Water for the coffee is suctioned in from an external container. Since the system needed to be transportable, a permanent water supply was out of the question.
At this stage, let's examine how the PC coffee machine works. Since the system doesn't have a fixed water supply, a pump suctions water from a container outside the case. The pressure doesn't rise above 5 bars, as can be clearly seen in the video. With a fixed water supply, an increase to 10 bars would be quite imaginable, and using thinner hoses would also increase the pressure.
The kettle is capable of heating water to 205° Fahrenheit (96° Celsius) although the optimal temperature for brewing coffee is between 176°F and 183°F (80°C to 84°C). Higher temperatures don't present a technical problem, but they burn the coffee, making it taste bitter.
While the water heats, the coffee beans for each cup are drawn from the holding container into the grinder. After the coffee grounds are tamped, the pressurized water is piped into the brewing unit, from which the finished coffee starts to flow. Note that during the brewing process we detected a power input of 3,000 watts, which was close to the critical value of the electrical fuse!
René G.'s system is configured to allow eight different products to be programmed. Several attributes can be adjusted, including the amount of coffee and water, the tamping pressure, and whether or not the coffee grounds should be moistened prior to brewing.