<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> <META content="MSHTML 6.00.2900.3020" name=GENERATOR></HEAD> <BODY> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>Dear Monika,</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>your second approach with an additional zone should work well: </SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>I tried it once and succeeded in holding the supply air temperature as well as the humidity</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>of supply air constant by using a zone-control function for this additional zone upstream ....</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>This additional zone upstream might represent the AHU ....</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>For a constant air flow into your zone I recommend an air flow component of constant mass flow component</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>(because the mass balance is solved and a constant volume component might vary a little bit</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>due to varying density ...) between the ahu-zone and your room zone.</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>Do not forget an air opening towards outside for the air flow of ambient air into your AHU ...</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>If you use only a constant air flow unit (without an AHU-zone) the humidity of the incoming air is the same</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>as at the node the air comes from: In most cases the ambient air humidity .... </SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=083000315-19022007>Gunter</SPAN></FONT></DIV> <BLOCKQUOTE dir=ltr style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px"> <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> esp-r-bounces@lists.strath.ac.uk [mailto:esp-r-bounces@lists.strath.ac.uk]<B>On Behalf Of </B>Hall Monika<BR><B>Sent:</B> Monday, February 19, 2007 3:57 PM<BR><B>To:</B> esp-r@lists.strath.ac.uk<BR><B>Subject:</B> [esp-r] air flow with constant humidity<BR><BR></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007>Dear all,</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007>I would like to control the humidity of an incoming air flow in a zone. My first approach is to control the humidity with the flow network. </SPAN></FONT><FONT face=Arial size=2><SPAN class=587504114-19022007>I took the air network component no 30 "constant volume flow rate component". But this componet allowes only an input of a constant volume flow. Does anyone know on which humidity the air flow is based?</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007>The second approach will be with an additionally zone, which could be humidity controlled and an air flow from this zone to the main zone.  I hope that will work.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007>Had anyone done some work with an air flow with a constant humidity into a zone? How is the best practice?</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007>Thanks a lot for helping me.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=587504114-19022007>Monika</SPAN></FONT></DIV></BLOCKQUOTE></BODY></HTML>