"Einsteins first famous contribution to science was to quantum mechanics."
I always thought it was his refrigerator :-) (IIRC Electrolux now holds the patent).
The frig work was done ~1926. Here's
the frig. I wonder if this is the propane frig used in motor homes and such. The efficiency obtained from the link was 0.08 to 0.18. Electrolux had the patent.