<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
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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@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
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Ciarán Flynn
Research Scientist
Aalto University
Department of Energy Technology
P.O.Box 14100, 00076 Aalto
Otakaari 4, 02150 ESPOO