Full Answer
What is heat flux?
through a surface. Heat flux or thermal flux, sometimes also referred to as heat flux density, heat-flow density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI its units are watts per square metre (W/m 2 ). It has both a direction and a magnitude, and so it is a vector quantity.
Is heat flux vector or scalar quantity?
It has both a direction and a magnitude, and so it is a vector quantity. To define the heat flux at a certain point in space, one takes the limiting case where the size of the surface becomes infinitesimally small. , the subscript q specifying heat flux, as opposed to mass or momentum flux.
How do you find the heat flux through insulation?
Diagram depicting heat flux through a thermal insulation material with thermal conductivity, k, and thickness, x. Heat flux can be determined using two surface temperature measurements on either side of the material using temperature sensors if k and x of the material are also known.
Why calibrate a heat flux sensor?
Once the heat flux sensor is calibrated it can then be used to directly measure heat flux without requiring the rarely known value of thermal resistance or thermal conductivity. One of the tools in a scientist's or engineer's toolbox is the energy balance.
kingdal Super Member Verified Member ECF Veteran
Ever since I started building coils, I've always built to certain resistances. Wire gauge was something I used to control the number of wraps and the size of the coil. The other day I saw on the Steam engine calculator that different gauges and resistances affect something called heat flux.
readeuler Ultra Member Verified Member ECF Veteran
My understanding is that it's a measure of how concentrated the heat is - it tells you how much heat will radiated from a small 'unit' of coil surface area. Take-away: It's really just a ratio of wattage to coil surface area.
nasca Super Member Verified Member ECF Veteran
I dont understand it, either. But if I aim for somewhere between 200 and 260, I'm good.
kingdal Super Member Verified Member ECF Veteran
Heat flux is in reference to the "balancing act" between wire gauge/length, physical wrap count/coil ID that will actually fit in the atomizer and coil temperature per wattage applied... in this instance, radiant heat is expressed in milliwatts divided by square millimeters of surface area, or mW/mm².
vapemac Veteran
Maybe ask this guy? I heard he knows his stuff when it comes to flux capacitors
jjde Postman
Now, my usually MTL setup is 1.2 ohms, 2.5mm rod, 6 wraps on 28g Kanthal build. Vape that at 12w, 178 mW/mm2 & it's a cool vape, about what I like
jjde Postman
Second part I'm not so clear So is it as simple as more wattage = more heat, even with the same Heat Flux on both tanks?
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Overview
Heat flux or thermal flux, sometimes also referred to as heat flux density , heat-flow density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI its units are watts per square metre (W/m ). It has both a direction and a magnitude, and so it is a vector quantity. To define the heat flux at a certain point in space, one takes the limiting case where the size of the surface beco…
Fourier's law
For most solids in usual conditions, heat is transported mainly by conduction and the heat flux is adequately described by Fourier's law.
where is the thermal conductivity. The negative sign shows that heat flux moves from higher temperature regions to lower temperature regions.
The multi-dimensional case is similar, the heat flux goes "down" and hence the temperature grad…
Measuring heat flux
The measurement of heat flux can be performed in a few different manners. A commonly known, but often impractical, method is performed by measuring a temperature difference over a piece of material with known thermal conductivity. This method is analogous to a standard way to measure an electric current, where one measures the voltage drop over a known resistor. Usually this method is difficult to perform since the thermal resistance of the material being tested is oft…
Relevance to science and engineering
One of the tools in a scientist's or engineer's toolbox is the energy balance. Such a balance can be set up for any physical system, from chemical reactors to living organisms, and generally takes the following form
where the three terms stand for the time rate of change of respectively the total amount of incoming energy, the total amount of outgoing energy and the total amount of accumulated ener…
See also
• Radiant flux
• Latent heat flux
• Rate of heat flow
• Insolation
• Heat flux sensor