EnergyPlus Walk-in Freezer Model Issue: Compressor Runtime Fraction Not Equal to 0 When Power is 0W

asked 2024-01-25 16:12:59 -0500

Zakaria's avatar

updated 2024-01-31 05:55:36 -0500

Hello community,

I've been working on modeling a walk-in freezer in EnergyPlus with a volume of 38 m3, utilizing a ThermostatSetpoint:SingleCooling set at -18°C with a 4 deltaC for Temperature Difference Between the Cutout and Setpoint. The simulation accurately reflects temperature fluctuations between -22°C and -18°C, as shown in the attached graph below, that present Air Zone Temperature, Compressor Electric Power, and Compressor Runtime Fraction.

However, I've observed an anomaly: when the compressor is not working (Compressor Electric Power = 0W), both Compressor Heat Transfer Rate and its Runtime Fraction is not equal to 0, which seems abnormal (the highlited parts in Fig.1 and 2 below).

It can be seen in the EXCEL table, between the timestep 0.08h and 0.22h the compressor is off but the Runtime Fraction in this period is equal to that of the last timestep (0.07h) and equals 0.82, and the same thing for the Compressor Heat Transfer it gives the capacity value of the last timestep.

Is this a bug in the code, or is there an explanation that I don't know?

Any insights or suggestions on addressing this issue would be greatly appreciated!

Fig.1 image description

Fig.2 image description

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