Research-stage literature benchmark
Taccani compressed-H₂ loading
An adiabatic compressed-hydrogen carrier loading case. The primary mass gate currently fails and is intentionally preserved as an open evidence issue.
Acceptance rule
Final hydrogen mass on board at 300 bar must be within 5% of the published value. Current deviation: −5.6% (−7.6% before the October 2026 entry-temperature correction). The tolerance has not changed.
Source
Taccani, R.; Maggiore, G.; Micheli, D. (2020), “Development of a process simulation model for the analysis of the loading and unloading system of a CNG carrier equipped with novel lightweight pressure cylinders,” Applied Sciences 10, 7555.
Values taken from the paper
| Input | Value | Source |
|---|---|---|
| Ship water volume | 44,800 m³ | Table 2 |
| Final/design pressure | 300 bar | Tables 2 and 4 |
| Initial cargo state | 30 bar, 40 °C | Sections 6.1–6.2 |
| Storage volume | 2 × ship volume | Section 6.1 |
| Storage initial pressure | 240 bar | Section 6.1 |
| Cooler outlet temperature | 40 °C | Section 6.1 |
| Compression arrangement | Two-stage; two compressors in parallel | Section 6.1 |
| Maximum polytropic efficiency | 0.73 | Section 6.1 |
| Hydrogen loading thermal boundary | Adiabatic | Section 7 / Table 4 case |
Generated comparison
| Metric | Published | OffshoreLH2 | Deviation | Basis | Status |
|---|---|---|---|---|---|
| Mass on board at 300 bar | 724 t | 683.4 t | −5.6% | Independent, 5% tolerance | FAIL |
| Gas temperature at the end of loading | about 393 K (120 °C, read from Figure 22) | 418.5 K | +6.4% | Descriptive | REPORTED |
| Initial mass at 30 bar / 40 °C | 100.6 t implied | 102.3 t | +1.7% | Descriptive | REPORTED |
| Compressor energy | 163.6 MWh | 75.51 MWh | −53.9% | Descriptive | REPORTED |
| Specific compression energy | 945 kJ/kg loaded | 467.8 | −50.5% | Descriptive | REPORTED |
What the investigation found
- The model solves its stated physics. A separate step-by-step energy balance of the storage terminal and the ship, written without the model’s loading classes, reproduces it: 669.3 t against 668.7 t under the model’s original assumption.
- One assumption was not physical, and is corrected. The model let all gas enter the ship at the 40 °C cooler setting. Gas that flows freely from the storage passes a valve and keeps the storage gas enthalpy, and that gas cools to about 250 K as the storage empties; compressed gas leaves coolers that can cool it but not heat it. With the entry temperature computed this way the model gives 683.4 t, and the separate energy balance gives 683.3 t. In the offshore reference case the correction changes the 2020 delivery by 0.1 t.
- The published values agree with each other within about 1%. The end state in Figure 22, 300 bar and about 120 °C, holds 722 t, so the published mass matches its own figure. The loaded volume in Table 4 corresponds to 733 t.
- The remaining gap depends on inputs the paper does not state. The model ends at 145 °C against about 120 °C, so the gas it receives carries more energy. With storage gas at 25 °C instead of the assumed 40 °C, the model would give 701 t (−3.2%), inside the tolerance. The paper gives no storage temperature, so choosing one to pass would be tuning; the comparison keeps the stated assumption and stays a failure.
Why it remains open. Closing it needs the paper’s storage state and centrifugal compressor maps, or measured loading data. Until then the failure stays visible and blocks promotion of the compressed-hydrogen pathway.
Reproducibility
Source register: python/offshore_lh2/data/carrier_benchmark_references.json. Runner: scripts/run_carrier_benchmarks.py. Separate energy balance: scripts/check_taccani_loading_energy_balance.py.