Andrea Bacchi: the Leonardo da Vinci of espresso - Page 4

Want to talk espresso but not sure which forum? If so, this is the right one.
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Lvx

#31: Post by Lvx » Dec 17, 2009, 4:43 pm

Hi Teme,
I'm just the final user, but you are lucky :wink: , i work in a power plant and i've a degree in thermodynamics.
You are right, if we know that Pressure x Volume = K x Temperature , we should imagine that there is a drop pressure when the volume increase.
But.. in the meantime there is an increase in the temperature due to the heater still on (in my case the flame).
I've seen a technical report which says that you have a variable pressure from 9.9 to 9.5 before opening the valve , and during the extraction the machine mantain the 8.5 pressure.
If you want more technical info, i will send you via pm mr. Bacchi email (you can easily find it on the web). :mrgreen:

regards
Lucio
Audaces fortuna iuvat

http://caffettiere.blogspot.com/

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Teme

#32: Post by Teme » Dec 17, 2009, 5:03 pm

Lvx wrote: But.. in the meantime there is an increase in the temperature due to the heater still on (in my case the flame).
I've seen a technical report which says that you have a variable pressure from 9.9 to 9.5 before opening the valve , and during the extraction the machine mantain the 8.5 pressure.
Hi Lucio,

That makes sense, but I (apparently incorrectly) assumed that there would be no way that the temperatrre increase could take place quickly enough to maintain pressure. I guess that would depend on the kind of stove used - gas or induction and you might be ok, but a "regular" electric stove? I guess the small water volume and aluminium construction help here.

Anyway, quite an interesting "machine" albeit fairly impractical (especially for multiple coffees) and slow.

Br,
Teme