005, 03:37 AM
Vincent,

Another idea for you to consider: using liquid nitrogen as an expendable refrigerant. If this application you have is only used periodically, an expendable refrigerant may be a much easier system to design and use.

A gas supplier should like BOC should be able to provide additional information on costs, etc.

TXiceman
21-08-2005, 04:45 PM
As suggested above, using liquid N2 is the easy way if you are doing this project short term. Other wise you are looking at a 3-step cascade. Since this is a relatively small load, equipment maybe hard to source.

Just recently Bitzer has introduced to the US market a high pressure CO2 recip which you may be able to use. Part of the problem with compressors at such low temperatures is the casings are not designed for such low temperatures and you will need to superheat the gas to an acceptable level for the compressor. A lot of the compressors are limited to -50 to -70 dF suction.

Also as pointed out, you will have problems with system stand by pressure so you will have to allow for an expansion tank or fade-out drum to allow the entire refrigerant charge to go to vapor state in order to stay below you system DWP when shut down. Another issue is oil return from the evaporator at such low temps.

Designing such a low temp system is a highly specialized field and you wil find most refrigeration engineers do not have a clue as to how to approach the design.:eek:

I can put you intouch with a consultant that can handle the design spec if you need some help. (He does not work for free.)

Just remember the old "Buyer beware."

Ken

Lc_shi
22-08-2005, 12:45 AM
Hi Dear all,
is there any useful website for low temp refrigeration design?

rgds
LC

US Iceman
22-08-2005, 04:16 AM
Most of the web resources you will find are from specialty manufacturers for this type of equipment. Mostly small systems and storage requirements for medical or product testing. The refrigeration design is guarded as a closely held secret, in my experience.

You will find general specifications and performance data, but not refrigeration system details.

Larger systems for oxygen, or other gas separation (air plants, or gas processing) are custom engineered. Usually by the larger industrial refrigeration manufacturers.

This is not an area for casual experimentation, unless you are looking for upset customers.

You may find some casual references in some of the better refrigeration books, but in-depth design knowledge is not commonly documented for the general public.

The last one of these I worked on (about 10 years ago) required 50 Tons of cooling. System cost was about $2.5 million US at that time. You cannot afford to guess too many times when the system costs are this expensive.

Regards,
US Iceman

Lc_shi
22-08-2005, 04:48 AM
Hi Iceman
Right. You can't get the system details by searching website. I believe it's more useful by communicating with the experienced guys. Low temperatue refrigeration is a not widely used field and there are not so many engineer as normal AC&refrigeration ones.
http://www.xtremesystems.org/forums/
It's a forum related to cooling issue,may helpful for us.

rgds
LC

Peter_1
23-08-2005, 08:14 AM
Lc
Some of the posters here only do this kind of work.
Forgot their names but one of them works at Revco www.revco-sci.com

You can also search through the patent databases on the net to learn how others solved it. I have maps full of printed material of these databases, also on cryogenics.

The autocascade is a wonderfully piece of technique. We service at a client some units from Polycold (-110°C with a 10 HP Carlyle compressor in it which cools only +/- 15 m of 5/8 copper tube)
I know and understand the great lines how this system is working (+/- the same principle how they liquefy nitrogen, this can be found in the ASHRAE books) but to build it yourselves is not that easy at all. All the HE and capillary tubes must match very precisely.

Vincent Yu
23-08-2005, 03:04 PM
Thank everyone for the valuable suggestions. Currently our company builds 2-stage cascade systems. Normally they are used in vacuum chamber and testing chamber. Two ¼ HP compressors are used. The system can reach -100 degree Celsius. We do have some experience to design and manufacture two-stage cascade systems.

Recently, a customer has an application which needs the temperature goes down to -130 degree Celsius. We plan to develop a 3-stage system based on our current 2-stage systems. Following is an outline of my design. Please give me your opinions:

Three ¼ HP compressors are used. For two stage systems, it is a good choice to use 2 compressors having the same power. I am not sure if this principle still works for three stage systems.

First Stage: condensing temperature: 35C; evaporating temperature: -30C. Refrigerant: R404A or ISCEON89. A fined tube air cooled condenser is used.

Second Stage: condensing temperature: -25C; evaporating temperature: -75C. Refrigerant: R23 or (R508 + R14).

Third Stage: condensing temperature: -70C; evaporating temperature: -140C. Refrigerant: R14.

