[TRNSYS-users] Type 158 - Unstable temperatures

[thornton at tess-inc.com]

On 2022-08-30 03:12, Adrian Riebel Brummer via TRNSYS-users wrote:

> I have a question about Type 158 (vertical constant-volume storage
> tank without immersed heat exchangers).
> 
> I want to know if Type 158 uses the same method as Types 153 and 154.
> If not, does Type 158 mix the nodes at the end of the time step, when
> their temperatures are already "unstable"?? Or does it repeat the time
> step with both nodes being mixed?

Adrian,

Type 158 uses an instantaneous, adiabatic, mixing that occurs at the end 
of each timestep to eliminate any temperature instabilities in the tank. 
This mixing happens AFTER all of the energy calculations have been 
performed but before the setting of the temperature outputs.  I will 
also point out that the Type 1531-1536 tank models can perform the same 
mixing as Type 158 or the user can choose to use the mixing algorithm 
and the sub-timestep approach in those models.

Jeff

----
Jeff Thornton
President
Thermal Energy System Specialists (TESS)
3 N. Pinckney Street - Suite 202
Madison WI 53703
(608) 274-2577
www.tess-inc.com