AnyGasExpander

Christian Peter Kaiser

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About this app

AnyGasExpander calculates single-stage turbo-expander expansion for many pure gases. Thermodynamic properties come from a Helmholtz equation of state. Expansion into the wet region is allowed; wetness is then shown.

Precise numeric entry and inlet/exhaust states.

WHAT IT IS
A point design energy balance — not a process simulator and not a machine map.
• Dry or saturated-vapor inlet
• Exhaust may be superheated, dry saturated or wet
• Isentropic efficiency η_s as input (η_s = Δh / Δh_s)
• Shaft power P = ṁ · Δh (produced)
• Polytropic efficiency η_p shown from the end states
• Pressure ratio π = p₁ / p₂
• Wetness y = (1 − x) when the exhaust is two-phase

GASES
Always in the Gas menu:
• Air (dry)
• Nitrogen (N₂)
• Oxygen (O₂)
• Carbon dioxide (CO₂)
• Hydrogen (H₂)
• Methane (CH₄)
• Argon (Ar)
• Water / steam (H₂O)
• Ammonia (NH₃)
• Ethane (C₂H₆)
• Propane (C₃H₈)
• Propylene (C₃H₆)
• Ethylene (C₂H₄)
• Helium (He)
• Carbon monoxide (CO)
• n-Butane (n-C₄H₁₀)
• Isobutane (i-C₄H₁₀)
• Sulfur dioxide (SO₂)
• Chlorine (Cl₂)
• Hydrogen sulfide (H₂S)

Specialty gases (Info → show specialty gases):
• Nitrous oxide (N₂O)
• Sulfur hexafluoride (SF₆)
• Neon (Ne)
• Krypton (Kr)
• Xenon (Xe)
• 1-Butene (1-C₄H₈)
• Isobutene (i-C₄H₈)
• Hydrogen chloride (HCl)
• Ethylene oxide (C₂H₄O)
• Vinyl chloride (C₂H₃Cl)

Missing a gas? Further gases can be added on request if a suitable Helmholtz equation of state exists. Use the in-app message.

FEATURES
• Helmholtz equation of state
• Precise numeric input; landscape compact keypad
• Full states: h, s, v and volume flow at inlet and exhaust
• Solve for power, mass flow or isentropic efficiency
• Wetness at exhaust when the expansion enters the two-phase region (caution above 10 % / 15 %)
• Wet/liquid inlet warning (lower p or raise t)
• Copy results to the clipboard
• Light and dark themes, German and English UI

HOW IT WORKS
• Choose the gas
• Enter inlet pressure, inlet temperature and exhaust pressure (bar absolute, °C)
• Enter two of: mass flow, η_s, power — the third is calculated
• Check exhaust temperature, Δh, π, η_p and wetness if shown

DEFAULTS
3.0 bar a / 20 °C → 1.0 bar a, 10 kg/s, η_s = 80 %.
Exception: water at 3 bar is liquid at 20 °C — the app starts steam about 20 K above saturation.

UNITS
Pressure: bar absolute · Temperature: °C · Mass flow: kg/s · Power: kW · Efficiency: % · Volume flow: m³/s (actual, at local v) · Wetness: %

IMPORTANT
Coded in good faith without warranty of correctness or completeness. Always check critical calculations. This is not NIST REFPROP; compare Δh and t₂, not absolute enthalpy (reference state). Stay within the limits of each gas equation of state.

What’s new

First issue