Lower heating value range

The volatiles contents of product chars decreased from ca 25—16% with temperature. Char (lower) heating values, on the other hand, increased from ca 26.75 MJ /kg (11,500 Btu/lb) to 29.5 MJ /kg (12,700 Btu/lb) with temperature. Chars in this range of heating values are suitable for boiler fuel apphcation and the low sulfur content (about equal to that of the starting coal) permits direct combustion. These char products, however, are pyrophoric and require special handling in storage and transportation systems. 

Pressurised alkaline water electrolysis technology has been state-of-the-art for many years. The system efficiency of real electrolysers ranges from 62% to 70%, including all auxiliaries (AC/DC converter, pumps, blowers, controls, etc.) based on the lower heating value of hydrogen. 

Electrolyzer systems of this scale should be capable of operating with an overall efficiency of 63.5 percent lower heating value [LHV], including all parasitic loads other than compression. The electrolyzer is assumed to be able to generate hydrogen at an internal pressure in the 150 psi range ... 

It can be seen that compared with petroleum diesel fuel, methyl esters (1) have higher density, (2) fall into the lower range of viscosity, (3) have the same or higher cetane numbers, and (4) have lower heating value. Canola methyl esters are in the middle range of properties among the three oils, with low viscosity, good cetane... 

In many practical appliances, which range from steam engines to internal combustion engines, the carbon dioxide and water products are released to the atmosphere at comparatively high temperatures and the heat that these gases hold above the reference temperature of 298.15 K is lost. This heat consists of both the sensible heat i.e., the heat carried by the substance - its heat capacity ) and the latent heat of condensation of the steam. For practical engineering purposes, it has become customary, therefore, to define a lower heating value (LHV), which corresponds, arbitrarily, to the maximum heat recoverable when the reaction products are emitted at 423.15 K. 

Natural-gas-to-hydrogen conversion efficiency, defined as the ratio of the lower heating values of the hydrogen output and the natural gas input, is in the range 70-80% for both the FTR and ATR conhgurations shown in Figs 10.1 and 10.2. 

Fuel Formula Sulphur content [wt. ppm] [only commercially available fuels] Lower heating value [kj/mol] Flammability limits lower, higher [Vol.%] Density [kg/m ] Boiling point or boiling range [°C] Heat of vaporization [kJ/mol] Heat capacity [J/(mol K)] At 20° C... 

A similar concept study was performed by Seo et al. [449] for natural gas reforming. However, fixed-bed reactors were used and the heat supply originated not from autothermal reforming, but from a catalytic burner in the centre of the fuel processor. Two fuel processors of this type were then built with 1- and 2-kW electrical power equivalents [450]. The smaller system was operated at a S/C ratio 3.0 and 89% methane conversion was achieved, while other hydrocarbons present in the natural gas feed were completely converted. The fuel processor efficiency was calculated as the ratio of the lower heating value of the hydrogen produced to the lower heating value of natural gas fed to the reformer and the burner. It was in the range between... 

Efficiencies of present fuel cell plants are in the range of 30 to 55 percent based on the lower heating value (LHV) of the fuel. Hybrid fuel cell/reheat gas turbine cycles that offer efficiencies greater than 70 percent LHV, using demonstrated cell performance, have been proposed. 

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