Cryogenic Hydrogen Boil-Off Rate Calculator
Estimate daily hydrogen boil-off from cryogenic storage by combining tank surface area, measured heat flux, latent heat, and optional parasitic loads.
Engineering estimation aid—validate against calibrated tank mass balance or instrumentation when making commercial commitments.
Examples
- 210 m² surface, 4.5 W/m² heat flux, 446 kJ/kg latent heat, 350 W parasitic, 12,000 kg inventory ⇒ Net heat leak 1,295 W → 250.58 kg/day boil-off. That equates to 2.09% of the stored mass per day.
- 95 m² surface, 6.2 W/m² heat flux, 452 kJ/kg latent heat, optional fields blank ⇒ Net heat leak 589 W → 112.41 kg/day boil-off.
FAQ
Can I enter varying heat flux for different surface zones?
Average each zone's flux weighted by its area before entering a single blended value. For higher fidelity, run separate scenarios for warm roofs, penetrations, and walls, then sum the boil-off results.
How do I include intermittent events like pump starts?
Estimate the duty cycle and convert it to an equivalent continuous watt load. Multiply event power by the fraction of time it runs over 24 hours and add the result to the optional parasitic heat field.
What latent heat value should I use for pressurised tanks?
Look up latent heat at the storage pressure and temperature from hydrogen property tables. Latent heat decreases slightly as pressure rises, so avoid using 1 bar data for elevated-pressure LH2 vessels.
Does the percentage output work for partially filled tanks?
Yes. Enter the actual kilograms currently stored. The calculator divides the daily boil-off mass by that inventory to express a percent-per-day loss.
Additional Information
- Result unit: kilograms of hydrogen lost per day, derived from steady-state heat ingress divided by latent heat.
- Latent heat input expects kJ/kg; calculator converts to J/kg internally for unit consistency.
- Additional parasitic heat defaults to zero when left blank, representing ideal insulation without penetrations.