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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">It’s a little unclear from this thread if the original post is asking about decreasing the tower DESIGN approach (i.e. evaluating a different tower design),
or decreasing the approach of some given tower DURING OPERATION via the control settings of the condenser water temperature.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">In eQUEST, and I think in the tower design world, the “approach” is a design parameter, not just a control parameter.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The post says “the tower” has a 44 kW fan in both cases. But typically for the same heat rejection, to achieve a closer approach requires either the same physical
tower with a “bigger fan” (more air through the tower, often just by higher rpm) and higher fan rated fan kW, or a bigger physical tower with that higher airflow, but lower velocities and dP, to achieve the same RATED fan kW.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">One can separately set the condenser water loop temperature
<b>setpoint</b> (in eQ, that’s the tower leaving temperature, aka chiller entering condenser water temperature) or setpoint strategies so any given tower attempts to achieve less than the design approach during some or most hours. That will increase tower fan
energy, but will decrease compressor energy in attached systems. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Fred<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Fred Porter, BEMP, LEED</span></b><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">©</span></b><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">
AP<o:p></o:p></span></b></p>
<p class="MsoNormal" style="margin-bottom:2.0pt"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#7F7F7F">Principal Engineer<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:2.0pt"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#7F7F7F">Sustainability Services<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#005DAA">NORESCO<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Bldg-sim [mailto:bldg-sim-bounces@lists.onebuilding.org]
<b>On Behalf Of </b>Peters, Judith M via Bldg-sim<br>
<b>Sent:</b> Monday, June 19, 2017 10:26 AM<br>
<b>To:</b> Danielle Bond; Dan Nall<br>
<b>Cc:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [External] Re: [Bldg-sim] Cooling Tower Approach<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Dan and Danielle,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thank you for your excellent comments. The results make more sense to me now.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks again,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Judy<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#0D0D0D">Judy Peters, PE LEED-AP BEMP<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#0D0D0D">Energy Modeling Engineer<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#0D0D0D">Daikin Applied<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#0D0D0D">763.553.5155<o:p></o:p></span></p>
<p class="MsoNormal"><u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:blue"><a href="mailto:judith.peters@daikinapplied.com">judith.peters@daikinapplied.com</a></span></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#0D0D0D">
| <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.daikinapplied.com_&d=DwMGaQ&c=ilBQI1lupc9Y65XwNblLtw&r=3xdcdPfNRiIRbdcNOFLTvgBFEa2F6BAz_UMLqgqXn6k&m=wTrSz7jpELLIQueGCv4m5qWPPYVpheqlLap10Y7IxFI&s=RqZ_dsCG6N2XAQg73o0GaqqM1jQyKJ_Qv1Hddny9rz4&e=">
www.DaikinApplied.com</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Danielle Bond [<a href="mailto:danielle@ecapnet.com">mailto:danielle@ecapnet.com</a>]
<br>
<b>Sent:</b> Monday, June 19, 2017 11:07 AM<br>
<b>To:</b> Dan Nall<br>
<b>Cc:</b> Peters, Judith M; <a href="mailto:bldg-sim@lists.onebuilding.org">bldg-sim@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Bldg-sim] Cooling Tower Approach<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">In general, a smaller approach means the cooling tower is more efficiently rejecting heat, i.e. better performance. This overview is pretty good: </span><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__spxcooling.com_pdf_TR-2D016.pdf&d=DwMGaQ&c=ilBQI1lupc9Y65XwNblLtw&r=3xdcdPfNRiIRbdcNOFLTvgBFEa2F6BAz_UMLqgqXn6k&m=wTrSz7jpELLIQueGCv4m5qWPPYVpheqlLap10Y7IxFI&s=EOHIMO4Z2p9zDaAx0ZYENGgubrMSmdHJWFO-YrhG5cA&e=" target="_blank"><span style="font-size:9.5pt">http://spxcooling.com/pdf/TR-016.pdf</span></a><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:9.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">Best,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">Danielle<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">Danielle Bond, Ph.D.<o:p></o:p></p>
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<p class="MsoNormal">Energy Engineer, <span style="font-size:9.5pt">eCap Network</span><o:p></o:p></p>
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<p class="MsoNormal"><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.ecapnet.com_&d=DwMGaQ&c=ilBQI1lupc9Y65XwNblLtw&r=3xdcdPfNRiIRbdcNOFLTvgBFEa2F6BAz_UMLqgqXn6k&m=wTrSz7jpELLIQueGCv4m5qWPPYVpheqlLap10Y7IxFI&s=syhTrCg01_YaMQf7Uo9XhfZ4YGadvTsY5FRO-tQK1oA&e=" target="_blank">http://www.ecapnet.com/</a><o:p></o:p></p>
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<p class="MsoNormal">On Mon, Jun 19, 2017 at 11:50 AM, Dan Nall via Bldg-sim <<a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">If you input a tower with a lower approach but with the same fan power, you would wind up with less annual fan energy consumption,
because your fan with the lower approach temperature would hit the minimum condenser water temperature at a higher wet-bulb temperature, allowing the fan to back off more hours of the year. <o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span class="gmail-"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">-----Original Message-----
</span></span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"><br>
<span class="gmail-">From: "Peters, Judith M via Bldg-sim" </span><br>
<span class="gmail-">Sent: Jun 19, 2017 11:13 AM </span><br>
<span class="gmail-">To: "<a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a>"
</span><br>
<span class="gmail-">Subject: [Bldg-sim] Cooling Tower Approach </span></span><span class="gmail-"><o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black">I am looking for tips on how to properly compare tower approach temps. Currently, I am comparing a 7 F approach with a 5 F approach. The tower has 4
cells with 44 kW fan energy for each cell and a 10 F range. </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black">Regardless of control parameters, the program shows less tower energy for a smaller approach and I was expecting the opposite.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black">Can anyone shed some light on this issue?<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black">Thank you!<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="color:#0D0D0D">Judy Peters, PE LEED-AP BEMP</span></b><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#0D0D0D">Energy Modeling Engineer</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="color:#0D0D0D">Daikin Applied</span></b><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#0D0D0D"><a href="tel:(763)%20553-5155" target="_blank">763.553.5155</a></span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><u><span style="color:blue"><a href="mailto:judith.peters@daikinapplied.com" target="_blank">judith.peters@daikinapplied.com</a></span></u><span style="color:#0D0D0D"> |
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www.DaikinApplied.com</a></span><span style="color:black"><o:p></o:p></span></p>
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