By my rough calculation, if the refrigerants are selected as above, the condensing and evaporating temperatures in each stage should be the values I give. But I am not sure if the system is optimal in these conditions. It is very difficult to get the optimal solution just by calculation. I will adjust the system based on test result.

Plate heat exchangers (WTT) are used between first and second stage, and second and third stage. Five degree temperature difference is enough for efficient heat transfer.

The metering device in first stage is a thermal expansion valve. Capillary tubes are used in second and third stages.

Cylinders are used as fade-out drums in second and third stages. They are place in the low side between the evaporator and the compressor. The size of the tank will be determined by experiments. There is no harm that the fade-out drum is a little bit oversize. Is it correct?

Coalescent oil separators (Temprite) are used in second and third stages for oil separation.

The principle of cascade system is very simple. But to select parts and build it is very challenge. I start to test the performance of the first and second stages, and hope it can provide about 300 ~ 350 watts cooling capacity at -80C for the third stage.

Now I still have trouble to find a suitable compressor for the third stage. And I also need to confirm that R14 is the best choice for the third stage. Any information and suggestions about the compressor and the refrigerant for the third stage are welcome.

Ken, Could you give me more information about the consultant you talked about? If he is really very professional in cascade system design, and if we really have trouble to develop it by ourselves, maybe my boss is willing to pay him for his help.

Thanks again. I am willing to share all the information with you, and will report you guys my work on this project regularly.

Lc_shi
31-08-2005, 06:32 AM
Hi Vincent,
It's a website i just encountered which provide supercooler down to -150C degree,may be of some help for you.

http://www.qdrive.com/index.php?page_id=61

rgds
LC

Polypete
01-09-2005, 09:52 PM
Hi Vincent,
We started using British built 3-stage cascade systems (RSS of Worthing) capable of -126 Deg. C. in the late 70's. We also tried the Harris (USA) and Lada 2-stage units but now use the autocascade systems built by Polycold and systems previously made by S-10 Technology. The autocascades are by far the most efficient and most reliable although the mixed refrigerant charges they use are also the most expensive ! The oil used for the low temperature stages was Zerol 150, this is less prone to waxing at temperatures below 70 Deg. C. but there are Polyolester equivelants available these days. Your local supplier should be able to point you in the right direction with these.

Peter_1
02-09-2005, 06:22 AM
Were these machines also used for a vacuum chamber/cold trap application?

I service also Polycold at a client and the gas costs indeed a fortune. Theyu have special top-off cilinders but even then, filled with small gold particles I think.

We once had serious troubles with a Polycold machine and a technician from Germany had to come.
He had a book with him with sevral pictures while they're were building a Polycold machine in the factory.
The gas mixs consists of 5 different refrigerants. Helium was the final ne, R114, I forgot the others.
But I found several autocascade gas-mixes on the net (patent databases)

Peter_1
02-09-2005, 06:22 AM
Were these machines also used for a vacuum chamber/cold trap application?

I service also Polycold at a client and the gas costs indeed a fortune. Theyu have special top-off cilinders but even then, filled with small gold particles I think.

We once had serious troubles with a Polycold machine and a technician from Germany had to come.
He had a book with him with sevral pictures while they're were building a Polycold machine in the factory.
The gas mixs consists of 5 different refrigerants. Helium was the final ne, R114, I forgot the others.
But I found several autocascade gas-mixes on the net (patent databases)

brightfu1
02-09-2005, 04:59 PM
FOR more informations,you can go to US PATENT。BUT IT'S NOT TOO DETAILed
http://www.uspto.gov/

ksvinod
02-09-2005, 06:28 PM
i from electrolux , i would like to hnad over all ultracold medical cascade refirgeration system data
regards

vinod,india

Peter_1
02-09-2005, 07:25 PM
Well, I should say, post as lmuch information as possible.
Do you have experience with larger autocascade systems?
Experience with a 3 stage system?
What gasses used?
Brand of compressors?
Brand of oil?
Special modification made on the compressors?
Expansion tanks?
....
....

Polypete
02-09-2005, 09:43 PM
Vincent, Pete_1
The compressors used for cascades and autocascades are standard units. The oil used needs to be capable of surviving the low temperatures of the final stages (Zerol 150 for example). A typical set of refrigerants used for a standard 3-stage cascade could be R404A, R23 & R14. An expansion tank for the R14 stage would be useful in keeping the static pressure down (it also helps during the defrost stage too) but is not essential ! There is an expert on autocascades within RE. His member name is JTSTEN, he has a website: http://s-10tech.com which gives his contact details. If you are serious about designing a low temperature system, he could be your man. The autocascade systems we use are capable of driving relatively large meisner coils (cryo coils) in our vacuum chambers. These reduce the temperature from ambient to >100 Deg. C. within a few minutes and can also defrost the coil in a similar time.

