Construction of a copper coil heat exchanger

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
dedeleco
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Registration: 16/01/10, 01:19
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by dedeleco » 23/02/12, 22:09

There is no error on the 100 turns if you take 50m, but they probably took less than 50m.

The heat exchanges in water and air are increased and limited by convection and turbulence and determined by the thickness of the laminar boundary layer on the surface left by turbulence, generally a few mm, which means that with the thermal conductivity of the water of 0,6W / (m ° C) we obtain for 1mm = 1m / 1000 of laminar layer water (high speed, small dimensions to have strong turbulence), we have a thermal flux 0,6 , 1000x600 = 2W / (mXNUMX ° C)

But, by weak turbulence at low flow, with 5mm of boundary layer, this flux is reduced to 600/5 = 120W / (m2 ° C).

to encrypt an exchanger comprising:
http://fr.wikipedia.org/wiki/Nombre_de_Nusselt
http://en.wikipedia.org/wiki/Nusselt_number
http://fr.wikipedia.org/wiki/Couche_limite
http://en.wikipedia.org/wiki/Boundary_layer
http://en.wikipedia.org/wiki/Boundary-layer_thickness
http://en.wikipedia.org/wiki/Logarithmi ... f_the_wall
http://fr.wikipedia.org/wiki/Nombre_de_Reynolds
http://en.wikipedia.org/wiki/Reynolds_number
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gyg07
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I discovered econologic
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Registration: 22/02/12, 18:50
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by gyg07 » 24/02/12, 09:45

thanks for that answer and the links. I will therefore reflect on the reverse on the capacity of my recovery balloon in tube length. I therefore orient myself on a narrower coil upwards (a cone) and has almost contiguous turns which will widen going downwards which should give a chimney phenomenon with an acceleration of the warmer water in part central. The arrival of the heat transfer fluid will pass through an insulated central tube so as not to disturb the flow.
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Christophe
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by Christophe » 24/02/12, 17:59

Keeping the value 150 to 200W / ° C.m² is a correct value for a simple coil in self-construction ...

Obtaining a precise value is a matter of modeling or testing ...
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