BDD & PD: Radiation

This diagram shows the Block Radiation with a supporting ConstraintBlock RadiationConstraint:
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As we saw earlier, the fan power ratio is either 1.0 (on) or off (0.0), as determined via the input Port iWaterFanPower. Note that even when the fan is completely off there is some radiation (and it turns out the intrinsic radiationFactor for this is equal in strength 0.1 to the fanEfficiency).

Through dimensional analysis it was determined that:

This implies the explicit ValueTypes RadiationFactor and FanEfficiency have units J/(K⋅s).

It seems the radiation rate is proportional to the difference between the water temperature (as received via the iWaterTemperature Port from the Heating computation block) and the roomTemperature.

BTW: This is yet another example of where the Single Source of Truth (SSOT) and Don't Repeat Yourself (DRY) policies are broken, because the roomTemperature here and the roomTemperature under block VaporPressureCalculation would seem to be the same (30 °C), so SHOULD be shared via some common system-wide block!

Although the full physical setup of the system is not described in the spec example, it seems that the radiating water is somehow interacting with the room environment. (Later we'll see that the WaterTank seems to be exposed also to a lower environmental temperature of 20 °C.)

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