This paper summarizes the results of tests run on a small (c.4.5 RT) air-cooled water chiller in which lower GWP refrigerants were
"dropped in”. The first set of tests evaluated R32 and refrigerant blends with capacities and pressures similar to R410A. Following a change of
compressor and TXV, a second set of tests evaluated refrigerant blends with capacities and pressures more similar to R22. The refrigerants tested
covered a range of operating pressures, global warming potentials, and flammability ratings.

In general, the experimental results agreed reasonably well with the predictions of a simple thermodynamic model with some refrigerants
showing a positive deviation in capacity and COP from the model prediction and others showing a negative deviation. In particular, refrigerant
blends with large glide did not perform well in the tested equipment. Several "near drop-in" candidates exist for R410A with GWPs of 400-
500. All are "mildly flammable" (class 2L), as is R32 (GWP = 675). R22-like blends can have GWPs as low as 200-300, although these
are also class 2L. On the other hand, R22-like blends can be made that are non-flammable (class 1). However, they have relatively higher
GWPs of 1300-1600. In conclusion, lower GWP options to R410A and R22 are possible. Trade-offs between specific capacity, efficiency,
GWP, and flammability will need to be made. These trade-offs may result in the need for changes to existing equipment designs.