bosco Posted August 1, 2017 Report Posted August 1, 2017 I forgot how nice it is not to require deflector stones. I was helping a buddy install his new big joe the other day and remembered just how much I hated them. I hated the smell and taste dirty stones would impart into my cook so I always foiled them. Removing them to add wood and always worry about them cracking or dropping. So nice to add a small piece of foil and an instant deflector. Someone asked me how this is possible. I really don't know but assume it has to do with the fire to grate distance being greater on a KK then other ceramics. 3
tony b Posted August 1, 2017 Report Posted August 1, 2017 Basically what the foil is doing is blocking the direct infrared radiation from the coals, which is what the stone deflector was also doing. However, the stone, once heated, will radiate heat the same as the walls of the KK, but to a much lower extent than directly from the burning coals. The foil, being very shiny, reflects a lot of radiation and doesn't absorb nearly as much as the ceramic heat deflector (especially a used one that is darker in color). Both also absorb heat via convection (hot air/gasses) and conduction (direct contact with the hot grate), and while the foil is a metal, which transfers heat better than the ceramic, the foil has so much less mass than the stone, that again, the stone will transmit more heat than the foil. 3
bosco Posted August 1, 2017 Author Report Posted August 1, 2017 WOWZA!!! sounds good to me my friend!
tony b Posted August 1, 2017 Report Posted August 1, 2017 Thanks, Bosco. But remember, I am an Engineer after all and heat transfer was my area of specialization. 2
5698k Posted August 1, 2017 Report Posted August 1, 2017 I are a geologist, so inganeerin escaped me quite a bit. The foil will effectively block more heat than the stone?Sent from my iPad using Tapatalk
Pequod Posted August 1, 2017 Report Posted August 1, 2017 1 hour ago, 5698k said: I are a geologist, so inganeerin escaped me quite a bit. The foil will effectively block more heat than the stone? Sent from my iPad using Tapatalk The foil will absorb and therefore re-radiate less heat. For the mathematically inclined, heat transfer from radiation decreases with the square of the distance. So...let's say distance from KK grate to burning fuel is double that of a garden variety (i.e. glazed pot) Kamado. This means that radiative heat transfer in the KK is 1/4 that of ceramic pots. There's still convection, but overall heat transfer will be lower due to the decreased impact of radiation, and re-radiation from a ceramic deflector. 1
tony b Posted August 1, 2017 Report Posted August 1, 2017 1 hour ago, 5698k said: The foil will effectively block more heat than the stone? Not initially, but once you reach equilibrium conditions (stable temperature in the stone), the stone on the lower grate will transfer more heat to the main grate than the foil. Here's a tip about foil. Notice that there is a shiny side and a duller side on aluminum foil. That's on purpose. And most folks probably use it back-asswards. If you are wrapping a pan/casserole, etc. and putting it into the oven, the shiny side of the foil should be facing the food, not the oven, for faster cooking, especially in an electric oven that relies more on radiative heat transfer than a gas oven. It just like light bouncing off a mirror. If the shiny side is facing the heating element, it will reflect more energy away from the food than if the dull side is on the outside of the dish.
CeramicChef Posted August 1, 2017 Report Posted August 1, 2017 (edited) And here I thought that based on the title of this post we would be talking about a shrimp cook! Nothing to add to what @tony b and @Pequod have to say. I always loved the transport sciences even though I am/was a thermodynamicist. We have some classically warped minds here. All the rest of y'all should really rethink the company you're keeping! Edited August 1, 2017 by CeramicChef 2
5698k Posted August 1, 2017 Report Posted August 1, 2017 Like I said...inganeerin escapes me often, that's why I ask questions. Sent from my iPhone using Tapatalk
CeramicChef Posted August 1, 2017 Report Posted August 1, 2017 Heck @5698k, years back I couldn't spell injaneee, today I are one!
Pequod Posted August 1, 2017 Report Posted August 1, 2017 Been a lot of years since I did fluid dynamics and heat transfer for a living. Today, I do my darndest to keep that dark side of my past hidden from my employer, lest they ask me to do it again! 3
tony b Posted August 1, 2017 Report Posted August 1, 2017 1 hour ago, CeramicChef said: We have some classically warped minds here. All the rest of y'all should really rethink the company you're keeping! Preach on, preach on! @Pequod - a very smart plan, indeed! Last year, I "retired" my PE license, so I'm off the hook if anyone wants me to do any engineering work now! 1
Pequod Posted August 2, 2017 Report Posted August 2, 2017 1 hour ago, tony b said: Preach on, preach on! @Pequod - a very smart plan, indeed! Last year, I "retired" my PE license, so I'm off the hook if anyone wants me to do any engineering work now! Well, I'm still an engineer for the next little while, but have moved into more bleeding edge researchy sorts of things. Don't live in the D.C. area for nothin'. Lots of R&D agencies out here. I've just moved away from "rocket science," because it turns out it ain't rocket science! Our mantra back then was "build 'em and burn 'em." If they don't blow up, ship 'em! No technology in that. Much more fun now. 1
CeramicChef Posted August 2, 2017 Report Posted August 2, 2017 Oh come on guys! The transport sciences, mass, heat, and momentum, all use the same forms of the same equations! That's why I liked it so much. Only had to learn one set of equations. And the reason I'm a thermodynamicist is there are only 3 equations to remember. Simple things for simple minds like mine! 1
Pequod Posted August 2, 2017 Report Posted August 2, 2017 4 minutes ago, CeramicChef said: Oh come on guys! The transport sciences, mass, heat, and momentum, all use the same forms of the same equations! That's why I liked it so much. Only had to learn one set of equations. And the reason I'm a thermodynamicist is there are only 3 equations to remember. Simple things for simple minds like mine! And it turns out Maxwell's equations are really just the ideal fluids form of the Navier-Stokes equations, so they apply to electromagnetism as well. I remember skating through an electromagnetism class in college by just treating the entire thing like a class in ideal fluid flow. Aced it until I got to the final, when the first questions was, what are the units for various e/m things. No clue, but it wasn't psi, m/s, or anything I knew about! What was this thread about again? 2
CeramicChef Posted August 2, 2017 Report Posted August 2, 2017 I think it was about a shrimp cook ... 1
Pequod Posted August 2, 2017 Report Posted August 2, 2017 9 hours ago, CeramicChef said: I think it was about a shrimp cook ... I always pictured bosco being on the taller side. Who knew?? 2
Aussie Ora Posted August 2, 2017 Report Posted August 2, 2017 I've used my deflector once .on all my low cooks I just use foil I'm sure there will be a study out there that it's killing me just like the food I'm eating and the drink that goes with it. Lol coming from a kj with the divide and conquer set up I love how the foil has helped me keep this upOutback Kamado Bar and Grill 1
