Coffee Data Science
Thermal Imaging of the Decent Espresso Grouphead
Working through the input of water and heat
The past few months, I have had the deep realization that when brewing espresso, both water and heat are being pushed through the coffee puck. Previously, we treated them as the same, but they are not. Heat can travel faster using metal thermal conductivity compared to coffee, and this can heat the coffee next to the metal faster than the center of the puck.
Channeling caused by the water input must consider initial water flow as well as initial heat flow. To investigate, I used a thermal camera and looked at a few of the components.
Water Input Refresher
Most espresso machines input water into the puck using water inlet, dispenser, diffuser, and shower screen. Some times there are combinations.
For the Decent Espresso machine:
- Water comes in through an inlet into the water dispenser.
- Water exits the water dispenser through 12 outlets into the water diffuser.
- Water spreads out or should spread out in the diffuser and exits to the shower screen.
- Water exits the shower screen into the filter basket.
Thermal Imaging
I used a thermal camera to look at the dispenser first. I flipped it upside down so you could see how both sides look. The metal is not even in thickness which could lead to some heat issues.
Thermal imaging metal even dirty metal can be challenging, which is the main caveat. The images seemed to come out well though.
It showed the unevenness in the heat of the dispenser. So let’s look at the diffuser.
It looks a little more even, but the center clearly has a low temperature spot. There could be issues with the angle of the thermal off of the metal, but I don’t think that can overcome the unevenness in thermal.
This is a piece of the puzzle, and I hope this type of teardown will help others see there are multiple tests to understand how well a machine is built. To Decent’s credit, I haven’t done this for other machines, so these differences in thermal energy could be small relative to competitive espresso machines.
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