Heater

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Description

The Heater is a component that converts electrical power into thermal energy. It extends the Power Sink class and integrates with the Thermal Model system to simulate controlled heating of spacecraft components. Power can be drawn from a Power Bus or operated independently, with an optional control message for dynamic power adjustment.

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Example Use Cases

• Temperature Regulation: Maintain component temperatures within operational limits during eclipse or cold phases.
• Propellant Conditioning: Heat propellant tanks to ensure proper fluid properties for thruster operation.
• Battery Thermal Management: Keep batteries within their optimal temperature range for charging and discharging.

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Module Implementation

Power Conversion

The heater converts electrical power to thermal energy. The thermal power delivered is determined by the minimum of available power, commanded power, and the maximum thermal rating:

$$P_{\text{thermal}}=\min (P_{\text{available}},P_{\text{nominal}},P_{\text{max}})$$

where $P_{\text{available}}$ is the power from the electrical system, $P_{\text{nominal}}$ is the commanded power setting (default 10 W), and $P_{\text{max}}$ is the maximum thermal power rating (default 10 W).

Operating Modes

Independent Mode: When not connected to a Power Bus, the heater sets thermal power generation directly based on the nominal power setting.

Bus-Coupled Mode: When connected to a Power Bus, thermal power is limited to the actual electrical power delivered by the bus, ensuring realistic behavior when power is constrained.

Control Message

An optional power control message allows dynamic adjustment of the heater power during simulation. When present, the control message sets the nominal power (capped to the maximum thermal rating):

$$P_{\text{nominal}}=\min (P_{\text{control}},P_{\text{max}})$$

This enables duty cycling for temperature control loops, power throttling under limited bus conditions, and scripted heating profiles.

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Assumptions/Limitations

• The heater has 100% efficiency; all electrical power is converted to thermal energy.
• Thermal coupling is instantaneous; there is no thermal lag between the heater and its parent’s thermal node.
• Inrush current and switching transients are not modeled.
• Thermal protection mechanisms (over-temperature cutoff) must be implemented externally.
• Variable efficiency under different voltage or temperature conditions is not modeled.