Liquefaction of Hydrogen

At atmospheric pressure, H2 condenses at -423°F (-253°C). As the pressure rises, the condensation temperature also increases. The liquefaction process utilizes a number of heat pumps in series to reduce the H2 temperature from ambient to the liquefaction temperature. The efficiency of this compression-condensation process ranges from 35 to 60% as a function of size and the refrigerant used in the heat pumps. One of the most efficient refrigerants is a mixture of helium and neon (Quack cycle). The energy consumption of liquefiers theoretically ranges from 5 to 15 kWh/kg 

Post-Oil Energy Technology After the Age of Fossil Fuels 

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It is to be noted that the difference in dissipation of energy between the thermal energy demanded by organic chemical hydrides and the mechanical energy by compression or liquefaction of hydrogen is quite significant because the former is supplied as waste heat, whereas the latter is lost at the site of hydrogen utilization for fuel cells or ICEs. 

The activated hydrogen molecules can be attracted to each other more than normal hydrogen molecules in the reaction medium and these attractions may result easily in liquefaction of hydrogen in reaction conditions (Fig. 5.12). 

The experiments of nanocatalytic liquefaction of hydrogen were carried out using a platinum-supported carbon nanolayer. In the experiments, H PtClj, 6HjO or H PtClj was used as a Pt precursor. To prepare the Pt catalytic reaction nanolayer, the required amounts of H PtClj were mixed with 5 wt.% carbon prepared by burning naphthalene in air (Demirbas, 2008). 

Fignre 5.12 shows the structure of the activated hydrogen molecnle. The Pt catalyst may canse the increase of activation of the hydrogen molecnle. As mentioned before, since the activated hydrogen molecnles are more likely to be attracted each other than normal hydrogen molecules in the reaction medium, these attractions may result in liquefaction of hydrogen. 

Demirbas, A. 2008. Nano-catalytic liquefaction of hydrogen. Energy Sources Part A 30 1540-1547. 

Attractive forces are also operative between non-polar molecules, as is evident from the liquefaction of hydrogen, helium, etc. These universal attractive forces (known as dispersion forces) were first explained by London (1930) and are due to the polarisation of one molecule by fluctuations in the charge distribution in a second molecule, and vice versa. 

Gavroglu, K. (1994). On Some Myths Regarding the Liquefaction of Hydrogen and Helium. European Journal of Physics 15 9-15. 

An atomic property with relevance for the liquefaction of hydrogen molecules is its spin, the quantum analogy to the rotation of an elementary particle about its axis. If the spins of two hydrogen protons are parallel, the molecule is called ortho-hydrogen. 

Large-scale liquefaction of hydrogen was developed in the USA in the 1970s to provide fuel for space rockets. The low specific mass of hydrogen is vital in... 

A conunonly applied method in large-scale liquefaction plants is the Claude process. The necessary refrigeration is provided in four principal steps leading to the liquefaction of hydrogen (Fig. 5-13) ... 

In the liquefaction of hydrogen, the energy expended in compression is 30% of the potential energy yield of the stored hydrogen. 

Pros and cons must always be weighed against each other for the specific application. As far as safety is concerned the associated problems of liquid storage are well manageable. Since the liquefaction of hydrogen was first accomplished in the late nineteenth century this form of storage has not had any unusual problems. 

Faraday s paper, under his own name, was read to the Royal Society by Davy on 10 April 1823 and is followed by two short notes by Davy. The first, read 17 April, announcing the liquefaction of hydrogen chloride, begins ... 

The liquefaction of hydrogen produces 25% P-H2 + 75% 0-H2, and the slow conversion of 0-H2 to P-H2 adds an additional heat source to the storage system. Hence, it is desirable to cmivert the 0-H2 to P-H2 either completely in the liquid state (by adding charcoal) or preferably partially in the precooled gas phase (at 77°K, liquid N2, the equilibrium mixture of H2 vapor, is 60% P-H2) followed by complete conversion in the liquid state. This reduces the losses on storage from 25%/day for 25% P-H2 to 0.02%/day for 98% P-H2. 

It is difficult to solve file volume problem physically for hydrogen. Liquefaction of hydrogen results in substantial volume reductimi but suffers from the practical difficulties associated with using a fuel at 20 K in a 300 K envircmment. Hydrogen is a well-studied element, and its behavior under pressure, volume, and temperature conditimis (the phase diagram) is well known. These parameters define the required volumes of hydrogen. When storing the element in a container, there is no way to alter them. 

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