Vapour ejectors, the company’s latest innovation, are helping to tackle an issue that had previously held back the efficiency of CO2 technology – high ambient climates. But Danfoss is determined to overcome such limitations in this fast-evolving market.
Developed through extensive lab testing and in close collaboration with OEMs (Original Equipment Manufacturers), ejectors are predicted to sound the death knell for the CO2 equator.
Focused on improving current technologies rather than on the next line of refrigerants, ejector technology is a clear reflection of Danfoss’ tagline ‘Engineering tomorrow’. This philosophy guides the company’s efforts to deliver technologies that improve the energy efficiency of current infrastructure.
During the development phase, Danfoss worked across the spectrum of industry stakeholders and sought to share knowledge as widely as possible. The company hopes this approach will bring a full understanding of the best use of the technology, and ensure that this know-how is harnessed by end users, other OEMs, and Danfoss itself. In Juul’s opinion, this will enable the creation of a durable, efficient solution.
We have had a very open approach. We do not want to keep this technology a secret. Instead, we share it with OEMs, and try to work as closely as possible with them.”
So how do ejectors work?
Ejectors address one of the major thermodynamic drawbacks of the conventional vapour compression refrigeration cycle: throttling loss in the expansion device, which reduces the refrigeration effect. Ejectors provide pre-compression for the parallel compressor, delivering greater load for the latter.
For Danfoss, they represent one of the most promising solutions for CO2 refrigeration systems in hotter climates. They save manufacturers from having to dimension refrigeration racks for peak loads whilst also reducing compressor running time, in turn providing energy savings. All of this yields significant long-term cost benefits for end users.
Thanks to the ability to switch an ejector on and off remotely, Danfoss has been able to collate large amounts of data on the impact of running a refrigeration system with or without an ejector.
In one particularly successful field trial, using an ejector led to energy savings at a very small cost. The customer involved was initially very surprised by the results. They did not understand how they could maintain the same cooling capacity with just the parallel compressors running. “Normally they would expect empty compressors to run but? in this case the ejector was lifting so much pressure that all parallel compressors were needed to run,” explains Juul.
With initial cost and a quick payback (rather than total lifetime cost, a key criterion for many retailers) this is an important benefit.
Whilst it is clear that ejector efficiency relies upon the application and how the system controls are set up, Juul openly admits that they still have a lot to learn. “We have begun to make what we believe is a winning ejector configuration, but we know there is still much to discover. It’s an exciting technology and there is plenty more that we can achieve.”
Ejector technology gaining traction
According to Juul, OEMs and retailers have a key role to play in driving CO2 technology innovation. In the last twelve months alone, Danfoss has been involved in around 2,000 CO2 transcritical installations. Interest in CO2 is also growing in the industrial refrigeration arena.
What is more, this is a global trend. Although Europe remains Danfoss’ most important market for CO2 components, thanks in part to the revised EU F-Gas Regulation, South Africa and North America are rapidly catching up.
Not keen to rest on their laurels, Danfoss is already trying to solve the next challenge: making ejectors suitable for small systems. Juul says that testing on a traditional booster system without a parallel compressor, where the ejector lifts the discharge pressure from the evaporators and the compressor, is proving successful. “I see a lot of interest in small systems,” he enthuses.
The full version of this interview appeared in the inaugural edition of Accelerate Europe. Please click here to read it.