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-   -   Any one familiar with how home coffee makers work ? (http://www.cfd-online.com/Forums/lounge/69656-any-one-familiar-how-home-coffee-makers-work.html)

Ahmed October 29, 2009 23:39

Any one familiar with how home coffee makers work ?
 
hot water rises and cold water gets down, is that enough to complete the circulation of water inside a coffee maker?
Do I need to break my coffee maker to see if there is something else or some one could explain that to me
Thanks for reading

nsalpeter November 5, 2009 16:28

To what kind of coffee maker are you referring?

A percolator works differently than a stovetop italian espresso maker, or a drip coffee machine. All of them employ buoyancy principles in some fashion (although the espresso maker actually uses the phase change to create a high pressure steam that is driven through the compacted grinds, up through the tube into the top chamber.)

Ahmed November 6, 2009 07:50

Quote:

Originally Posted by nsalpeter (Post 235261)
To what kind of coffee maker are you referring?

A percolator works differently than a stovetop italian espresso maker, or a drip coffee machine. All of them employ buoyancy principles in some fashion (although the espresso maker actually uses the phase change to create a high pressure steam that is driven through the compacted grinds, up through the tube into the top chamber.)

Hello There
Thanks for reading my post. Now I am confused more than before
1- percolator type.
2- Stove top.
3- drip type.
You introduced new concepts that I was not aware of their use in making coffee, any how, I was referring to a simple home appliance "Mr Coffee model" and I wish you could expand on your answer. Is there a small boiler inside this Coffee maker? this is one question I wanted to ask.

Chromatix February 20, 2010 16:54

A simple and cheap coffee machine will probably be of the drip type, unless it is obviously a percolator.

A percolator uses a semi-continuous convection flow to push the water repeatedly through the grounds, and the coffee is made within the body of the jug. Modern designs typically resemble a standard electric kettle; older ones were to be put on a stove like an ordinary kettle.

A drip coffee machine has an input water tank and a removable output jug, between which is the basket for the grounds. There is no way for coffee to flow back to the input tank, so convection is not the main mechanism here. I'm not sure whether a double phase-change or thermostatically-controlled pumping is the usual mechanism to get water from the tank to the basket, but based on there not being an explicit cooler at the top of mine, I suspect that uses pumping.

Espresso machines are a bit of a dark art, but they do seem to use phase changes.


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