Researchers at Purdue University developed a sensor to monitor the oil circulation ratio (OCR) in real time for heating, ventilation, air conditioning and refrigeration systems. The oil circulation ratio provides data on the health and functionality of the overall system.

Researchers at Purdue University developed a sensor to monitor the oil circulation ratio in real time for heating, ventilation, air conditioning and refrigeration systems. (Image courtesy of the researchers)

“Our technology is needed because more businesses are using variable-speed HVAC systems,” said senior research engineer Orkan Kurtulus. “The ability to measure the OCR is critical to ensure the system is using the correct amount of oil for effectiveness and efficiency. Our sensor allows businesses to check the oil circulation without disrupting the system or requiring the tedious process previously used to monitor circulation.”

Capacity control in HVAC&R systems is being used by a growing number of businesses because it increases efficiency and reduces costs by slowing the speed and energy level when a system does not need to operate at full capacity.

The team’s approach for OCR quantification allows otherwise immiscible refrigerant pairs to be separated and analyzed by a sensor in the suction line of HVAC&R systems. This has remained an unmet need to mitigate oil retention in vapor compression systems, as this can cause inefficiency and even shorten the lifetime of HVAC&R equipment, especially in lieu of new variable speed and tandem compressor technologies, which implement repeated cycles.

The Purdue team verified the autonomous sensor method using the latest standards from ASHRAE.

For more information, contact Chris Adam at This email address is being protected from spambots. You need JavaScript enabled to view it..


Sensor Technology Magazine

This article first appeared in the March, 2021 issue of Sensor Technology Magazine.

Read more articles from this issue here.

Read more articles from the archives here.