If I may expand somewhat on Jeff's comments:
R410A has roughly 40% greater saturation vapor density than R22. The higher working pressures allow smaller cross section in the same sense that high voltage lines permit smaller wire cross section.
This has multiple benefits. Smaller tubing has lower hoop stress for a given pressure, allowing for thinner walls. Thinner walls increase heat transfer and lower cost. More tubes in a given HX area further increase heat transfer. Higher fluid velocity also increases heat transfer.
R410A gets a bad rap because it doesn't work in old equipment. Systems designed for R410A can outperform R22 and R290.
Ref. " Effects of refrigerant properties on refrigerant performance" Prapainop and Suen. 2012
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