Heat exchanger between TL and 2P fluid

Hi,

I am building a Simscape model with two loops, a thermal liquid and water/steam. I tried to program the heat exchanger to work only when there is an influx of heat on the thermal liquid side (which is time controlled), so unless there is an increase in the temperature there is no flow into the heat exchanger, from either the thermal fluid or the water/steam loop. This is controlled by a 3 way directional valve in the thermal liquid loop and a 4/2 DCV on the water/steam side. I get barely any flow into the heat exahxnger, however, I still get this following error.

"An error occurred during simulation and the simulation was terminated Caused by: ['Current_single_phase_tank_HP_gen_comp/Solver Configuration1']: At time 3972.407000, one or more assertions are triggered. See causes for specific information. Temperature of thermal liquid volume must be greater than or equal to Minimum valid temperature. The assertion comes from: Block path: Current_single_phase_tank_HP_gen_comp/Condenser Evaporator (TL-2P) Assert location: o (location information is protected) o (location information is protected)"

I don't understand why there is a drop in temperature eventhough there is no flow into the heat exchanger from either side. Could anyone help me with this. Please let me know if you need any more information.

Answer 1

[Kwon]

Hi Emin,

The Condenser Evaporator (2P-MA) block models convection and conduction independently. For more info, see https://www.mathworks.com/help/hydro/ref/condenserevaporator2pma.html

By the conduction, a small amount of heat transfer can exist even when the flow rates are zero, and this could cause non-negligible effects in certain cases (e.g., the elapsed time is long). I am not sure, but it could be that the TL liquid is already quite cold, and the conduction later makes the liquid colder, triggering the error message.

If you'd like to seek more help, contacting MathWorks Technical Support or Consulting Services could be options for you.

Thanks,

Kwon

[Emin]

Yes, thank you for the reply. After I posted the question I tried increasing the initial temperature for both TL and the water/steam system in the condesor-evaporator as I had a thought that heat exchanger between the TL and the 2P material was the cause within the heat exchanger and this issue was mitigated.