Multi-ejectors, ocean-source heat pumps, and water-refrigerant chillers were among the natural refrigerant system innovations showcased at ATMOsphere America 2017.
Hayato Sakamoto, Kawasaki Heavy Industries, presents the MiZTURBO water-refrigerant turbo chiller in San Diego
In a sign of the growing penetration of natural refrigerant-based HVAC&R technologies into the U.S. market, a wide variety of innovative case studies were presented at ATMOsphere America 2017 in San Diego, highlighting among others the progress of transcritical CO2 in warm climates, increased efficiency of heat exchangers, and water-refrigerant chillers.
Danfoss has developed a multi-ejector for improving the efficiency of CO2 transcritical systems. “We now have 180 installations worldwide,” said Jim Knudsen, North America segment leader for food retail at the Danish manufacturer.
Knudsen highlighted the company's progress in improving the efficiency of transcritical CO2 in warm climates in particular. Danfoss has been trialing its ejectos since 2013 with good results, and expects to see further improvements with the launch of its liquid ejectors in 2018.
““When you add the ejector, there is an additional 5-10% better efficiency. We expect better results when we add liquid ejectors,” said Knudsen.
Ejectors are not the only innovative solution to help increase efficiency of natural refrigerant systems.
Impressive evolution of heat exchangers, heat pumps
Yoram Shabtay, a veteran designer of heat exchangers at Heat Treansfer Technologies LLC, stressed how the gradual reduction in size of heat exchangers had delivered significant efficiency improvements.
Shabtay showed that the refrigerant charge for an R290 mini split room air-conditioning unit was reduced by 36% using a compact 5mm copper tube evaporator.
“Thousands of heat exchangers are made daily, mainly in China. The awareness of heat exchangers is quite low, that is why I am here,” he remarked.
Heat pumps are another growth area in the United States.
“They said that heat pumps don't have a place in North America. That's not true," said Andy Baker, owner of Alaska-based YourCleanEnergy, a consultancy.
Baker detailed how a transcritical CO2 heat pump installation at the Alaska Sealife Center in Seward, Alaska, is providing lower cost hydronic heat than oil boilers.
The installation was done in January 2016 and features four 20-ton Mayekawa transcritical CO2 heat pump units, which draw heat from the ocean.
“Most of the year, we run 95% CO2 heat pumps, 5% electric,” remarked Baker.
Hayato Sakamoto, assistant manager, engineering & development section, Kawasaki Heavy Industries, detailed Kawasaki’s world-first commercialised water-refrigerant turbo chiller, dubbed 'MiZTURBO'.
Sakamoto detailed the water-refrigerant turbo chiller’s key innovations: its high performance centrifugal compressor, its compact size, and its oil-free operation.
Based on Sakamoto’s calculations of the theoretical operation of the MiZTURBO water-refrigerant turbo chiller unit in San Francisco, an end user would see a 67% reduction of direct and indirect carbon emissions compared to a traditional HFC chiller.
Participants in the session were left with optimism and reassurance that the industry was headed in the right direction. It was obvious from the session that innovation would continue at state-level in the U.S. and on an individual level around the world, despite the uncertain political climate in Washington.