With the approaching HFC phasedown, the demand for environmentally friendly cooling systems is driving chiller manufacturers to innovate. Washington-based Pro-Refrigeration, Inc., a manufacturer and supplier of chillers for the industrial and beverage processing market, developed the idea of a CO₂ chiller that brought big dividends to a California dairy farm and ultimately, to the environment.

Since CO₂ is a natural refrigerant with a global warming potential (GWP) rating of 1, not only does it have zero impact on global warming, it also allows refrigeration systems to recover 100%—three times that of chillers using synthetic refrigerants—of the heat rejected from their systems, generating hot water at up to 200°F. For Pro-Refrigeration, heat recovery capability is an essential product feature, as beverage plants, dairy farms in particular, use a high amount of natural gas or propane to heat water for sanitizing and wash-down. Heat recovery technology lowers both their costs and climate impact.

The components utilized in the CO₂ chiller work together to monitor the cooling system, gather data from the sensors, control when the compressors cycle on and off and ensure the fans and expansion valves are working correctly. As part of its constant monitoring and adjustment to external conditions, the system manager generates alerts and alarms, so that the facilities staff can immediately identify and address potential mechanical problems. The refrigeration control system also allows Pro-Refrigeration engineers to access the data remotely for improved customer support and troubleshooting capabilities.

A California dairy farm was a willing and ready client for the inaugural CO₂ chiller. Since installation, the milk temperature has averaged 37.1°F, whereas the dairy’s previous chiller was unable to cool below 40°F. As a result, the farm was able to earn a quality bonus from milk processors and see revenue increases in the range of $1,400 to $2,800 per day.

The chiller also recovers the waste heat from the chiller system to heat the wash water, heating 3000 gallons of well water per day from 70°F to 140°F and eliminating the need to use fossil fuels (propane) as a heating source. Early results tracking indicates that the heat recovery operation is saving the farm 30 gallons of propane each day, totaling about $2,100 in savings per month.

The CO₂ chiller is installed at a California dairy farm, decreasing propane heating costs and improving milk quality with nearly a three-degree temperature improvement. Photo courtesy of Danfoss

Changing out HFC chillers to CO₂ is a win for the environment in terms of cutting greenhouse gasses. Less propane used means less carbon dioxide emitted into the environment. The dairy wins long term with additional revenue from improved milk quality, and with propane prices only going up, its savings will most likely continue into the foreseeable future.