[TRNSYS-users] Type 512 (TESS): Mass balance warning message

[Jeff Thornton]

<I am running my simulation with a type 512 heat exchanger and I get
the following warning message (no convergence errors, just warnings) at
the end of my simulation (time step: 0.1 hour):> 

Type 512 has internal
controls to vary the speed of the hot-side flow rate through the heat
exchanger. I'm guessing that you're hooking up a pump to this heat
exchanger and the flow rate into the HX is not the flow rate out of the
HX - as 512 is setting the flow rate. The best way to use 512 is to use
a variable speed pump model and make sure the maximum flow rate
parameter for both the pump and HX models are identical. Then put the
pump either upstream or downstream of the HX and connect the 6th output
of the heat exchanger model to the control signal for the pump - so that
they both produce the same flow rate. 

Jeff 

---

Jeff Thornton


_President - TESS LLC_ 

_22 N. Carroll Street, Madison WI USA 53703_


_Office: (608) 274-2577 Fax: (608) 278-1475_ 

_www.tess-inc.com_


_E-Mail: thornton at tess-inc.com_ 

On 11/28/2012 6:11 am, Flynn Ciaran
wrote: 

> Hello, 
> 
> I am running my simulation with a type 512 heat
exchanger and I get the following warning message (no convergence
errors, just warnings) at the end of my simulation (time step: 0.1
hour): 
> 
> *** Warning at time : 39384.000000 
> 
> Generated by Unit
: 45 
> 
> Generated by Type : 512 
> 
> Message : Heat exchanger mass
balance failed during 112810 time steps. Please check the connections.

> 
> I do not understand what could be the reason for this. I have gone
through my connections and they all seem fine (I do not get this problem
with heat exchanger type 91). 
> 
> Thanks for your help, 
> 
> Ciarán

> 
> _----------------------------------------_ 
> 
> _Ciarán Flynn_ 
>

> _Research Scientist_ 
> 
> _ _ 
> 
> _Aalto University_ 
> 
>
_Department of Energy Technology_ 
> 
> _P.O.Box 14100, 00076 Aalto_ 
>

> _Otakaari 4, 02150 ESPOO_
 
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