Re:Sony’s wearable air conditioner is pretty cool
by dragontamer on Monday July 27, 2020 @12:04PM
(#23966387)
Hmmm...
Peltiers are inefficient, but very small. They are pretty simple to use: one side is hot, the other side is cold (when powered). The Peltier, given a voltage, will try to set the thermal-difference of the hot-side and cold-side to a set value. (Lets say a 45 degree difference).
Finally, there's a wattage involved: the amount of heat that the Peltier can "pump". The Peltier's actual temperature is mostly based on the wattage (500-units of heat flowing out may result in an actual 10-degree difference, instead of its theoretical maximum 45-degrees... or whatever the device's limit is).
An actual air-conditioner with a compressor is more efficient. But a Peltier is a purely electric device (literally: the electrons flowing through the wires carries the heat itself and dumps it to the hot side). As such, the Peltier is small, but inefficient (Electrons moving through wires generate heat. So the more electrons you send (aka: current), the more waste-heat is generated). An actual air-compressor would do better in any circumstance where the additional size / weight is allowed.
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As such, the only practical use of this "wearable air conditioner" are situations where a larger, more efficient, air conditioner is not available.
Even then: an ice-pack (ie: using a large refrigerator to cool down a thermal mass) would be far more efficient, and probably a cheaper, use of electricity.
I'm finding it difficult to think of a situation where ice-packs distributed from a proper compressor are unavailable. Water / Ice is a surprisingly good "cold storage" mechanism.
Peltiers are inefficient, but very small. They are pretty simple to use: one side is hot, the other side is cold (when powered). The Peltier, given a voltage, will try to set the thermal-difference of the hot-side and cold-side to a set value. (Lets say a 45 degree difference).
Finally, there's a wattage involved: the amount of heat that the Peltier can "pump". The Peltier's actual temperature is mostly based on the wattage (500-units of heat flowing out may result in an actual 10-degree difference, instead of its theoretical maximum 45-degrees... or whatever the device's limit is).
An actual air-conditioner with a compressor is more efficient. But a Peltier is a purely electric device (literally: the electrons flowing through the wires carries the heat itself and dumps it to the hot side). As such, the Peltier is small, but inefficient (Electrons moving through wires generate heat. So the more electrons you send (aka: current), the more waste-heat is generated). An actual air-compressor would do better in any circumstance where the additional size / weight is allowed.
--------------
As such, the only practical use of this "wearable air conditioner" are situations where a larger, more efficient, air conditioner is not available.
Even then: an ice-pack (ie: using a large refrigerator to cool down a thermal mass) would be far more efficient, and probably a cheaper, use of electricity.
I'm finding it difficult to think of a situation where ice-packs distributed from a proper compressor are unavailable. Water / Ice is a surprisingly good "cold storage" mechanism.