Geothermal heating

[Externet]

Ian:
That is called heliostat:
http://www.egis.org/Helio_us.html<p>Reading some irradiation figures, I found a 1.85 KW/m² for full solar spectrum (not only visible light). That is meaningful !<p>Oh, boy, if I had one of those freebie dishes...

[Externet]

A little better figures...<p>The solar radiation, averaging only the coldest 6 months, comes to 23 Mjoules each 24 hour day per every square meter at latitude 40°N. [from tables]<p>1 Kcalorie is 4185 Joules<p>23 MJoules in 24 hours is 5495 Kcalories <p>5495 Kcalories in one day can raise 1°C to 5495 litres of water
Or, can raise 50°C to 110 litres of water <p>A 4m² antenna dish (~8'Ø) can raise 4x110= 440 litres of water 50°C in one day. (That is 116 gallons of water raised about 90°F - two 55 gal. drums)<p>That amount of hot water in holding tanks should be capable of heating a not lossy house 24 hours trough a fanned radiator and provide hot water consumption.<p>The hotter 6 months of the year can provide excessive hot water consumption as no space heating is needed, the collector would have to be turned off most of the day.<p>Not bad, I think... maybe not much for a mansion, but...<p>Now about losses... ¿Wouldn't the losses be heat loss? If the heat losses happen inside the home, it would not be exactly losses, as they would be doing exactly heating, right?<p>About efficiency... well, there is clouds; figures would have to be derated to 70%?<p>Miguel

[peter-f]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by sofaspud:
What is that last statement again? The hour hand will exactly follow the sun, from sunrise to sunset?? You have 6 hour days there in Bieber?
For most clocks, the hour hand makes two revolutions for each revolution of the Earth.<p>[ May 08, 2005: Message edited by: sofaspud ]<hr></blockquote><p>OK, Sofa... he's exaggerating a bit!
Your (analog) wristwatch also serves as a crude compass... using the Hour hand. <p>OK.. it's no GPS... but it's not a slave to military satillites, either! And you probably carry the equipment with you.
But you do need the sun to do this. Or knowledge of its position behind the clouds.<p>Interested? - follow these instructions:<p>Look toward the sun.
Align the hour hand to point AWAY from the sun (if the axis of the watch hands was a pole, its shadow should fall onto the hour hand)
Now.. from the axis to 12 o'clock position is aligned (roughly) to the north. <p>(and now we can find Ian!)<p>Hope I helped... you should learn something every day. And have FUN doing it.

[sofaspud]

Only interested enough to find this procedure on several websites:
Determine direction using the watch method without a compass.
a. Point the hour hand at the sun when you are north of the equator. South will be halfway between the hour hand and 12 o'clock.
b. Point 12 o'clock at the sun when you are south of the equator. North will be halfway between the hour hand and 12 o'clock.
As an experienced outdoorsman, if I were lost in the wilderness military satellite slavery would be the furthest thing from my mind.

[ian]

Externet, did you get your radiation values based on no atmosphere? Because atmospheres is the biggest variable when calculating solar radiation.<p>Secondly, you have to discount for angles, if you're reflecting the sun at a 45 degree angle isn't that a 50% loss right there?<p>What about the reflectivity of a window? What are your losses for that?

[Externet]

Ian:
Those figures are for atmospheric, zero altitude tables. There is other tables for orbital irradiation.<p>For parabolic concentrators on tracking, there is no lossy angles. The parabola axis is always aiming the sun.<p>Reflectivity of a window? What are you talking about? Heliostats? I am talking about parabolic water heaters for space heating.<p>The amount of heat collected by those 4m² may not be enough for the coldest days, but it will be enough for the less cold ones.<p>--->Should we start another thread for non-geothermal, just solar heating ? <---edited<p>Miguel <p>[ May 11, 2005: Message edited by: Externet ]</p>

[Chris Smith]

Peter-f
I guess you have never seen a 24 hour clock?
Oh well? <p>It rotates much like the earth, actually, it rotates exactly like the earth. <p>Oh well?
*****************
And personally I like the cornerstone mirror configuration, self tracking and no need for movement of the collector or dish.<p>[ May 12, 2005: Message edited by: Chris Smith ]</p>

[peter-f]

Chris-
I'm not (!) disputing you... Sofaspud was challenging that it could be done so simply... <p>While I agree it can, I was a bit wrong on procedure. Seemed it always worked for me, though. I never had a critical need for the trick, so off by 20 degrees was always good enough for my uses.<p>BTW... still works with late-hour sunsets (summer months), and works better when ignoring politics (i.e., daylight savings time).

[peter-f]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Externet:
Ian:
That is called heliostat:
http://www.egis.org/Helio_us.html<p>Reading some irradiation figures, I found a 1.85 KW/m² for full solar spectrum (not only visible light). That is meaningful !<p>Oh, boy, if I had one of those freebie dishes... <hr></blockquote><p>Sheesh! seems its as expensive as a solar panel installation.. and it's just a reflective surface!<p>Something's wrong with this marketing plan.

[sofaspud]

Ya know, I have no desire for longwinded debates on this, nor personality clashes. Or even "gee, I'm so smart" ego trips. I consider this a classroom where everyone can be both student and teacher. That said... and this said:
>I guess you have never seen a 24 hour clock?
>Oh well?
>It rotates much like the earth, actually, it rotates exactly like the earth.
>
>Oh well?
The length of day, from sunrise to sunset, changes throughout the year. This is a well-known occurrence. And it's a fact that makes clockhand/sun synchronization an impossibility.
Oh well, not literally impossible. The hour hand of the 24-hour clock can track the sun correctly 2 days out of 365, on each equinox.
Of course a 24 hour day and 24 hour clock are synchronized. That's the purpose; it's not the refuted claim.<p>[ May 12, 2005: Message edited by: sofaspud ]<p>[ May 12, 2005: Message edited by: sofaspud ]</p>

[Externet]

Peter:
The intention of the link was to show ian what he asked about.
I did not look for quotations; but it's easy to believe it is another major ripoff for a tracking mirror.
Something is very wrong with too many marketing plans; too many trying to become rich in the shortest time doing the least work by hoping to find wealthy naive customers.
Miguel

[ian]

Hey Miguel, ok, it's a tracker but what about realistic losses???<p>Can you really get all the heat from the dish into the water? I think you would lose 75% of the heat right at the collector. <p>Here in Canada a device like that is very impractical because you have to heat the whole line from the barrel to the collector. No matter how well insulated you'd lose all your heat in the line and the collector/exchange unit.

[Externet]

Hi.<p>Losses, yes, they are very real, I would say mainly from wind hitting the uninsulated "boiler" chamber at the parabola focus. I guess losses would not be beyond 10% if that much.<p>The "boiler" chamber would have several hundreds of degrees temperature, and water flow trough it would need to be fast enough to avoid boiling... and maybe melting the focus chamber.<p>For the underground insulated pipes running towards the dwelling, losses should not be something of consideration. Unless the parabola be 60 metres away.<p>If the parabola is on the roof, losses on the pipes are negligible as they enter the dwelling shortly.<p>Heating the pipe ? Yes, sure, it may take a minute to heat it, depends on the water mass flow.
Just as your water heater heats up the pipes from the tank to your shower head.<p>That heat loss for your shower head pipes is not actually a loss, contributes to warm your home.<p>This heating system is something that am firmly determined to implement some day.<p>As Chris says, the cost for the dish can be zero, and the NEW prices found on the net are:<p>http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 84180&rd=1<p>----quite low.<p>Miguel