Peter_1
03-09-2005, 03:04 PM
Perhaps Jsten uses less gold particles in his gass mixes.:D
An address to remember, especially we buy sometimes gasses for Polycold machines (we have to buy it in Germany, Ferrotec..)

Polypete, what about the very low temperatures encountered when cooling to such a low temperatures: motor windings, the changing of the molecular structure of the cast iron body (justified comment of TXIceman...)

Polypete
03-09-2005, 04:27 PM
I have not seen the suction end of the compressors used for cascades and autocascades cooled to temperatures much below -30 Deg C.. In the cascade systems we used, the R14 TEV was mounted on the outside of the vacuum chamber, usually more than 3 metres away from the cascade unit. By the time the vapour got back to the compressor, low temperatures were not a problem, sure we had frost on the suction valves and sometimes (if a TEV stuck open) frost starting to appear on the compressor body, but this did not cause any longer term problems. In the autocascade the return line in the unit is basically one long heat exchanger all the way back to the suction side of the compressor, so the high pressure refrigerant gases on the other side of this heat exchanger supply enough heat to ensure all liquid refrigerant is boiled off and by the time it reaches the compressor suction valve, the low boilers are sufficiently superheated not to cause a problem. As you can observe on your Polycold compressors Pete, a light frost on the suction valve with some condensation on the compressor back plate is about as cold as they get. In fact the rear of the compressor gets coldest during the defrost cycle when the liquid in the cryocoil is being pushed through ahead of the defrost gas. The biggest problem with both types of cascade, for us, has been oil. If it gets up to the cool solenoid valve where temperatures are probably around -90 or lower, it causes the valve to stick. Sometimes to stick open, sometimes to stick shut. The other problem with the oil is ensuring it gets returned from the colder areas in the stack and the cryocoil, back to the compressor. Oils are not always miscible with the low boilers, but the people who developed these units (including the cascades) took account of this. You will find that one component of the refigerant charge is purely for transporting the oil through the systems colder reaches.

Vincent Yu
07-09-2005, 04:06 PM
Polypete,

Thank you for your information. Comparing with traditional cascade systems, autocascade systems have many advantages. Only one compressor is needed. It does not work at very low temperature. Standard units can be used. The system is also more reliable. For low temperature applications, I feel this is the way to go. Now I am thinking about the possibility to design the unit as an autocascade.

Normally, there is an oil separator between the compressor and the condenser. It separates oil from refrigerant in the 99% efficiency range. Why do we still have oil problem at lowest stage?

In an autocascade system, all stages share one suction line. How do we control the evaporating pressure in different stages? Do we need to set the evaporating pressures at different stages to be the same value? If the evaporating pressures are different, I think cap tubes are needed between the evaporator outlet and the suction line to balance the pressure. Is it correct?

For autocascade systems, I think to mix the refrigerant is the key. Do you have any idea about selecting refrigerants? In my project, I need about 15 watts cooling capacity at -140 degree C.

Any information about Autocascade systems is appreciated.

Regards,
Vincent

KeithCA
07-09-2005, 07:30 PM
Dumb Question? Have you looked at already made products yet? Like Revco or Sanyo Scientific? They have various -150C chest and reach in freezers. or are you looking to make something larger.

