heating element

[Myint Mo]

I am looking for heating element for my project. Which type of heater can I use for temperature around 80-100C with lowest power consumption

 

[picbits]

A heat pump would be your lowest power consumption but they are very expensive. Resistive heaters are generally 100% efficient.

 

[rjenkinsgb]

Power consumption depends on the amount of energy you need to draw from the heater; eg. a small flashlight lamp filament glows white hot with a tiny amount of power, as little heat escapes.

What do you want to heat, and how fast must it reach temperature??

As an example, I built a little heating pad to use for evaporating solvent (vapor polishing). That uses seven, 33 Ohm ceramic power resistors (17W rated) in parallel, so around 6.6 Ohms, just under 2A as 12V; around 22 watts.

The resistor are high power for the size and contact area, rather than because they are individually dissipating a lot of power.

They are sandwiched between two 100mm square pieces of aluminium plate, with a piece of silicone rubber "heat resistant" honeycomb style cooking mat at one side, pressing the resistors towards the top plate. I also included a couple of thermistors pressed against the top for temperature feedback.

I just plugged it in for the photo, so it's only been heating up a few second. The temperature controller is from ebay. I've just tried it and it will get up to 100'C, though it takes a few minutes - there is quite a lot of heat capacity in the 5mm aluminium plate.

 

[Externet]

"Lowest power consumption" means nothing. Doing your project in your Alaska backyard winter is not the same power consumption doing it in your Texas kitchen.
What is the voltage supply ? 12V? Tried a car light bulb? Tried a car cigarette lighter ?
Is it 120VAC ? Tried an incandescent light bulb of the many wattages it works for you ? Tried a wall plug scent heater ?
And remember heat is not temperature.

 

[crutschow]

Which type of heater can I use for temperature around 80-100C with lowest power consumption

As noted, all resistive type heaters are 100% efficient.
It makes no difference what type it is if it's resistive.

So when you see those ads for electrical plug-in room heaters and they say they are "efficient", that really means nothing, as that's true of any plug-in heater.
They all convert 100% of their input electrical energy to heat in the room.
Even the energy to power the heater fan (if it has one) is all converted into heat that goes into the air.

 

[vu2nan]

Hi Myint Mo,

The quantity of heat required to raise the temperature of a substance is given by the equation

Q = mst

'Q' is the quantity of heat in calories, 'm' the mass of the substance in grams, 's' its specific heat in calories / gram / degrees Celsius and 't' the difference in temperature in degrees Celsius.

The energy (kWh) required can be estimated (1 calorie = 4.18 Joules and 1 Joule = 1 Watt second).

The temperature gradient would also need to be taken into consideration to arrive at the heater wattage.

You need to specify whether the required heating is through conduction, convection or radiation. In other words, is the requirement for a hot plate, immersion heater or air / space heater.

Nandu.