Recirculation - Components Order

[Edward Halawa <Edward.Halawa@xxxxxxxxxxxx>]

Dear Michael/David/Nathan/TRNSYS users,

I ran a TRNSYS example EX1 residing in
\TRNSYS15\IISiBat3\Data\Samples\Example1\EX1 by removing the control component
(Type 2b) and directly connecting the collector outlet temperature to pump
inlet temperature and pump outlet temperature to collector inlet temperature.
This creates "water recirculation" where the water temperature is expected to
constantly increase when the radiation is available (see Figure below).

     |DATA READER|----->|RAD. PROCESSOR|------>|COLLECTOR|---->|PUMP|----.
                                       |                                 |
                                       |
|
                                        ---------------<----------------

Some of the results relevant to my enquiry are as follows:

RESULTS with Components order: Types: 9a - 16a - 3d - 1b - 24 - 65 - 25b
TIME      SOLS  TCol.In  TPump.Out  QU
0.00    0.00  17.68    17.51       0.0
1.00    0.00  17.51    17.37    -176.16
2.00    0.00  17.37    17.26    -319.25
3.00    0.00  17.26    17.17    -431.83
4.00    0.00  17.17    17.09    -525.99
5.00   24.96  17.09    17.01    -637.17
6.00  237.52  17.01    16.86    -822.38
7.00  833.22  30.22    30.50    -463.09
8.00 2005.91  50.75    51.23     141.17
9.00 3846.33  82.20    83.02    1169.16
etc.

As can be seen, during periods of no solar radiation (SOLS = 0) the inlet
temperature of the collector at TIME = 0 is 17.68 C. The pump outlet at this
step is 17.51 C. At the next time step (TIME = 1.00) the collector inlet
temeprature is 17.51 C which was the pump outlet temperature at previous time.
This "match" between pump outlet temperature and the collector inlet
temperature continues until TIME = 6.00.

Starting from TIME = 7.00 the collector inlet temperature does not match with
the pump outlet temprature at the previous time step.

My first question is: why does this "match" stop after collector receive solar
radiation ?

RESULTS with Components order: Types: 9a - 16a - 1b - 3d - 24 - 65 - 25b
TIME       SOLS  TCol.In  TPump.Out  QU
0.00     0.00  17.77    17.59       0.0
1.00     0.00  17.61    17.61    -201.25
2.00     0.00  17.48    17.48    -367.50
3.00     0.00  17.37    17.37    -501.46
4.00     0.00  17.28    17.28    -615.33
5.00    24.96  17.18    17.18    -744.70
6.00   237.52  17.02    17.02    -946.69
7.00   833.22  30.25    30.54    -590.76
8.00  2005.91  50.69    51.18      19.24
9.00  3846.33  82.07    82.89    1060.59
etc.

With this components order, (collector comes before pump) the collector inlet
temperature is the same as the pump outlet temperature at the same time step
which seems incorrect.

My second question is: which of the above orders correctly represent the
components given in the Figure ? I noticed that every time I make any 
change in
the TRNSYS "workspace" we need to check and correct the "Component Order" 
which
is "distorted" by the change.

Regards,

E. Halawa
Sustainable Energy Centre
University of South Australia
Mawson Lakes SA 5095