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Let's say there are three chillers as follows.

• Chiller no.1: 500RT
• Chiller no.2: 1000RT
• Chiller no.3: 1000RT
• Chiller Sqeuence: Chiller no.1, Chiller mo.2, Chiller no.3
• Minimum Part Load Ratio for all chillers: 0.1
• Maximum Part Load Ratio for all chillers: 1.0
• Optimum Part Load Ratio for all chillers: 0.75

If I choose SequentialLpoad or Optimal for Load Distribution Scheme of PlantLoop, how is the load distributed to Chiller no.1 and Chiller no.2 the moment cooling demand exceeds 500 RT? The Minimum Unloading Ratio of chillers is set to 0.1. Is the evaporator cooling rate of Chiller no.1 reduced in consideration of the evaporator cooling rate of Chiller no.2? Or does the cooling rate of Chiller no.1 remain the same because the cooling rate of chiller no.2 is "false load" at the moment?

Engineering Reference says "Note: For all schemes, if the load for any individual component is less than the component load at the minimum PLR, the individual component model will false load or reduce duty cycle while operating at the minimum part load ratio until the load is met.", but I don't know the details of chiller load distribution when the second or third chiller is turned ON.

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No answers. OK. I tested with a simple model: an adiabatic cube with hourly increasing plug load. Chiller Minimum Unloading Ratio was changed to 0.25 to clarify its impact.

• Chiller no.1: 500RT
• Chiller no.2: 1000RT
• Chiller no.3: 1000RT
• Chiller Sqeuence: Chiller no.1, Chiller mo.2, Chiller no.3
• Minimum Part Load Ratio for all chillers: 0.1
• Maximum Part Load Ratio for all chillers: 1.0
• Optimum Part Load Ratio for all chillers: 0.75

The evaporator cooling rate of Chiller no.1 did not explicitly decrease when Chiller no.2 turned ON. I revised my graphs as follows. To be precise, "false load" is not included in Chiller Evaporator Cooling Rate, but it affects Chiller Electric Power. If Minimum Unloading Ratio is the same as Minimum Part Load Ratio, chillers do not have false loading.

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