Hydrogen liquefaction with catalytic ortho-para conversion — a COOLPROP process flowsheet
A Linde-Hampson JT-cycle liquefaction loop for H2 (the same recycle topology as helium-liquefaction), but H2's real liquefaction process needs one more step helium doesn't: normal H2 feed is ~75% ortho-/25% para-spin-isomer, while the equilibrium mix at liquid-H2 temperature is ~99.8% para -- liquefying without converting first leaves the ortho fraction far above its new equilibrium value, and its slow natural relaxation releases heat (the textbook explanation for uncatalyzed LH2 tanks self-boiling). This closes a real gap: ortho_para_converter.py (a catalytic cold-box converter, real equilibrium-para-fraction statistical mechanics) existed in this codebase but was never wired into a showcase example -- and turned out to also be missing from the backend's unit-type validation catalog entirely (fixed alongside this example, in catalog.py). Precooling to 30 K (deep enough that H2's JT effect actually condenses it -- verified numerically: 77 K/60 K/45 K precool all give zero liquid yield at 20 atm -> 1.3 atm here, since H2's JT-cooling window needs real precooling well below LN2 temperature, unlike simpler gases) also happens to sit right where the ortho-para conversion actually matters. Honesty notes: (1) real plants reach this depth of precooling via a multi-stage refrigeration cascade (LN2 first stage, then a closed H2 or He Brayton/turboexpander cycle) -- collapsed here into one utility heater node, same simplification as every other liquefaction example in this codebase; (2) the converter's approach_to_equilibrium=0.9 is a stage-efficiency simplification (no cited Fe2O3/Cr2O3 rate constant exists to verify a real kinetic model), disclosed in the unit op's own docstring, not fabricated here.
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- Rigorous COOLPROP thermodynamics, solved by the same engine every simulation runs on.
- 6 unit operations modeled: MIX, COMP, 2× Precool, OPC, JT, Flash.
- Focus areas: Hydrogen liquefaction, Ortho-para conversion, Cryogenics, Joule-Thomson, Recycle.
- Thermodynamics
- COOLPROP
- Components
- h2
- Unit operations
- MIXCOMP2× PrecoolOPCJTFlash
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Read the step-by-step guideReproduce this exact result from Python — the real client.get_example() → run_and_wait() path, not a mockup.
from flowsim.sdk import FlowSimClient
client = FlowSimClient()
example = client.get_example("hydrogen-liquefaction")
sim = client.create_simulation(example["title"], example["flowsheet"])
result = client.run_and_wait(sim["id"])
print(result["status"]) # "converged"
streams = client.streams(sim["id"])Related models
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