[TRNSYS-users] Difficulty in understanding some parameters in type 919

[Mehdi Shahrestani]

Dear Trnsys users

 

In the supporting documents of ground source heat exchanger (type 919) I
could not find a clear cut definition about some parameters; for instance
number of boreholes in series and number of radial regions.

 

I want to raise it through an example:

 

I have 30 boreholes, in each borehole 1 U-tube. I want to link each 5
boreholes series together. Therefore, there are 6 parallel loops where each
parallel loop includes 5 boreholes. Total flow rate is 30000 kg/hr. 

 

I was wondering if you could give me your comment whether the following
parameters are correct. 

 


Parameter/Input number

Description

Value


Par-4

Number of boreholes

30


Par-6

No. of boreholes in series

5


Par-7

Number of radial regions

5


Par-8

Number of vertical regions

10


Par-11

Negative of u-tubes/bore

-1


Par-19

Reference borehole flow rate

5000


In-2

Inlet flow rate (total)

30000


 

 

 

 

Beside, if it is correct (my understanding on loops arrangement) , it seems
that changing the arrangement (changing number of series boreholes) does not
seriously change the heat exchanger output. Have you ever have such results.
I made different arrangement 2 parallel loop with 15 series borehole, 10
parallel loops with 3 series borehole,.) but the outlet temperature of the
heat exchanger was not significantly different. 

Any comment based on your experiences on using this component would be
highly appreciated. 

 

 

Thanks for your time spending on this issue.

Regards

Mehdi

 

 

 

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