<p class="MsoNormal" style="line-height:normal">Dear TRNSYS users, </p>
<p class="MsoNormal" style="line-height:normal"> </p>
<p class="MsoNormal" style="line-height:normal">I am trying to use a Type 919
water heat pump coupled with a Type 997 horizontal ground heat pipe model to
provide heating and cooling to a typical residential building (Type 56) to
optimize its energy usage with GenOpt. This is the initial step toward a bigger
optimization problem. I In doing so, I have some questions about how to design the
optimization study to be consistent with the common design practices also some
questions on details of Type 919 and Type 56. <span style> </span></p>
<p class="MsoNormal" style="line-height:normal">My goal is to optimize the simple
cost of the HVAC system for the house by varying the parameters below: </p>
<p class="MsoListParagraphCxSpFirst" style="line-height:normal"><span style><span style>1.<span style="font:7.0pt "Times New Roman""> </span></span></span>1. Heat
pump heating capacity</p>
<p class="MsoListParagraphCxSpMiddle" style="line-height:normal"><span style><span style>2. 2.<span style="font:7.0pt "Times New Roman""> </span></span></span>Heat
pump cooling capacity (assumed sensible=total) </p>
<p class="MsoListParagraphCxSpMiddle" style="line-height:normal"><span style><span style>3. 3.<span style="font:7.0pt "Times New Roman""> </span></span></span>First
stage heating set point </p>
<p class="MsoListParagraphCxSpMiddle" style="line-height:normal"><span style><span style>4. 4.<span style="font:7.0pt "Times New Roman""> </span></span></span>First
stage cooling set point </p>
<p class="MsoListParagraphCxSpLast" style="line-height:normal"><span style><span style>5. 5.<span style="font:7.0pt "Times New Roman""> </span></span></span>Ground
pipe length</p>
<p class="MsoNormal" style="line-height:normal">I have fixed variables: </p>
<p class="MsoListParagraphCxSpFirst" style="line-height:normal"><span style><span style>1.<span style="font:7.0pt "Times New Roman""> </span></span></span>1. 0.2
$/KW</p>
<p class="MsoListParagraphCxSpMiddle" style="line-height:normal"><span style><span style>2. 2.<span style="font:7.0pt "Times New Roman""> </span></span></span>20
$/meter of pipe installation and equipment cost</p>
<p class="MsoListParagraphCxSpMiddle" style="line-height:normal"><span style><span style>3.<span style="font:7.0pt "Times New Roman""> 3. </span></span></span>800
$/ton of heating/conditioning </p>
<p class="MsoListParagraphCxSpMiddle" style="line-height:normal"><span style><span style>4.<span style="font:7.0pt "Times New Roman""> 4. </span></span></span>20-year
service </p>
<p class="MsoListParagraphCxSpLast" style="line-height:normal"><span style><span style>5.<span style="font:7.0pt "Times New Roman""> </span></span></span>5. Constant
dead band temperature difference of 0.5 C</p>
<p class="MsoNormal" style="line-height:normal"> </p>
<p class="MsoNormal" style="line-height:normal">Questions:</p><p class="MsoNormal" style="line-height:normal"><br></p>
<p class="MsoNormal" style="line-height:normal">1. I was wondering if you would
choose similar optimization parameters? In other words, does this seem reasonable
to assume these parameters and constants to optimize the problem in your
opinion? Are the constant values close to reality in your opinion? </p>
<p class="MsoNormal" style="line-height:normal">I am assuming continuous variable
in GenOpt, with rather coarse step sizes at this time. Here is the list of
initial and step sizes for optimization probelm in GenOpt: </p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Parameter {</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Name<span style>
</span>= Th;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Min<span style>
</span>= 14;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Ini<span style>
</span>= 15;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Max<span style>
</span>= 21;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Step<span style>
</span>= 1;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Type<span style>
</span>= CONTINUOUS;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>}</p>
<p class="MsoNormal" style="line-height:normal"> </p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Parameter {</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Name<span style>
</span>= Tc;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Min<span style>
</span>= 22;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Ini<span style>
</span>= 24;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Max<span style>
</span>= 28;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Step<span style>
</span>= 1;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Type<span style>
</span>= CONTINUOUS;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>}</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span></p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Parameter {</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Name<span style>
</span>= L;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Min<span style>
</span>= 50;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Ini<span style>
