Conversion for Discontinued Compressors

[Metz]

I have a job that is using a SABROE SMC3-65 compressor, 6510 kcal/hr at 1700 rpm. This compressor was discontinued about 20 years ago, and I am looking for a replacement. The compressor feeds five evaporator coils in a refrigeration system from freezer to dry stores. I calculate (from the cylinder diameter and stroke) that the volume moved of R-22 is just under 10 cubic ft/min. Assuming I did the calculation right, what conversion is needed to go from ft3/min to lbs/hr?

 

[CESSNA1]

METZ: Multiply FT^3/min times 60 to get ft^3/hr. Then multiuply this result by the density, in pounds/ft^3, of the R22 to get pounds/hr.

The equation looks like

#/hr = (60 ft^3/min)*(p #/ft^3)

The problem is what density do you use for the R22 since the temperature, pressure, and phase of the R22 vary throughout the process. I would suggest starting with the actual density at the suction side of the compressor.

One thought - did you consider the volumetric efficiency in your calculation?

Regards
Dave

 

[MintJulep]

Is the existing compressor open-drive, semi-hermetic, hermetic? Do you want to replace with the same, or go for something more modern, efficient, quite.....?

If you are going to change the compressor, consider changing to something other than R-22 now as well.

10 CFM is pretty run-of-mill. You should have no problems finding a comparable flow compressor from any number of manufacturers.

 

[imok2]

There are refrigerant flow rate tables for all refrigerants at different operating conditions: For example R-22
If you are running the compressor at 0*F evaporator and a saturated liquid temperature of 90*F then you have a refrigerant flow of ~ 3# R-22/min/ton and at 100*F (SLT) it would be about 3.15#/min/ton. If you are interested in using a different refrigerant then I suggest you read this:

http://www.dupont.com/suva/na/usa/products/faq.html