3 ms·

My understanding is that wax motors are based on actuation - they are intentionally and deliberately either heated to extend or cooled to retract, and if ambien

My understanding is that wax motors are based on actuation - they are intentionally and deliberately either heated to extend or cooled to retract, and if ambient temperature is used as one endpoint, the other will not be ambient (i.e. a heating element or cooling peltier). Thermostatic valves are ambient at both sides - they expand and contract naturally with the existing temperature, so they are not motors per se, because there's no actuation beyond the temperature.

VygmraMGVl 8d ago
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 8d 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 8d ago
    The wax expands due to ambient (even uniform) temperature. It's a linear actuator, so warm -> expanded and cool -> retracted.
    - echoangle 8d ago
      I think by thermal gradient they mean a change in temperature over time, not space.
      - jaggederest 8d ago
        Correct. Delta t
  - echoangle 8d 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 8d 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 7d ago
      [dead]
  - numpad0 8d 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

VygmraMGVl 8d ago

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 8d 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 8d ago
  The wax expands due to ambient (even uniform) temperature. It's a linear actuator, so warm -> expanded and cool -> retracted.
  - echoangle 8d ago
    I think by thermal gradient they mean a change in temperature over time, not space.
    - jaggederest 8d ago
      Correct. Delta t
- echoangle 8d 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 8d 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 7d ago
    [dead]
- numpad0 8d 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