“The compressor and system are completely free of oil. It runs on magnetic bearings so no lubrication is required, and, because it is variable speed, it saves energy at all operating conditions.

Bishop said oil-free compressors offer approximately 30 percent higher energy savings when compared to single-speed compressors. Danfoss believes as much as 950 million tons of CO2 could be saved annually in the U.S. through the use of a Danfoss Turbocor oil-free compressor.

“Oil-free, magnetic-bearing technology also dramatically improves reliability because it eliminates complex oil management systems, and reduces bearing wear,” he said. “Further, there is no oil to foul the heat exchangers, so the energy savings are sustainable for the entire service life of the equipment.”

Bishop said oil-free compressors primarily are used in large chiller applications including hospitals, hotels, universities, and data centers.

Embraco also manufactures oil-free compressors. The technology adheres to the company’s guideline to “develop new products and improve the current ones so they are more efficient in the use of electrical energy and raw materials.”

“Oil free means sustainable compressors,” said Fabio Klein, research and development product director at Embraco (Brazil). “This technology has the potential to be the most efficient compressor in the market.

“Energy efficiency is important. We’ve been talking about it for the last 20 years, but it is becoming more important, not only in the U.S., but in other parts of the world. Today, sustainability is also important. In the past, nobody was worried about that, but today, it’s crucial.”

David Hawkes, director of engineering at Tecumseh Products Co., said Tecumseh does not currently offer an oil-free product.

“If it’s an affordable technology, if the applied cost is correct, and if the manufacturability and everything else is where it needs to be, I think it’s a great technology,” Hawkes said. “But I think its biggest opportunities today are in larger commercial systems where the cost of the compressor isn’t as big of a component as it is in smaller systems.”

Oil-Free Future

Danfoss Turbocor Compressors recently launched three new oil-free, magnetic-bearing, variable-speed centrifugal compressors, calling it a significant expansion of its offerings.

The TT350 380-V compressor has been specifically targeted for fast growing markets such as China, India, Russia, and Brazil. A 575-V version of the TT400 compressor was released for the Canadian market. Danfoss also announced the commercialization of TG310 compressors, which were released as a developmental prototype in early 2012. The TG310 uses the ultra-low global warming potential (GWP), zero ozone depletion potential (ODP) refrigerant, HFO-1234ze (or Solstice L13), from Honeywell.

The 380-V version of the TT400 was an honorable mention in the AHR Expo Innovation awards’ cooling category. “In 2012, we were very pleased to make available prototype TG310 compressors suitable for outdoor, air-cooled applications,” said Bishop. “One year later, Danfoss Turbocor is excited to announce that several of our OEM customers are progressing with field trials and are very pleased with the performance of the TG310 regarding energy efficiency and reliability.

“The end-user interest in the TG310 compressor with this ultra-low GWP refrigerant is very high, and we are now finishing the code compliance work in support of a commercial production launch to Danfoss Turbocor OEM customers by mid-year 2013.”

Publication date: 4/1/2013