Re: [TRNSYS-users] Type666’s stage control

[David BRADLEY <d.bradley@tess-inc.com>]

Wu,
  Type666 models a chiller that can modulate its capacity using internal controls to maintain a steady chilled water outlet temperature. I would think that using the chiller on/off signal would result in the outlet chilled water temperature either being equal to the inlet temperature or being equal to the user-defined chilled water setpoint temperature so long as the chiller has enough capacity to meet the setpoint. Usually when I have seen staged chillers in a project each chiller is able to modulate its capacity internally and multiple chillers are staged sequentially as they reach their respective capacities. I have not run across a chiller that did not have the ability to run at part load so as to maintain a setpoint. If you are looking for a model of a chiller stack that contains multiple variable capacity chillers then I have written such a component. In order to use it you would need to define equations or use a controller component that would decide how many of the chillers should be on at any given time. If you are interested in purchasing the component, please contact me directly and I can estimate the cost.
kind regards,
 David

On 10/28/2015 00:12, 吴伟伟v v wrote:

Dear users,

 

Hi all!

I’m using TRNSYS to model a typical HVAC system,i.e.,chiller( type666) and fan coil(type 508a) combined a building model(type 56). I set a room thermostat(type645) for room temperature control, but I found that the chiller has oscillations which result in chilled water temperature fluctuated strongly  several times even in an hour。My question is as following:

 

1.  Is there any idea to control Type666 to output its cooling capacity as 0.25,0.5,0.75, 1,like stages control?

2.  Should I set more chiller(equally sized) in the model to realize the number of chillers control instead of one chiller? 

 

I did not found the relevant information in the forum. Can someone please help me with this issue?

 

With best wishes

Yours sincerely

Wu weiwei

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David BRADLEY
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