Heating coil

[ydoaPs]

I'm building something requiring a heating coil that hovers at 500-600F and quickly jumps to about double that, sustains the high temperature for 1-5 seconds, and then drops back down to the original temp. How do we get the temp to double extremely quickly? I'm thinking we just make the high voltage for a temperature that is WAY higher and it will reach the actual desired high temperature more quickly, but I don't know whether or not that will work.

[swansont]

I'm building something requiring a heating coil that hovers at 500-600F and quickly jumps to about double that, sustains the high temperature for 1-5 seconds, and then drops back down to the original temp. How do we get the temp to double extremely quickly? I'm thinking we just make the high voltage for a temperature that is WAY higher and it will reach the actual desired high temperature more quickly, but I don't know whether or not that will work.

 

It depends on how much power the system requires. Doubling the temperature requires up to 16x the power, assuming you have radiation transfer/losses. This is not a big problem if it only requires a few (or even tens of) Watts, but much more of a problem if it requires hundreds of Watts.

[Suxamethonium]

You could probably look into PMW- pulse width modulation. (i.e. changing the percent of duty cycle the coil current turns on and off)- That would allow you to control the heating with a simple microcontroller device.

 

I think your problem will actually become, what material do you need to use that won't retain the heat and hence cool back down quickly- metals will do so quite quickly, but anyone who has an electric stove knows it still takes quite some time to air cool. Likewise, if you were using the coil to heat something with a high heat capacity (I'm going to say water for example), the coil would quickly cool back down, but the water would cool down much slower.

 

Anyway- back to the heating, generally PWM allows you to use a significantly higher current in your circuit, and gives you easy digital control over a temperature- but as for 500-600F you would need to calculate the required current and duty cycle yourself, and I'm not sure how to do that (but there will be a formula somewhere?).

 

That's about the extent of my knowledge however, best of luck.

 

Edit: Really bad spelling mistake.

Edited January 27, 2012 by Suxamethonium

[ydoaPs]

It depends on how much power the system requires. Doubling the temperature requires up to 16x the power, assuming you have radiation transfer/losses. This is not a big problem if it only requires a few (or even tens of) Watts, but much more of a problem if it requires hundreds of Watts.

We're kind of experimenting right now. We're starting with nickel chromium wire for the element and a 12V power supply.

[Xittenn]

The parameters aren't well defined and so I suggest consider using an infrared heat lamp if it meets your constraints as an alternative.

[ydoaPs]

The parameters aren't well defined and so I suggest consider using an infrared heat lamp if it meets your constraints as an alternative.

I'm not sure what the actual parameters will end up being. Right now all I know is that we will need a heating coil and a cooling system. Our plan right now is to play with it and adjust as necessary to get what we want.

 

We were using a 5V supply, but that wasn't heating the nichrome up much at all. We've yet to try the 12V.

 

You could probably look into PMW- pulse width modulation. (i.e. changing the percent of duty cycle the coil current turns on and off)- That would allow you to control the heating with a simple microcontroller device.

I'll look into it. We were looking at eventually using a digital controller anyway.

[ayeshaaakter]

This system gets its name fromthe way it uses the difference between the outdoor air temperature and theindoor air temperature to heat or cool a home. During the summer, the air sourceheat pump functions as an air conditioner; during the winter, it runs inreverse to provide heat. Properly installed and connected to a well-designed (andtight) duct system, an air source heat pump can deliver up to three units ofheating (or cooling) energy for every unit of electric energy it consumes exceptin very cold weather, when a backup resistance heating system must supplementthe heat pump's output.

 

Because it heats and cools, anair source heat pump is a good choice for replacing an existing heating andcooling system or when you need a new furnace and want to add centralair-conditioning. Look for a heat pump with a high HSPF and SEER rating. Thebest units have a two-stage compressor that runs in a low-power, energy-savingmode most of the time, along with a variable speed blower motor that minimizesnoise and energy consumption.