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

[José María Roca]

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