topbanner.gif
Login
Username

Password




Not a member yet?
Click here to register.

Forgotten your password?
Request a new one here.
Shoutbox
You must login to post a message.

10/26/2021 1:55 AM
Welcome, Ukwoody, liamsmith, timbarnes, SydHagen and GISpoIRiS !

10/25/2021 3:16 PM
MendoEB, Welcome to HRO! Welcome

10/21/2021 2:41 AM
muckymuck, mckinleyharris and williamjonex welcome cup

10/19/2021 6:22 AM
Welcome tarunk!

10/17/2021 12:40 PM
Ploni and nader fouad, Welcome!

In Memory Of Ginny
Donations

Latest Donations
JackH - 25.00
snwcmpr - 10.00
Anonymous - 2.00
Anonymous - 5.00
Anonymous - 5.00
Users Online
Guests Online: 23

Members Online: 0

Total Members: 7,377
Newest Member: Ukwoody

View Thread

Who is here? 1 guest(s)
 Print Thread
Correcting a big mistake!
dBndbit
Many apologies, homeroasters. I need to correct a mistake.

In threads here talking about heat requirements for roasting, I've quoted a figure of 28 watts/lb as a number derived from Michael Sivetz book Coffee Technology. I even put it on my website. I had worked through a table of values he gives for a very large continuous roastmonster, trying to convert between BTUs, joules and watts, and also from a continuous roaster to a fixed profile. And I made two separate stupid mistakes. Only two, you say? I believe I've corrected my mistakes (I hope), and the numbers are much higher.

I believe the Coffee Technology table uses 242 BTUs/lb of green beans, which is 255,000 joules/lb. The watts required depends on the length of the roast profile. A 15 minute roast would require 284 watts. An 11 minute profile would need 387 watts. And these numbers are just the basic requirement to heat only the beans themselves from 80F-380F. Obviously many more watts are needed to keep the oven hot, depending on it's efficiency.

I've been doing more homework on the subject getting ready for my next roaster build. So partly to make up for my mistake, I'm pulling together all the basic info I can find into one paper on heating calculations. Naturally I'll post it and I would be very glad to have buddy-checks on my info and any feedback you guys care to give.

Humbly,
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
seedlings
What were you thinking!?! I mean, shut down the website already!

Just kidding, Jim. You're helpful 600 ways from sunday AND humble to boot.

Now to find something else for my entire life to be about,
CHAD

Grin:):P
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
Koffee Kosmo
I forgive you my forum friend
May the bean be with you Shock

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://forum.hom...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
dBndbit
Thanks guys. But coffee is my whole life!!! If I can't get coffee engineering right,... I'm a failure!

(When you get older you need to keep cranking up your motivation.)
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
John Despres
Ah, Jim, don't sweat it.

See, here's the deal. 'Fessing up makes you all the cooler. Then fixing it is, well, cooler yet.

If it weren't for that little bidding incident a couple months ago, you'd be the coolest. But you'll have to settle for pretty darn cool.

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
dBndbit
John, you've got me all wrong. Do I look like I care about cool? Look at the difference in our hats. Your hat is cool. Mine is... functional. I don't want to feel better, I want my numbers to work. Kind of like how my numbers worked on the bidding incident!!!

(The Zass is a sweet little machine. I use it almost every day just because it's quieter than my Baratza.)
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
seedlings

Quote

dBndbit wrote:
Kind of like how my numbers worked on the bidding incident!!!

(The Zass is a sweet little machine. I use it almost every day just because it's quieter than my Baratza.)



Uh-oh. I'm sitting back, munching popcorn to see how this throwdown pans out.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
John Despres
Not much of a throwdown. I like my Zass as well. A rebuilt one would be cooler, though.

Besides, I want a hat like yours. Mine is about 30 years old, cotton and excellent in the rain, wind and sunshine. The age and sweat stains don't show in the photo very well.

How's the popcorn, CHAD? Pass the bowl over here, willya? Got any root beer?

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
seedlings
Aye!

Popcorn on the Whirly-Pop, lil bit o' sugar and salt for a kettle corn taste, plus, how 'bout a root beer float (IBC root beer & Homemade vanilla with a sprig of mint for color)?

...wish I had some too... and a Zass.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
John Despres
A float? Why, yes. In a huge glass. Cancel the popcorn.

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
greeneggsandsammy
Great numbers! That is super insightful. Thanks for posting!
Jump to Forum:

Similar Threads

Thread Forum Replies Last Post
Correcting Distilled Water Preparing Coffee 18 05/22/2011 8:49 PM
Homeroasters Association Logo, and all Content, Images, and Icons © 2005-2016 Homeroasters Association - Logos are the property of their respective owners.
Powered by PHP-Fusion Copyright © 2021 PHP-Fusion Inc
Released as free software without warranties under GNU Affero GPL v3
Designed with by NetriX