Constant heat equipment

[CSunny]

Hello,
I am in the search for an equipment that gives out constant heat output. The equipment can be similar to an immersion heater, the output should not vary with the electrical input. This is to be used in the calorimetric testing of a two phase liguid (ice in brine solution).

Thanks for your replies.

 

[EdStainless]

So you want a constant Q irrespective of temperature?
IF the heat transfer isn't limited at the heater then you can do it with a power regulator.
You will need constant (or excess) power available at all times for this to work.

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P.E. Metallurgy, consulting work welcomed

 

[CSunny]

@EdStainless Yes, That is one of the ideas that came up. I am looking for any alternative options that can work in the same scenario.

 

[IRstuff]

Not clear what you're looking for.

You need a control system that effectively measures, or calculates, the heat output, so power, or current*voltage, which controls the heater.

How did you think that an alternative was going to work?

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[EdStainless]

Other methods get rather involved.
Circulate the solution through a Coriales flow meter to give you true mass flow, then across your heat source.
Measure very accurate (and there is the rub) inlet and outlet temperatures.
Then have a PLC or other device look up cp as a function of temperature and calculate the total Q.
And use this as feedback either for flow control or heating input control.
I wouldn't consider this unless I had to use something other than electricity as the power source.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[rothers]

Like IRsuff says and assuming the calorimeter & associated electric heating element is well constructed so all electrical input power is converted into heat then you just monitor V & I and adjust either of both to maintain a constant W. I'd do it with a PLC and a mosfet bridge driver.

 

[MintJulep]

How much constant do you really need?

In most of the first world the electrical supply is pretty stable. Not always, but usually.

A simple resistive heater will be constant power when connected to a constant power supply. Or pretty close. The resistance might change a bit with temperature.

If you need better, you need a power regulator.

Except that you asked for a device that remains constant as the power supply changes - which is sort of impossible for an electric heater.

 

[TugboatEng]

I disagree about the simple resistive heater. A tungsten filament lightbulb starts at 9x power until it reaches operating temperature. Learned this lesson the hard way, who thought lightbulbs had inrush?

 

[IRstuff]

I've never seen a tungsten bulb used as a resistive heater, electrical heaters are typically resistive.

Additionally, the recommendation was to measure BOTH current and voltage to determine the heat output.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[CSunny]

Thank you everybody for your views and suggestions. My current plan is to hookup the heater to a watt meter and measure the input energy. Assuming the heater would have an efficiency close to 100%, I would know the heat output. Let me give it a shot and see how the setup works.