A new compressor was developed for a refrigerant called R1234ze, which is better for the environment than R134a. The researchers tested the performance of this compressor with R1234ze and compared it to R134a. They also looked at another eco-friendly refrigerant called R515A, which performed similarly to R1234ze and is not flammable. The R515A was tested with the same compressor to see how it compared to R1234ze.