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Dear TRNSYS users,
Hi,
I am trying to model a Variable air volume (VAV) system to meet the building’s HVAC loads (heating and cooling loads) by taking into account the mutual dependence of the air flows and air temperatures.
As you know, Type 151 existed in TRNSYS library is used to model a VAV system. However, regarding Type 151 is an energy rate control device, I am wondering whether it is possible to use this component (Type 151) in conjunction with TRNFlow.
I would be very thankful for your answer.
Kind regards,
Ali
Ali,
I think the answer depends a bit on what you are trying to calculate with TRNFlow. If you are using it to compute the building's infiltration then I think you can use it in conjunction with the VAV Type.
If you are using TRNFlow for interzonal air flows then you have to be a little bit more cautious. The idea of energy rate control is that you precalculate the heating and cooling requirements for a particular part of the building and then you treat those loads by imposing them on an HVAC system. If there is interzonal air flow then those flows need to be known ahead of time because they are part of the loads on the spaces. In reality, the state of two VAV boxes in adjacent parts of a building will have an impact on each other but energy rate control is an idealization and assumes that once you know the load, then each VAV box meets its load and what one VAV box is doing doesn't add more load to another. I suppose my point boils down to...even if you can couple an energy rate control VAV component with TRNFLow (for interzonal air transfers) I am not sure that it would be thermally valid to do so. Unfortunately, I am not aware of any temperature level control VAV components.
David
