<HTML><BODY><font size="2">Dear Ehsan<br /><br />some questions for clarification to help understand your model:<br />a) what is "massiv" (your back wall)?<br />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"?<br />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.<br />d) do the air changes (outside air) change with changed opening sizes?<br />e) how large are the air changes befor / after changing the opening sizes?<br />f) do you have a bypass in your stack to allow for downward air flow (night time)?<br /><br />Best<br />Achim<br /><br /></font><p> </p><font size="2">--------- Original-Nachricht --------<br /> Von: "Ehsan Baharvand" <ebaharvand@yahoo.com><br /> An: "esp-r@lists.strath.ac.u! k" <esp-r@lists.strath.ac.uk><br /> Betreff: [esp-r] solar chimney<br /> Datum: 01/04/11 09:05<br /></font> <br /> <div style="font-family: times new roman,new york,times,serif; font-size: 12pt"><div>Dear all,</div> <div> </div> <div> <div><u><strong>Problem</strong></u></div> <div>The free-floating of a solar chimney is simulated and a upward stream due to the solar energy occurs. </div> <div>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. </div> <div> </div> <div> <div><strong><u>Question</u></strong></div> <div>Do I forget something? W! hat can be the problem?</div> <div>I'm certain about the configurations and the Air Flow Network. </div></div></div> <div> </div> <div><strong><u>Model</u></strong></div> <div>The 22 zones solar chimney uses a air flow network and has 2 wind pressure boundary nodes at the inlet and the outlet. </div> <div>Each zone has a separate connection with the outdoors through a air flow network connection, which simulates a opening between glazing panels <strong>meant for infiltration</strong>!</div> <div>The inlet and the outlet areas are connected to the ambient air thourgh a orifice with a Cd of 0.67. </div> <div>Between the cubic thermal zones fictitious surfaces are used. </div> <div>The backwall is a massive construction with adiabatic BC at the surface outside node. </div> <div>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. </div> <div>The chimney is South oriented for a Cl! imate catagory 3A according to Ashrae 90.l. </div> <div> </div> <div><strong><u>Not included</u></strong></div> <div>Wind effect is not included.</div> <div> </div> <div> </div> <div>Kind regards,</div> <div> </div> <div>E. Baharvand </div> <div> </div></div><br /> <br /> <hr /> <br /> _______________________________________________<br /> esp-r mailing list<br /> <a href="mailto:esp-r@lists.strath.ac.uk" class="autolink">esp-r@lists.strath.ac.uk</a><br /> <a href="http://lists.strath.ac.uk/mailman/listinfo/esp-r" target="_blank" class="autolink">http://lists.strath.ac.uk/mailman/listinfo/esp-r</a></BODY></HTML>