nx_ac_enthalpy_metrics.nx

nx_ac_enthalpy_metrics.nx -- the AC PERFORMANCE crown, built on the psychrometric floor. This is the R4 rung the HVAC-efficiency workstream flagged as "the crown number, NOT built": independent delivered-capacity, COP/EER, and efficiency-drift measured from out-of-band sensors -- the data-center air-side method (delivered capacity = airflow * enthalpy drop), which SOTA DCIM (Vertiv/Schneider/Sunbird) uses per cooling unit. Everything here is a physics quantity a vendor thermostat cannot fake and does not report. Paired with nx_hvac_efficiency (fault verdict) and the reading-level liar-killer (nx_ac_sensor_verify), it is the measurement core of the "Flume for AC" product. KEY LIAR-KILL SURFACE (why this organ is trustworthy, not just a calculator): - delivered cooling with h_return <= h_supply returns NEGATIVE (loud): the air is not being cooled -- never a fabricated positive capacity. - COP with electrical power <= 0 returns INFEASIBLE (loud), never inf. - the CARNOT COP ceiling Tc/(Th-Tc) is a HARD physical bound: any measured or claimed COP above it is thermodynamically impossible -> the downstream liar-killer rejects the reading. carnot with T_cold >= T_hot is INFEASIBLE. - superheat / subcooling / evaporator-split are returned VERBATIM incl. negatives, so a flooded coil or a swapped/failed sensor shows as an impossible value the liar-killer flags -- not silently clamped. NO-FLOAT integer fixed-point (ecosystem doctrine): temperature = milli-degC (mC) airflow = CFM power = W air density = g/m^3 (1200 = 1.2 kg/m^3; data-driven for altitude/temp) enthalpy = J/kg dry air cooling = W COP = x100 (centi-COP) EER = x100 Carnot COP = x100 drift = permille (positive = degraded) abs temp = centi-Kelvin (cK): cK = mC/10 + 27315 (0 degC = 273.15 K) NEVER-BRICK #26: pure computation, read-only, no device/firmware write. genealogy_id: project-hvac-efficiency-sclass-2026-06-23 (R4 COP/EER crown) + project-nishi-sensor-gap-census-2026-07-14 (axis-4 external-comp) license_tier: ORIGINAL nx_capability_claims: needs: [nx_psychrometrics] provides: [delivered_cooling_capacity, cop_measure, eer_measure,