SolarThermalControl
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Use
The solar thermal controller model controls the heat power output of a solar thermal collector via reference volume flow of the circulation pump. It ensures that the specified temperature is reached if possible. E.g. this setpoint can be a desired storage tank temperature.
Recommendation: Use the newer version of this model under local, which also allows cooling with the solar collector.
Parameters and Connectors
The SolarController provides a Boolean (▶CPon) and a real signal (▶qvRef) to control the circulation pump on the solar collector. These are switched on if heating is required (▶EnableHeating) and the temperature difference (▶TCollector-▶TStorage) is greater than deltaTon. It is switched off if the temperature difference (▶TCollector-▶TStorage) is less than deltaToff. To avoid numerical difficulties, the switch-off level must be defined slightly below the switch-on level (deltaToff < deltaTon).
To ensure safe system operation, the ambient temperature (provided via ▶EnvironmentConditions) must be within the TAmbientMax and TAmbientMin limits. If the temperature exceeds or falls below these limits, the circulation pump is not given a switch-on signal.
The reference volume flow ▶qvRef is regulated when the controller has switched-on. It dependents on the desired temperature range of the heating medium between flow (▶TFlow) and return (▶TReturn) pipe of the solar collector. This difference of the temperature difference should be within the limits of deltaTFlowReturnLow and deltaTFlowReturnUp and the volumetric flow within the limits qvMin and qvMax.
Model Background
Volume Flow Control
For the calculation of the volume flow the following principles are applied and shown in the image:
If: abs(▶TFlow-▶TReturn) < deltaTFlowReturnLow, ▶qvRef is min
In the image: deltaTFlowReturnLow = 3 K and qvMin = 0.7 m³/s
If: abs(▶TFlow-▶TReturn) > deltaTFlowReturnUp, ▶qvRef is max
In the image: deltaTFlowReturnUp = 7 K and qvMax = 3 m³/s
Between the two temperature boundaries the reference volume flow is linearly interpolated.
