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<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><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>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<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 NOSEND="1"></A> </DIV>
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Washington, Suite 200</SPAN><BR><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">Portland,
OR 97204-2640</SPAN><BR><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">T.
503.227.5280<SPAN style="mso-spacerun: yes"> </SPAN>F.
503.274.7674</SPAN></DIV>
<DIV><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">D.
503.345.6286<BR><BR><STRONG><SPAN
style="FONT-SIZE: 10pt; COLOR: #333333; FONT-FAMILY: Arial">Thinking. Inside
the building.</SPAN></STRONG><BR><STRONG><SPAN
style="FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #333333; FONT-FAMILY: Arial"><A
href="http://www.glumac.com/">www.glumac.com</A></SPAN></STRONG></SPAN>
</DIV></FONT></SPAN></DIV>
<DIV><SPAN class=149124914-22082007><FONT face=Arial
size=2></FONT></SPAN> </DIV><PRE>
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