There are three working fluids (butane, water and ammonia) and it works by exploiting differences in partial pressure (that is, the pressure contributed by each component of a gas mixture). Instead of using a compressor to change the overall pressure, it changes the composition of the mixture.

The cycle basically works by adding and removing ammonia at different points to make the butane refrigerant evaporate and condense in the appropriate places.

On the "condenser" side of things, water is used to remove the ammonia from the gas mixture by absorption. Because the total pressure is approximately the same throughout the system, removing ammonia increases the butane mole fraction and therefore its partial pressure, causing the butane to condense. This is the heat rejection side.

On the evaporator side, ammonia is added again. This lowers the butane partial pressure, shifting the equilibrium and causing the liquid butane to evaporate. That's where the cooling effect occurs.

The other part of the cycle is regenerating the ammonia by separating it from the water again. That's where heat is added, and that heat input is what ultimately drives the process.

I actually found a picture of the exact model from a museum

https://digitaltmuseum.no/011014769284/evalet-kjoleskap/

I looked at bit more and it seems the original article is quite misleading. It seems the Einstein-Szilard refrigerator is a type of absorption fridge and a major reason they did not come to market was a related absorption fridge, the Platen-Munters absorption refrigerator made by Electrolux and Evalet. The Einstein-Szilard refrigerator was not completely unique, but an attempt at improving this design with other gases.

Both machines use heat instead of a mechanical compressor, both can operate with essentially no moving mechanical parts, and both exploit partial pressure so a refrigerant can evaporate at a low temperature. The crucial difference is which fluid does which job.

The conventional diffusion-absorption refrigerator, developed by Platen and Munters in the 1920s, uses ammonia as the refrigerant. Hydrogen occupies the evaporator and lowers ammonia’s partial pressure, allowing liquid ammonia to evaporate at a low temperature. The ammonia vapor is subsequently absorbed into water. This is the basic technology that became familiar in gas-powered and RV refrigerators.

From the specific standpoint of a field-built jungle refrigerator, the Einstein–Szilard working-fluid combination arguably makes the better plot device. The Platen–Munters choice has the advantage of commercial precedent, but the hydrogen charge is decidedly the awkward ingredient. Even though once the system is charged the constituent chemicals stay put, I would rather schlep through the jungle with butane in a canister than the requisite amount of hydrogen.

“The Mosquito Coast” is an interesting movie.

> the total mass of the completed apparatus is around 400 kg with 20 kg of alcohol in the refrigeration cycle

> The group, led by Malcolm McCulloch noted that the design was still "nowhere near commercialised", but might allow the efficiency of the original Einstein–Szilárd design to be quadrupled.

It would be great if someone could improve this tech to where there's a breakeven point of ownership (preferably less than 20 years) when it becomes a better deal than other modern refrigerators.

The ab-chiller is likely best known these days as the "propane fridge" in RVs.

Sadly, the only online resources for Cowan's work I can find are either Scribd paywalled [1], the entire book in which Cowan's piece is a chapter on the Internet Archive [2] or a pointer-to-a-pointer from a piece in the Guardian [3] to a boingboing piece [4] that seems to be offline.

(Background: I work in Direct-Use geothermal. Such ad/absorption chillers are one major tool in the toolbox for low-T cases where it is uneconomical to turn geothermal heat into electrical energy -- mostly due to Carnot's Law considerations.)

[1] https://www.scribd.com/document/527479452/Cowan-How-the-refr...

[2] https://archive.org/details/socialshapingoft0000unse_g5b0

[3] https://www.theguardian.com/science/political-science/2014/f...

[4] https://boingboing.net/2012/08/20/how-the-refrigerator-got-i...

https://news.ycombinator.com/item?id=38616289

Was there also an Oppenheimer-Bohr outdoor grill?

Einstein–Szilard refrigerator: https://en.wikipedia.org/wiki/Einstein_refrigerator :

> The three working fluids in this design are water, ammonia, and butane. [1] The Einstein refrigerator (co-invented with Leó Szilárd) was actually a modification of an earlier three-fluid absorption design created by Swedish engineers Baltzar von Platen and Carl Munters

https://en.wikipedia.org/wiki/Absorption_refrigerator

I didn’t know that they had had a long relationship before that.

Is it just me?

I found his partnership with Satyendra Nath Bose one of the most fascinating, when Bose couldn't get his paper published Einstein took it upon himself personally to translate it and get it published for him

(Bose was BRILLIANT, he discovered the Boson particles by mathematical statistics!

https://en.wikipedia.org/wiki/Satyendra_Nath_Bose#Bose%E2%80... )

I'm very sound sensitive but rarely do I hear any noise from them unless I recently opened them for an extended period. Do we just have quieter appliances in Scandinavia than the rest of the world or something?