basic explanation of tonnage to a non-Refrigeration person
basic explanation of tonnage to a non-Refrigeration person
(OP)
I wonder if somebody could explain, in quite simple terms, (or point me to a decent informative website)how the term 'tonnage' is derived with respect to chiller refrigeration. I found the statement that "A refrigeration ton is the power required to cool 1 short ton of water by 1 °F" but am having difficulty relating this. I come from the motor control business and as I hear tonnage quite often talking to chiller folk, I just want to brush up on the basic knowledge.





RE: basic explanation of tonnage to a non-Refrigeration person
Regards,
Wolfie82
RE: basic explanation of tonnage to a non-Refrigeration person
This is in case you start with numbers trying to figure it out as I did as a young Engineer.
RE: basic explanation of tonnage to a non-Refrigeration person
RE: basic explanation of tonnage to a non-Refrigeration person
Using Willard3's 144 btu/lb latent heat the conversion is
144 btu/lb x 2000 lb / 24 hr = 12000 btu/hr
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RE: basic explanation of tonnage to a non-Refrigeration person
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.
RE: basic explanation of tonnage to a non-Refrigeration person
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.
RE: basic explanation of tonnage to a non-Refrigeration person
RE: basic explanation of tonnage to a non-Refrigeration person
although I'm not a young pup, I had the same thoughts on "wow, that doesn't look 400tons...there must be something more to this tonnage idea.." and thanks for the metric conversion, I can certainly relate to that a little better. However, tonnage seems to be universal whether you are metric, imperial or ambidextrous.
RE: basic explanation of tonnage to a non-Refrigeration person
RE: basic explanation of tonnage to a non-Refrigeration person
One can add that the TR, ton refrigeration, is a unit for the rate of heat flow equal to 200 Btu/min or ~3516.85 watts. Aka standard ton.
RE: basic explanation of tonnage to a non-Refrigeration person
Generally, you can consider the following ranges.
Centrifugals (above 200TR) - 0.5 to 0.75 kW/TR
Screws (above 100TR) - 0.7 to 0.9 kW/TR
Recips (below 100TR) - 0.9 to 1.2 kW/TR
RE: basic explanation of tonnage to a non-Refrigeration person
When you asked for a rule of thumb did you mean: tons/H.P.?
For general a/c compressors, positive displacement; it is about 1 H.P. per ton, open drive centrifugals for typical 45 degree chilled water systems, that still holds pretty true. When you go to medium and low temp. refrigeration the ratio goes to heck because the specific volume of the gas goes up and so does your compression ratio. You will need more horses for that same ton of refrigeration.
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.
RE: basic explanation of tonnage to a non-Refrigeration person
another question, on the same topic. Is there a rule of thumb guideline between tonnage/btu/kw and electrical rating (kW/hp)for the compressor?
snip
"Rules of thumb" are the one method guaranteed to make troublesome HVAC systems because the "rule of thumb" is subsituted for thorough analysis.
RE: basic explanation of tonnage to a non-Refrigeration person
On the other hand, sometimes a rule of thumb can send up a red flag when I see a system performing outside an expected norm. It will cause me to look a little closer to what pressures and tempratures are indicating and try to resolve the cause of the discrepancy.
A mentor of mine once said, "If you can't verify a problem with accurate instrumentation and, or prove it through mathmatical analysis you really haven't identified the problem". So is the life of a refrigeration service mechanic!
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.