By Michael Young, Pr. Eng.
Part 2: The drive for greener refrigerants and it’s impact on the data centre industry
Cooling equipment that is used for data centre applications requires some form of refrigerant to transport heat from the white space to an area outside of the data centre.
When choosing the ideal refrigerant for a data centre, the toxicity, flammability, environmental impact, performance, efficiency, sustainability and the cost of both the refrigerant and equipment needs to be considered. No single refrigerant is perfect in all applications and compromises need to be made to strike the correct balance.
The two most common HFC refrigerants used in a data centre are R410A for DX systems and R134A for chilled water systems. Since the signing of the Paris climate agreement in 2016, one hundred and ninety-six countries all have a common goal to limit the global temperature rise to 2°C and to pursue further efforts to limit the increase to 1.5°C.
Since refrigerants have a direct impact on the global temperature rise and electrical consumption of a cooling unit, manufacturers are currently developing alternative refrigerants to reduce the effects of global warming.
The markets response for the replacement of R410A was R32. Initially this refrigerant looked like a suitable replacement, as it had a 67% lower GWP than R410A and an atmospheric life of five year. R32 cooling capacity is 9% less than R410A which requires the cooling unit to increase in size and costs. While R32 looks promising, it will not comply with the F gas regulations after 2030 as the GWP exceeds a value of 500.
The next alternative is R454B which has a 77% lower GWP compared to R410A, it has an atmospheric life of 3.6 years and has a 3% lower cooling capacity. R454B is, however, more flammable and expensive to purchase than R410A.
Some alternatives for R134A that are used in water chiller type of applications include R1234ze and R1234yf. The refrigerant R1234ze has a GWP as low as seven but has a 25% lower cooling capacity than R134A. R1234yf has a GWP as low as four and has a 5% lower cooling capacity than R134A. Both refrigerants are more expensive than R134A, however the price may begin to decrease as demand increases.
While it seems simple on the surface, the migration of one refrigerant to another for either a DX or chilled water system is complex. If the alternative refrigerant has less cooling capacity, the evaporator and condenser of the cooling unit need to increase in size, which impacts the price and electrical consumption of the unit.
Compressor performance of a cooling system is also affected by using different refrigerants. When alternative refrigerants are used, the associated condensing and evaporating temperatures change as a function of pressure. Therefore, use of one refrigerant may yield good compressor performance but an alternative refrigerant may cause the compressor to operate outside of its envelope.
This is the challenge that data centre cooling manufacturers face in the drive towards environmental sustainability. To learn more on how refrigerants impact compressor performance, drop us an email on email@example.com or stayed tuned for next month publication.
Wishing you a successful month ahead.