Author Topic: CoffeeJack: One Million Dollars of Bad Coffee  (Read 1689 times)

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Online dunkemhigh

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Re: CoffeeJack: One Million Dollars of Bad Coffee
« Reply #25 on: January 09, 2020, 07:10:40 pm »
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not espresso

I drink gallons of coffee, but it's all instant so really just flavoured water. So, bearing that in mind...

Isn't the mark of real espresso the foam stuff that floats on the top? If so, surely the clincher for this thing is not how it works but whether that espresso marker exists in the cup at the end. I presume it doesn't (although, personally, I wouldn't really care since it's bound to be more coffee-like than the dishwater I drink :) )
 

Online Cerebus

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Re: CoffeeJack: One Million Dollars of Bad Coffee
« Reply #26 on: January 09, 2020, 08:21:52 pm »
Exactly.

Water is incompressible. So watch the video again, Cerebus.

When you let go of the lever on an espresso machine, the coffee stops coming out, right? It doesn't continuously spew coffee out like diarrhea, once you hit that 10 bars. That coffee leaving is taking the pressure with it. What is your storage medium for all this pressure? A big pressurized air tank? I don't think pressurized air and boiling water are a good mix in chintzy consumer garbage that you operate within arms reach of your face.

This is some kinda hybrid drip coffee maker thing that you can speed up a little to make extra weak coffee (or use 10x as much grounds to start), not espresso.

I'm not arguing for their design, I'm just countering the argument that you couldn't produce 10 bar odd manually without excessive effort. I'd imagine a practical working design would involve an input manual pump, with non-return values before and after, an intermediate chamber of 2-3ml to smooth out the pressure pulses from the pump with a restriction allowing water into the actual brewing chamber to permit flow and provide a pressure drop to 9 bars  - in other words something that looks a lot like the existing group head on most espresso machines.

You seem to be arguing that the old espresso machine that sits in my kitchen can't work - which it does - without some pressure storage mechanism - which it doesn't possess, it's a 'thermoblock' design that uses unpressurised brew water. It's a pump (which by its nature provides pressurization and fluid drive in pulses) some intermediate plumbing (through a heater block), a group head and a portafilter.

Similarly, my shiny new Christmas present to myself, a fancy 'dual boiler' espresso machine has an essentially unpressurised water feed on the brew side and all the water pressure comes from the pump (it has a brew 'boiler' but the set point for this is 93C, below boiling - so no pressure). I know it develops at least 10 barg, because it has an honest to goodness pressure gauge attached to the group head.

The whole point here bring that no stored pressure system is required to brew espresso, just a pump. If you can make that pump work effectively on muscle power you can make a portable espresso machine.

My shiny new dual boiler machine does have a pressure vessel in it, for the steam side of things and that operates at 135C (which equates to about 3 bar) which one can quite safely operate within arm's reach otherwise it would be pointless. Saying that you can't safely use a pressure vessel in consumer equipment smacks of FUD being used to support an unsupportable argument to me.

There's a weird dynamic going on here. I don't think CoffeeJack's design is there yet, it may never be 'there'. But some people, including a slightly hysterical rather self absorbed Thunderfoot, are making this out to be a scam and impossible to achieve "because physics". It's achievable, if it wasn't no extant espresso machine would work. It doesn't need any new physical principles it just needs engineering development.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 


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