Polypete
08-09-2005, 09:37 PM
Vincent
I can only comment on what I have seen of autocascades. The oil only becomes a problem when the condensing water temperature rises above around 28 Deg. C. I believe most of the oil in the discharged mixture would be condensed with the first stage (high boiling point) refrigerant in the (water-cooled) condenser, therefore too high a condensing water temperature could allow more oil vapour to move into the colder stages of the system. Having too much of the first stage refrigerant in the system has similar consequences when it reaches the colder sections in that it causes partial blockages or the cool solenoid valve to stick. I would imagine the ideal condition would be that all of the discharged compressor oil and all of the discharged first stage refrigerant are fully condensed in the first stage condenser and then fed into the first stage evaporator and back to the compressor.
With regard to different evaporating pressures, I have never considered this to be an issue. If evaporating pressures are the same throughout the unit, just apply the evaporating temperatures of the different components at that given pressure. The capillary tubes would then only be needed to control the flow of the liquids from the high pressure side heat exchangers (condensers) to the low pressure evaporators. The trick, I imagine and as you suspect, is in selecting the refrigerants with the desired temperature steps between them. The refrigerants we used in the 3-stage cascades may be be a good starting point - R502/R13/R14 (modern equivalents R404A/R23/R14) although with 404A being a blend, you may want to consider something else for the high end boilers. I believe the aim with the autocascade refrigerant mix is to produce a mixture which will separate out at each stage rather than a blend of refrigerants working at similar temperatures. Although achieving -140 Deg. C. with R14 alone may be a challenge if a negative evaporating pressure is to be avoided....
Did you think about contacting JTSTEN ? He designed some of the low temperature (-120 Deg. C.) autocascades we are currently using.
Regards, Pete

Vincent Yu
09-09-2005, 03:05 PM
Pete,

Thank you for your comments. I will pay more attention to separating the oil in my design. I am trying to contacting JTSTEN now. Recently I found two US patents about autocascade system (Patent No: US 6631625 B1 and 5408848). They come from the same inventor. One focuses on non-HCFC refrigerant mixture, the other one focuses on the system. Some technical details are given. Please take a look when you get a chance.

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=6,631,625.WKU.&OS=PN/6,631,625&RS=PN/6,631,625

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=1&p=1&f=G&l=50&d=ptxt&S1=(autocascade+AND+refrigeration).TTL.&OS=ttl/(autocascade+and+refrigeration)&RS=TTL/(autocascade+AND+refrigeration)

About the refrigerant mixture, for -140 degree C application, the refrigerant mixture is composed of five gases: R142b or R600 (25.5%), R134a (23.2%), R23 (12.8%), R14 (23.7%), and R740 (14.8%). If the system does not need to work at such a low temperature, R740 is not needed.

About the system, the schematic diagram is very complicated. It takes me more than 2 hours to understand it. If no-CHFC refrigerants are used, the compressor is very hot. In order to avoid overheating of the compressor, the system should bypass some liquid first-stage refrigerant to reduce suction temperature.

Peter, for autocascade system, we do not need to worry about the low compressor temperature. Actually what we need to do is to avoid overheating of the compressor. I have just learned about it. Based on the data from the patents, the suction temperature is about -5 degree C. The discharge temperature is about 120 degree C. I am interested in the idea you mentioned about adding gold particles in the refrigerant. What is the purpose to add it? Increasing the specific heat, improve the heat transfer or other purposes? The specific heat of the gold is only 128J/(kgK).

Regards,
Vincent

Lc_shi
23-09-2005, 12:42 AM
Hi Vincent
Any update for your project?
Hope you make much progress on it-:)

rgds
LC

Vincent Yu
26-09-2005, 02:54 PM
Hello LC,

Based on theoretical analyze and the information I got, An autocascade system is more efficient than a 3-stage cascade system in my application. I am thinking about designing the unit as an autocascade system. Now I am trying to collect information about autocascade systems and select components.

Regards,
Vincent

Jingle
26-07-2006, 09:58 AM
Hi everybody,
Eventhough I recently joined, I have been visiting this site for quite some time. I am in the process of designing a cascade refrigetation system for -80 deg. C chamber. I think R-23 in the low stage and R-404a in the high stage is a good solution. In this regard I need somebody to through some light on the following.
1) What exactly is gliding problem associated with R-404a?
2)Why some manufacturer use few circuits in the aircooled condenser of R-404a (whose disch temperature is about +70 deg C) for low stage (R-23) discharge whose discharge temperature is +20 deg C( I hope this is correct)
3) Is copper coil with aluminium fins evaporator OK for -80 deg.C
4) What fans to be used for -80 deg.C.
5)Is there any special precaution to be taken for oil return for R-23 and R-404a.
6) I remeber somebody suggesting capillary tubes instead of Thermostatic expansion valve. How to size capillary for these refrigerants.
7) How to calculate the refrigerant charge needed. I think this is needed to design expansion tank.
8) The refrigeration load is around 3 Kw. Can somebody suggest the size of compressors and other equipments needed?

