Analysis of New Refrigerant As Drop-in Replacement on Centrifugal Compressors

The necessity for more efficient, adaptable, and environmentally friendly systems is ever-increasing, especially in the HVAC industry. One of the main focuses in this area is the development of novel refrigerants. Therefore, designing and adapting HVAC systems to novel refrigerants is an essential step to comply to new marketing and regulatory demands. In this work, the performance of an oil-free centrifugal compressor is investigated with a new refrigerant: R1234YF. The analysis is carried out numerically with CFD modelling with an existing oil-free, magnetic bearing centrifugal compressor. The model is validated across different speedlines with experimental test data utilizing the working fluid for which the compressor was originally designed: R1234ZE. The validated model is investigated with R1234YF across the whole operating range with focus on the aerodynamic results, such as pressure ratio and isentropic aerodynamic efficiency. The analysis reveals that the use of R1234YF as a working fluid leads to the ability for higher lift and lower power consumption when compared to R1234ZE, albeit at a reduction of cooling capacity. A close inspection of the thermodynamic properties of R1234YF and R1234ZE was carried out, showing a reduction in speed of sound and density for R1234YF compared to R1234ZE at similar condenser and evaporator temperatures. The perspectives for the employment of R1234YF on the compressor is discussed, highlighting the flexibility that the refrigerant provides with regards to the compressor application, as it allows the compressor to operate in regions with lower evaporator temperatures or higher condenser temperatures.