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WSHP with single water loop- plant and condenser loop in series

asked 2015-03-23 13:50:34 -0500

updated 2015-07-11 19:07:01 -0500

I am working on a commercial WSHP design modeling that consists of unit WSHPs in different zones hooked up to a boiler and cooling tower in series. A schematic of this system can be found in the link below.

This configuration allows a single closed water loops with bypass around boiler and cooling tower, which is great for circulating the heating/cooling loads from different parts of the building and balancing the demand during the swing seasons. I am wondering if there is a way to directly model this in EnergyPlus? Traditionally, the condenser and plant loop in EnergyPlus do not mix and my understanding is that the plant loop demand side outlet needs to be directly connected to the condenser loop demand inlet for the configuration to be a single closed-loop.

Has any one modeled one of these or has ideas on how to model it?


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answered 2015-03-23 14:24:26 -0500

Archmage gravatar image

I suggest one PlantLoop with component setpoint based operation. There is no longer much difference between CondenserLoop and PlantLoop and you can put a cooling tower on a PlantLoop.

See the input object PlantEquipmentOperation:ComponentSetpoint. The idea is you put the boiler and tower in series on the supply side of the plant loop. Place separate temperature setpoints on the outlet node of boiler and on the outlet node of cooling tower ( using SetpointManager:Scheduled). The loop will run between the boiler's lower bound and the cooling tower's upper bound while serving the WSHP units. A fairly wide temperature range can take of advantage of simultaneous heating and cooling.

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answered 2016-04-26 05:37:43 -0500

Alternatively you can use a PlantLoop with a plant loop demand calculation scheme set to DualSetpointDeadband and then use a Setpoint:Manager:Scheduled:DualSetpoint on the plant outlet node.

This is the way the HVAC:Template:Plant:MixedWaterLoop seems to do it.

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Asked: 2015-03-23 13:50:34 -0500

Seen: 547 times

Last updated: Apr 26 '16