Align PlantLowFlowRateToler with DataHVACGlobals::VerySmallMassFlow

[lymereJ]

Pull request overview

• Fixes Plant low flow rate tolerance prevents minimum pump flow rate to be enforced #10456

Align PlantLowFlowRateToler with DataHVACGlobals::VerySmallMassFlow so minimum pump flow rate can be correctly enforced during simulations.

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[lymereJ]

Absolute tolerances are defined below (perhaps these should be relative to the plant loop flows?):

EnergyPlus/src/EnergyPlus/DataHVACGlobals.hh

Lines 72 to 79 in 9d7789a

	Real64 constexpr SmallHumRatDiff(1.0E-7);
	Real64 constexpr SmallTempDiff(1.0E-5);
	Real64 constexpr SmallMassFlow(0.001);
	Real64 constexpr VerySmallMassFlow(1.0E-30);
	Real64 constexpr SmallLoad(1.0);
	Real64 constexpr TempControlTol(0.1); // temperature control tolerance for packaged equip. [deg C]
	Real64 constexpr SmallAirVolFlow(0.001);
	Real64 constexpr SmallWaterVolFlow(1.0E-9);

To avoid further failures, probably the best (and the most consistent with what's already use) is DataHVACGlobals::VerySmallMassFlow. It is currently only used for airloops but its name doesn't exclude other fluids.

[lymereJ]

Once converted to 24.1 the defect files complete successfully without running into this issue. It is possible that other incremental changes on the component sides are preventing very low flow requests.

[dareumnam]

I merged the develop and resolved conflicts. CI is all happy here. This PR looks fully clean and ready to go. @Myoldmopar

[Myoldmopar]

Thanks @dareumnam ! Merging this in now.