Solar distiller showdown

Today, Thursday, December 12, 2019, in Perth, Western Australia, latitude 31 degrees in the Southern Hemisphere, it is mid-summer. The prediction for today is 40 deg C (104 Fahrenheit) and sunny. I decided it is time for a showdown, a "shootout" between the F-Cubed Carocell 1000, my tilted wicking-type prototype #4, and my simple basin-type prototype #2.

There were individual tests done on these:

https://bkhome.org/news/201906/testing-f-cubed-carocell-1000-solar-distiller.html

https://bkhome.org/news/201911/solar-distiller-prototype-4-first-test.html

https://bkhome.org/news/201912/testing-basin-type-solar-distiller-prototype-2.html

In those tests, I published comparative efficiency figures, however, they were based on tests taken at different times of the year, different weather conditions, and also some figures published by the F-Cubed company.

The only way to accurately compare them is to test them together. Which I have done today.

I started putting them out in my backyard about 7.00am. A gusty breeze. They are in the shade of my garage, but that is only a temporary situation. This photo shows the shading:

...which does put the F-Cubed panel at a disadvantage, however, none of them were producing any output at this time, and the shade rapidly disappeared. By 8.00am, there was just a bit of shade in the bottom corner of the F-Cubed panel.

One good thing, the placement, and being mid-summer, avoids the afternoon shade from the patio, so I was able to run the test until late afternoon.

There was some haziness in the sky, which persisted for most of the day, though still got fairly high sun intensity readings -- but perhaps, the distilled water output might not be quite as high as if the sky was clear blue.

Here are the tabulated readings. The "Top" temperature measurements are taken with the IR meter, held about 3 inches above the glass, about 3/4 of the way up. Ambient readings were obtained by pointing the IR meter into the patio.

Time am/pm	Sun W/m2	Amb. degC	Top, degC C1000, wick, basin			Comments
8.00	840	26.5	30.7	29.1	25.7	No water o/p yet
9.00	900	29.4	50.3	44.5	40.1	Official: 28degC, 23km/h
10.00	950	30.8	63.3	54.8	53.8	Official: 31degC, 21km/h
11.00	910	34.1	70.2	62.5	64.1	Official: 34degC, 26km/h
12.30	750	36.4	66.8	61.9	70.7	Problem with C1000 panel
1.00	1005	37.2	66.8	61.9	70.7	C1000 almost recovered
2.20	965	37.0	66.0	62.3	73.4	Official: 38degC at 2.00pm
3.15	960	36.8	65.8	59.1	71.0
4.00	950	36.0	58.9	53.2	65.5	Official: 39degC, 16km/h
5.00	855	36.6	45	46.8	56.8	Official: 39degC, 18km/h

The test was stopped at 5.45pm.

There was a problem around midday with the C1000 panel. I had reduced the water inlet flow, by turning the tap from the water container to nearly off. This was because I thought too much water was flowing through the still. I probably should have just lowered the water container to reduce the head. Anyway, at 12.30pm discovered that most of the wicking cloth had gone dry.

This is a bad situation, as it can take awhile for the cloth to wet right through again. When dry, water tends to run over the surface, instead of seeping into the cloth. Anyway, it recovered fairly quickly, and the cloth looked Ok by about 1.00pm. It will be expected that this will reduce the distilled water output.

Notice also the sun irradiance (intensity) was only 750 watts per metre-squared. This was due to increased haziness in the sky around midday.

Here are the results, the accumulated distilled water output for the day:

	C1000	Wick	Basin
Tally (litres)	5.32	1.27	1.86
Normalized (litres/m2)	5.32	3.817	5.314

There was only 5.32 litres from the C1000 panel, I would have expected about 6 litres. This test will have to be repeated, probably tomorrow.

The table shows the simple-basin-type giving almost as much output as the C1000, and even higher than the previous test of 1.85 litres (see previous test link at top of this page). That previous test was a hotter day, and higher sun intensity -- so how come I got an extra 0.01 litres today?

In the previous test of the basin-type, the distiller was sitting on a small picnic table, same today, but I placed a 12mm thick sheet of MDF on the table, so there was more insulation, which is known to be an important factor for efficiency.

Note, the distillers were not moved all day. They were oriented facing due North.

My tilted wicking-type distiller gave very poor performance. It is now eliminated. Though, will probably include it in tomorrow's showdown, since it is setup. 

Tags: nomad