</span>= 100;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Max<span style>
</span>= 500;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Step<span style>
</span>= 50;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Type<span style>
</span>= CONTINUOUS;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>}</p>
<p class="MsoNormal" style="line-height:normal"> </p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Parameter {</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Name<span style>
</span>= CapH;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Min<span style>
</span>= 18991.08;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Ini<span style>
</span>= 18991.08;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Max<span style>
</span>= 75964.32;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Step<span style>
</span>= 6330.36;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Type<span style>
</span>= CONTINUOUS;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>}<span style> </span></p>
<p class="MsoNormal" style="line-height:normal"><span style>
</span></p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Parameter {</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Name<span style>
</span>= CapC;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Min<span style>
</span>= 12660.72;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Ini<span style>
</span>= 18991.08;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Max<span style>
</span>= 75964.32;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Step<span style>
</span>= 6330.36;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>Type<span style>
</span>= CONTINUOUS;</p>
<p class="MsoNormal" style="line-height:normal"><span style> </span>}</p>
<p class="MsoNormal" style="line-height:normal"><br></p><p class="MsoNormal" style="line-height:normal">As you can see, I have set the
step capacity values to 6330.36 Kj/hr which is equal to half a ton. </p>
<p class="MsoNormal" style="line-height:normal"><br></p><p class="MsoNormal" style="line-height:normal">2. When a parameter is assigned as
“STRING” in the deck file, the default TRNSYS units will be assumed, right? </p>
<p class="MsoNormal" style="line-height:normal"><br></p><p class="MsoNormal" style="line-height:normal">3. I also have some technical
questions about how to use Type 919 in this optimization. Mainly, I am not sure
how to define the relationship between the heat pump capacities and the
electric consumption power? Does a linear relationship like Powe=a*Capacity make
sense? If yes, where can I find reliable data to make a reasonable assumption about
the value of “a”? </p>
<p class="MsoNormal" style="line-height:normal">I am not sure how the normalized
performance curves handle the inputs? I assume that the curves account for the
effects of four <span style> </span>varying parameters at
least: rated capacity, rated liquid and air flow rates and rated required power.
So, would it be a safe assumption that if I can come up with a reasonable
mapping scheme from rated capacity to power then all I need as input to the
optimization algorithm is the fluid mass flow rate and capacity? I guess my
main problem arises from not understanding how the “Normalized performance curves”
work? I am not also sure if I can keep a constant liquid flow in my model and
only change the capacity and power? Would this be a reasonable assumption that
same rated liquid flow rates can exist for different capacity of the heat pump?
</p>
<p class="MsoNormal" style="line-height:normal"><br></p><p class="MsoNormal" style="line-height:normal">4. My other alternative to optimization
of the heat pump specifications is to come up with a list of heat pumps with
their input variables (capacity, power, air and liquid flow rates, etc…) from manufacturers
(for which I am also soliciting for your comments on how and where to find data,
easily transferable to TRNSYS performance data template) then perform a discrete
optimization scheme that chooses between the available pumps! How about this? </p>
<p class="MsoNormal" style="line-height:normal"> </p>
<p class="MsoNormal" style="line-height:normal">5.<span style> </span>Last but not least, is there a way to introduce
the hourly building loads, humidity rations as well as indoor temperature
values (obtained from a run of the building model w/o HVAC systems-temperature
level control) to Type 919 in a separate file than the .BUI file? I am thinking
of reducing the simulation time by approximating the input values to Type 919 from
the previous time step throughout the year. I understand that the actual indoor
air characteristics will not be modeled this way since the dynamic relationship
between the indoor air and the heat pump will not be “emulated”. First of all,
not sure which type to use to this simplifying assumption? Then, I was
wondering how realistic the substitution of the building model with pre-imposed
load, temperature and humidity values will be? </p>
<p class="MsoNormal" style="line-height:normal"><br></p><p class="MsoNormal" style="line-height:normal">Thank you so much in advance for
taking the time to read and respond. </p>