Physical And Chemical Properties Of Hydrogen Pdf
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Hydrogen H , a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements.
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Accurate estimation of the thermodynamic and transport properties of H 2 mixed with other gases found within the storage system is therefore essential for the efficient design for the processes involved in this system chain. Moreover, to increase ease of access to the data, a user-friendly software H2Themobank is developed and made publicly available.
To meet the Paris Agreement climate targets, global carbon emissions need to reach net-zero by 1. To achieve this the emissions from fossil fuels must be reduced and the energy mix transition to low carbon energy sources must be accelerated. Hydrogen can support this transition by replacing natural gas for domestic and industrial uses; replacing coal and natural gas for power generation; replacing fuel oil and gasoline to decarbonise transport and facilitating increased renewable energy by acting as an energy carrier to balance supply and demand.
To enable hydrogen as a low carbon energy pathway, gigawatt-scale storage will be required 2 , 3 , 4 , 5. Geological gas storage in underground salt caverns, depleted oil and gas fields and deep aquifers are proven technologies that could provide the necessary scales for hydrogen storage 6 , 7 , 8.
Furthermore, several types of gas have been successfully stored in geological formations, such as natural gas, compressed air and CO 2. Recent work has shown that leakage of injected and stored gas is unlikely, if rigorous standards are in place As depleted gas fields are being considered as storage sites for subsurface hydrogen storage, the in situ gas could be used as cushion gas and hence the working and cushion gasses will be of different compositions 7.
For gas storage in saline aquifers, where there is very little in situ gas present, there is a requirement to use a cushion gas that is significantly cheaper than the working gas. Considered options for aquifer storage cushion gasses are nitrogen, due to its low price, and CO 2 due to its high compressibility and potential for secure storage of this greenhouse gas 14 , 15 , The numerical simulation of any storage scenario must confirm that the working gas can be produced with minimal cushion gas contamination.
Once mixing takes place, the different gaseous components will alter the properties of the gas and introduce significant uncertainty into the expected behaviour of the injected, stored and produced gas, as shown for different gas storage applications 18 , For gas storage modelling, accurate thermodynamic reference data for relevant fluid mixtures, which can either be directly imported into fluid flow modelling software or can be used to confirm existing reservoir engineering software outputs, is an important tool to enhance the compliance for scenario modelling results.
Furthermore, the thermodynamic data for hydrogen-containing systems can enable scientists to have a deeper understanding of reactive flow through porous media during the hydrogen storage process.
Another target in a hydrogen-based economy is to establish a fundamental understanding of metering technologies and the flow measurement principles behind them. In this regard, the thermo-physical properties of hydrogen mixed gases are crucial to understand and model hydrogen transportation and flow measurement processes. Thermo-physical properties of hydrogen-containing gas mixtures over a wide range of pressures and temperatures are pivotal to the design and optimisation of hydrogen production units, transportation, and storage processes see Fig.
Potential applications of thermodynamic properties of hydrogen-containing streams for geological hydrogen storage, flow metering, gas separation 62 and other types of hydrogen storage purposes such as gas hydrates 63 , 64 or metal-organic framework Significant effort has been made to investigate the thermodynamic properties of hydrogen-containing mixtures systematically 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , While the thermodynamic properties of pure hydrogen are well established 36 , 37 , published properties of gas mixtures in relation to geological hydrogen storage 17 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 do not cover the full range of additional gasses and often do not encompass the pressures and temperatures encountered within the hydrogen storage system see Fig.
Pressure and temperature ranges for various hydrogen-based economy systems. Note that the pressure range for depleted gas fields is based on the data available for the UK only 66 , 67 , 68 , To efficiently design and operate the technical processes involved in gas-based energy industries, precise representation of the thermodynamic properties using an accurate EoS is essential. Here, the established and well regarded GERG EoS 46 was used to predict phase behaviour and density of gas mixtures relevant to hydrogen storage, covering the thermodynamic properties of gas phase, liquid phase and supercritical regions.
This equation is valid over a wide range of pressures and temperatures for 21 gas components including 1-methane, 2-nitrogen, 3-carbon dioxide, 4-ethane, 5-propane, 6-n-butane, 7-iso-butane, 8-n-pentane, 9-isopentane, n-hexane, n-heptane, n-octane, hydrogen, oxygen, carbon monoxide, water, helium, argon, n-nonane, n-decane, and hydrogen sulphide. The thermodynamic properties of the fluids that are predicted here at certain temperatures T are based on a multi-fluid approximation using the dimensionless Helmholtz energy obtained from:.
