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Did the article even read the patent? The article goes on about an electromagnetic pump. A device never mentioned in the patent. The patent describes(as best

by somat 3y ago

Did the article even read the patent? The article goes on about an electromagnetic pump. A device never mentioned in the patent. The patent describes(as best I can tell) an ordinary gas fired absorption refrigerator. of the type found in many RV's. A genius design to be sure. But not one that was suppressed or lost. https://www.dometic.com/en-us/outdoor/rv-and-van/refrigerators/rv-refrigerators/dometic-americana-ii-dm2672-refrigerator-183082 https://www.dometic.com/en-us/outdoor/rv-and-van/refrigerato... My father, who worked for a gas company, used to tell me that Einstein invented the gas fired refrigerator. I always thought he was pulling my leg.

atombender 3y ago
They probably got it from Wikipedia [1], which the article appears to have been based on: > One variant, the Einstein–Szilard electromagnetic refrigerator used a Einstein–Szilard electromagnetic pump to compress a working gas, pentane. [1] https://en.wikipedia.org/wiki/Einstein_refrigerator https://en.wikipedia.org/wiki/Einstein_refrigerator
angiosperm 3y ago
The absorption refrigerator already existed, but had room for refinement as seen in the patent cited. Einstein's and Szilard's real innovation, maybe not seen there, was for a different, electric design with a moving part, sealed inside, that was moved back and forth by a varying magnetic field applied from outside. It is often described incorrectly as having no moving parts. (I used to think ammonia was itself diamagnetic or ferromagnetic, which would have been very cool, until I got a look at their design.) What was innovative was that it had no need for sealed bearings that might leak. Nowadays just the wires for the motor pierce the fluid chamber, less elegantly than a strictly magnetic coupling. Absorption refrigerators are strictly better than the compressor designs used everywhere today, running continuously, silently, and efficiently. The main driver of the latter was that General Electric wanted people to use electric refrigerators, not gas-fired, and wanted them to buy electric motors. Mass production soon gave GE an insuperable economic advantage except in niche applications. Modern institutional refrigeration systems often use ammonia as their working fluid, but nobody likes putting ammonia systems in houses or cars. The modern alternative to freon/"cfc" and "hfc" is liquid CO2 at very high pressure. Hfc that leaks traps heat more than 2000x as well as CO2, so there is a push on to replace it.
- a_gnostic 3y ago
  Such a linear pump was invented by a Japanese guy, and is commonly used in ENGEL brand RV freezers.
- cyberax 3y ago
  > Absorption refrigerators are strictly better than the compressor designs That's not true! CoP of ammonia absorption refrigerators struggles to get past 1. You can easily get a CoP of 4-5 with a compression refrigerator. Ammonia absorption fridges are useful when you have a source of waste heat, then it's basically "free" for you.
  - angiosperm 3y ago
    I am corrected. Compressor refrigeration benefits from decades of refinement. Just a few decades ago, 3 was considered good.
    - londons_explore 3y ago
      CoP isn't really about engineering refinement to eek out the best efficiency. In fact, we have known how to get really close to the Carnot limit for nearly 100 years. The Carnot limit for a fridge in room temperature is a CoP of ~20. However, getting close to that limit requires huge evaporators and condensers, big pipes, large amounts of working fluid, and multi stage pumps. All of that costs money, and historically people didn't care much about efficiency if it means spending more money.
      - cyberax 3y ago
        The Carnot limit for 26C -> 5C rerigeration is around: 1 / (T_high / T_low - 1) = 1/(300/278-1) = 13. Industrial refrigerators can get to CoP of around 4 for this temperature delta. The overall system performance will typically be much lower, due to the need to run fans and other systems. A couple of interesting technologies to watch in this area: 1. Acoustic refrigerators that use acoustic waves in helium. They theoretically can approach the Carnot limit. 2. Supercritical CO2 cycles. They can be used for larger deltas without losing efficiency.

by somat 3y ago

atombender 3y ago

They probably got it from Wikipedia [1], which the article appears to have been based on: > One variant, the Einstein–Szilard electromagnetic refrigerator used a Einstein–Szilard electromagnetic pump to compress a working gas, pentane. [1] https://en.wikipedia.org/wiki/Einstein_refrigerator https://en.wikipedia.org/wiki/Einstein_refrigerator

angiosperm 3y ago

The absorption refrigerator already existed, but had room for refinement as seen in the patent cited. Einstein's and Szilard's real innovation, maybe not seen there, was for a different, electric design with a moving part, sealed inside, that was moved back and forth by a varying magnetic field applied from outside. It is often described incorrectly as having no moving parts. (I used to think ammonia was itself diamagnetic or ferromagnetic, which would have been very cool, until I got a look at their design.) What was innovative was that it had no need for sealed bearings that might leak. Nowadays just the wires for the motor pierce the fluid chamber, less elegantly than a strictly magnetic coupling. Absorption refrigerators are strictly better than the compressor designs used everywhere today, running continuously, silently, and efficiently. The main driver of the latter was that General Electric wanted people to use electric refrigerators, not gas-fired, and wanted them to buy electric motors. Mass production soon gave GE an insuperable economic advantage except in niche applications. Modern institutional refrigeration systems often use ammonia as their working fluid, but nobody likes putting ammonia systems in houses or cars. The modern alternative to freon/"cfc" and "hfc" is liquid CO2 at very high pressure. Hfc that leaks traps heat more than 2000x as well as CO2, so there is a push on to replace it.

a_gnostic 3y ago
Such a linear pump was invented by a Japanese guy, and is commonly used in ENGEL brand RV freezers.
cyberax 3y ago
> Absorption refrigerators are strictly better than the compressor designs That's not true! CoP of ammonia absorption refrigerators struggles to get past 1. You can easily get a CoP of 4-5 with a compression refrigerator. Ammonia absorption fridges are useful when you have a source of waste heat, then it's basically "free" for you.
- angiosperm 3y ago
  I am corrected. Compressor refrigeration benefits from decades of refinement. Just a few decades ago, 3 was considered good.
  - londons_explore 3y ago
    CoP isn't really about engineering refinement to eek out the best efficiency. In fact, we have known how to get really close to the Carnot limit for nearly 100 years. The Carnot limit for a fridge in room temperature is a CoP of ~20. However, getting close to that limit requires huge evaporators and condensers, big pipes, large amounts of working fluid, and multi stage pumps. All of that costs money, and historically people didn't care much about efficiency if it means spending more money.
    - cyberax 3y ago
      The Carnot limit for 26C -> 5C rerigeration is around: 1 / (T_high / T_low - 1) = 1/(300/278-1) = 13. Industrial refrigerators can get to CoP of around 4 for this temperature delta. The overall system performance will typically be much lower, due to the need to run fans and other systems. A couple of interesting technologies to watch in this area: 1. Acoustic refrigerators that use acoustic waves in helium. They theoretically can approach the Carnot limit. 2. Supercritical CO2 cycles. They can be used for larger deltas without losing efficiency.