Short answers, pulled from the story.
The Einstein refrigerator was jointly invented by Albert Einstein and his former student Leó Szilárd. The two began collaborating in 1926 and received their U.S. patent on the 11th of November 1930. Together they were granted 45 patents in six countries covering three refrigerator designs.
The Einstein refrigerator is an absorption refrigerator that uses water, ammonia, and butane as its three working fluids. It operates at constant pressure and requires only a heat source to run, with no moving parts. Cooling is achieved through a chemical process rather than mechanical compression.
The Great Depression of 1929 dried up development funding before the device could reach production. The introduction of Freon made existing refrigerators safer, removing the main argument for the Einstein design. Nazi political violence also forced both inventors to flee Germany in the early 1930s, disrupting further development.
Einstein and Szilárd received $750 for the sale of their most promising patents to the Swedish company Electrolux, a sum equivalent to roughly $10,000 in 2017.
The Einstein-Szilárd electromagnetic pump, a variant of the refrigerator design that compressed a working gas called pentane, was later applied to cooling breeder reactors in nuclear engineering. Its reliability and safety made it well suited to an application where component failure was not acceptable.
Electrical engineers at Oxford University's Energy and Power Group, led by Malcolm McCulloch, revived the Einstein refrigerator design in 2008 as a possible solution for refrigeration in rural areas without electricity. McCulloch's team acknowledged the design was still "nowhere near commercialised" but calculated that efficiency could be quadrupled over the original figures.