kiln_controller

Connected electric kiln controller -> esp32, max31855, thermocouple type K, relay, contactor and energy meter. Including Kiln built plans.

TODO

• Temperature Ramp rate monitor;
• Cooling monitor;
• Cool upload progress: https://codepen.io/takaneichinose/pen/jOWXBBd

VOID

"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."

Bil of materials

Description	Price
4x Modules enclosure	€8.00
Energy meter with S0 output	€13.00
HDR-15 Power Supply	€13.00
12v/16A Relay	€13.00
esp32	€5.00
max31855	€10.00
Type-K thermocouple	€50.00
Cables, terminals, etc	€10.00

Total: €120.00

Element calculations

Element power

• This is determined by the power outlet, i.e 230Vac@16A -> 3680W

• Some resources indicate 0.6 - 1.3 W/cm2 of wall -> Aw = (30.4 * 30.4 * 2) + (30.4 * 34.2 * 4) = 6,007.04 cm2 therefore Element should be between 3604W and 7800W.

• KMT-614 and Ecotop 20 are both ~20L with 2300W element and rated to Cone 6, aka ~1260°C

Element size

Using Kanthal D - Other variants were hard to find, Kanthal D can be bought at eveks.se

• 1.6mm -> R = 0.67 Ohms/m
• L = ( 3680 / 16^2 ) / 0.67 = ~21.5m

Surface Load

• Accordingly to Kanthal datasheet, kiln application should have a Surface Load between 3-9 W/cm2:

3680 / (2pi x 0.08 x 2150) = **3.4**W/cm2

• furnace handbook page 7 indicates max 2.4W/cm2 @ 1100°C

Coil Diameter

• In order to avoid deformation on horizontal coils, the coild diameter should stay below 10mm accordingly to:

• Therefore let's use a M8 rod to coil the wire.

Coil Length

• The internal element perimeter is ~1216mm, if 3x turns are planned, we end up with a 3648mm coil;

Coil Pitch

Coil pitch is normally 2-4 times the wire diameter page_79 -> aka 2-4mm

s = (11.2 - 8) x pi / sqrt((21500 / 3648) ^ 2 - 1) = ~**2mm**

Bricks

The kils was build with JM23 bricks

Bricks thermal heat loss

PCB

PCB layout and files are found at open it with KiCad

Known Limitations

Credits

Github Shields and Badges created with Shields.io