A Cambridge startup is betting on plastic crystals to transform refrigeration by replacing gases with solid materials that change temperature under pressure, in a technology still under development and initially aimed at commercial systems. A startup affiliated with the University of Cambridge is working on a refrigeration technology that exchanges gases for solid materials capable […]
  • toiletobserver@lemmy.worldEnglish
    14·
    2 days ago

    Doesn’t squeezing add energy to a system? In other words, make it hotter. My tiny brain can’t break rules of thermodynamics.

    • SirEDCaLot@lemmy.todayEnglish
      36·
      2 days ago

      Yes. You are always adding net energy to the system. That’s why a heater is a self-contained unit (turns energy into heat) while an air conditioner requires two units- one to suck up the heat outside, another to reject that heat outside. It’s not ‘creating cold’, it’s using energy to pump heat from the inside to the outside. The total amount of heat rejected outside is a net addition- it’s the heat sucked up from inside, plus the waste heat from the compressor.

      The air conditioner (current design) works on the simple principle that the boiling point of a liquid changes based on ambient pressure, and that phase change (between liquid and gas) carries a lot of latent energy. To boil water with heat alone, it takes about 100 calories to heat a gram of water from just above freezing to just below boiling. But to boil it, to heat it less than one more degree and turn it into gas, takes another 433 calories. That means if you adjust its boiling point by pressurizing and depressurizing it, whenever it boils or condenses it’ll suck up or release a lot of heat at the same time.

      Obviously we want colder than 100c, so we use a refrigerant like tetrafluoroethane with a boiling point of -26c.

      This gadget uses a similar concept. Instead of using pressure to tweak the boiling point of a refrigerant, it uses a solid that heats or cools in response to pressure. Then water carries the heat around.

    • spongebue@lemmy.worldEnglish
      9·
      2 days ago

      Squeezing (pressurizing) certain gases are basically how air conditioners work. Under pressure, the gases can absorb more heat (think pressure cooker - those get hotter because they raise the boiling point of water with the higher pressure). Shuffle that pressurized gas somewhere else with lower pressure, and it can no longer hold all that heat and needs to release it. Tada: heat has been moved from one location to another.