Scace Thermofilter Temperature Device - Page 9

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barry

#81: Post by barry »

Abe Carmeli wrote:In practice, the two methods produce different results. Temp variation within a shot is different, and also average brew temperature. Just as an example, in a few comparisons I did, thermofilter reported temp variation from 10th second on which was twice as large as one measured with coffee. Highest temp reached in the shot on dual boiler was also higher by ~ 1 f.
i'm still not clear about what you're trying to measure. if you know, and accept, that coffee grounds will attenuate the indicated brew temperature, then i don't understand why you have resistance to the data generated by the thermofilter. think of measuring in the coffee as watching a movie (or sunset, or whatever) with sunglasses on; think of measuring with the thermofilter as watching the same thing with sunglasses removed. or think of plato's allegory of the cave....

Abe Carmeli
Team HB

#82: Post by Abe Carmeli »

HB wrote: It would be a welcome bonus if a coffee puck simulation accurately modelled a thermodynamic reality, but I would still taste the coffee before I'd believe it.
Yes Maan. I'm widja. Here's the thing: I think with experimentation, one can come up with a formula that will give us that value, without changing anything with the Thermofilter. It will take some time to do all those tests, but it is doable. Greg may be able to run some numbers and come up with an approximation of what the formula would look like. Say: If average thermofilter reading is 203, brew temp with coffee will be 202. If variation within shot is 2 f, with coffee it is 1f, etc.
Abe Carmeli

Abe Carmeli
Team HB

#83: Post by Abe Carmeli »

barry wrote: i'm still not clear about what you're trying to measure. if you know, and accept, that coffee grounds will attenuate the indicated brew temperature, then i don't understand why you have resistance to the data generated by the thermofilter.
What I want to know is by how much it will attenuate. I don't want to live in the Matrix. Let's get the simulation as close as possible to a real shot.
Abe Carmeli

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barry

#84: Post by barry replying to Abe Carmeli »

then you need to know the temperature of the coffee grounds for each shot and the temperature gradient of those grounds from top to bottom and from outside to inside. further, you need to know the amount of heat radiating from the showerscreen, and from the portafilter & basket. you need to know the space between the bottom of the showerscreen and the top of the grounds. you need to know the time between pf insertion and the start of brewing. you'll need to account for heat loss of the wave front as it travels through the puck, and you'll have to account for soluble and non-soluble solids transfer to the effluent.

if you want to know how much the coffee attenuates the brew water, then just measure the temp of the effluent at the underside of the brew basket. this is what some manufacturers do and then claim "stability". it's pretty meaningless.

Abe Carmeli
Team HB

#85: Post by Abe Carmeli »

barry wrote:
then you need to know the temperature of the coffee grounds for each shot and the temperature gradient of those grounds from top to bottom and from outside to inside. further, you need to know the amount of heat radiating from the shower screen, and from the portafilter & basket. you need to know the space between the bottom of the shower screen and the top of the grounds. you need to know the time between pf insertion and the start of brewing. you'll need to account for heat loss of the wave front as it travels through the puck, and you'll have to account for soluble and non-soluble solids transfer to the effluent.

if you want to know how much the coffee attenuates the brew water, then just measure the temp of the effluent at the underside of the brew basket. this is what some manufacturers do and then claim "stability". it's pretty meaningless.
I don't think I need to know all that. There is no need to make it more complicated than it is. A simple test logging & comparing 50 shots of the Thermofilter against 50 of real coffee with the T/C in it on a PID'ed machine will give me a fair idea of the deviation between the two. All I want is a formula, I'm not sending it to space.
Abe Carmeli

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barry

#86: Post by barry »

Abe Carmeli wrote:A simple test logging & comparing 50 shots of the Thermofilter against 50 of real coffee with the T/C in it on a PID'ed machine will give me a fair idea of the deviation between the two. All I want is a formula, I'm not sending it to space.

and what does this tell you that a thermofilter measurement alone doesn't? are you just looking for an adjustment factor you can apply to a tc/coffee measurement so you don't have to use a thermofilter? "hey everybody, don't bother with the thermofilter, just take your plain ol' thermocouple reading and multiply by 5, divide by 9, and add 32, and you'll get the same results!"


--barry "if it was that easy, don't you think we would have done that?"

