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RE: [EnergyPlus_Support] Equipment capacity





The respond from helpdesk:

 

The chiller capacity is sized based on the Sizing:Plant object delta T and the sum of thecoil water flow rate.

Qchiller = rho * sum(coil water flow) * Cp * SizingPlantDeltaT

If you decrease the plant delta T

Sizing:Plant,
Chilled Water Loop, !- Plant or Condenser Loop Name
Cooling, !- Loop Type
6, !- Design Loop Exit Temperature {C}
6; !- Loop Design Temperature Difference {deltaC}

you should see a corresponding decrease in chiller capacity.

Or you could simply change the chiller sizing factor to 0.5

Chiller:Electric:EIR,
Central chiller, !- Name
0.5; !- Sizing Factor


You should also compare the chilled water delta T during the simulation to ensure the sizing inputs represent the actual simulation.

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of jeannieboef@xxxxxxxxx
Sent: Friday, September 13, 2013 19:10
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Cc: <energyplus_support@xxxxxxxxxxxxxxx>
Subject: Re: [EnergyPlus_Support] Equipment capacity

 

 

Sizing is tricky, make no mistake. You can include a sizing oversize factor in the sizing:zone objects. You could also or instead use a global sizing factor with the sizing:parameter object (see documentation). Here is also a sizing interval time which you specify which has a major impact! Further your schedules for other objects should include "sizing"day parts. Very important are that during sizing days in the zone thermostat settings, the zone setpoint remains steady for sizing days, otherwise the equipment will be sized to meet the time interval load step at the setpoint change from setback temperatures to normal setpoint temps. 

Mit freundlichen Grüßen- Sent from my iPhone (excuse the brevity)

 

i. A.

Jean Marais

b.i.g. bechtold

Tel.   +49 30 6706662-23


On 13.09.2013, at 09:32, Artem Zhukov <artem.zhukov@xxxxxxxxxxx> wrote:

 

Please explain me why there is so big difference between Nominal Capacity of the equipment in “All Summary report: Equipment summary” and the maximum Heating Rate [W](Hourly) or Cooling Rate if track it in hourly time steps for the design days.

In my case in the capacities in Equipment summary is almost in 3 times bigger than in Variables.



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