Friday, July 23, 2004
A completely random thought
Why don't the compressors in refrigerators turn off when the door is open?
When the door is open, the compressor has to effectively lower the temperature of the room - an impossibility as the compressor is dumping extracted heat back into the room. But if it turned off when the door was accidentally left open, a bit of energy could be saved.
Seems simple enough to do as there's already a sensor in place (the light) and on/off circuitry is pretty easy and cheap to implement.
Comments(3) |
When the door is open, the compressor has to effectively lower the temperature of the room - an impossibility as the compressor is dumping extracted heat back into the room. But if it turned off when the door was accidentally left open, a bit of energy could be saved.
Seems simple enough to do as there's already a sensor in place (the light) and on/off circuitry is pretty easy and cheap to implement.
Comments(3) |
I always thought that turning on/off repeatedly was worse for it or took more energy. kinda like why air conditioners overshoot the desired temp by a few degrees and then wait to come back on until a few degrees over the desired temps. i.e. the hysteresis curves are offset along the x-axis of temperature depending on which way you're coming from. does that make any sense?
For a similar reason it's best to leave flourescent lights on than repeatedly turn them on and off. It 's more energy to start it up than to keep it running once it's on.
Good speculation by both Rog and Mike that switching losses make such a scheme prohibitively expensive from an energy pointof view.
However, most of the time when you open the door, the compressor is off to begin with unless the fridge is really lousy (like my Kung Fu).
So the incidence of door openings causing the compressor to turn off would be rather low (plus fridge doors are opened only irregularly). I expect the savings from turning off the compressor when the door is left open for 10-15 minutes or more will more than offset any switching losses.
As a "best of all worlds" solution, maybe if the scheme includes a little timer - say 2 minutes - so that the compressor cut-off scheme primarily catches times when the door is left open for excessive periods of time.
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However, most of the time when you open the door, the compressor is off to begin with unless the fridge is really lousy (like my Kung Fu).
So the incidence of door openings causing the compressor to turn off would be rather low (plus fridge doors are opened only irregularly). I expect the savings from turning off the compressor when the door is left open for 10-15 minutes or more will more than offset any switching losses.
As a "best of all worlds" solution, maybe if the scheme includes a little timer - say 2 minutes - so that the compressor cut-off scheme primarily catches times when the door is left open for excessive periods of time.
