IKA C 6000 global standards, Руководство по эксплуатации

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The standard calorimetric procedure
Determining the calorific value
Test condition
Combustion is carried out in a calorimeter under
specific conditions. The
IKA
®
C 6000 global stan-
dards/isoperibol is filled with a weighed fuel sam-
ple, the fuel sample is ignited and the temperature
increase in the calorimeter system measured.
The specific calorific value of the sample is calcu-
lated as follows:
• Weight of fuel sample
• Heat capacity (C-value) of calorimeter system
• Calculated temperature increase of water in the
calorimeter system
For complete combustion the decomposi-
tion vessel is filled with pure oxygen (qual-
ity 3.5). Adjust the pressure of the oxygen
atmosphere in the decomposition vessel at
3 MPa (possible max. 4 MPa). The exact de-
termination of the gross calorific value of
a substance requires that the combustion
proceed under precisely defined conditions.
The applicable standards are based on the
following assumptions:
• Depending on the start temperatur that is set,
the temperature of the fuel before the combus-
tion is 20 °C upto 30 °C.
• The water contained in the fuel before the
combustion and the water that is formed when
compounds comprising the fuel containing hy-
drogen undergo combustion is present in a liq-
uid state .
• No oxidation of the atmospheric nitrogen has
taken place.
The gaseous products after combustion consist
of oxygen, nitrogen, carbon dioxide, sulfur diox-
ide and the oxidation products of the sample.
• Solid substances may be formed (for example
ash).
Often, however, the combustion products that
form the basis of the standards are not the only
products that are formed. In such cases, an analy-
sis of the fuel sample and the products of com-
bustion are necessary to provide data for a cor-
rection cal-culation. The standard gross calorific
value is then determined from the measured gross
calorific value and the analysis data.
The gross calorific value Ho is formed as the
quotient of the amount of heat liberated upon
total combustion of a solid or liquid fuel and the
weight of the fuel sample. The compounds com-
prising the fuel that contain water must be pres-
ent in liquid state after the combustion.
The formula for the calorific value is
Ho = (CV * DT – Qext) / m
where
Ho Calorific value
m Mass of the sample
DT Measured and corrected increase in tem-
perature
Qext All external energy originating from the ig-
nition wire, the ignition aids, the combus-
tion aids and the formation of acids
CV C value (thermal capacity) of the calorimeter
The heat value Hu is equal to the gross calorific val-
ue less the energy of condensation of the water that
was contained in the fuel and was formed by the
combustion. The heat value is the more important
quantity for technical purposes, since in all impor-
tant technical applications, the heat value is the only
quantity that can be evaluated in terms of energy.
For information on the fundamental princi-
ples of calculation for gross calorific value and
heat value, please refer to the applicable stan-
dards (for example: DIN 51 900; ASTM D 240;
ASTM D 1989, ISO 1928).