<html><head><style type="text/css"></style></head><body><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? What 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 Climate 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></body></html>