<html><div style='background-color:'><P>Is there documentation about how these systems are represented in EnergyPro?<BR><BR>Vaibhav Potnis <BR><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma,sans-serif">www.greenbuildingservices.com
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From: <I>"Tara Frentrop" <tstreck@WoodHarbinger.com></I><BR>Reply-To: <I>tstreck@WoodHarbinger.com</I><BR>To: <I><BLDG-SIM@gard.com></I><BR>Subject: <I>[BLDG-SIM] Citi Multi Variable Refrigerant System</I><BR>Date: <I>Wed, 22 Aug 2007 12:28:42 -0700</I><BR><BR>
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<DIV dir=ltr align=left><SPAN class=815212619-22082007><FONT face=Arial color=#0000ff size=2>Dana,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=815212619-22082007><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=815212619-22082007><FONT face=Arial color=#0000ff size=2>A model has been created which can simulate Mitsubishi City Multi. It is called EnergyPro and was developed by Energy Soft. Their web address is:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=815212619-22082007><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=815212619-22082007><FONT face=Arial color=#0000ff size=2><A href="http://www.energysoft.com/">http://www.energysoft.com/</A></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=815212619-22082007><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
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<DIV align=left><FONT face="Palatino Linotype" size=2><STRONG>Tara Frentrop</STRONG></FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2>Mechanical Engineer</FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2>LEED Accredited Professional</FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" color=#800000 size=2><STRONG>Wood Harbinger, Inc.</STRONG></FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" color=#800000 size=2><STRONG>Mechanical/Electrical Engineers</STRONG></FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2>3009 112th Ave NE, Ste 100</FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2>Bellevue, WA 98004-8008</FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2>(425) 822-9499</FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2>(425) 822-4338 Fax</FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" size=2><A title=mailto:tstreck@woodharbinger.com>tstreck@woodharbinger.com</A></FONT></DIV>
<DIV align=left><FONT face="Palatino Linotype" color=#0000ff size=2><U>www.woodharbinger.com</U></FONT></DIV></FONT></DIV></DIV></SPAN></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> BLDG-SIM@gard.com [mailto:BLDG-SIM@gard.com] <B>On Behalf Of </B>Dana Troy<BR><B>Sent:</B> Wednesday, August 22, 2007 11:41 AM<BR><B>To:</B> BLDG-SIM@gard.com<BR><B>Subject:</B> [BLDG-SIM] Citi Multi Variable Refrigerant System<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=195213618-22082007>Hello again,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=195213618-22082007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=195213618-22082007>I recieved some great information from Sam Mason who is an environmental designer at Atelier Ten Consulting Environmental Designers in New York. He researched the City Multi for his Masters. Thank you Sam for your help! </SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=195213618-22082007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=195213618-22082007>Here it is:</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=195213618-22082007></SPAN></FONT> </DIV>
<DIV><FONT size=+0><SPAN class=195213618-22082007>
<P><FONT face=Arial color=#0000ff size=2>Dana,</FONT></P></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>The City Multi was the topic of my master's project and I ran into<SPAN class=195213618-22082007> </SPAN>several </FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>problems trying to the model the system. My conclusion was that</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>using eQUEST, it is not possible to model the system for a few reasons.</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>There is also a lack of information from Mitsubishi that makes modeling</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>tough.</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>First, with regards to each indoor unit, setting a constant EIR (like</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>you mentioned doing) does not allow for the variation in performance due</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>to temperature changes in the space and outdoors. If you look in the</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>engineering manual, there are power and capacity relations for each unit</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>at various temperatures. These corrections need to be incorporated for</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>each indoor unit and this may be possible using ms-dos batch files.</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Second, there is no way to account for the free-energy BC controller</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>operation in terms of refrigerant transferred to/from zones and the</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>effectiveness at which the refrigerant used. Even though the coil loads</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>would be known for each zone from DOE2, the state and temperature of the</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>refrigerant would be needed to figure out how much energy is available</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>fro space conditioning in other zones.</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Third, DOE2 is steady-state modeling software, but this system is hugely</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>dynamic. From my monitoring of the system, I found that the compressor</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>cycles at various frequencies over the course of one minute, thus</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>changing the capacity of the system hundreds of times an hour. Energy</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Plus might be a better tool because it can run at 15 minute intervals.</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Fourth, Mitsubishi does not supply the part load curves for the</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>compressor operation. This means there is no way to accurately model</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>the unloading and part load performance of the compressor. In addition,</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>it is an inverter driven and not a hard start compressor, so the part</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>load performance should be quite good.</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>These systems are going to become</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>more popular and already are in certain areas. I have found one paper</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>referring to a module for energy plus that models these types of</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>systems, but I cannot get a hold of the author. I also know that energy</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>soft has been working on developing a module for their software, but I</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>do not know the status.</FONT></DIV>
<DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><FONT face=Arial color=#0000ff size=2></FONT></FONT></FONT></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Sam</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>--</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Sam Mason</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Environmental Designer</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Atelier Ten</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Consulting Environmental Designers</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>45 East 20th Street, 4th Floor</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>New York, NY 10003</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>T +1 (212) 254-4500</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>F +1 (212) 254-1259</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>E sam.mason@atelierten.com</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2>W www.atelierten.com </FONT></DIV>
<DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff></SPAN></FONT></FONT></FONT></FONT> </DIV>
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<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> BLDG-SIM@gard.com [mailto:BLDG-SIM@gard.com]<B>On Behalf Of </B>Dana Troy<BR><B>Sent:</B> Wednesday, August 22, 2007 8:29 AM<BR><B>To:</B> BLDG-SIM@gard.com<BR><B>Subject:</B> [BLDG-SIM] Citi Multi Variable Refrigerant System<BR><BR></FONT></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2>Hello all,</FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial color=#0000ff size=2><FONT color=#000000>We have recently performed an analysis on</FONT> <FONT color=#000000>a building that is potentially going to incorporate the City Multi system. After many hours of going through eQUEST, I devised a method of modeling it that I would like to run past you all for any thoughts/ideas. </FONT></FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial color=#0000ff size=2><FONT color=#000000></FONT></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial color=#0000ff size=2><FONT color=#000000>First, for those not aware of the problems, here is a <STRONG>background of the systems</STRONG>:</FONT></FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2>The City Multi system consists of essentially three parts: the condenser, the BC controller, and the heat exchanger unit at each zone. Refrigerant is the only property used for heat exchange, i.e. there is no water running from the condenser to the controller to the zone units. Each zone unit is essentially a fan coil, in that there is no compressor work at the zone, only fan energy. The BC controller is essentially a heat exchanger which gives the City Multi system a large advantage by being able to transfer heat, say from the south face of a building, to the north face, which is in the shade. All of the individual zone units connect to the BC controller and the BC controller distributes the refrigerant accordingly. If there is not enough free energy being generated by the system, the compressor kicks in and supplies or rejects heat from the loop to meet the demand. </FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2>To model this in eQUEST, which has been suggested before, the water source heat pump system should be selected in order to account for the free transfer of heat from zone to zone. There are, however, several problems with this. One is that pumping energy is required to pump the water throughout the building. The second problem is that at each zone, each heat pump runs a compression cycle in order to supply or reject heat to or from the zone to the water loop. The third is that a boiler and cooling tower take the place for the condenser in the City Multi system. Each system requires a make-up air unit which can be modeled the same in each simulation.</FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2><STRONG>Now here is what I would like you all to review</STRONG>: </FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007></SPAN><SPAN class=149124914-22082007><FONT face=Arial size=2>These are some of the steps I went to in order to make the water source heat pump as much like the City Multi as possible.</FONT></SPAN></DIV>
<UL>
<LI><SPAN class=149124914-22082007><FONT face=Arial size=2>Made the boiler and electric boiler (to simulate the electric compressor) and gave it the appropriate heating EIR that was specified in the Citi Multi specification manual. <SPAN class=149124914-22082007><FONT face=Arial size=2>I gave the fan the same EIR as the cooling side of the compressor in the same manual.</FONT></SPAN></FONT></SPAN>
<LI><SPAN class=149124914-22082007><FONT face=Arial size=2>I made a spreadsheet to subtract out the pumping energy (only from the water loop! Not the DHW loop!) to simulate the suction of the refrigerant through the building in the City Multi system. I had to do this in the BEPS and the BEPU report which made it kind of a hassle to find the energy cost savings.</FONT></SPAN>
<LI><SPAN class=149124914-22082007><FONT face=Arial size=2>For each heat pump, I set the EIR equal to 0.0001 to simulate the fan coil in the City Multi system. Therefore, whatever heat is transferred to or from the water loop is only shown with the fan energy from blowing the air over the coils. IF this is not a proper way to do it, then what should the EIR be? It cannot be the EIR from the condenser, because that has nothing to do with the free heat transfer energy at the zones. </FONT></SPAN></LI></UL>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2>What do you guys think about this approach? I figure that since this is a tough problem that other people have encountered as well, I might as well use this huge resource that has many great minds to come to a solution. </FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2>Please, any feedback would be greatly appreciated. </FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007></SPAN> </DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial size=2>Regards,<FONT face=Arial size=2></FONT><FONT face=Arial size=2></FONT><FONT face=Arial size=2></FONT>
<DIV><BR><STRONG><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Dana Troy</SPAN></STRONG></DIV>
<DIV><STRONG><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></STRONG><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN><FONT face=Arial size=2>Energy Analyst </FONT><BR><BR><A href="http://www.glumac.com/"><IMG src="http://www.glumac.com/glumacsig.gif" border=0></A> </DIV>
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