Ahmad,
A few thoughts, not in any particular order:
- The flow rate at which collectors are tested is not always the
flow rate at which the manufacturer recommends that the collector
be operated.
- Some amount of pump chatter (rapid turning on and off) in the
morning is normal.
- Type71 does not consider the thermal mass of the collector so
it can be expected that the model reacts faster than perhaps a
real life collector would. You can look at some of the solar
collector models in the TESS Solar library for versions that do
account for the thermal capacitance of the collector itself.
- A 5C turn-on temperature difference is on the low side. If you
want to reduce the chatter, you can increase the turn-on
temperature difference and allow the collector outlet temperature
to go higher before you turn on the pump.
kind regards,
David
On 05/15/2017 00:58, ahmad abbasian via
TRNSYS-users wrote:
Hello
I'm using an evacoaed tube solar collector (type 71).
the colector efficiency curve, area and test flow rate
is based on a test report. The collector pump is
controlled by a differential controller to be turned on
when th difference of collector inelt and outlet
temperatures is higher than 5 and to be turned off when
it is lower than 2. Based on the area multiplied by test
flow rate, the flow rate of pump could be 375kgr/hour.
But using this flow rate the pump is turned off and
turned on repeatedly, using low flow rate about 100
kgr/hour, the pump works well, but the outlet
temperature is really low.
attached picture named 100 is for using 100kgr/hour
wter flow rate and the other named 375 is for 100kgr/hour wter flow rate. As the
longitudinal IAM data was not in the report, the
default IAM data of trnsys is used.
Please give me your comments to solve
it
Thank you
..............................................................................................
Ahmad abbasianzadeh
Solar energy Researcher
Harrisburg, Pensylvania
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Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
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