Refrigeration 101

[desA]

Acording Braydert's " Designing refrigeration installations" error-free performance of evaporator possible only with 0.5...0.7 of the TD.

This will very much depend on the magnitude of the TD itself.

For instance:
TD=10K ; SH = 0.5*10=5K; SH = 0.7*10=7K
TD=20K ; SH = 0.5*20=10K; SH = 0.7*20=14K
TD=30K ; SH = 0.5*30=15K; SH = 0.7*30=21K !!!

That's asking for a fair-sized SH. In all likelihood, you'd have a tremendously high Tc,discharge temperature.

The Magoo rule seems to be applicable in low TD applications & may need to be adjusted for high TD applications.

Like everything in the rhvac game, some level of sound engineering judgement will need to be made in each specific application.