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Hi, it’s me again, I looked more closely at the flow rates, on the cold side both the entering and exiting flows are equal, however on the hot side there seems to be some lag
between the entering and exiting flow rates. I tried reducing the time step (from 0.1 to 0.01 hours) but the problem still persists… Thanks for helping, Ciarán From: Flynn Ciaran
Hi Jeff, Thanks for your quick reply. I checked the connections and flow rates and they all seem to be ok. On the hot side I have a type 3b variable speed pump, on the
cold side a Type 3d single speed pump, both of which have the same maximum flow rates. And this particular flow rate I used as parameter 4 of Type 512 “Rated flow rate of hot side”. I also connected the 6th output of type 512 to the control signal
of the variable pump on the hot side of the exchanger.. I still get this mass balance problem. Any ideas what is going wrong? Ciarán From: trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu]
On Behalf Of 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 E-Mail: thornton@tess-inc.com On 11/28/2012 6:11 am, Flynn Ciaran wrote:
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