[TRNSYS-users] Help with two parallel ground loop heat exchangers simulation (Borehole and Horizontal Loop)

[Jeff Thornton]

<I got a problem during the simulation. When the heat pump is not in
operation (also the fluid flow rate in both ground loop heat exchangers
are 0), the outlet temperature of the borehole is same as the inlet
temperature of the borehole. But the outlet temperature of the
horizontal loop is lower than the inlet temperature when the fluid flow
rate in the pipe is 0. I cannot understand why there exists a
temperature difference of the horizontal loop when the system is not in
operation.> 

I'm not sure what you're doing wrong without taking a
closer look, but neither the vertical nor horizontal ground heat
exchanger models set the outlet temperature to the inlet temperature
when there is no flow. Both models calculate the fluid temperature in
the pipes and report the temperature as it decays with time towards the
local soil temperature. To check this, run both models with a high inlet
temperature (100 C) and vary the flow on and off each for 24 hours using
a forcing function. You'll notice neither model sets the flow to the
inlet temperature and both models show a decay when the flow is off.


Jeff 

---

Jeff Thornton 

_President - TESS LLC_ 

_22 N. Carroll
Street, Madison WI USA 53703_ 

_Office: (608) 274-2577 Fax: (608)
278-1475_ 

_www.tess-inc.com_ 

_E-Mail: thornton at tess-inc.com_ 

On
08/15/2013 4:35 am, Su Huang wrote: 

> Dear All, 
> 
> Results.jpg 
>

> I did one test with a simple GSHP system, in which one horizontal
loop heat exchanger and vertical borehole heat exchanger connect in
parallel with one water source heat pump. 
> I got a problem during the
simulation. When the heat pump is not in operation (also the fluid flow
rate in both ground loop heat exchangers are 0), the outlet temperature
of the borehole is same as the inlet temperature of the borehole. But
the outlet temperature of the horizontal loop is lower than the inlet
temperature when the fluid flow rate in the pipe is 0. I cannot
understand why there exists a temperature difference of the horizontal
loop when the system is not in operation. 
> Much appreciated if anyone
can help! 
> Many thanks! (Attached is the file). 
> Regards, 
> Su 
>

> -------------------------
> Su Huang 
> 
> Ph.D Candidate in
Sustainable Buildings Research Centre 
> 
> University of Wollongong 
>

> Email: sh377 at uowmail.edu.au [1]
 

Links:
------
[1]
mailto:sh377 at uowmail.edu.au
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