(The ambient temperature in our part of the country is +40 deg.C)
Regds,
Jingle

Rob S
08-08-2006, 04:57 AM
Jingle with a 3KW load...
I suggest you look for a chamber with two 7.5HP compressors.

irwinchong80
28-08-2007, 09:06 AM
hihi.. i m new ppl join refrigeration. i was very interesting in this sector. like cascade system unit, if we want the servicing in this system. anyway we can buy the equipment like manifold. any brand is good.

thanks,

shadi
18-11-2007, 10:16 PM
pleas send tom pleasssssssssssss
shadi842008@yahoo.com

shadi
17-12-2007, 04:47 AM
Hi
im asking if any body can help us how to determine heat transfere convection coffecint in refrigerated space @-65c



how to select components

Peter_1
17-12-2007, 08:40 AM
Hi
im asking if any body can help us how to determine heat transfere convection coffecint in refrigerated space @-65c

It depends if it's a cast iron, a glass or a wooden enclosure.
That's the first thing we need to know to answer your question.

how to select components
You haven't said which gas you want to use, NH3, sulfurdioxide, glycol, ... so once again, to less information.

Charles Hambly
20-06-2008, 08:57 PM
Question, It was mentioned in an earlier quote regarding reaching -100c in minutes from ambient and also the ability to defrost the same coils in the similar amount of time. I would be very interested to know how your achieving this. We have a -80c box with redundant systems and are using pressureized dry air -100 dew point to limit moisture. Our product storage will not stand temperature rise for defrost. What is it your doing to prohibit temperature loss and still be able to clear a coil?

Shaukat
22-06-2008, 11:51 AM
i from electrolux , i would like to hnad over all ultracold medical cascade refirgeration system data
regards

vinod,india
is it [-140°c] ?

Blaster
05-08-2008, 12:02 AM
Question, It was mentioned in an earlier quote regarding reaching -100c in minutes from ambient and also the ability to defrost the same coils in the similar amount of time. I would be very interested to know how your achieving this. We have a -80c box with redundant systems and are using pressureized dry air -100 dew point to limit moisture. Our product storage will not stand temperature rise for defrost. What is it your doing to prohibit temperature loss and still be able to clear a coil?


The way to do it is by a hot gas bypass

TXiceman
05-08-2008, 02:47 AM
To prevent the defrost heat gain from much impact on the space is to use insulated doors on the coil inlet and outlet. Close the doors and defrost away. Chill the coil before opening to the space.

Food industry has done this for years.

ken

Peter_1
05-08-2008, 06:52 AM
Hi
im asking if any body can help us how to determine heat transfere convection coffecint in refrigerated space @-65c



how to select components

Already selected your system? Or will you stay with this one post?:mad:

icecube51
08-08-2008, 05:40 PM
Yep Peter,

die zie je nooit meer ....terug.:p

Ice

icecube51
08-08-2008, 05:48 PM
its pity, because its a nice tread. i love to read about other opinions, and done some calculations of mi one.
i can not build mi outcomes because the lack of money and time.
O, and extremesystems is wonderfull to browse around to.

hope we get more of this cind to follow.

Ice

cwiedemann
22-12-2008, 10:09 PM
Ken
good afternoon
i am intrested in the low tempture cascading system that i found on this site.
you refer to a consulant who is knowable. can you forward how to contact this person.

thanks in advance
chuckw

TXiceman
23-12-2008, 02:41 AM
Chcukw, send me a PM and I can send you the name of a good consultant.

Ken

cwiedemann
23-12-2008, 05:51 PM
Thank everyone for the valuable suggestions. Currently our company builds 2-stage cascade systems. Normally they are used in vacuum chamber and testing chamber. Two ¼ HP compressors are used. The system can reach -100 degree Celsius. We do have some experience to design and manufacture two-stage cascade systems.

Recently, a customer has an application which needs the temperature goes down to -130 degree Celsius. We plan to develop a 3-stage system based on our current 2-stage systems. Following is an outline of my design. Please give me your opinions:

Three ¼ HP compressors are used. For two stage systems, it is a good choice to use 2 compressors having the same power. I am not sure if this principle still works for three stage systems.

First Stage: condensing temperature: 35C; evaporating temperature: -30C. Refrigerant: R404A or ISCEON89. A fined tube air cooled condenser is used.

Second Stage: condensing temperature: -25C; evaporating temperature: -75C. Refrigerant: R23 or (R508 + R14).

Third Stage: condensing temperature: -70C; evaporating temperature: -140C. Refrigerant: R14.

