Introduction
The Energy centre Placeholder is an ideal production unit intended for early-stage design before the energy concept has been decided yet. It allows you to already simulate a system without having an actual energy centre concept yet. You can drop it on the canvas as a placeholder for a real production concept and still run meaningful simulations to validate your secondary-side design and control strategy.
In subsequent design stages, the placeholder can be easily converted to an inspiration library template using the template replacement concept (Ctrl+P).
The energy centre placeholders are available for heating, cooling and changeover as depicted in the figure below.
How to use them
Library location
You can find the energy centre placeholders BCs under “Production” in the corresponding libraries. The library location is shown in the figure below.
Parameters
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P&ID identifier
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A user-defined label used to identify the placeholder in the P&ID and on the canvas.
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Pressure drop in design
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The pressure drop in design attributed to the placeholder (used in optimise component step).
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Contains distribution pump
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A toggle to indicate if a pump is present in the virtual energy centre.
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When disabled: the placeholder has no distribution pump.
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When enabled: an internal pump is activated inside the energy centre placeholder.
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The remainder of the pump parameters are identical to other pump usages, see Pumps.
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Control connections
The changeover placeholder exposes three control connectors:
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Heating supply temperature setpoint
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The requested heating supply temperature that will be used in simulation when the activation signal indicates heating.
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Cooling supply temperature setpoint
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The requested cooling supply temperature that will be used in simulation when the activation signal indicates cooling.
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Activation signal
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Defines the operating mode of the changeover placeholder:
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1: heating
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-1: cooling
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0: off
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When a setpoint connector is not connected, the design supply temperature for that mode will be used as constant supply temperature during simulation (heating or cooling, depending on the activation signal).
Simulation behaviour
In simulation, the Changeover Energy centre Placeholder acts as an ideal source with no maximum capacity or thermal inertia. The simulated supply temperature is determined by the activation signal:
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If the activation signal is 1 (heating): the heating supply temperature setpoint is used as effective supply temperature.
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If the activation signal is -1 (cooling): the cooling supply temperature setpoint is used as effective supply temperature.
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If the activation signal is 0 (off): the placeholder does not provide heating or cooling power; the supply temperature is set equal to the return temperature.
The simulation behaviour of the system is shown in the example figure below. It is clear that the selected input supply temperature setpoint (heating or cooling) is directly fed as supply temperature towards the secondary side as read on the sensor.
Placeholders are not actual production units and are excluded from the Pareto analysis. Pareto results may therefore be inaccurate. If you want to use the Pareto analysis for your model containing placeholders, replace the placeholder with an energy centre template for changeover or with a 2-pipe reversible heat pump.
From placeholder to Energy Centre
The Energy Centre placeholder is designed in such a way that it can easily be replaced with an actual energy centre concept from the inspiration library. Instead of manually selecting a template from the inspiration library, you can replace the placeholder using Ctrl+P or using the Template configuration button to automatically insert a template at the location of the placeholder.
More information on the template replacement algorithm can be found at the template configuration window.
Any energy centre placeholder can be easily converted to an energy centre template using the template replacement mechanism via the template configuration screen (Ctrl+P).
Conclusion
The Changeover Energy centre Placeholder is an ideal production unit with unlimited capacity that can be used as placeholder for a real energy centre, primarily intended for early-stage simulations. It supplies a heating or cooling temperature depending on the activation signal: 1 selects the heating setpoint, -1 selects the cooling setpoint, and 0 turns the placeholder off (supply equals return). This makes it useful to validate secondary-side design choices, return temperatures, and control strategies before committing to production technology details.
Once the system’s secondary side is stable, the placeholder can be easily converted to actual energy centre templates to smoothly support the energy centre optioneering phase.