watt density?
watt density?
(OP)
I am using an electric heating element to heat up some SAE 10 hydraulic oil. Someone warned me to be carefull about the watt density of heating element, that is if the liquid is too dense or viscous you can actually overheat and ruin the electric heating element.
does anyone have any experience with this problem? that can offer me some advice
Thank you
does anyone have any experience with this problem? that can offer me some advice
Thank you





RE: watt density?
In some cases whatever is being heated has to be taken into account too. Like your suggestion.
If the media you are heating can only move past the heating element via convection then you will have a greatly reduced heating rate over the media being pumped past the element or mechanically agitated.
Keith Cress
kcress - http://www.flaminsystems.com
RE: watt density?
if i have a heating element and i know the watts, is the watt density the watts divided by the surface area of the heating element?
I have seen the watt density for stagnant oil be 15watts/in, Am I correct to assume that this is the maximum alowable watt density for the fluid befor you burn up your electric heating element?
RE: watt density?
When I was young and knew I was smarter than everybody else, I did all the calculations. Now that I have learned that I will not live long enough to learn everything, I try to concentrate on learning how to ask good questions of those who know.
Charlie
RE: watt density?
But I agree with itsmoked and CharlieGill that better you'll contact the manufacturer for your application. See for instance:
http://www
RE: watt density?
Remember you will have a watt density that a heater can handle and then you will have 'other' watt densities relating to the medium being heated.
That nice link of 7anoter4's notes 10 watts per sq inch as being about right for lube oil heating. Higher temps and the elements will start to cook the oil which plates onto the element. Then the element starts running hotter yet. Small less coated areas are then pushing much higher WSI and they cook on more oil faster. It all sea saws around until the element fails due to the heating element melting or oxidizing into an open.
So you always want as low a watt density as you can afford or have room for (sqin).
Keith Cress
kcress - http://www.flaminsystems.com
RE: watt density?
RE: watt density?
If you are using an analog signal e.g. RTD and PLC dont forget to include loss of signal protection in the heater circuit.
RE: watt density?
Control would be done from the oil-immersed feedback device, and overtemp limiting with the heater-mounted device.
RE: watt density?