Description

"Solar heater system for domestics waters"

1.Historical framing

Since some year ago, I began to become interested t>y the use of solar energy to heat domestic water.

So I started to sell same Portuguese solar heater systems that were available in the Portuguese market.

The low performance of those systems, make ours clients to began disappointed, because electric energy (supplementary energy for this systems) consume was high.

So tried to find outland solutions that could be more efficient.

All that work was inutile because those systems had almost the same performance.

Since then, I really would like to do something to develop those kinds of systems, to my clients became satisfied.

After thinking of the problem, arise some ideas.

The results were amazing.

The high performance is the result of association between panels, as well as a utilization of a high stratification reservoir (which the cold water that enter does not miss with the warm water that goes to consume, and just after the first 150 litres are sufficiently warm is when it start to heat the others 150 litres) .

So, we obtain a much better performance that implies water much more warm for the same solar radiation.

From now on, I'm gone explain how does the others solar heater systems works, and then I will confront wi_ th my system.

2.Th.e way that the others solar heater systems work

The solar heaters Kits to get domestic water warm are composed by a primary circuit, which has fifteen litres on an average .

This circuit works just with the gravity force and by density water alteration, because of temperature variation.

So, in case of solar radiation, the water in the primary circuit is constantly doing the course from the panels to reservoir (where happens ttie heat transference to the consume water) and then from the reservoir to the panels.

In the others Kits (See fig.l), the water course in the primairy circuit is: a) The water less warm that had just gone out of reservoir goes down by an exterior tube, out of the heater zone (Fig. 4, number 1) and by that fact causes same performance wastes. b) When the water comes into the panels, and supposing that each panel has two metros height and one width, will go four metros long inside the heater zone (See fig.4).

So, whichever is the watercourse inside the tubes, it will go thorough two metros outs ide the heater zone and four metros inside the two panels. c) The water when returns to reservoir, transfer all the heat for just one reservoir witch means that in case of low solar radiation days, ttxe temperature water raise in all reservoir is not enough to any kind of warm water use. d) By the fact of the others solar heater Kits has just one reser-voir, the consume cold water that enter will directly mix with the warm water: that goes out, that is a very unfavourable mix.

3. The way tha t our solar hea ttsr system work

In our system the primary circuit course is completely different ( See fig . 3 to understand) a) The main question is to know how possibJLe is the water go down, after gone out of t he reservoir, i f it is in tti ie heater zone and so wants to go up .

That is possible because of the stopper (See fig . 2 , &-£\' cut) .

So, in each panel of 10 tubes _r in nine tubes the water power that is imposed when wants to go up is enough to happens a sucking irx the other tube , whe re the water even warming up _±s going down. . b) Because there are no connections between panels in the inferior side ( See fig . 2 ) , tine water is forced to enter r±n the second panel in the superior side . c) So tine course of this primary circuit is 10 metros long inside the heater zone, really bigger than the four metros of the others systems ( See fig .3 ) .

And by ttist fact the water d_n our primary circuit is much more warm. d) The reservoir has two permuting in distinct reservoi.es ( See fig. 2 ) .

So the water that comes from the panels ancl enter in first permuting will start warming ixp the consume water in the Ie=Et reservoir _r and so when the water enters j_ nto the second permuting (that is in the rignt reservoir) , it ' s already with a temperature much inferior (minim consume water temperaturrre of the lefft reservoir) .

So, foxr example, if the water arrives at the first permuting with 80 ° degrees temperature, may cause a consume water temperature of 50 ° degrees in the superrior side of tine reservoir and 30 degrees in the inferior side ( for that happens time heat transfer was already too much) , and then tine primary circuit water that arrives to the othier permuting rLs no much more then 30 degrees and so wil 1 not warm tap significantly the consume wate x of the right reservoir .

As long" as the consume water temperaturre of the Ie=Et reservoir grows , more will Joe the heat trransfer for ttie second res ervoir .

So, if we already have 7 O ° degrees temperature in tine superior side of the first reservoir arid 50° degrees temperatuire in the inferior s ide, the primar- y circuit water that arrives to the second permuting is already with 5C ° degrees axid continues warming up the consume water of tine second res ervoir .

e) The cold consume water that enters in thie right reservoir (the reservoir that has less warm water) "will not directly mix with the hot water that goes to consume (goes out ff rom the left reservoir) (See fig.2) ,. and by that fact does-n't provoke big temperatures breaks between the water that ojoes to consume and the cold consume water that enters. f) The consume water that goes from the rright reservoir to the left reservoir is still forced to go to the bottom, of left reservoir with the same objective, tϊiat is retard how far is possible ttie "contact" between the consume water that enters and the one that goes out .

So, for example, if the consume water enters with 15° degrees temperatunre, it might gjrow up for 35° in the first reservoir and then in the second reservoir can grows from 35° to 50° degrees triat implies there are not a thermal "shock" between the consiαme water that enter and the one that goes out .