Water Cooled Chiller的一些注意事项

"Water cooled chiller" means that the refrigerant in the condenser releases heat to water instead of air.
 
In addition to the chilled water loop, there will be another waterloop in this system: a condensing water loop from the condenser, to atower where the water will be cooled by evaporation, and then back tothe condenser.
And a conscientious water quality program is absolutely essential toprevent scale, slime, and even corrosion inside the condenser.
Ifyou don‘t have a water quality program in place, contact themanufacturer of your water cooled chiller, and a local water treatmentprofessional if necessary.
If you‘re looking for some information about troubleshooting, ourChiller Evaluation Manualhas cycle diagrams for air and water cooled reciprocating chillers, alog sheet, and guidance on evaluating chiller pressures andtemperatures.
Are you troubleshooting a Trane centrifugal water cooled chiller that‘s running with poor cooling capacity?
The following tips might help, if you don‘t have a good set ofmanuals for the machine, and can‘t get an experienced chillertechnician to check it for you.
To check for air in the system, check the temperature of the liquidrefrigerant at the upper liquid line well leaving the condenser, andcompare it to the condensing temperature.
If the temperatures aren‘t within 3 degrees of each other, there are non-condensables in the system.
Condensing water delta t (temperature rise through the condenser) may look normal.
Check the purge system operation, and you might want to start checking for leaks.
Do you know what ‘condenser approach‘ and ‘evaporator approach‘ are?
Evaporator approach is the difference between evaporatingtemperature measured at the well in the evaporator, and leaving chilledwater temperature.
Condenser approach is the difference between liquid refrigeranttemperature as measured on the liquid line, and leaving condenser watertemperature.
Normal condenser approach is 0 to 3 degrees.
If approach is 4° or more, it‘s an indication your water cooled chiller has fouled tubes.
If condenser approach is 4° or more and the condensing water delta tis low, it‘s an indication of non-condensables in the condenser,insulating the tubes and reducing heat rejection to the water.
With non-condensables, condensing pressure will be higher than normal.
Whether your water cooled chiller has a reciprocating, screw, orcentrifugal compressor, If the head pressure is rising and your pumps,tower, and piping all seem to be ok, get a tube cleaning machine andgasket material ready, and don‘t hesitate to pull an end bell off toinspect the tubes and clean them if they need it.
Evaporator approach can be used to evaluate the refrigerant charge.
In a 1 pass evaporator, approach should be 10° to 14°.
In a 2 pass evaporator, approach should be 7° to 10°.
In a 3 pass evaporator, approach should be 3° to 6°.
Take all readings with the water cooled chiller at full load.
A higher than normal evaporator approach can indicate an undercharge.
A lower than normal evaporator approach can indicate an overcharge.
Evaluate all other operating characteristics.
Another condition you might be encountering with your centrifugal water cooled chiller is ‘surging‘.
This would be when the chiller makes a noise like a squealing elephant, and it indicates that there‘s a problem.
It happens when the difference between the evaporating temperatureand condensing temperature exceeds design conditions, which is about 70degrees.
When this difference, which is called lift, exceeds designconditions, refrigerant flow will reverse through the impellers, whichcauses the squeal, and can lead to other problems.
Surging can be caused by non-condensables, fouled condenser tubes,low condenser water flow, high entering condensing water temperature,and low refrigerant charge.
Surging can damage the thrust bearings and impeller, so if you hearyour centrifugal water cooled chiller surging, find and correct theproblem immediately.