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Optimal operation of plant chillers (EnergyPlus)

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

joooon's avatar

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

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

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."

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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?

dana's avatar dana  ( 2018-02-26 22:43:45 -0600 )edit

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

Seen: 450 times

Last updated: Nov 08 '17