Re: [EnergyPlus_Support] Re: heating mode of ground source heat pump

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Chaoqin:

Here is a response from someone familiar with the GSHP model.

Mike

--------------

My initial thoughts are that the heat pump may be producing lots of 
errors because the fluid temperatures are going outside the usual 
range. You could get an idea of this by looking for high load side 
loop temperatures. This might happen if the ground loop design is 
questionable. What number of borehole did the user actually use? As 
to the UA value, the parameter values in the example are for a 
particular model of heat pump. Check if the number and capacity of 
heat pumps can meet the design load. Increasing the UA value may or 
may not work. Effectively the heat exchanger is increased by the 
compressor is the same. If the user wants to get closer to 48 
boreholes they could try putting three of the 4x4 ground loops in 
parallel. This will not be exactly equivalent as the actual pattern 
(say 6x8) would have a different response. 8x8 should certainly work 
but it also depends on the borehole depth - what is the system 
designed on?  

-----------------------

On 13 May 2003, at 22:55, zhaicq98 wrote:

> I changed the source side heat transfer coefficient from 3998 W/K (I
> got it from the example file) to 5000 W/K, and then the warning msg is
> gone. Now my question is that I have no idea if my new value is a
> reasonable one. 
> 
> In addition, does those warning messages mean that my number or depth
> of boreholes is not big enough to provide required amount of heating?
> 
> Moreover, the LNTTSn, GNFCn given in the datasets folder is for 1*2,
> 4*4 and 8*8 borehole configurations. But I have different number of
> boreholes (48). Could anyone pls tell me how much influence these
> numbers will have on my results?
> 
> Many thanks,
> Chaoqin
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "zhaicq98" <chaoqinz@a...>
> wrote: > Hi, > > I am trying to simulate a ground source heat pump,
> but I am always > getting trouble with the heating mode. I got many
> warning messages > which said the heating mode did not converge with
> disconverge ratio > about 20%. The heat transfer of load side is
> greater than that of > source side. Does anyone have any idea about
> what the problem might > be. The ground source heat pump simulation in
> E+ almost drives me > crazy... :-( > > > Thanks, > Chaoqin
> 
> 
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