CO₂ refrigeration offers a sustainable alternative to HFC/HFO refrigerants, but achieving energy efficiency at high ambient temperatures is a challenge. High operating pressures and compression requirements often result in wasted energy. But Danfoss engineers developed a solution. 

The company’s recently released whitepaper, “Danfoss Multi Ejector High Pressure (HP): Unlocking 21% Savings over Traditional CO₂ Booster Systems,” details how Danfoss’ Multi Ejector HP, in conjunction with parallel compression, can result in significant energy savings, particularly in warm climates.

In a traditional transcritical CO₂ booster system, energy is often wasted as highly pressurized CO₂ fluid is created in the compression cycle and pumped through the system, resulting in the rejection of its excess heat. Using parallel compression and ejector technology can harness this potential energy, reducing overall energy consumption and compressor workload.

Danfoss engineers installed the Multi Ejector HP, an ejector specifically designed for high pressure systems, in a Hussmann transcritical CO₂ booster system using parallel compression. Also installed was a Danfoss pack controller, to manage variable pressures in the receiver and to control rack operation, valve logic, and ejector staging, thereby ensuring optimal performance under all conditions.

The entire system was installed in two new supermarkets, one in a mild climate and one in a warm climate and tested with the ejector both on and off.

Several months of testing revealed:

• •At ambient temperatures of 95 degrees Fahrenheit, using the ejector resulted in actual incremental energy savings up to 13.4% vs. using parallel compression alone. The total energy savings over a traditional booster system was 21%.
• With the ejector on, compressor cycling was also reduced with 43–47% reduction in on/off cycles, which reduced cumulative inrush current and mechanical wear.

“The test results showed the value of the Multi Ejector HP in helping supermarket customers achieve the full benefit of CO₂ refrigeration,” said DJ Frye, director of sales for food retail in North America at Danfoss. “Ensuring energy efficiency and reduced operating costs in almost any climate is a necessary step to increasing the adoption of CO₂ across the food retail industry.”

About Danfoss A/S
Danfoss engineers solutions that increase machine productivity, lower energy consumption, enable electrification, and reduce emissions. Our solutions are used in areas such as refrigeration, air conditioning, heating, power conversion, motor control, industrial machinery, automotive, marine, and off- and on-highway equipment. We also provide solutions for renewable energy, such as solar and wind power, Power-to X, heat recovery, as well as contribute to district energy solutions for cities. Our innovative engineering dates back to 1933. Danfoss is family-owned and employs over 39,000 people. We create long-term value for our customers in more than 100 countries with a global footprint of around 100 factories.