United States. Carrier developed a prototype high-speed screw compressor and tested it with a new low-pressure non-flammable HFO refrigerant, as a potential long-term solution for air conditioning systems.
Addressing global warming concerns is one of the biggest challenges facing the HVAC industry today. While A2L refrigerants are important options to consider for certain sizes of HVAC units, there are still many systems that require category A1 refrigerants.
Among the various refrigerants available, Carrier considered Chemours' DR-12 refrigerant as one of the attractive refrigerants. In addition to being in category A1, its very low GWP value (32) and high cycle performance make it an excellent long-term solution if applied successfully. A major challenge to overcome with this refrigerant is its low density. The DR-12 will require almost 7 times the volumetric flow for the same cooling capacity compared to R410A.
Current displacement or rotary technologies are not realistic to be applied in a low-density refrigerant system. The development of a new large and compact CFM compressor is key to realizing the scope of the project successfully.
The authors have explored various types of compression mechanisms and have identified screws as one of the most suitable technologies for this refrigerant. To obtain a high volume flow (19.8L/s, 42CFM), a unique screw rotor design and a high-speed PM motor were employed. The innovative bearing design and new compressor design also allowed the compressor to be compact (cphgr145mm) and cost-effective. A prototype compressor was built and tested. This concept provided a capacity of 17.6kW (5 tons) at 11,000 rpm and 4.4kW (1.25 tons) at 2,500 rpm, meeting the requirements of its target.
The tests were conducted in accordance with the ASHRAE 23.1 compressor test standard, and the compressor was said to have run for more than 800 hours without any problems.
You can learn about the project report by clicking here.
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