Hydrogen thermo physical properties

Interest in the use of SC solvents as a reaction media is founded upon recent advances in our understanding of their unique thermo-physical and chemical properties. Worthy of special note are those thermophysical properties (6) which can be manipulated as parameters to selectively direct the progress of desirable chemical reactions. These properties include the solvent s dielectric constant (7), ion product (8,9), electrolyte solvent power (10,11), transport properties"[viscosity (12), diffusion coefficients (13) and ion mobilities (14)], hydrogen bonding characteristics (15), and solute-solvent "enhancement factors" (6). All these properties are strongly influenced by the solvent s density P in the supercritical state. 

Table 4.12 shows a comparison of safety-relevant thermo-physical and combustion properties of hydrogen with those of methane, propane and gasoline [26]. The flammability limits are affected by temperature, as shown in Figures 4.9 and 4.10, so that a preheated mixture has considerably wider limits for coherent flames [27]. An increase in pressures up to lOkPa has only a small effect. Water vapor has a strongly inhibiting influence on the oxyhydrogen reaction. 

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