Pizza dome

Introduction

Tuscan dome.

• higher dome
• more space above the door opening: holds heat longer
• easier to work with pans etc.
• easier to build

Neapolitan dome.

• more aggressice curve, lower dome.
• more to pizza: gets hotter
• smaller door opening.

Theory

Fornobravo Neapolitan

Interior Diameter	Interior height	Outerior height	Opening Width	Opening Height	Insulation
105 cm	40 cm	66 cm	50 cm	28 cm	10 cm (min)

Base

100 mm insulation. 100 mm iron-concrete. $A=1.7$m². Volume $V=1.7\times 0.1=0.17m^{3}=170\ell$. $S={\sqrt {A+a^{2}}}={\sqrt {1.7+0.57^{2}}}m=1.42$ m.

• 

  Image from the top

• 

  The Octagon base

• 

  The initial layout of the bricks.

Firebricks

Fire brick

• absorbing the heat
• radiating the heat back into the oven.

Usually, a standard (64 x 114 x 230 mm³) brick cut in half will give the shape of the dome.

https://www.k-rauta.fi/kategoria/rakennusmateriaalit/talon-julkisivu/tiilet

• Tulitiili ulkolainen 230x114x65mm
• Tulitiili Terca 230x114x65mm
• Tulitiili Wienerberger 257x123x57mm 324kpl/lava
• Tulitiili ulkolainen 257x123x57mm
• Taloustulitiili 257x123x57 kotimainen
• bauhaus https://www.bauhaus.ee/samottkivi-hart-keramik-250-x-124-x-64-mm.html
• https://www.k-rauta.ee/otsing/?q=terca
• https://www.k-rauta.ee/otsing?q=Keraamiline+tellis+
• https://www.bauhof.ee/et/search?term=tellis&sort=PRICE_ASC

Insulation

Perlite or Vermiculite.

• The bottom: A mixture of perlite/ vermiculite and cement 5:1, small amount of water. Use reinforcing steel.
• The dome: A mixture of perlite/ vermiculite and cement 13:1, small amount of water. About 3 cm on top of the fire blanket (do not compress the blanket). Make multiple layers, minimum of 10 cm.

Aluminium foil:

• reflects the radiation.
• prevents the oven structure from drawing water from the cement mix.

A woven ceramic insulating blanket, such as Fire blanket (or welding planket).

• Use chicken wire to hold it into place.
• Minimum 3 cm layer of insulation.
• Note that the insulation properties are because of the air inside the blanket.

Empty glass bottles. The bottles are covered with sand. The firebricks can be laid directly upon the sand/glass bottle insulation.

See more information at https://pinkbird.org/w/Pizza_oven_insulation

Physics of insulation

The mechanisms of heat transfer are

• Advection: $\phi _{q}=v\rho c_{p}\Delta T$ or ${\frac {\partial \psi }{\partial t}}+\nabla \cdot (\psi {\dot {u}})=0$.
• Conduction (diffusion): Fourier's law, $q=-k\nabla T$.
• Convection: Newton's law of cooling; ${\dot {Q}}=hA(T-F_{f})$
• Radiation: $\phi _{q}=\epsilon \sigma F(T_{a}^{4}-T_{b}^{4})$.

Engineers have four types of thermal coefficients.

• K-value: thermal conductivity
• C-value: thermal conductance; no thickness ($K=C\times {\text{thickness}}$.)
• R-value: thermal resistance
• U-value: thermal transmittance

Heat flux $q$ is the rate of heat flow:

$q=-k{\frac {T_{2}-T_{1}}{L}}$

where $L$ is the thickness. This is to be generalized to The Fourier's law of heat conduction: $q(r,t)=-k\nabla T(r,t)$

Thermal diffusivity $\alpha$ combines thermal conductivity with density and specific heat; $\alpha =k/(\rho c_{p})$.

Thermal conductivity

Substance	k [W/(mK)]	T (°C)	Ref
Air	0.026	25
Styrofoam	0.033	25
Perlite	0.065	25	https://www.engineeringtoolbox.com/perlite-insulation-k-values-d_1173.html
Perlite concrete 1:3			https://www.perlite.org/overview-of-perlite-concrete-2/
Perlite concrete 1:5	0.71		https://www.perlite.org/overview-of-perlite-concrete-2/
Perlite concrete 1:8	0.54		https://www.perlite.org/overview-of-perlite-concrete-2/
Vermiculite
Vermiculite concrete 4:1	0.16		https://www.vermiculite.org/wp-content/uploads/2014/10/Vermiculite-Concrete.pdf
Vermiculite concrete 6:1	0.11		https://www.vermiculite.org/wp-content/uploads/2014/10/Vermiculite-Concrete.pdf
Vermiculite concrete 8:1	0.09		https://www.vermiculite.org/wp-content/uploads/2014/10/Vermiculite-Concrete.pdf
Aluminium foil	162	20	https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
Insulating blanket	0.28	100	https://www.knaufnorthamerica.com/en-us/products/elevated-temperature-insulation/blanket-1000
Mineral wool	0.035	25	https://www.engineeringtoolbox.com/mineral-wool-insulation-k-values-d_815.html

See eg https://booksite.elsevier.com/samplechapters/9780123735881/9780123735881.pdf

The Dome

The thicker the wall is, the more greater the thermal mass is. Note the insulation; insulation should be at least 10 cm.

The first course is usually half bricks cut in half and set upright. Low dome or high dome!

References

https://www.fornobravo.com/pompeii-oven/starting-the-oven-dome/ http://pinkbird.org/images/b/b9/Pompeii_oven_plans.pdf

http://ocean.pinkbird.org/w/How_to_construct_a_pizza_oven_dome_out_of_brick

https://www.contractortalk.com/threads/low-dome-neapolitan-pizza-oven.120794/

https://www.instructables.com/Wood-Fired-Pompeii-Oven/

http://rbwolves.blogspot.com/2011/04/neopolitan-oven-step-by-step.html

https://www.rakentaja.fi/keskustelut/202421/luonnonkivesta_muuraaminen https://keskustelu.suomi24.fi/t/2945473/kesakeittio-luonnonkivikuorella https://www.masinistit.com/keskustelupalsta/viewtopic.php?t=6643 http://megamarketlux.ru/muurattu-grilli-luonnonkivista/