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Hello everybody,

I am trying to model a fully discretized borehole heat exchanger (coaxial). The diameter of the outer ring changes stepwise with the depth. The outer pipe is modeled as a vertical 2D discrete element.

How do I model the change of the diameters of the outer ring? The discrete element representing the smaller diameter is not  underneath the element representing the bigger diameter.  This is because the discrete elements are positioned in the centre of the surplus, the center, of course, differs between the two diameters.

Thanks a lot for your help

Nils Deecke

Hello Everybody,
I want to modell a fully discreted bore hole heat exchanger, and callculate the extracted energy.
So I inject water at a well(s) with a constant temperatur (BC1 (heat) and BC4 (flow)). At another well I withdraw water again (BC1(flow) or BC4(flow)).  On the way between the wells the water gets heated.
How can I callculate the energy the borehole heat exchanger is extracting? So i want feflow to do something like this:

E= Q*T[sub]in[/sub]*C -  Q*T[sub]out[/sub]*C = delta(T)*Q*C

E= Heat (J/d)
Q=discharge (m³/d)
T[sub](in)[/sub]=Temperatur(°K)
T[sub]out[/sub]=Temperature(°K)
C=Heat capacity (J/°K/m³)

This should be possibe with the budget analyzer but how?

Thanks a lot for your answers/comments
special thanks to Mr.Rühaak, your are really helping me with my thesis

regards
Nils

Hallo everybody,
How does the anisotropy factor, for the heat conductivity work?
In which direction do I define the heat conductivity, if I assign a value for the heat conductivity (fluid, solid) in the heat materials menu?
Is it the z-direction (vertical)? And the horizontal (x,y) is calculated by dividing the assigned heat conductivity value by the anisotropy factor?

e.g. I need to model a heat conductivity of 0.1(J/m/s/K) in z-direction( vertical) and a heat conductivity of 10 in x,y-direction,
what values do I have to use for the heat condutivity and for the anisotropy factor?

Thanks a lot for help
Nils

Hallo,

I want to modell a fully discreted coaxial borehole heat exchanger. To model the waterflow in the tube I want to use 1D discrete elements.

Is this a right way to modell this problem?
I connect all nods within the tube (of each slice) with horizontal 1D discrete elements. And I connect all the all  slices of the heat exchanger with vertical 1D discrete elements. I do so for both the pipe-in and the pipe out, just seperated by the pipe wall between. At the bottom of the heat exchanger, where the water changes its flow direction, I connect all the nods of the entire base area with horizontal 1D discrete elements.
Is this the right way? Or should I use just one vertical 1D element with a corresponding hugher diameter?

What kind of wells (4th BC) do I need for the pipe-in (outer part of the coaxial exchanger) and for the pipe out (inner part)?
What diameter do I have to use for the vertical 1D element (if I use an element for each node)?

Thanks a lot for your answers, I also happy with comments or partial answers.

Nils

input of fixed coordinates which are outside the actual desktop view

Hallo
I want to create a superelements whitch dimensions are 10cm * 1km. It is not possible for me to enter the fixed coordinates because the points are outside of the desktop. I also cannot skroll down durring creating the superelement.
What can I do.
Thanks a lot

Nils

Hallo,
Is it possible to model a borehole heat exchanger with varying diameters. eg. the first 100 meters with a diameter of 0.2m and from 100 to 200 m below surface a diameter of 0.15m.
Thanks
Nils Deecke