Cacade refrigeration system

[lowtempref]

Hi,

I have designed and commissioned cascade system working at Minus 75 Deg C. I have problem in measuring the outlet temperature of brine. I have provided Resistance temperature detector (RTD PT100) surface mounting type. Pl. suggest which type of measuring instrument would be more suitable for this type of application for measuring temperatures?

lowtempref

[NoNickName]

Try browsing for kryothermometers on the web

[Peter_1]

We do it with K or T thermocouples.
Toolman, your comment doesn't fit in this forum

[lowtempref]

Thanks. I will check with this. Is it more accurate than RTD?

[Peter_1]

http://www.veriteq.com/thermocouple-...ger/type-j.htm

http://www.thermometricscorp.com/acstan.html

http://www.omega.com/rtd.html

[Josip]

Hi, lowtempref

Hi,

I have designed and commissioned cascade system working at Minus 75 Deg C. I have problem in measuring the outlet temperature of brine. I have provided Resistance temperature detector (RTD PT100) surface mounting type. Pl. suggest which type of measuring instrument would be more suitable for this type of application for measuring temperatures?

lowtempref

Can you tell us what kind of brine you use in your system? Thanks.

Best regards, Josip

[Peter_1]

Josip, good question, I even hadn't noticed this.
Brine????

[US Iceman]

I believe R-11 was used as a brine for some of these systems a long time ago.

It would be interesting to find out what he is cooling?

[Josip]

Hi, US Iceman

I believe R-11 was used as a brine for some of these systems a long time ago.

It would be interesting to find out what he is cooling?

Maybe you are right, but we always name it ***** 11 and not a brine, but...

I remember how nice was to work with (centrifugal compressor driven by steam turbine) and charging the system with bucket of refrigerant in one brewery (very important product to cool down ).

See here about:
http://www.trane.com/commercial/issu...ade-offs06.asp

Best regards, Josip

[US Iceman]

For the most part R-11 was used only for centrifugal chillers (or cleaning parts).

However, in a liquid state it had very low viscosity which helped to reduce the pump input energy. from this standpoint R-11 was much better than glycols or salt brines.

Methanol or Ethanol might also work.

[lowtempref]

Josip, good question, I even hadn't noticed this.
Brine????

We have use R11 as brine in one job and Methylene Chloride as a brine in the other.

[lowtempref]

Josip, good question, I even hadn't noticed this.
Brine????

We have used R11 as brine in one job and Methylene Chloride as a brine in the other job.

[lowtempref]

We have used R11 as a brine. In some other plant we have used methylene di chloride

[kasperDK]

Hi
I think we are using syloterm xlt for brine at our lowtemp storerums brinetemp =-70 deg rum temp =-55deg

[winfred.dela]

Have start up an immersion freezer up to minus 70C with secondary solution from U.S.
My customer would not give the name of the solution.
It taste and smell like a Lime. Maybe it is 100 percent because i tried a bottle of lime bought from a store and it freezes around minus 30.

I also have seen immersion freezer @ minus 60C with alcohol as the secondary medium.

[US Iceman]

winfred.dela,

Without more details, this solution sounds like it might be a product called D-Limonene (I think I spelled that right).

It is an oil based liquid which is derived from oranges.

[winfred.dela]

Thanks U.S. Iceman.

I might have to import that D-Limonene in the near future as i have some inquiry for a -60C to -70C immerssion freezer. Am still finalizing my cascade system design R507/R23.

Do you know some links to this D-Limonene? Would greatly appreciate your help for a source.

Thanks in advance US Iceman

[US Iceman]

Here you go...

http://www.floridachemical.com/

Be sure to read the MSDS sheets and the material compatibility notes. I seem to remember this fluid will leach copper out of coper pipes and turn the solution a slight green color.

I investigated this fluid once for a project, but unfortunately the owner would not try it.

[winfred.dela]

Hello US Iceman,

Thanks a lot for the link to d Limonene

[weeksy]

Hey Winfred,

I've used D-limonene whilst testing cryobaths & ULT circulators down to -90C....it does a job but as US Iceman states, this fluid can be quite reactive/destructive when in contact with certain materials.

The BEST low-temp fluid I've ever found is a solution called GALDEN HT fluid. This stuff is amazing, maintaining a constant viscosity throughout its working temperature range, & its totally inert, so it does not react badly with other materials, does not conduct electricity & is not toxic or harmful to skin etc.

The only draw back with this fluid is the cost....its very expensive!

All the best,

weeksy.

weekstechnic.com

[winfred.dela]

The BEST low-temp fluid I've ever found is a solution called GALDEN HT fluid. This stuff is amazing, maintaining a constant viscosity throughout its working temperature range, & its totally inert, so it does not react badly with other materials, does not conduct electricity & is not toxic or harmful to skin etc.

Thanks weeksy. I will definitely consider this fluid when the project push through.

Does the problem of evaporation not the same with other solution: d Limonene & alcohol?

[TXiceman]

A pressurized R-11 brine was about the most efficient brine to use from a heat transfer view. Good thermal properties and low viscosity at lower temperatures. Most brines suffer from higher viscosity and poor thermal performance at low temps.

As for which to use, TC or RTD, it depends on your monitoring equipment...is it TC or RTD compatible. If you are starting from scratch, I'd go with an RTD.

Ken