<div dir="ltr">Hi everyone! I have read previous mails about problems with convergence in closed loops but I can't solve my problem...I have tried with diferents options: rearranging components in control cards (in logic order), decreasing time step, putting types with higher thermal mass at the end of the order of calculation. Just one option I haven't tried: putting type 31 instead of just links between types.<div><br></div><div>But one option worked and helped with convergence: putting type 661 (delayed output device). The problem about this is that results are not correct. </div><div><br></div><div>About my simulation: I'm working on a hybrid heating system for a house. It consists in a heat pump that gives heat to the house through radiant floor, and extracts heat through horizontal ground heat exchanger and flat plate solar collectors. This system has two tempering valves: </div><div><br></div><div>1. First valve controls that mass flow does not pass through horizontal ground heat exchanger if soil is very cold (mass flow goes through a bypass) </div><div><br></div><div>2. Second valve <span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">controls that mass flow does not pass through tank if tank outlet towards the load is colder than mass flow. </span></div><div><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></div><div><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">The diagram is attached to this mail. </span></div><div><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></div><div>I ran the simulation and I obtained results so weird: sometimes the thermostat gives the signal of 1 (on, when the house need heating) and the flow out (to source) of heat pump is 0. And sometimes thermostast gives the signal 0 (off, house doesn't need heating) and the flow out (to source) of heat pump is 1532 kg/hr or 3065,83 kg/hr. Mass flow of heat pump to load is ok, but to source is strange. Then I realized that all mass flows of the side of the source were weird in the system: diverters, pumps, ICG, tank...The side of load is ok. </div><div><br></div><div>I think that some type is giving outputs in a different time compared to other types, but I don't know what type is giving the problem: when I see the list file, it says:</div><div><br></div><div><br></div><div><div>*** Warning at time : 2935.000000</div><div> Generated by Unit : Not applicable or not available</div><div> Generated by Type : Not applicable or not available</div><div> TRNSYS Message 441 : The inputs to the listed units have not converged at this timestep. The values at the last iteration will be used and the simulation will proceed.</div><div> Reported information : UNITS: 21 23 42 46 45 38 40 22</div><div> </div><div> </div><div>*** Warning at time : 3000.000000</div><div> Generated by Unit : 27</div><div> Generated by Type : 2</div><div> Message : The controller was stuck during 12 percent of the simulation timesteps.</div></div><div><br></div><div><br></div><div><br></div><div><div>*** Warning at time : 3000.000000</div><div> Generated by Unit : Not applicable or not available</div><div> Generated by Type : Not applicable or not available</div><div> Message : The simulation failed to converge during 2 timesteps (2% of the time).</div></div><div><br></div><div><br></div><div><div>*** Warning at time : 3000.000000</div><div> Generated by Unit : 23</div><div> Generated by Type : 114</div><div> Message : Pump mass balance failed during 7 timesteps. Please check the connections.</div></div><div><br></div><div>So I don't know which type is giving the problem (messages indicate problem with heat pump, pump, tees, tempering valves and tank) , and I don't know if type 661 can help in this situation. Somebody can help me please or give me some idea of what is happening? I can't detect the problem since two weeks! <br></div><div><div><br></div><div>Thank you in advance! And sorry about this too large text! </div><div><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div><div><b>Alejandra Vargas Cáceres<br></b></div><i>Estudiante Ingeniería Civil Mecánica<br></i></div><i>Facultad de Ciencias Físicas y Matemáticas<br></i></div><i>Universidad de Chile <br></i></div></div>
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