Homeroasters - Home Roasting Coffee Community » BUILDING A ROASTER » Fluidbed Roaster
Who is here? 1 guest(s)
 Print Thread
Cooling the beans in the roasting chamber?
Motmot
Top  #1 Print Post
Posted on 08/23/2021 12:56 AM
Quick question :
Is it possible to cool the beans directly in the roasting chamber?

I understand that there is some disadvantages :
- The RC is still hot and it can continue to transfer the heat to the beans;
- If you roast a batch afterward, your RC is now cold;
- If you roast a batch afterward, your need to wait for the RC to be free of the cooling beans before roasting again.

Side question :
What's the difference between cooling the beans on a perforated plate VS in a tumbling high volume of air?

Thanks!
 
renatoa
Top  #2 Print Post
Posted on 08/23/2021 1:50 AM
Yes, possible if your air system provides a serious airflow margin.
If your air system works all the time above 70%, then probably not a good candidate as a cooling machine.
If you finish the roast with air at 50%, then a fast cooling is possible.
The cool time will tell you how effective is the cooling, if you can keep the beans in hand (50-60C pain skin test) after 3 minutes, for me is ok.

I would not worry about the other worries in your list... if beans are at 50C when dumped, then glass is at 70C or above, high enough to start a new roast immediately, FB does not require a high temperature preheat, energy is in the air, not in the walls.

Even the perforated plate means high volume of air flowing around beans, sucked by a pump through the holes.
 
Motmot
Top  #3 Print Post
Posted on 08/23/2021 3:18 AM
Thanks!

I'm planning to build a FB roaster and I'm wondering if it's worth the trouble to build a "traditional" bean cooler or if I just turn off the heat and wait 3 minutes.

I'll probably try directly in the roasting chamber first.
 
greencardigan
Top  #4 Print Post
Posted on 08/24/2021 8:27 PM
I have always cooled in the roast chamber in both my 300g and 1kg roaster.

Both my roast chambers are quite light weight and don't hold a lot of heat. I can cool 1kg to < 100C in < 3 minutes
 
JETROASTER
Top  #5 Print Post
Posted on 08/25/2021 11:25 AM
Hello,
Fluid Bed makes this easy. They typically have less thermal mass. I cool 5 Kilos in 4 minutes.
Have fun -Scott
 
mcudogs
Top  #6 Print Post
Posted on 08/28/2021 6:38 AM
Hi,
I've built several 0.5kg drum roasters that are similar to the Behmor design and have always cooled the beans using an electric garden blower while in the mesh roasting drum. I just open the door and turn on the blower aiming at the middle of the drum while its still turning. The bean temperature drops down to 50c in about 90 seconds.
 
renatoa
Top  #7 Print Post
Posted on 08/28/2021 7:09 AM
And the chaff ?! Shock
 
mcudogs
Top  #8 Print Post
Posted on 08/29/2021 4:31 AM

Quote

renatoa wrote:

And the chaff ?! Shock


I've got a cyclone setup beside the oven that picks up the chaff. The drum has larger holes each end that allow chaff to escape during roasting. The oven is powered from a 2200 watt fan forced oven element with fan so there is a lot of air flow to help the chaff escape the drum. The chaff seemed to collect at the front left of the oven so I connected the cyclone inlet through the oven wall at that point. It does a pretty good job and there is very little chaff left by the time I turn on the blower.
 
koffeegrounds
Top  #9 Print Post
Posted on 09/15/2021 10:10 PM
i would not recommend cooling off in the roast chamber most fluidbed roasters have a fair amount of residual heat
 
progen
Top  #10 Print Post
Posted on 10/08/2021 10:34 AM

Quote

koffeegrounds wrote:

i would not recommend cooling off in the roast chamber most fluidbed roasters have a fair amount of residual heat


Can you name the parts of a fluid bedder's roast chamber which might retain so much heat that beans inside cannot cool down when the heating element is off? Grin

The reason why fluid bedders are often described as being 'agile' is because the moment the heating element is throttled, the incoming air temperature drops immediately. So what do you think the air temperature is when you turn off the heating element completely?

Furthermore, I'm speaking from the point of view of someone living in the tropics. I'm sure those of you in temperate countries will have ambient temperatures somewhere in the low 20s which makes it even easier to cool beans.
 
progen
Top  #11 Print Post
Posted on 10/08/2021 10:38 AM

Quote

mcudogs wrote:

Hi,
I've built several 0.5kg drum roasters that are similar to the Behmor design and have always cooled the beans using an electric garden blower while in the mesh roasting drum. I just open the door and turn on the blower aiming at the middle of the drum while its still turning. The bean temperature drops down to 50c in about 90 seconds.


I bragged about fast cooling in a Facebook fluid bed group and was brought down to earth by someone linking to an article which stated that the ideal cooling time was somewhere around 3.5 minutes. I can't find that link right now since that post was somewhere in April this year but try hunting around for articles on cooling. It did make sense because that fast cooled batch which I was bragging about tasted bland compared to later batches which I cooled on an external cooling tray at 20% speed and completed at 40%. I speed up the fan after the beans had cooled down for the sake of chaff removal.

Perhaps you might say that your coffee tastes alright even with such fast cooling but try dragging the cooling time to around 3 minutes and see whether they taste better. You can't lose anything, can you?
 
renatoa
Top  #12 Print Post
Posted on 10/08/2021 3:14 PM
I am playing right now with a chinese clone of FreshRoast and the cooling is the fastest I experimented ever: 90 seconds for 50 C degrees, on BT sensor, and also hand test, I can keep beans in hand for more than five seconds, which means they are somewhere in the 48-55 C ballpark.

Curiously, the most heat accumulation part is the chaff collector, much hotter than the beans, even after three minutes I can't hold in hand for long time. Is made from a Bakelite style plastic, judging by the smell.
The glass is inbetween, can be touch after about two minutes.
 
progen
Top  #13 Print Post
Posted on 10/09/2021 12:19 PM
Here's the post by the way about cooling beans too quickly.

https://www.faceb...4581324494
 
Jump to Forum: