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Emmett
07-12-2009, 06:00 PM
required capacity 10TR
what is TR?

ssk7899
08-12-2009, 11:48 AM
Required Capacity 35 KW
TR - Ton per Refrigeration

My design capacity is 35 KW

Emmett
08-12-2009, 05:08 PM
ssk7899,
Thank you for the clarification. I have been working on mainly cascade refrigeration for over 15 years, I have worked for one of the major manufacturers here in the states and currently work for one of my former customers. In my experience:
(1) screw compressors are very uncommon
(2) Bitzer is an excellent compressor
(3)it is not necessary to have the first stage compressor larger then the second unles you intend to use it for space cooling as well
(4) R508B and R404A are common choices currently in the states
(5) with the above mentioned refrigerants POE oil is recomended
(6) type of evaporator is dependent on what will come in contact with it, if it is not a corrosive enviornment for the copper evap then that is the less expensive choice.
(7) as to the capacity of the intermediate condenser I am not sure I understand that question, please clarify.

ssk7899
08-12-2009, 06:51 PM
Thanks For your reply,,,

The Intermediate Condenser i.e
The inter state condenser cum Evaporater.
for both R508 and R404 gases.

Could you help me in one more problem ..that is
i am desigining ultra low temperature chiller
Required Capacity 35KW and
Temperature is -120Deg C.

For this Shall i use three stage cascade system.
Could explain me breifly ..how to design it.
What compressors HP required for it.'
What the Precautions i need to take.

NoNickName
08-12-2009, 07:53 PM
Answered privately with a solution for the two stage cascade.

No solution for the three stage cascade.

shmo
12-12-2009, 09:46 AM
hi all

cascad cycles consisting of two separate cycle connicting by heat exchanger. in high stage or condinsing side you can using any refrigerant (410) because the evaporating temperature will be -30,-40 and this refrigerant have boiling point about -46 C
and for low side cycle you can use R 23 boiling point for it -80 C


best regards

Eng. ShMo