The residual part of the dimensionless Helmholtz energy is given by:. One example is isobaric heat capacity which is given by:. Similarly, enthalpy h , entropy s , Gibbs free energy g , pressure P can be obtained from:. Other thermodynamic properties such as compression factor, internal energy, speed of sound, Joule-Thomson coefficient, etc. The parameters for the components studied in this study are provided in figshare entry The binary interaction parameters used for the components in this study are provided in figshare entry Plots of the other derived thermodynamic properties of H 2 with CH 4 and the thermodynamic properties of H 2 with CO 2 , N 2 , and the typical natural gas are presented in figshare entry Density values are greater in the presence of higher mole fractions of CH 4 in the studied systems as the density of CH 4 is considerably higher than that of H 2.
Thermal capacities have higher values for higher H 2 mole fractions as the heat capacity of pure H 2 is significantly higher than that of pure CH 4 at temperatures and pressures above the critical point of CH 4. Generally, it can be noted that with increasing pressure, the thermal capacities increase for all temperature conditions due to increased intermolecular forces. The peaks in the graphs can be attributed to the fact that near the critical points of the components the heat capacities undergo sudden changes because of the changes in their phase.
In these examples, as the temperatures and pressures are close to the critical conditions of CH 4 , peaks have emerged. Reducing the mole fraction of CH 4 in the system composition moves the system away from the critical point and as such the peaks reduce or do not appear in the graphs iv and v. SuperTRAPP viscosity model is composed of a dilute-gas and residual contribution part, where only the latter is treated with corresponding states.
The dilute gas viscosity is calculated using Chung et al. The terms f and h are so-called equivalent substance reducing ratios, relating the reference fluid to the studying fluid using critical parameter ratios.
For a more detailed examination of the formulations used for calculating viscosity, the reader is referred to reference Plots of the viscosity of H 2 with CO 2 , N 2 , and typical natural gas are presented in figshare entry The thermal conductivity is obtained from:. The former term can be further divided into three contributions i. We refer the reader to the article by Huber 49 for detailed formulation and parameters of the thermal conductivity.
The plots of thermal conductivity of H 2 with CO 2 , N 2 , and the typical natural gas are presented in figshare entry The viscosities of the mixtures are suppressed with increasing H 2 mole fractions in the system as H 2 has a significantly lower viscosity than CH 4 due to its smaller molecule size.
The viscosities of the blends increase with increasing pressure and temperature. This can be attributed to the fact that an increase in pressure or temperature increases the velocities of the random motion of molecules and as such collisions of gas molecules increase, which resists the flow of gas and increases the viscosity.
The unusual behaviour of CH 4 -rich blends at lower temperatures is because of their proximity to the CH 4 critical point. These behaviours can be attributed to the fact that increasing pressure or temperature increases the molecular motion and as such improves the conduction of heat within gas molecules. The unusual behaviour of CH 4 -rich streams at lower temperatures is because of the proximity of these points to the CH 4 critical point. Generally, thermal conductivity values increase with increasing hydrogen mole fractions as pure H 2 has a considerably higher thermal conductivity than CH 4.
For calculating phase equilibrium of the studied mixtures, we used a method established by Michelsen The vapour—liquid phase envelopes calculated for the system studied are provided in Fig. For these points, we used isothermal multi-phase flash to calculate fraction and composition of gas and liquid phase. Here, we followed stability analysis by the successive substitution method which was introduced by Michelsen 54 to minimise the Gibbs energy of the system.
This was followed by the calculation of thermodynamic properties for each phase. Modelled Vapour liquid Equilibria VLE diagrams using the developed tool in this study for various H 2 containing mixtures with different H 2 mole fractions over a wide range of pressures and temperatures. Comparing Fig. We refer readers to an excellent book on thermodynamics and phase behaviour of fluids to read more details about the behaviour of mixed fluids under various pressure and temperature conditions Note that the presence of water vapour, other impurities within the natural gas composition or selecting a different natural gas composition will affect the accuracy of the properties calculated.
An open-source user-friendly software developed using C code in visual studio to ease the access of data for any user. The data is uploaded to figshare and is publicly accessible Some selected data points with large steps are plotted and provided in figshare entry The validity of the code developed for this study is checked by comparing the calculated results for a sample natural gas with existing data in the literature.
Numerous pressure and temperature points were randomly selected for this comparison. The manual validation revealed no error in the written script for this study.
The GERG EoS is valid over a wide range of temperatures, pressures, and gas compositions achieving high accuracy in the prediction of thermodynamic properties of the 21 components listed in the methods section.
