[TRNSYS-users] Solar Steam (steam drum) + type 22 iterative controller

Jeff Thornton thornton at tess-inc.com
Mon Sep 16 17:58:26 PDT 2019


The new accumulator model is available in both v17 and a 
soon-to-be-released v18 version.  The only difference is that the v18 
code will contain the handy SSR reporting feature.


Jeff Thornton
President - TESS LLC
3 N. Pinckney Street, Suite 202, Madison WI USA 53703
Office: (608) 274-2577  Fax: (608) 278-1475
E-Mail: thornton at tess-inc.com

On 09/16/2019 3:13 am, Dr D.A.G. Redpath via TRNSYS-users wrote:
> On 2019-09-14 15:52, Jeff Thornton via TRNSYS-users wrote:
>> Jose,
>> Your timing couldn’t be better.  We just finished (literally
>> yesterday), a steam accumulator model that is intended to do exactly
>> as you suggest; store steam in a pressurized vessel for periods of low
>> steam production and higher load.  If you search for STEAM ACCUMULATOR
>> online you’ll be able to see how they work.  The key is you have to
>> store steam at a higher pressure than the load pressure to be able to
>> use the stored steam.  This model will be part of the new TESS
>> Libraries v18 package but can be made available as a stand alone
>> component now if needed.  Let me know and I can get you a quote.
>> As for Type 22, I’ll start with my usual questions when people ask
>> about controls:
>> 1) Are you using a small timestep?
>> 2) Do you have capacitance in your solar loop (pipes etc) to dampen
>> the oscillations?
>> If you do then I’d like to know which collector model you are using?
>> Many of the TESS ones have an option for internal controls where you
>> can set the desired outlet temperature.
>> Jeff - TESS LLC
>> Sent from my iPhone
>>> On Sep 14, 2019, at 8:31 AM, José María Roca via TRNSYS-users 
>>> <trnsys-users at lists.onebuilding.org> wrote:
>>> Hello community,
>>> I’m trying to model solar steam generation and I was wondering if 
>>> there is some kind of storage that could hold steam and saturated 
>>> water, that could act as buffer in case the radiation falls for a 
>>> small gap of time (1h, 2h, etc).
>>> I’m using to generate steam the type 637a HRSG using as hot source 
>>> pressurized water from the solar field. I looked into the flash tank 
>>> but it doesn’t have volume parameters, so this can’t hold steam and 
>>> it works pretty much as the 637. Am I right?
>>> On the other hand regarding the second part of the question, I’m 
>>> using the type22 to modulate the speed of the pump in the solar 
>>> field, to try and keep an outlet temperature at a certain value. The 
>>> problem I’m having is that this controller in some (many) occasions 
>>> goes into “stuck at previous value”, controller status value 17. This 
>>> in turn makes the colector output temperature go to the maximum value 
>>> and no flow goes through the solar field, until some time steps in 
>>> the future it starts working again. I can’t figure out why this 
>>> happens, the only thing I can think is that as the direct radiation 
>>> falls in those time periods perhaps de controller can’t resolve a 
>>> pump flow to keep the temp at the setpoint, but this makes the 
>>> temperture to raise to maximum, seems odd.
>>> Thanks for reading and for any comments.
>>> Best,
>>> José M. Roca
>>> _______________________________________________
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>>> TRNSYS-users at lists.onebuilding.org
>>> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org
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> Hi Jeff,
> Would it be possible to obtain this model for version 17 of TRNSYS?
> I've been working on a steam accumulatoras well but in the process of
> building the component myself. Thanks
> --
> Best Regards,
> David Redpath
> Research Associate,
> Generation Integrated Energy Storage,
> Cambridge University Engineering Department,
> Trumpington Street,
> Cambridge,
> CB2 1PZ,
> UK
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> TRNSYS-users at lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

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