Heating a volume of air (Thermodynamics)

Asked by PhysicsGuy (31

) October 22nd, 2010

ANTI-EDIT-QUEUE:::::: This proposed convection heater is designed for tobacco products only. If you are under the age of 18 or the consumption of tobacco products is illegal in your area do not read this question. This question is about physics and does not encourage the use, injection, smoking, insulfation, manufacturer, distribution, sale, or concealment, of any drug, device and\or paraphernalia designed to violate or circumvent ANY law of the United States or its legal territories as well as the law of any state. The heater described in this question does not encourage the use of tobacco products by minors under the age of 18 if this is illegal in your territory. This qu estion is for informational purposes only.:::::

I am designing a convection hea ter for an Arduino. The basic design of this heater will be to have a fan blow room temperature air across a heated coil. The air will need to be heated to 250–300 degrees C. In order to control t\he temperature of the coil I will have a sensor located just before the product to be heated. The sensor will cycle power to the coil on\\off to maintain the desired temperature. The air wil l flow through a tube the size of a quarter (about 25mm diameter).

Given the above informAtion what are my CFM requirements? Please explain the equati on used as I would like to understand the theory behind this.

Here is my intended des ign

http://img251.imageshack.us/img251/6725/diagramt.png

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5 Answers

The weird spaces and capitals were used to successfully post the question due to automatic filtering.

PhysicsGuy (31

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I guess my previous answer was consumed with the previous question, so here it is in brief:

Can’t calculate CFM without fan specs, but can fudge air flow just fine.

~200 degrees C is your target temp

Probably should use a manual on/off switch instead, use the sensor only as an indicator.

notdan (383

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Need to figure out the delta P across the heater and screen. You might need to experiment with a variable throttle between the fan and the heater. You don’t want to blow the tobacco out the exit. 250–300C is pretty hot. Heater will be red hot. Need to keep the user from getting burned.

RocketGuy (15494

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I don’t know shit from Shinola about this but is interesting to see a PhysicsGuy and a RocketGuy on the same page.
It is 6:29 am. How long will this comment last?

anartist (14813

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