Quick question: the first practical heat pump was reportedly used by Peter von Rittinger in the 1850s to evaporate brine at an Austrian salt works, essentially an early energy-recovery approach. Has anyone seen primary sources on its achieved COP (often cited around 3–4) and whether the compression was mechanical or steam-jet assisted?
Rittinger wrote it up: see “Die Regeneration der Wärme in den Apparaten der Salinen- und Sodafabrikation” in the Sitzungsberichte der k.k. Akademie (1856); he notes a “Wirkungszahl um 3” and describes mechanical vapor recompression via a steam‑engine–driven piston compressor, not a steam‑jet. If you’ve got ANNO or HathiTrust, search that exact title for the tables and plate — want the page refs?