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Silvia heats up and cools down
This test was to measure the heating and cooling cycles
of Silvia. The intention was to start with a cold Silvia, but there was a small
mistake with the data logging and after the repair the test was continued
already with a warm Silvia:
The picture shows clearly, how Silvia repeats the same
cycle. It was a small surprise that there was such a big lag with the maximum
measurement and the heating disconnection. The red dots show the temperatures,
where the element was shut down around 112 degC, but the surface temperature
keeps increasing for 10 degrees and one minute. Which shows the lag of the
measurement due to the thick wall of the boiler. At the disconnection point the
temperature increases almost a degC per second.
However, at the minimum point there is almost no
lag at all. The changes in temperature are now so slow (one degC per 45..50
s). The minimum value and the conncetion of the element took place almost
simultaneously.
Lookin closer the several cooling curves, one can
notice that they are almost identical and one could estimate the temperature
change:
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The middle column is the time from the maximum
point and the right column from the disconnection of the element.
A bit similar results are presented in
this test, although it is not quite clear, which column should
be compared. |
Simply put, 104 degC is achieved six
minutes after the maximum pointa (or seven minutes from the shut off). This
could be a good starting point to reversed temperature syrfing, but it does
not take into account all the use that is needed for brewing coffee
The lag has no essential effect to a PID control, as
the controller is used to keep a constant temperature for the boiler before the
brew. Normally, the changes in temperature usually are small at this stage.
Measurement reports
Heating and cooling testing
Blank Shot testing
Single shot testing
Temperature measurements - main page |