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Originally Posted by ham789
Very nice work.
Which is the Solid PP core and which is distanced????
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Maybe I did not explained it properly.
The Solid PP is the one with no distance between the sheets.
You can see it on
this picture.
The distanced is the one with the PP sticks glued on both sides and center (the first pictures I posted).
Quote:
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How are you measuring efficiency?
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I used the following formula:
Efficiency (%)= (T4-T1) / (T3-T1)x100 where,
T1 is the external fresh air coming into the HX
T3 is the internal stale air coming into the HX (extracted from the house)
T4 is the internal fresh air getting out of the HX (pulled into the house)
Now, the first time I made the measurements I got as follows:
Aluminum core: 83,7%
PP solid core: 88,2%
PP distanced core: 78%
I then tried the dual core solution excluding the PP distanced core:
Aluminium dual core: 97,6%
PP solid dual core: 99,2%
Hybrid (aluminium - PP solid) dual core: 87%
But, I repeat, I had really small fans that means that air moves slowly into the HXs and it has more time to exchange heat.
Calculating the temperatures of my
previous post using the ultimate version of the HRV (aluminum and PP solid dual core, at least double size than previous but with 220V fans) I have 81,1% efficiency.
Quote:
Dual core rates quite the same, but allows much more air to pass trough.
The last dual core photo was a combination of PP and aluminum cores, same results (but that was quite obvious..)
I'm confused by that paragraph.
Two equal cores in series should have twice the resistance
to air flow. If e is the efficiency of one core, I'd expect
n cores in series to be something like 1-(1-e)^n...but it's
too early in the morning to try to prove that.
What am I missing?
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Maybe I was wrong about that last statement.
The numbers above prove that the dual core configuration has better performance as it offers double exchanging surface.
The resistance to air flow can be solved increasing the fan speed, but more resistance means also more turbulence, hence more heat exchange.
At least that's what I understand by observing the data.
I'm going to do some more measurements these days and try to be more precise.