[esp-r] Re: solar chimney

[Achim.geissler]

Dear Ehsan

some questions for clarification to help understand your model:
a) what is "massiv" (your back wall)?
b) how long is your pre-simulation period, how long is your simulation
period and what does "temperature does not change" mean? "Not at all" or
"not as much as expected"?
c) what do you mean "wind effect is not included"? An afn takes wind into
account by the cp-value table you must define for external nodes.
d) do the air changes (outside air) change with changed opening sizes?
e) how large are the air changes befor / after changing the opening sizes?
f) do you have a bypass in your stack to allow for downward air flow (night
time)?

Best
Achim



 --------- Original-Nachricht --------
 Von: "Ehsan Baharvand" 
 An: "esp-r at lists.strath.ac.uk" 
 Betreff: [esp-r]  solar chimney
 Datum: 01/04/11 09:05
 
 Dear all,    Problem The free-floating of a solar chimney is simulated and
a upward stream due to the solar energy occurs.  However when increasing the
infiltration (colder ambient air) by increasing the opening area to outside
the backwall inside surface temperature doesn't change!  Other thing is
that the heat load inside the chimney is being removed by the infiltration
air exchange. Eventhough I increase the infiltration air exchange, the heat
load being removed increases, but the surface temperature of the backwall
remains the same.     Question Do I forget something? What can be the
problem? I'm certain about the configurations and the Air Flow Network. 
  Model The 22 zones solar chimney uses a air flow network and has 2 wind
pressure boundary nodes at the inlet and the outlet.  Each zone has a
separate connection with the outdoors through a air flow network connection,
which simulates a opening between glazing panels meant for infiltration! The
inlet and the outlet areas are connected to the ambient air thourgh a
orifice with a Cd of 0.67.  Between the cubic thermal zones fictitious
surfaces are used.  The backwall is a massive construction with adiabatic BC
at the surface outside node.  At 1.8 meter distance from the backwall there
is a glazing surface with a G-value of 0.8 and 80% of glass and it has a
external BC.  The chimney is South oriented for a Climate catagory 3A
according to Ashrae 90.l.    Not included Wind effect is not included.    
Kind regards,   E. Baharvand   
 
  
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