By my rough calculation, if the refrigerants are selected as above, the condensing and evaporating temperatures in each stage should be the values I give. But I am not sure if the system is optimal in these conditions. It is very difficult to get the optimal solution just by calculation. I will adjust the system based on test result.

Plate heat exchangers (WTT) are used between first and second stage, and second and third stage. Five degree temperature difference is enough for efficient heat transfer.

The metering device in first stage is a thermal expansion valve. Capillary tubes are used in second and third stages.

Cylinders are used as fade-out drums in second and third stages. They are place in the low side between the evaporator and the compressor. The size of the tank will be determined by experiments. There is no harm that the fade-out drum is a little bit oversize. Is it correct?

Coalescent oil separators (Temprite) are used in second and third stages for oil separation.

The principle of cascade system is very simple. But to select parts and build it is very challenge. I start to test the performance of the first and second stages, and hope it can provide about 300 ~ 350 watts cooling capacity at -80C for the third stage.

Now I still have trouble to find a suitable compressor for the third stage. And I also need to confirm that R14 is the best choice for the third stage. Any information and suggestions about the compressor and the refrigerant for the third stage are welcome.

Ken, Could you give me more information about the consultant you talked about? If he is really very professional in cascade system design, and if we really have trouble to develop it by ourselves, maybe my boss is willing to pay him for his help.

Thanks again. I am willing to share all the information with you, and will report you guys my work on this project regularly.

Vincent
good morning
i have been enjoying this site about the low tempture cascading systems.
have you had any sucess with your efforts.
i would appreciate any info that you are able to share.
it sound like your idea has some merit.
chuck Wiedemann

cwiedemann
23-12-2008, 05:55 PM
Chcukw, send me a PM and I can send you the name of a good consultant.

Ken
Ken

good morning
my contact info is
Cwiedemann@space.nrl.navy.mil
202-404-2592

thanks in advance
c

hundred
14-03-2009, 04:29 PM
Hi.Everybody I had used a cascade system at -80 c with Bock compressor . Who have been use bock.pleses advise.because I not sure the HA compressor run with R 23 can use longtime.

sawasuar
07-04-2009, 10:32 PM
Hi everyone,
I have a graudation project that is a blood storage. The blood storages are cascade system, thay works about -40 degree celcius.
But I dont know that How I can design it after calculating cooling load.
Please help me about design a two satge cascade refrigerator. where I will start?

5inatribe
09-04-2009, 03:10 AM
Depending on the capacity you need at -40 you may not need a cascade a compound single stage could be used.

sawasuar
09-04-2009, 06:08 PM
For blood storage cascde systems are used. I need design procedure of cascade system. You know that is is a graduation project so that it has a small capacity. It may be for 10 lt blood.

sawasuar
14-04-2009, 05:15 PM
are there anyone for help me? :)

TXiceman
15-04-2009, 01:58 AM
Sawasuar, not to be rude, but I thought this was your design project. People would be willing to help by answering questions which show you had put some thought into the design.

Several of us have ideas on how to approach this project, but we are not the ones being graded.

Best of luck,

Ken

azahedi
05-06-2009, 08:12 AM
Hi
I am trying to design a R23-R22 cascade system. I have decided to have a 5HP scroll Comp for low cycle and 10HP comp for high cycle and a Plate cascade heat exchanger and air cooled condensor. My cooling load is at most 5KW and operating temperatures are -70C for evaporating and 35C for condensing.
I have to have a tight temperature control +/-1C within the range.
I wanted to know if it is ok?!
I don`t have enough catalogues for selecting my compressor, Plate HE, TEV, Solenoid valves,...
whould you please help me?

azahedi
22-06-2009, 08:17 PM
Hi
I am trying to design a R23-R22 cascade system. I have decided to have a 6HP scroll Comp for low cycle and 10HP scroll comp for high cycle and a Plate cascade heat exchanger and air cooled condensor. My cooling load is at most 5KW and operating temperatures are -70C for evaporating and 35C for condensing.
I have to have a tight temperature control +/-1C.
I wanted to know if it is ok?!
I don`t have enough catalogues for selecting my compressor, Plate HE, TEV, Solenoid valves,...
whould you please help me?

D.D.KORANNE
24-06-2009, 01:20 PM
What issues you have with ha series ? What problems & reservatiions with ha series ?

