4 ms·

Why does there need to be a thermal gradient? It seems like the action driving the actuator is the expansion of the wax due to temperature. You don't need a per

Why does there need to be a thermal gradient? It seems like the action driving the actuator is the expansion of the wax due to temperature. You don't need a persistent heat flux to get that, the wax just needs enough heat warm up and change phase. Edit: also, the actuation from the wax motor only happens while it is absorbing (or losing) heat, even if it later ends up in a steady state with no heat flux.

jaggederest 14d ago
There needs to be a gradient or the wax won't move due to temperature. The motion is the change in state, as you say, but it won't change state if you don't heat or cool it. That's why it's a motor, like in dishwashers, not a thermostat like in e.g. greenhouse windows or radiators. It doesn't need to be persistent, but without some way to create a state that is different than ambient, it's not a motor.
- weltensturm 13d ago
  The wax expands due to ambient (even uniform) temperature. It's a linear actuator, so warm -> expanded and cool -> retracted.
  - echoangle 13d ago
    I think by thermal gradient they mean a change in temperature over time, not space.
    - jaggederest 13d ago
      Correct. Delta t
- echoangle 13d ago
  I disagree, I think motor in this case only means “creating movement”. The motor is the thing creating movement depending on the ambient temperature. Also you seem to have a miscommunication with the person replying to you where they are talking about a spacial thermal gradient and you mean it in a temporal sense.
- TeMPOraL 13d ago
  Apples and apple seeds to me. The way I see it, the thermostat contains the motor (EDIT deleted the rest of explanation). EDIT: the way I see it, talking about gradients here is nonsense. The wax motor works by expansion/contraction due to point temperature. No gradient is involved. Gradients are thermostat-level thinking, and even then, in the greenhouse scenario, there is no gradient to talk about, because the whole point is just to vent the heat from inside to outside when inside crosses certain absolute value of T, and the only "gradient" that matters is the assumption that outside side is less than T at all times.
  - jaggederest 13d ago
    [dead]
- numpad0 13d ago
  no the material inflates proportionate to absolute temperature, causing motion, iiuc things lietrally change its volume maintaining mass when its temperature changes, due to atoms moving more energetically, like something be 4x4x4 inches at 40F, but 4 1/16 x 4 1/16 x 4 1/16" at 200F this isn't a Stirling engine with a displacer, just a sealed off piston

jaggederest 14d ago

There needs to be a gradient or the wax won't move due to temperature. The motion is the change in state, as you say, but it won't change state if you don't heat or cool it. That's why it's a motor, like in dishwashers, not a thermostat like in e.g. greenhouse windows or radiators. It doesn't need to be persistent, but without some way to create a state that is different than ambient, it's not a motor.

weltensturm 13d ago
The wax expands due to ambient (even uniform) temperature. It's a linear actuator, so warm -> expanded and cool -> retracted.
- echoangle 13d ago
  I think by thermal gradient they mean a change in temperature over time, not space.
  - jaggederest 13d ago
    Correct. Delta t
echoangle 13d ago
I disagree, I think motor in this case only means “creating movement”. The motor is the thing creating movement depending on the ambient temperature. Also you seem to have a miscommunication with the person replying to you where they are talking about a spacial thermal gradient and you mean it in a temporal sense.
TeMPOraL 13d ago
Apples and apple seeds to me. The way I see it, the thermostat contains the motor (EDIT deleted the rest of explanation). EDIT: the way I see it, talking about gradients here is nonsense. The wax motor works by expansion/contraction due to point temperature. No gradient is involved. Gradients are thermostat-level thinking, and even then, in the greenhouse scenario, there is no gradient to talk about, because the whole point is just to vent the heat from inside to outside when inside crosses certain absolute value of T, and the only "gradient" that matters is the assumption that outside side is less than T at all times.
- jaggederest 13d ago
  [dead]
numpad0 13d ago
no the material inflates proportionate to absolute temperature, causing motion, iiuc things lietrally change its volume maintaining mass when its temperature changes, due to atoms moving more energetically, like something be 4x4x4 inches at 40F, but 4 1/16 x 4 1/16 x 4 1/16" at 200F this isn't a Stirling engine with a displacer, just a sealed off piston