I used information from the following links:
http://www.specialmetals.com/documents/Nickel 200 & 201.pdf
Electrical resistivity and conductivity - Wikipedia, the free encyclopedia
Kanthal A-1 — Kanthal
American wire gauge - Wikipedia, the free encyclopedia
Fahrenheit to celsius conversion
My spreadsheets are here:
1. This sheet works out the resistance per meter for different gauges of Kanthal and Ni 200 and calculates combined (parallel) resistance per meter. Using the combined resistance one can determine the 'equivalent' resistance for Ni 200 only (which is what the mod will read).
Based on a few combinations I get:
28N | 32K = -15C (-30F)
28N | 30K = -25C (-50F)
26N | 32K = -10 C (-20F)
So, for example, for 28N | 32K twisted for a coil temperature of 450 F, one would set the mod temp to 420F
I had to interpolate the Ni 200 values between what I could find from the Ni 200 PDF (above). I used exponential regression as it seemed to fit best but it's not entirely accurate (it was better than linear though).
2. This sheet I created to design coils (select 'Sheet2'). It is very similar to how steam-engine.org works it out. I have input custom wires for the above combinations of Ni 200 and Kanthal based on their 20C (70F) room temperature resistances and diameter based on the sum of their diameters (my approximation for dual twisted wire diameter). This is very useful for working out the surface area and as such the number of wraps to achieve a desired mW/mm2 heat flux.
The values in the sheet as entered are for 28N | 32K twisted. Single coil can push 35W for ~200 mW/mm2 (cool / slightly warm vape). I plan on putting two of these coils in my Cthulhu mod as it seems it will fit (coil height 5.7mm) ID 2.5mm. So, on my snow wolf it should handle up to 70W without limiting (I hope
)
http://www.specialmetals.com/documents/Nickel 200 & 201.pdf
Electrical resistivity and conductivity - Wikipedia, the free encyclopedia
Kanthal A-1 — Kanthal
American wire gauge - Wikipedia, the free encyclopedia
Fahrenheit to celsius conversion
My spreadsheets are here:
1. This sheet works out the resistance per meter for different gauges of Kanthal and Ni 200 and calculates combined (parallel) resistance per meter. Using the combined resistance one can determine the 'equivalent' resistance for Ni 200 only (which is what the mod will read).
Based on a few combinations I get:
28N | 32K = -15C (-30F)
28N | 30K = -25C (-50F)
26N | 32K = -10 C (-20F)
So, for example, for 28N | 32K twisted for a coil temperature of 450 F, one would set the mod temp to 420F
I had to interpolate the Ni 200 values between what I could find from the Ni 200 PDF (above). I used exponential regression as it seemed to fit best but it's not entirely accurate (it was better than linear though).
2. This sheet I created to design coils (select 'Sheet2'). It is very similar to how steam-engine.org works it out. I have input custom wires for the above combinations of Ni 200 and Kanthal based on their 20C (70F) room temperature resistances and diameter based on the sum of their diameters (my approximation for dual twisted wire diameter). This is very useful for working out the surface area and as such the number of wraps to achieve a desired mW/mm2 heat flux.
The values in the sheet as entered are for 28N | 32K twisted. Single coil can push 35W for ~200 mW/mm2 (cool / slightly warm vape). I plan on putting two of these coils in my Cthulhu mod as it seems it will fit (coil height 5.7mm) ID 2.5mm. So, on my snow wolf it should handle up to 70W without limiting (I hope
)
