SCT and SST

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28-03-2003, 01:25 AM
bender

SCT and SST

In replies to my chiller problems some of you asked for more information.(temps)
I am not a refrigeration engineer (operations manager for a small blow molding plant) but I do have a maintainence background. I have had some local refrigeration guys out, and two refrigeration service companies. They did not do anything for it and did not seem to have the necessary knowledge.
Where do I read SST and SCT?
This is a small, closed loop chiller. The demand is minimal, only a five degree difference in temp across the process. I am trying to maintain a cooling water temp of 45 degrees F. On starting the chiller it reaches this set point, but when Running the blow mold, the temp creeps up over several hours. It used to reach about 70 degrees F. I recently removed the glycol/water solution and ran a de-scaler through the system. I flushed it and am now running water only. The temp will maintain about 58 degrees F.
Also:
1. There is always frost beyond the TEV where refrigerant enters the evaporator. Is superheat incorrect?
2. Low side pressure seems slightly to low.
:confused:
28-03-2003, 01:59 AM
herefishy

When you read the pressure on your gauges..... reference that pressure to the "temperature column" on your pressure/temperature chart for that refrigerant.

Without putting my foot in my mouth... I will leave you with that thought. Maybe your lightbulb will illuminate !!! :)
28-03-2003, 02:11 AM
Gary

SST is low side pressure converted to temperature.

SCT is high side pressure converted to temperature.

If you tell us the pressures and the type of refrigerant, we can do the conversion.
01-04-2003, 05:59 PM
Kathleen

Re: SCT and SST

Hello bender

Quote:

Originally posted by bender
Where do I read SST and SCT?

As gary said your is your suction temperature and condensing temperature at the saturated phase of the refrigerant and it is a direct relation with the pressure gage, I suggest to take the pressure at the outlet of the chiller on the suction line and at the compressor and at the outlet of the condensor and the entering, before TXV, of the chiller.

Also do not forget to take the temperature at the same location so we will be able to know the superheat temperature and the subcooling temperature.