Optimal operation of plant chillers (EnergyPlus)

asked 2017-11-06 01:14:21 -0600

119 ●4

updated 2017-11-06 01:15:49 -0600

Hi! Now i am running a simulation of central plant system equipped with absorption chillers. The supply side has 3 chillers with headerd pump and common pipe. the following is the input parameter of the plant side system. i want each chiller to operate optimally with optimal part load ratio depending on the load(of course when multiple chillers operate, part load ratio could be below optimal PLR). so i expect that 'Pump Operating Pumps Count' should increase from 1 to 2, and from 2 to 3 depending on the load. but Pump Operating Pumps Count increases from 1 to 3 without being counted as 2. how can i control optimally these chillers?

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I have sort of the same issue here. The model I am working on contains 4 chillers with 4 pumps attached to it. I have hard sized the chillers accordingly. But I figured from the results that each of all the 4 pumps gets sized to the overall loop capacity of all 4 chillers. When I tried autosizing the pumps, the model was throwing Fatal errors stating Calculated efficiency higher than 100%. I am using Pump:VariableSpeed and 4 electric chillers. Kindly help me resolve this issue.

MaheshJayachander ( 2020-07-15 02:56:55 -0600 )edit

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answered 2017-11-08 10:31:20 -0600

aparker

8177 ●4 ●18 http://www.openstudio.net/

First, make sure that all chillers are needed by either hard sizing the chillers or setting each chiller's sizing factor to 0.33 (so that each chiller will be sized for 33% of the peak load). If you leave the sizing factor at 1, each chiller will be sized to meet the total cooling load of the PlantLoop, and therefore only 1 chiller will ever be needed.

Second, make sure that the "Number of Pumps in Bank" field in the HeaderedPump object set to 3, based on the assumption that you want 1 pump per chiller.

Third, to get the chiller dispatch working the way you want, check out the Load Distribution Scheme field in the PlantLoop object. Based on your description, I think you want to set this field to "Optimal."

Comments

Thanks for the kind explanation, I wonder that if these solutions (i.e. revise sizing factor, use a headered pump object and load distribution scheme) affect to actuate the pump's mass flow rate by using a BCVTB?