Heated Plate In Air
Heated Plate In Air
(OP)
I am trying to model a system and so far haven't been able to do exactly what I want. I have a plate, heated by electric heater cartridges, about 4000 watts total. For now I will assume the surface temperature is the same as the internal temperature, unless anyone knows of a good way to do that. The plate is in air, no air flow. I know that an object in air that is cold will decrease by:
dT/dt=kA(Tobj-Tair). What I don't know how to do is find the temperature of the plate when an internal heat source is added. I am thinking it is similar to that of a car going against the force of drag in air, but I don't know the equations.
Similarly, I was hoping to see if I can model the change in air temperature around the plate too. When the plate is heated, the air temperature changes as well, effecting the plate temperature. This may be a little too complicated, but I haven't found much out there so far.
Any help would be great, I appreciate it.
dT/dt=kA(Tobj-Tair). What I don't know how to do is find the temperature of the plate when an internal heat source is added. I am thinking it is similar to that of a car going against the force of drag in air, but I don't know the equations.
Similarly, I was hoping to see if I can model the change in air temperature around the plate too. When the plate is heated, the air temperature changes as well, effecting the plate temperature. This may be a little too complicated, but I haven't found much out there so far.
Any help would be great, I appreciate it.





RE: Heated Plate In Air
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RE: Heated Plate In Air
RE: Heated Plate In Air
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RE: Heated Plate In Air
RE: Heated Plate In Air
1. A plate in air will be exposed to air flow due to natural convection.
2. A plate in air will radiate to other objects.
3. The plastic material will require energy to melt, and thus will affect the plate temperature.
4. If the plate surface temperature is not controlled the plastic nearest the plate may become too hot before the outer plastic softens.
RE: Heated Plate In Air
RE: Heated Plate In Air
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RE: Heated Plate In Air
For now, I am just curious to the plastic contact. What happens to the temperature when it comes down onto the plastic, or specifically, how to model that temperature drop.
RE: Heated Plate In Air
RE: Heated Plate In Air
RE: Heated Plate In Air
RE: Heated Plate In Air
Regards
RE: Heated Plate In Air
RE: Heated Plate In Air
RE: Heated Plate In Air
Tnew = Told + Cp*Vplate*Power*Time
now, if you want to add convection effects do a very low airflow over the plate and subtract the heat flux
RE: Heated Plate In Air
To account for the heat absorbed by the plastic you need to know the mass you melt per unit time (as it is a batch process, this will be an average value) and the amount of heat required to heat up and melt a unit mass of plastic (you'll likely find this in a material data sheet). Add this power to Q above and you get the average power required by your process: the heating system should be capable of delivering at least this power (likely with the addition of a substantial margin).
If I understand correctly your problem, this should be what you are looking for.
prex
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