Interpreting low pumps consumption/demand and heat rejection
Hi all,
In my building model, I have a boiler hot water loop and an absorption chiller cold water loop. Cooling is switched off during winter months (JAN-MAR and OCT-DEC) and heating is switched off during summer months (APR-SEP).
How would you interpret low pumps consumption and demand during heating for the months of Jan till Mar and Oct till Dec as per the openstudio results below ? Do they seem logical ?
Also what is heat rejection here referring to ?
Thanks.
Pumps consumption mainly depends on Pump Head[Pa]. What is the Pump Head of your hot water pump and chilled water pump? The type of pumps such as Constant / Variable, Primary / Primary+Secondary, etc. also affects pumps consumption.
Heat Rejection is the fan power consumption of cooling tower.
Thanks Keigo ! Both pumps are variable speed pumps. The hot water pump head is 198043 Pa and the chilled water pump head is 239221 Pa.
Not so much difference. The cause seems to be somewhere else. Did you check the result to see if the chilled water pump was running for 24hours?
What is the best way to check if it is running for 24 hours ? Also considering the pumps results like this, can they be interpreted as logical somehow ? Or this jump from high consumption in the summer to very low in the winter seem to show inconsistency ?
I'm not familiar with Openstudio, but maybe turn on
Pump Electric Powerin Output Variables, selectHourlyoutput, and run the simulation. I don't even know the building type and the weather of your model, but to me, the breakdown of the energy consumption appears to be very unbalanced. Either Interior Lighting and Interior Equipment are too high, or Cooling is too low. I feel like the latter. How about Unmet Hour? Are cooling load and heating load adequately handled?If your plant loop is this one, it has a
HeatExchanger:FluidToFluid. This may not be working properly.I'v done the simulation before with pumps electricity. I have the graph shown here in the link: https://www.dropbox.com/s/hi0zders6s0...
What do you think ?
The building is an office building with East Mediterranean climate (Rainy and mild in winter, hot and sunny in summer). For unmet hours, I have several thermal zones defined, about 83 thermal zones. There are unmet hours for heating and cooling as per each thermal zone.
Ah for the plant loop, I have changed it. I removed the fluid to fluid heat exchanger and left only one pump. See here: https://www.dropbox.com/s/d07vgyowsfr...
Also for the hot loop, see here: https://www.dropbox.com/s/83m5xucegk0...
Around 30MJ is not that big, but it is unnatural that th pump is always ON from May to Sep. If there is no cooling demand at night, the pump should be OFF.
How many hours is Unmet Hour per year for air cooling and heating respectively?
The tables here are summary for the yearly performance: https://www.dropbox.com/s/85cybu9qxg5...
The table shows that No cooling/heating load is handled. I’m sorry, but without looking into your model in detail, it’s difficult to give you further suggestions to solve this critical problem.
Thanks Keigo. Would you like me to provide you with my model separately ? If yes, how can I remove the simulation run in order to decrease the folder size ?
You can just upload your osm file. Or you can export the osm file as IDF file and upload it.
Here is the file: https://www.dropbox.com/s/56r20jpxhh3...
How can I explain such decrease in pumps consumption starting October (which shows very small values) till March, compared to other months ?