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Abstract
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The price of constructing hydrogen generation units is very high and sometimes it is not possible to
build them in the desired location, so the transfer of hydrogen from the hydrogen generation system
to the units that need it is justified. Since the storage of hydrogen gas needs a large volume and its
transportation is very complex, so if hydrogen is stored in liquid form, this problem can be resolved.
In transporting liquid hydrogen (LH2) over long distances, owing to heat transfer to the environment,
the LH2 vaporizes, forming boil-off gas (BOG). Herein, in lieu of only reliquifying the BOG, this study
proposes and assesses a system employing the BOG partially as feed for a novel liquefaction process,
and also the remaining utilized in a proton exchange membrane fuel cell (PEMFC) to generate power.
Using the cold energy of the onsite liquid oxygen utility of the LH2 cargo vessel, the mixed refrigerant
liquefaction cycle is further cooled down. In this regard, by using 130 kg/h BOG as input, 60.37 kg/h of
liquid hydrogen is produced and the rest enters PEMFC with 552.7 kg/h oxygen to produce 1592 kW
of power. The total thermal efficiency of the integrated system and electrical efficiency of the PEMFC is
83.18% and 68.76%, respectively. Regarding the liquefaction cycle, its specific power consumption (SPC)
and coefficient of performance (COP) were achieved at 3.203 kWh/kgLH2 and 0.1876, respectively. The
results of exergy analysis show that the exergy destruction of the whole system is 937.4 kW and also
its exergy efficiency is calculated to be 58.38%. Exergoeconomic and Markov analyses have also been
applied to the integrated system. Also, by changing the important parameters of PEMFC, its optimal
performance has been extracted.
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