Chillers can take on a plant’s largest electric load, which means it racks up quite a lot of operating costs. When you factor in things like leaking refrigerants, water temperature fluctuations, compromised tubes, and other damages, those operating costs can balloon to an alarming degree. You can avoid this by making sure your chiller is operating at peak capacity. Here’s how you can improve your chiller’s efficiency:
Keep your tubes clean
Your chiller’s efficiency declines when its tubes become fouled by contaminants like mud, algae, minerals, scale, and other pollutants. Fouling occurs over a period of time when impurities accumulate on the water side of heat transfer surfaces in both open and closed-loop systems. You can clean condenser tubes through brush cleaning or chemical cleaning. Using an air separator in a chilled water system can also help keep your chiller working smoothly. Air separators help water systems relieve the air contained in the solution which allows them to pump fluid and transfer heat efficiently.
Record a daily log
You should maintain a detailed history of your chiller plant’s operating conditions, including pressure levels, fluid levels, flow rates, and temperature. Microprocessor controls may be able to record these statistics, but it also helps to keep a written log that details your own findings from when you do daily inspections of controls in the chiller room.
Reduce the entering water temperature
On certain building systems, operators may be able to reduce the chilled water setpoint in order to reduce air handler deficiencies like dirty coils. Avoid this practice since it only makes the chiller put more effort into the same net cooling effect. Instead, you can lower the temperature of the water that enters the condenser to improve your chiller’s efficiency.
Checking the safety and sensor calibrations on your microprocessor controls ensures the efficiency of your starter and motor operations. Make sure to confer with manufacturer guidelines first, then the check chiller wiring, electrical connections, and switchgear for any sign of worn contacts and hot spots. Test motor windings for resistance to ground and winding-to-winding to prevent the risk of insulation faults. You should also check to see if there are any refrigerant leaks on the shaft seal on open drive motors.
Schedule regular preventive maintenance checks
Preventive maintenance checks for chillers involve general system testing, cleaning, monitoring temperature, and pressure. You should have a compressor oil analysis performed on your chiller annually. These tests include a spectrometric chemical analysis which contains information on moisture content, acids, metals, and other factors that affect your chiller’s performance. Besides this, you should replace oil filters if needed on a high-pressure drop or when you have the compressor oil changed.
Control the water velocity
Keep an eye on the flow rate. When it gets too low, this reduces your chiller’s efficiency which leads to laminar flow. A flow rate that’s too high causes noise, tube erosion, and vibration. The recommended minimum flow rate is often around 3 ft. per second, while the maximum recommended flow rate is somewhere around 12 ft. per second.
Keep your plant’s maintenance and operating costs down by keeping your chiller’s efficiency up with these handy and practical tips.