COO2
29-06-2009, 07:19 AM
For 20 Watt capacity(-140C), why not think about the pulse tube or Striling refrigerator? maybe it should be a cheaper and more convienent option for you.

jjzzshen
03-07-2009, 01:12 AM
I am thinking about buying some wholesale water pipes from this company in China
but I am not sure if they are legal to bring in to the states? What are the laws on water pipes, bongs, and pipes?

bharat
06-09-2009, 09:37 AM
i from electrolux , i would like to hnad over all ultracold medical cascade refirgeration system data
regards

vinod,india
plz help us we r making -90 C, cascade system of 400 litrs chest type, using tecumseh comp. , please advice condenser and evoperatr design, and the length of tube in tube system.
bharat

mad fridgie
06-09-2009, 11:18 AM
I built and was using (-190C)-(-196C )cryo chamber (metal treatment, cooling engine blocks 400kg a time)), using joule thompson effect (about 200watts,)
low capital cost, efficiency about 5%.
If you have a two stage system already your just about there.

jklydr
10-09-2009, 02:08 AM
Hi Vincent,
we have some experience with 3 stage cascade system with -130C evaporating temp. Talk to your boss, we can certainly help you!

Dean Harold
05-10-2009, 04:26 AM
You don't need three compressors, Sanyo does a -140 and a -150 with just one compressor. The oil is POE and Pentane mix at that temp.

bharat
15-01-2010, 10:17 AM
i from electrolux , i would like to hnad over all ultracold medical cascade refirgeration system data
regards

vinod,india
vinod plz help,we want design for -80 c,280 ltr cascade system.
Bharat, 09415157857

Polypete
16-01-2010, 01:32 AM
Anybody interested in low temperature Autocascade systems may find this article interesting. The author is Michael St Pierre, he worked many years ago with Dale Missimer, the inventor of Polycold cryocoolers. It's enjoyable reading if you're into these things!
WorldWideWeb.xtremesystems.org/forums/showthread.php?t=144007

bharat
28-01-2010, 04:28 PM
vinod plz help,we want design for -80 c,280 ltr cascade system.
Bharat, 09415157857
is there anyone who can help me design a cascade system -80 C, 300 litrs, .

Zpoint
28-01-2010, 04:43 PM
Greetings Mr. Vu,

20 Watts cooling @ -140 C using 750VA
See vvww.arscryo.com/MR.htm

Zpoint
28-01-2010, 04:49 PM
Sorry if that link wont work, just Google "ORCA MIXED REFRIGERANT COOLER"

vikas.surlekar
31-01-2010, 01:58 PM
Hi Friends,

I am Vikas. I did Charging of -86 deg C Freezer as per brochure of Manufacturer. First chargedone unknown refrigerant thru liquid line then Second refrigerant charged thru suction also inlquid state slowly as per instructions. Refrigerants were supplied by manufacturer as A and B. I got temp - 80 deg C however i was supposed to get suction of around 7 PSIG and disharge of 280 but got suction 40 PSIG and discharge 200 PSIG. the Freezer works on Autocascade and 2 nos of 3/4 HP Compressors are in parallel.

can anyone throw light on why I got 40 PSIG at suction?

Peter_1
31-01-2010, 05:20 PM
IS this a Polycold machine?

acdcmike
01-02-2010, 11:07 PM
Currently our company builds 2-stage cascade systems. Normally they are used in vacuum chamber and testing chamber. Two ¼ HP compressors are used. The system can reach -100 degree Celsius. We do have some experience to design and manufacture two-stage cascade systems.


May I ask at what temp this system is rated for?

Could your unit sustain a 200-250 Watt load on an evaporator that is designed and used in cooling CPU's in computers?

jcook1982
30-06-2011, 01:21 AM
The reason you still have problem at lowest stage with the oil is because of the flock point. Flock point is when the waxes or other components of the oil turn to solid or less viscous substance. Not allowing the refrigerant to flow freely causing it to meter where ever the oil freezes at.

Kompulsa
11-11-2011, 01:53 AM
This might be helpful: http://www.engr.sjsu.edu/ndejong/Multi-Pressure%20Refrigeration%20Systems.pdf
(http://www.engr.sjsu.edu/ndejong/Multi-Pressure%20Refrigeration%20Systems.pdf)

Shaukat
16-02-2012, 05:03 AM
Hello vikas,
You made [-140°c unit?
- 9825044534

Shaukat
16-02-2012, 05:04 AM
Mr bharat
you made[-140°c unit]?
- 9825044534