Although the GERG EoS has been fitted to a wide range of experimental data, for some binary mixtures only the reducing functions were used. This is because predicting a general rule for accuracy of the GERG EoS for such binary mixtures is a very challenging task as there is no experimental data available for some ranges, therefore the absolute value of error for such ranges is considered to be unknown.
Extrapolated range: which covers temperatures and pressures beyond the previous range. A number of studies using the same thermodynamic models have demonstrated the validity and accuracy of GERG EoS for different mixtures such as CH 4 mixtures 55 , 56 , CO 2 mixtures 57 , 58 , natural gas 59 , 60 and compressed air The average absolute deviations AADs of the GERG EoS calculated data used in this study from the experimental data for the various pressures and temperatures are 0.
The errors in viscosity and thermal conductivity estimates at various pressures, temperatures and gas compositions are uncertain due to the lack of experimental data. It is extremely time consuming and almost impossible to measure all the data required using existing laboratory methods.
A screenshot of the data bank software is provided in Fig. To calculate the required data, the user initially needs to select the gas composition of the closed system. Following this, the H 2 mole fraction in the closed system should be selected. For these systems, the user will be able to get both liquid and gas properties together with the mass fraction of the gas phase. Example of graphical user interface of H2Thermobank. The image presents the calculated thermodynamic and transport properties of the liquid phase and the gas phase.
In addition, the gas mass fraction for this mixture at the entered condition is obtained. The model has been applied to a wide range of pressures, temperatures, and gas mixture compositions which cover the temperature and pressure conditions experienced within the whole hydrogen-based energy system from production to storage in geological formations.
The obtained results could be employed by a range of different stakeholders to effectually design and develop innovative infrastructure for the hydrogen economy. To enable easy access to the data over a wide range of temperature, pressure and concentration conditions without requiring running the abovementioned application for each point, four excel files for each of gas mixture systems are provided. Each worksheet in the excel files is allocated to a different mole fraction of hydrogen.
Data provided here could be sorted and selected for a required range. Taylor, J. Technical and economic assessment of methods for the storage of large quantities of hydrogen.
Hydrogen - H
With a standard atomic weight of 1. The most common isotope of hydrogen, termed protium name rarely used, symbol 1 H , has one proton and no neutrons. The universal emergence of atomic hydrogen first occurred during the recombination epoch Big Bang. At standard temperature and pressure , hydrogen is a colorless , odorless , tasteless , non-toxic, nonmetallic , highly combustible diatomic gas with the molecular formula H 2. Since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays a particularly important role in acid—base reactions because most acid-base reactions involve the exchange of protons between soluble molecules.
As described in Section 8. In the case of neutral atomic hydrogen this orbital is occupied by one electron. Consequently, the chemistry of hydrogen is distinguished by stable bonding arrangements in which the 1 s orbital is "filled" by either. Common bonding arrangements for hydrogen. The E-H and EE bonds in the bridging hydride represent sharing of two or more electrons among the three atoms.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. This chapter summarizes relevant information on hydrogen gas, referred to as hydrogen in this profile. Selected chemical and physical properties are presented. The committee considered all those data in its evaluation of 1-h, h, and day guidance levels for hydrogen. Hydrogen is a colorless, odorless, and tasteless gas Budavari et al. In contact with chlorine, oxygen, or other oxidizers, hydrogen is flammable and explosive and burns with a nearly invisible flame Budavari et al.
Physical Properties of Hydrogen Its symbol is H, and its atomic number is 1. It has an average atomic weight of amu, making it the lightest element. Hydrogen has a melting point of °C and a boiling point of °C. Hydrogen has a density of g/L, making it less dense than air.
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Hydrogen H , a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements. The hydrogen atom has a nucleus consisting of a proton bearing one unit of positive electrical charge; an electron, bearing one unit of negative electrical charge , is also associated with this nucleus. Under ordinary conditions, hydrogen gas is a loose aggregation of hydrogen molecules, each consisting of a pair of atoms, a diatomic molecule, H 2.
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First element in the periodic table. The hydrogen atom, symbol H, is formed by a nucleus with one unit of positive charge and one electron. Uses: The most important use of hydrogen is the ammonia synthesis. The use of hydrogen is extending quickly in fuel refinement, like the breaking down by hydrogen hydrocracking , and in sulphur elimination. Huge quantities of hydrogen are consumed in the catalytic hydrogenation of unsaturated vegetable oils to obtain solid fat. Hydrogenation is used in the manufacture of organic chemical products. Huge quantities of hydrogen are used as rocket fuels, in combination with oxygen or fluor, and as a rocket propellent propelled by nuclear energy.
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