Psychrometric Batch

Batch psychrometric calculator for moist air. Computes humidity ratio, dew point, wet bulb, enthalpy, and specific volume from dry-bulb temperature and relative humidity. Required columns: case_id, dry_bulb_F, relative_humidity_pct. Optional: pressure_psia (defaults to 14.696).

CSV Input

Method: ASHRAE 2021 Fundamentals Handbook, Chapter 1 (IP units). Saturation pressure from Hyland–Wexler 1983 (Eq 5 over ice for T < 32 °F, Eq 6 over water otherwise). Humidity ratio W = 0.621945 · p_w / (p − p_w). Enthalpy h = 0.240·T + W·(1061 + 0.444·T) Btu/lb_a. Specific volume v = 0.3704·T_R·(1 + 1.6078·W) / p ft³/lb_a. Dew point inverted from saturation curve; wet bulb solved from the IP psychrometric relation. Both root-finds use bisection. Validated within <0.5% across the typical HVAC envelope (−50 to 200 °F, 5–30 psia).

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