Abe Carmeli
Team HB

#87: Post by Abe Carmeli »

barry wrote: are you just looking for an adjustment factor you can apply to a tc/coffee measurement so you don't have to use a thermofilter?
It's the other way around mister. I'm trying to get rid of the Pain in the Yass T/C in the coffee puck and use the Thermofilter instead.

<< Edited to be less obnoxious >>
Abe Carmeli

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barry

#88: Post by barry »

Abe Carmeli wrote: It's the other way around mister. I'm trying to get rid of the Pain in the Yass T/C in the coffee puck and use the Thermofilter instead. I'm wondering how many more times I'll need to repeat this.

it's hard to repeat something you haven't said.


if you want to use the thermofilter instead, then why do you need to know how the results from it translate to the other method? just use the thermofilter. easy.

i'm not trying to be difficult, i'm just trying to figure out what information you're really after and whether it is useful information and why (or why not).

Abe Carmeli
Team HB

#89: Post by Abe Carmeli »

barry wrote: then you need to know the temperature of the coffee grounds for each shot and the temperature gradient of those grounds from top to bottom and from outside to inside. further, you need to know the amount of heat radiating from the shower screen, and from the portafilter & basket. you need to know the space between the bottom of the shower screen and the top of the grounds. you need to know the time between pf insertion and the start of brewing. you'll need to account for heat loss of the wave front as it travels through the puck, and you'll have to account for soluble and non-soluble solids transfer to the effluent.
I don't think I need to know all that. A simple test logging & comparing 50 shots of the Thermofilter against 50 of real coffee with the T/C in it on a PID'ed machine will give me a fair idea of the deviation between the two. All I want is a formula.
Abe Carmeli

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barry

#90: Post by barry »

Abe Carmeli wrote:We are experiencing a classic example of a failure to communicate here. I will take my leave now.
i just went back and reread the entire thread. the only point i can see which might have lead to the confusion was when you used the phrase "measuring a real shot". i took that as you wanted the thermofilter to mimic the thermal performance of pulling a shot through coffee. what i think you might have meant, and what i didn't get until now, was you want the results from the thermofilter readings to better duplicate the results you get from using a tc on top of the puck during a real shot.

if that is the case, then once again i have to ask, why? why do you want the thermofilter to mimic the results of a method which has known flaws? sure, the thermofilter isn't a perfect measurement tool, but it's better than the tc on top of the puck. so, why do you want muted data? sure, a .8F variation is better than a 1.6F variation, but only if it really happens and isn't just an artifact of the measurement method. if you get .8F with a cold portafilter and 1.6F with a hot one, then the .8F doesn't really happen, it's an artifact of flawed methodology. if you get .8F variance using a tc on top of the puck, and 1.6F with the thermofilter, then the tc results are due to flaws in the procedure. if it was the other way 'round, and you got 1.6F on the puck, and .8F with the thermofilter, then i would be worried about the thermofilter performance.

to give you another example, i used to use a 1/4" probe in my roaster as a bean temp probe. i logged lots of data and looked at lots of curves. one thing which always bugged me was the turning point on my roaster (the shift from decreasing bean temp to increasing bean temp) was well over 2 minutes, when most experts i'd talked with said the turning point should occur around 90 seconds. hmmm... i was convinced my roaster was radically underpowered. a while back, i put in a couple of more probes, and decided all the probes in the roaster should be of the same type/size, so i replaced the 1/4" probe with a 1/8" probe. guess what? my turning point shifted to just over 90 seconds. so, did my roaster suddenly gain power? no, of course not. the thermal mass of the probe decreased, so the system lag was reduced. if i stuck a bare wire bead probe in there, the turning point might change yet again. so, the problem wasn't with the roaster, but with the measurement system.

so, back to espresso. we know the coffee grounds suck heat from the brew water. we know that how much suckage occurs depends upon a number of factors i've previously listed. if we're trying to measure/track/log machine brew water thermal performance, then minimizing/reducing/eliminating that suckage will give more accurate results; it will better reflect what the coffee encounters initially, prior to the suckage. if your suckage rate is relatively constant, then knowing the initial conditions is what is needed. if you want to know how much suckage occurs, then put a probe on top of the puck and at the bottom of the puck and measure away! :) (but it still won't tell you how well your machine performs)