[TRNSYS-users] Type60f Error: A negative flow was encountered

[David BRADLEY]

Chen,
   Type60 allows you to specify three of the four flows, in which case 
it will internally compute what the required fourth flow must be. The 
two inlet flows are defined as a positive value meaning flow into the 
tank. The two outlet flows are defined as a positive indicating a flow 
out of the tank. Flows may be zero but they cannot be negative (in other 
words you can't have fluid coming in through an outlet port nor out 
through an inlet port).

   In your simulation, inlet flow 1 comes from the load side of the heat 
exchanger, inlet flow 2 is set to the value zkmassflow, and outlet flow 
2 is set to the value of zkmassflow+zkflow.  If there is no flow from 
the heat exchanger into the tank and zkflow is positive then the mass 
balance can't work. In order for it to work, flow would have to enter 
the tank through outlet port 2.

   One other thing that I noticed: check the answer to the question 
about how many nodes there are in the tank on the Type60 "output" tab. 
The question is "besides the top and bottom nodes, how many nodes are 
there?" so the answer needs to be 8 whereas the other two tabs ask 
simply "how many nodes are there?"
Best,
  David



On 2/11/2013 11:34, Chen Luo wrote:
> Hello,
>
> I am using this model to simulate a water heating system.
> But there is always this problem "a negative flow was encountered". I 
> have tried to change the flow of cold water income, and change "-2" to 
> each of the 4 in/outlets of Type60f. However, it doesn't work.
>
> Chen
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu
> https://mailman.cae.wisc.edu/listinfo/trnsys-users

-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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