Thermodynamic investigation of a novel hydrogen liquefaction process using thermo-electrochemical water splitting cycle and solar collectors

Strategies To Improve the Performance of Hydrogen Storage Systems by Liquefaction Methods: A Comprehensive Review

“…Given that the numbers are α = prefix+ 1 2 and β = prefix− 1 2 , the nuclear spin quantum number is equal to italicI = ( 1 2 + 1 2 ) = 1 for ortho-H 2 , and the molecular form has three states. In para-H 2 , the nuclear spin quantum number is italicI = ( 1 2 − 1 2 ) = 0 and thus has only one state. , Therefore, the number of ortho states is 3 times that of para-H 2 at environment temperature (i.e., 75% ortho–25% para). , Figure illustrates the graphical layout of the parallel and antiparallel spins in ortho- and para-H 2 . It is also not possible to produce pure ortho-H 2 .…”

“…In its natural state, ortho-H 2 tends to cool slowly and over a long time frame, causing the reserved liquid H 2 to evaporate and become waste. The ortho- to para-H 2 conversion appears with a transition from the ortho triplet state to a para singlet state, which in the normal state of this transition is very slow, and more time is spent in this process. ,, …”

“…As a result, when storing liquid H 2 , some of the H 2 is wasted, which is called boil-off gas. , Thus, the ortho- to para-H 2 conversion is essential for LH 2 production in distant transport and to decrease IBOG losses. By storing normal H 2 inside a tank, the conversion enthalpy is released in the tank and causes the liquid H 2 losses. , The reactions occurring in the conversion reactors are listed as hydrogen → normalpara‐ hydrogen + heat The conversion rate is dependent on the reaction temperature as in eq conversion = italicC 0 + italicC 1 × italicT + italicC 2 × italicT ² The conversion coefficients can be defined using experimental information . The volume rate constant for the first-order reaction, k v true( mol cm 3 0.0ex0.0exnobreak0.25em normals true) , is obtained from eq , italick normalv = italicn italicV × ln ( 1 − C 0 C eq 1 − C C eq ) where n , V , and C 0 are the feed molar flow rate (mol/s), the cata...…”

“…Several strategies have been utilized to decrease the SEC in H 2 liquefaction systems. These techniques include using absorption and ejector cooling cycles, − LN 2 regasification, ,− LNG/LAC energy recovery, ,− cascade liquefaction process, ,, multicomponent refrigerant cycle, − integration with other integrated structures, , optimization algorithms, , combined with renewable energy sources, − and the pinch approach. , Yilmaz et al developed seven H 2 production and liquefaction cycles according to geothermal energy, the absorption cooling cycle (ACC) to precooling, and the L–H process for liquefaction. The price of H 2 liquefaction was calculated to be 0.98–2.62 $/kgLH 2 .…”

Modified Hollow Glass Microspheres/Reduced Graphene Oxide Composite Aerogels with Low Thermal Conductivity for Highly Efficient Solar Steam Generation

“…With the increase of the world’s population, the improvement of living standards, and the rapid development of industries, freshwater scarcity has become a serious global problem. , Although many technologies, such as multistage flash, multi-effect distillation and reverse osmosis, etc., have been employed for clean water production, they mainly rely on the consumption of nonrenewable energy sources such as fossil fuels and electricity, which aggravated the energy crisis accompanied by serious environmental pollution. As a renewable and clean energy, solar energy is applied in many fields. − Most recently, as one of the most promising water cleaning techniques, solar steam generation (SSG) has attracted significant attention not only because it uses inexhaustible and clean solar energy but also because of its unique “interfacial vaporization” manner to produce freshwater using a photothermal material with high energy conversion efficiency instead of the traditional water evaporation by heating the bulk water with a large heat loss. − …”