[stevehull]

I am interested in designs where the COP (and EER) can be markedly increased by dual compressor technology. Differing gasses offer advantages at each differing temperatures (latent curve) and it might make sense to have the first compressor do an efficient job of maximizing heat throughput at low temperatures, whereas the second compressor boosts it up to a higher temperature.

Right now, the compressors are engineered so that they are just OK at boosting temperature through a wide range of temperatures.

This would have immediate applications for water to water heat pumps where it is very hard to get water output more than 120 F.

I do see technical (proprietary for now) designs that have COPS in the 10+ range with EERs in the low 100's. I know this sounds amazing, but only thirty years ago, it was stated that "for thermodynamic reasons, a COP of over 5 will be impossible".

Imagine going to a homeowner with an AC unit EER of 10 and showing then the 90% costs savings going with an EER of 100 . . . . Same with COP.

Steve