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# Ammonia Chiller Power Saving

Expand refrigerant through turbine
 (0) [vote for, against]

In a normal refrigeration cycle working with ammonia (R-717), the refrigerant is expanded from high pressure, low temperature to low pressure & very low temperature using a manual expansion valve whose opening is set during plant commissioning. In some cases such valves are with auto controls.

My proposal is to put a turbine in place of expansion valve to recover power which is just wasted due to throttling. My gut feeling says there is significant potential for power recovery in large industrial systems.

 — vedarshi, Feb 04 2007

To find your power potential, look at the rating of the system, probably measured in BTU, multiply that by the duty cycle, measured as a percentage. Now multiply that by 1/3 and you have your base power in watts.
 — Galbinus_Caeli, Feb 05 2007

[Galbinus] if chiller rating is 300TR (300 ton refrigeration), what would be the possible power recovery in KW ? (1 TR = 3000 KCal/hour).
 — vedarshi, Feb 05 2007

But any power extracted by expansion in the turbine would be at the expense of cooling potential at the point of use ... and you would in any case extract less energy than was used to compress the gas in the first place. So this would work just like a perpetual motion machine, right ? I will have to think about the case of using a big turbine in the cooled space instead of the usual expansion coils ...
 — batou, Feb 05 2007

Sorry, I don't know that conversion.
 — Galbinus_Caeli, Feb 07 2007

 Online investigation finds: 1 TR = 3516 Watts. Typical duty cycle for a fridge = 50% ("Targeting Refrigerators for Repair or Replacement" by James Cavallo, Ph.D. Kouba-Cavallo Associates, and James Mapp, Ph.D., Wisconsin Energy Bureau) So a 300 TR fridge extracts (an average of) about 500 kW (peak 1MW) - that seems a tad high, even for an industrial unit...

I can't help feeling that it wouldn't work...
 — TheLightsAreOnBut, Feb 08 2007

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