Information on peltier cells

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harry ravi
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Information on peltier cells




by harry ravi » 20/03/08, 11:10

I know that this possessed is little used to produce electricity.

I don't want to produce electricity but heat and cold.

imagine a thermoelectric cell

with a difference of 100 ° C at the two welding points, we have 1W / h of product.
But then if I do the opposite (peltier cell)?
If I decide to send 1W / h in this cell, will I have a difference greater than, less than or equal to 100 ° C?

In addition in order to know a theoretical electrical consumption (in watt) of a Peltier cell, I need to relate in a formula:
- the temperature delta between the two welding points
- the peltier coefficient which differs according to the two conductors chosen
- the volume of conductor used (I think it does not act on the voltage but on the amperage)
- electrical power
- the weather

I found a formula:
c = dT / V
with:
- c peltier coefficient
- dT temperature difference
-V voltage

I miss in this formula the volume of conductor, the intensity and the time
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Christophe
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by Christophe » 20/03/08, 11:25

Hi henri :)

1) To produce electricity, this is normal, the yields are extremely low: less than 1% ...

Tests have already been done on forums, see the video here: https://www.econologie.com/forums/thermoelec ... t4884.html

2) In fact you want to use a peltier as it is usually used: ie cooling without moving parts.
In this case the efficiency on the cold is of the order of 20%.

If you send 5W of current, you would have 1W of cold and 4W of hot.

The max temperature detla depends on the module construction, not the power, it is around 60 to 70 ° C according to the pdf curve below.

3) You will find more info here: https://www.econologie.com/forums/post71842.html and in this doc: https://www.econologie.com/effet-peltier ... -3746.html
Last edited by Christophe the 20 / 03 / 08, 12: 18, 2 edited once.
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harry ravi
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by harry ravi » 20/03/08, 11:37

my goal in fact will be to couple a peltier module to several stirlings engines which both work on temperature differences.

the peltier module will supply the temperature delta and the stirlings engines would operate from this delta.

I wanted to know if in theory, this association will be viable.

But for that I need formulas on the peltier modules which takes into account the previous variables.
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by Christophe » 20/03/08, 12:01

Uh and what would provide the current to power the peltier?

If it is striling it sounds like unity your idea :)
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harry ravi
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by harry ravi » 20/03/08, 12:22

yes it will be fine as long as I can have access to the complete formula :P
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by Christophe » 20/03/08, 12:24

Well it's impossible ... even with the complete formula you will not do miracles.

Thermoelectricity makes it possible to recover, at best, a few% of the heat ...

Look at the links given above ...
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harry ravi
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by harry ravi » 20/03/08, 15:41

I make you a Grosomodo peltier cell:

_________.________
| X |
+ | X |
X |
- | X |
| X |
| ________. ________ |

we have our two poles + and -
we have our two solders.
we have our two conductors on either side of the solder.

we will say that the hot weld is that of the top and the cold, that of the bottom.

to mount a stirling on it, we will put it between the two welds in order to use the temperature delta (our X)

we can see that we can't put the stirling on the welds otherwise we will cancel the peltier.

so you have to put it to the left or to the right of the solder and take the same conductive material for the stirling and for the peltier (at least one side)

moreover, this configuration even if it will have to function, does not allow to take advantage of the upper part of the hot weld.

Basically it's not great.
With my configuration, I think we can mount 4 stirlings on a peltier module:

vvvvvvvvvv.aaaaaaaaaa
GO
GO
- % AT
+ vvvvvvvvvv.aaaaaaaaa
- % AT
GO
GO
vvvvvvvvvv.aaaaaaaaaa

v driver 1
V stirling in conductive material 1
driver 2
A conductive material stirlings 2
% electrical insulation
. solders
- electric pole 1
+ electric pole 2

we have 4 stirling on 1.5 peltier module (a hot weld and 2 cold welds) we have to see if it is possible but I think it's good

cold welds will be insufficient to properly cool the stirlings, it will probably add an auxiliary cooling system electrically isolated because already we have 1/4 of the electric power which is transformed into cold and 3/4 into hot, more there is less material provided at the cold welds.


I know it's a bit complicated, I made a little drawing on paper, I will try to provide it to you

EDIT: Have it forum do not like repeating spaces .... I will try to provide you with a drawing soon
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fredchav
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by fredchav » 20/03/08, 20:18

Hi,
I do not entirely agree on the qualification of superunitary, indeed the system can recover the calories from the ambient air.
There is already a project of the same type using heat pumps, stirling engines and alternators.

By cons in view of the performance of a peltier module, it should theoretically not work

Good night

Fred
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harry ravi
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by harry ravi » 20/03/08, 21:17

I am told that a peltier module produces 1/5 cold and 4/5 hot, but in the end we have a yield of 100%

instead of using one face of a peltier module, we could use the 4

in addition, just with the module, we could not cool the cold side of the stirlings enough, so we could use an additional cooling system like air by a system of fins but also by water (river or cell of convection) on condition of electrically isolating the exchange

which means that on X electrical energy supplied, there will be 100% + Y cooling energy

but after I can be wrong, that's why I need this formula to know how much a peltier module of a certain volume consumes to obtain this or that temperature delta.
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harry ravi
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by harry ravi » 20/03/08, 23:14

here is an illustration of what i plan to do

in the worms and blue hues, we have two different conductors forming the thermocouple

these thermocouples are made up of 4 stirling engines

I illustrated a possibility of cooling using a convection field using gravity to allow the circulation of the fluid

we also have our three welds, one hot and two cold

the stirlings engines are beta engines (I would like to include H2 there but it is necessary to solve the concerns of leakage by a good system of joint) which will gather their driving force in only one

so we used 2 faces of the peltier module but we can still use 2 others and create a hollow cube at the level of the hot weld to introduce an energy conservator in order to continue to provide hot energy at night if we uses a solar electric supply.

tell me what you think because for now we only use one side of a peltier module (and then it is clear that the current peltier modules are small modules) .... I would like to use 4 .... there is a heat source, so take it everywhere

EDIT: the purple lines are electrically insulating elements, otherwise the peltier effect cannot produce this

Image
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