initial ground temperature in SlabOnGround

[Mathadon]

  parameter Modelica.Units.SI.Temperature TeAvg=273.15 + 10.8
    "Annual average outdoor temperature";
  BaseClasses.ConductiveHeatTransfer.MultiLayer layGro(
    final inc=incInt,
    final nLay=3,
    final mats={ground1,ground2,ground3},
    final T_start={TeAvg, TeAvg, TeAvg},
    monLay(each energyDynamics=energyDynamics),
    final A=A)

The default start temperature TeAvg can be too low for some cases. Should be revised.

[jelgerjansen]

@Mathadon could you give an example of a case where this raised a problem? Since it is an initialisation, shouldn't this effect dissapear after some time?
Furthermore, is the problem the absolute value of TeAvg, or rather the fact that the same temperature is used to initialise all layers of the ground?

[Mathadon]

The problem is mostly that TeAvg (which is the annual average temperature) is used to initialise the ground, which may not be at the annual average temperature, e.g. when starting a simulation in summer. So it would make more sense to add a parameter T_start, which may well have TeAvg as default value.

[Mathadon]

Suppose you do a simulation for two weeks with an uninsulated floor, then you get free cooling which does not exist in reality.

[lucasverleyen]

I have made the suggested changes.

• I have added the parameter T_start_ground[3] to SlabOnGround. By default, T_start_ground = {TeAvg,TeAvg,TeAvg}, but now the user can modify these temperatures in the model. The number of layers in the ground equals 3, which is hard coded. Therefore, I have explicitly used T_start_ground[3] and not T_start_ground[nLay].
• I have propagated the parameter T_start_ground to the RectangularZoneInterface, such that T_start_ground is also available there for the same purpose as described in this issue.

The plot below shows the results of changing T_start_ground. I have simulated the example RectangularZone and have modified the floor type to SlabOnGround (ConcreteSlab) in zoneIntWal such that the effect of T_start_ground is visible. The blue line corresponds to the default settings with T_start_ground = {TeAvg,TeAvg,TeAvg} with TeAvg=10.8°C. The red line corresponds to T_start_ground = {50°C,50°C,50°C} and the green line corresponds to T_start_ground = {-50°C,-50°C,-50°C}. The trajectories show the zone temperature (TSensor). And the values of -50°C and 50°C are extreme values, but show clearly the effect of T_start_ground.