Re: [EnergyPlus_Support] Two systems in one zone

Weili,

ZoneCrossMixing/ZoneMixing objects may help you. Below is the description of ZoneCrossMixing object from InputOutput reference.

"The ZoneCrossMixing syntax is ideally suited for two zones that exchange an equal amount of air between each other and do not have any air exchange with other zones. As with Mixing (ref: Mixing), this is a simplified view of interzone airflow in EnergyPlus. The main difference between Mixing and Cross Mixing is that Cross Mixing has an energy effect on both the source and the receiving zone, thus maintaining both the air mass and energy balances in the two zones.

Cross Mixing can be entered once, in one of the mixing zones; or twice, once for each zone. The object should be entered once if Delta Temperature > 0.0 and it is desirable to have mixing only when the source zone is warmer than the receiving zone. This might be the case when the warmer zone is below the colder zone and the mixing is buoyancy driven. If the zones are next to each other, separated by an open doorway, it would be more suitable to input a cross mixing object for each zone. Then mixing would occur if the zone temperatures differed by Delta Temperature or greater regardless of which is the warmer zone.

If Delta Temperature = 0.0, Cross Mixing can be entered either once or twice: the effect is

exactly the same."

On Fri, Jun 20, 2014 at 8:02 AM, weilix88@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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Dear all,

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I am trying to model HVAC systems for a group of thermal zones, which each of them is designed to have two separate systems.

The main system is traditional VAV system with reheats. The cooling and heating coils are connecting to central chilled water loop and hot water loop respectively.

The other system is air-cooled package system using direct expansion coils. The air-cooled package systems are used as supplementary cooling sources for those zones.

Since EnergyPlus doesn't allow multiple air terminals in one zone, I think I have to play some tricks in order to model this type of system combinations. Currently I think about building an air wall (created in designbuilder) between these two zones, and put traditional VAV system in one zone and air-cooled package system in the other zone. (since these two zones are adjacent) However, the question for this strategy is, for example,if the VAV zone is too hot, but air-cooled package zone is controlled well, would the air-cooled package zone provide more cooling to cool the VAV zone down to desired level through conduction?Â

Also, if I want to build ventilation between these two zones, which module should I look into in EnergyPlus?
If you have better solutions or suggestions for modeling this HVAC design, it will be much appreciated as well!!

Thank you!

Weili