Construction of a copper coil heat exchanger

[Christophe]

Oula ...

1) Owen, physics is not a "belief" well not on these forums !

A heat exchanger is not dimensioned with a ladle ... if Tigger tells you that he put 25m in 3/4 dishes 6m if it amuses you and you will see the results ...

2) The dimensioning of an exchanger depends on 3 main parameters (in addition to others that I neglect):

a) the exchange surface
b) the difference in T ° between the 2 "fluids" (I put "" because the fluid can be a solid, the air is a gas but which can be considered as a fluid in the heat exchanges),
c) the conductivity of the material used (copper generally but also aluminum)

3) Martian no ...

The volume of 25m by 22mm is ridiculous:
section: 2.2² * 3.14 / 4 = 3,8 cm²
length: 2500cm

Total volume: 3,8 * 2500/1000 = 9.5 L ...
Or less than 1% of the volume of the buffer ...

At the surface level this exchanger at: 2,2 * 3,14 * 2500 = 17270 cm² or 1,73 m².

In addition you are doubly wrong because this volume of water contained in the exchanger when the circulator does not turn ... also contributes to thermal storage!

4) The plate heat exchanger is not a good solution in my opinion because it requires the management of a 2nd circuit with, at least, a circulator to manage ... short + complicated = + trouble ...

5) I will search some dimensioning formulas but basically you can compare the area needed to that of a 5kW aluminum radiator .... With a known delta, say, 40 ° C, these formulas will allow you to know which exchange surface you need.

But you should know that in heat exchange it is like driving: the theory has its limits and it only allows to have an idea of ​​reality (but the theory of heat transfers sticks more to reality than that motors). In addition, the theory is very complex.

[Christophe]

It's been an hour that I take my head with precise calculations that lead to nothing for the simple problem that we face.
For those who want to have fun: http://www.librecours.org/documents/8/899.pdf

Here is a very simplified approach:
http://fr.wikipedia.org/wiki/Transfert_ ... _thermique

By browsing the net a bit I found that a copper exchanger had a real K varying from 400 to 800 W / m². ° C (if there are specialists in the room ... average values ​​depending on the form of the exchanger would be interesting)!

Consider 400, the worst case, with a T ° delta of 10 ° C, the tigger exchanger would therefore have a power of:

P = 400 * 10 * 1,73 = 6,9 kW

So Owen, you would need an exchanger of more than 1.5m² of exchange surface.

With 22mm Copper this gives a length of at least: 21,4 m far from the 6m that you "thought" ...

But we are stupid: so look at the surface of the tubes of your solar panels ... by taking the same you will not be far from what you need in your buffer ...

Tigger how did you size your streamer?

[owen]

Martian raises the idea of ​​sizing 25 m of copper.

If not, did any of you build your heat exchangers and what are your tube sizes?

[loop]

Hello

Tigger's coil looks efficient

Otherwise you can download this spreadsheet available on Apper

http://forum.apper-solaire.org/download.php?id=12

Attention, the delta T is the difference between the heat transfer fluid which circulates in the coil and the liquid contained in the balloon

For my 1500L buffer I will start on 50 m of copper D22 ep 1

A+

[Christophe]

I haven't built, but we have this in our buffer, the surface of which must be several dozen m²!



Cf: https://www.econologie.com/forums/tampon-the ... t4517.html

[loop]

Calculation of the exchanger coil as a function of the collector area

http://forum.apper-solaire.org/download.php?id=14

A+

[Christophe]

Information

Sorry, but you are not authorized to view or download this file

Same looping!

Don't you want to put them on the ecp host ecp?

[loop]

OK

I'm watching this tonight after work

A+

[owen]

When I look at your Christophe heat exchanger, it looks like car radiators.

[Christophe]

Yes it looks like but in fact they are batteries from (large) air conditioning units. They are 3 m long, 30 cm wide and about 1 m high.

The new unit price must tate the 5000 € (I suppose they are therefore of recovery?).