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Thread: Drinks Chiller Design Issues
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18-11-2010, 09:14 PM #1
Drinks Chiller Design Issues
I site we work at has had 2 custom built-in chillers fitted about a year ago and have always had problems with not maintaining the setpoint. The manufacturer has returned a couple of times regarding this but states that this system is no different to any others they make and they aren't designed to run constantly - just over luchtime to display the food.
Went back to look at the smaller drinks chiller, repaired a leak on the evaporator, replaced drier, pressure test, vac, charge and here are the results.
SCT 50*C (320psig - R404A)
Temp at drier 44*C (about the only place I could get to measure)
Subcooling 6K
SST -12*C
Temp at compressor suction 6*C
Superheat to compressor 14K
Evap air on 12*C
Evap air off -2*C
Evap dT 14K
Condenser air on 22*C
Condenser air off 46*C
Condenser dT 24K
Setpoint 2*C, capillary system, integral with condensing unit underneath. Didn't want to add more refrigerant as head pressure going through the roof and subcooling suggests liquid at drier.
Before, the capillary came out the top of the drier, now it comes out the bottom but the only way to route the pipe was across the airflow off the condensor.
Capillary doesn't run along the suction line - completley separate.
No air curtain in the display side. Evap fan motors have tape over the lower half - maybe to reduce air flow so the air can get drawn back easier? These readings were taken with the blind down but the other chiller struggles to reach temp when room temp high unless blind pulled down and you can feel the cold air being blown out the case.
New drier is smaller than the original. Had to use what I had left as my new one managed to get the inlet blocked with braze during the repair works. Can't see that altering the refrigeration cycle though although it confirmed my amature status.
Although it reached setpoint (blind down) the readings suggest something wrong. It appears the condensor isn't rejecting enough heat and the possibly the SST a tad low but the manufacturer says everything is fine.
Obviously could have done with filter/cap issues, air curtain sorted at the design stage but before I let the site know just wanted your thoughts.
Thanks for reading,
Andy.Health and safety first..........unless I'm in a hurry.
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