Environmental Engineering Reference
In-Depth Information
Urban, W. (ed.) (2010) Gasnetze der Zukunft - Studie zu den Auswirkungen der
Biogaseinspeisung in das Erdgasnetz auf den Netzbetrieb und Endverbraucher.
UMSICHT, Oberhausen.
16.10 Appendix: glossary
Additional gas: (also referred to as supplementary gas) a gas with distinctly
different combustion characteristics and composition to those of the
local distributed natural gas (base gas) and that can only be admixed to
a limited extent with the base gas.
Base gas: local distributed natural gas with distinctive combustion behav-
iour and gas composition which sets default values for any gas feed-in.
Complementary gas: a gas whose combustion behaviour is the same as that
of the natural gas in the distribution network (base gas) but whose
composition and basic combustion characteristics are different.
Heating value (H): the heating value or energy value of a substance, e.g. a
fuel, is the amount of heat released during the combustion of a specified
amount of it. The heating value is a characteristic for each substance. It
is measured in units of energy per unit of the substance, usually mass,
such as: kJ/kg, kJ/mol. Within the gas industry the heating value is
usually related to m
3
STP.
Inferior heating value (H
i
): also known as lower heating value (LHV) (net
calorific value (NCV) or lower calorific value (LCV)) and is determined
by subtracting the heat of vaporization of the water vapor from the
higher heating value. H
i
assumes that the latent heat of vaporization of
water in the fuel and the reaction products is not recovered.
Liquefied petroleum gas (LPG): flammable mixture of hydrocarbon gases;
consists mainly of propane and butane and their isomers. Under
atmospheric conditions, LPG is gaseous, distinctly heavier than air and
can be liquefied at low pressure.
Relative density (d): quotient of the density of a distinctive gas (e.g. natural
gas) and density of dry air at equal temperature and pressure.
Superior heating value (H
s
): also known as higher heating value (HHV) (or
gross energy or upper heating value or gross calorific value (GCV) or
higher calorific value (HCV)), it is determined by bringing all the
products of combustion back to the original pre-combustion tempera-
ture and, in particular, condensing any vapor produced.
Wobbe index (W
i
): the quotient of the heating value and the square root of
the relative density. Depending on the underlying heating value, there is
a superior or inferior Wobbe index.
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