4 ms·

The patents having long expired, presumably there are practical reasons that this design is not competitive with modern compressor designs.. Would have been goo

The patents having long expired, presumably there are practical reasons that this design is not competitive with modern compressor designs.. Would have been good if the article had said what these are

kragen 3y ago
moving-parts-free ammonia-absorption refrigerators of the einstein-szilard type are in fact in wide use today, especially in camping trailers where the ability to run off propane without electricity is a big plus. i encountered one in a hotel room earlier this year. https://en.wikipedia.org/wiki/Absorption_refrigerator https://en.wikipedia.org/wiki/Absorption_refrigerator vapor-compression types with midgley's cfcs, and derivatives like hcfcs and hfcs, are less likely to kill you if they leak, and i think they also have a higher coefficient of performance ('efficiency'); consequently they are in even wider use einstein and szilard's no-moving-parts design does reduce the risk of leaks, but not to zero, as is obvious if you visit a junkyard to find spare parts for one of these
- biorach 3y ago
  ...and bingo! Thank you.
- londons_explore 3y ago
  Leaks in modern fridges are mostly caused by humans using a knife to try to defrost them and puncturing the pipes... And then 2nd most common cause is water leaks or dampness causing the pipes to corrode through. If you run a fridge till it dies like most people, you will probably see a leak on about 15% of cases (other causes of failure are motor capacitor failure, thermostat failure). With an ammonia based refrigerant, every single leak indoors would likely kill a few people, so such a fridge design still wouldn't be considered acceptable for use in the home today.
  - kragen 3y ago
    that depends on the speed of the leak and the amount of ammonia involved; as i said, ammonia-absorption refrigerators are in common use today, including in homes, and they do not have a high death toll (though large industrial ammonia-absorption systems do regularly kill people, about 20 people a year in all of prc, for example: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9318737/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9318737/) osha's idlh level is 300 ppm; in a typical small house of 200m³ that's 60 liters of gas, 2.5 moles at stp, about 40 grams of ammonia; this is a small enough amount of ammonia that you could definitely get it from a home refrigerator (https://www.dometic.com/assets/18/22/operating%20manual_51822.pdf https://www.dometic.com/assets/18/22/operating%20manual_5182... says it contains 226g of ammonia, which would be 1600 ppm in that houseful of air) but only if it's released quickly. lc50 for a one-hour exposure is in the 4000 to 11000 range https://www.cdc.gov/niosh/idlh/7664417.html https://www.cdc.gov/niosh/idlh/7664417.html which is several times more than the entire refrigerator's worth if diluted in a houseful of air the odor threshold is about 5 ppm https://en.wikipedia.org/wiki/Ammonia#Safety https://en.wikipedia.org/wiki/Ammonia#Safety so it's unlikely to go unnoticed

kragen 3y ago

moving-parts-free ammonia-absorption refrigerators of the einstein-szilard type are in fact in wide use today, especially in camping trailers where the ability to run off propane without electricity is a big plus. i encountered one in a hotel room earlier this year. https://en.wikipedia.org/wiki/Absorption_refrigerator https://en.wikipedia.org/wiki/Absorption_refrigerator vapor-compression types with midgley's cfcs, and derivatives like hcfcs and hfcs, are less likely to kill you if they leak, and i think they also have a higher coefficient of performance ('efficiency'); consequently they are in even wider use einstein and szilard's no-moving-parts design does reduce the risk of leaks, but not to zero, as is obvious if you visit a junkyard to find spare parts for one of these

biorach 3y ago
...and bingo! Thank you.
londons_explore 3y ago
Leaks in modern fridges are mostly caused by humans using a knife to try to defrost them and puncturing the pipes... And then 2nd most common cause is water leaks or dampness causing the pipes to corrode through. If you run a fridge till it dies like most people, you will probably see a leak on about 15% of cases (other causes of failure are motor capacitor failure, thermostat failure). With an ammonia based refrigerant, every single leak indoors would likely kill a few people, so such a fridge design still wouldn't be considered acceptable for use in the home today.
- kragen 3y ago
  that depends on the speed of the leak and the amount of ammonia involved; as i said, ammonia-absorption refrigerators are in common use today, including in homes, and they do not have a high death toll (though large industrial ammonia-absorption systems do regularly kill people, about 20 people a year in all of prc, for example: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9318737/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9318737/) osha's idlh level is 300 ppm; in a typical small house of 200m³ that's 60 liters of gas, 2.5 moles at stp, about 40 grams of ammonia; this is a small enough amount of ammonia that you could definitely get it from a home refrigerator (https://www.dometic.com/assets/18/22/operating%20manual_51822.pdf https://www.dometic.com/assets/18/22/operating%20manual_5182... says it contains 226g of ammonia, which would be 1600 ppm in that houseful of air) but only if it's released quickly. lc50 for a one-hour exposure is in the 4000 to 11000 range https://www.cdc.gov/niosh/idlh/7664417.html https://www.cdc.gov/niosh/idlh/7664417.html which is several times more than the entire refrigerator's worth if diluted in a houseful of air the odor threshold is about 5 ppm https://en.wikipedia.org/wiki/Ammonia#Safety https://en.wikipedia.org/wiki/Ammonia#Safety so it's unlikely to go unnoticed