Data Logging of a Chiller

[IACCHICAGO]

Is it safe to say that a chiller is at 50% of its capacity if the compressor is loaded 50% of the time? This comes from data logged in one minute intervals where the results showed the compressor was loaded every other minute. Any input would be helpful.

 

[cammax]

I dont have enough info - But that sounds more like a very lightly loaded chiller.

What type of chiller - if possible provide brand and model #

 

[IACCHICAGO]

It is a 40 ton, air-cooled recip. The brand name is Refrigerated Systems of Evansville. The model number is a bit problematic. I have been trying to get it, but I don't know if that's possible.

 

[IACCHICAGO]

Sorry, I ment Refrigeration Systems of Evansville.

 

[ChrisConley]

Depends to what percentage the compressor is loaded. If it is loaded to 100%, 50% of the time, or 75%, 60% of the time.

You could log the amp draw, compare it to design amps to get an idea of the loading.

 

[MintJulep]

No. Absolutely not.

Deleviered capacity is a function of suction and discharge saturation pressures, which in turn are functions of evaporator and condenser temperatures.

Unloader state gives an indication of if a cylinder or bank is pumping, and nothing else.

Compressor power or current draw is probably the eaiest thing to look at, if you have the capacity vs power curve.

Also, if you are sampling at once a minute, and your cycles appear to be one minute on, one minute off you very possibly have some aliasing happening.

 

[IACCHICAGO]

Thank you for your responses.

Chris Conley - From the data that we logged, the compressor is normally 100% loaded when loaded, except for a brief period when the chiller first starts up. Then it operates well into its service factor.

Mint Julep - I have not been able to track down any capacity vs power curve profile specific to this chiller or generic. I was attempting to derive one using a linear approximation between the loaded and unloaded power draws. This is based on power curves for a reciprocating air compressor. As far as aliasing, the loggers we have can do 15 sec intervals, but the batteries would not last for more than a couple days.