الملخص الإنجليزي
Hydrogen is a pure element, that is more prevalent in the environment and considered as
a source of energy. Many nations are switching from carbon-based economies to
hydrogen-based economies. The modern world is aware of the need to modify clean and
green energy methods and follow the international decarbonization measures like the Paris
agreement. Therefore, hydrogen is regarded as a solution to climate change, which is on
the verge of eradicating life on earth and is considered to be the greatest humanitarian
crisis of all time. However, hydrogen is a critical element to deal with due to its lower
energy content per unit volume. Therefore, long term storage and transportation of
hydrogen for long distance is a promising role. Hence, liquifying the hydrogen gas is a
solution to overcome this issue. However, hydrogen liquefaction is an energy intensive
process. If hydrogen is utilized to generate this energy, then between 25% to 35% of
hydrogen will be used. The commercial hydrogen liquefying plants that are currently in
operation have a specific energy consumption rage of 10-12 kW/kgLH2 and exergy
efficiency of 20%-30% with complicated equipment arrangements. This study presents a
compact, simple, energy efficient and economical process. A feed flowrate of 1 kg/s was
used in the suggested case, which functioned as an isothermal process.
Two refrigeration cycles (pre-cooling and liquification cycle) with varied refrigerants
flowrates are used. To create the ideal mix refrigeration composition, knowledge-based
optimization (KBO) was employed to the proposed hydrogen liquefaction process.
Additionally, two equilibrium reactors were used for ortho-para conversion. Energy
consumption of 6.961 kW/kgLH2 was achieved in the proposed process with exergy
efficiency of 37.23%. The coefficient of performance and figure of merit are 0.178 and
0.37, respectively. Furthermore, the economic analysis was done based on the capacity
parameter of each equipment. As a result, it was discovered that the proposed process is
more cost-effective than the base case. This study will help chemical engineers to build a
compact hydrogen liquefaction plant, where availability of the land is the main issue. Also,
it will help to achieve a sustainable green energy economy by improving overall hydrogen
value chain
