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The
CAL2k, ECO and e2K bomb calorimeter systems are "dry"
static jacket isothermal calorimeters.
Comparing
the different bomb calorimetry methods:
Adiabatic System:
In
the adiabatic system the environment is controlled so that no energy
is lost or gained. To achieve this state, the Calorimeter Vessel
(bomb) and bucket are surrounded by a water jacket which
is strictly temperature controlled by a system of circulators,
heaters and coolers, so that it has the same temperature
as the inner bucket.
Isothermal
System:
The
Isothermal calorimeter measures the effect that the environment has on the
bucket before and after the determination and corrects the result
accordingly. This implies that the environment is stable during the
determination. To achieve stability a large body of water surrounds the
vessel and bucket assembly, which is thermally stable.
DDS Developed
their first calorimeter system in 1972, this system was a full isothermal
system with water jacket. Prior
to development of the CP500, it was demonstrated by Digital
Data Systems that a polystyrene jacket, which has very little thermal mass
and negligible heat conductivity, could replace the water
jacket. The
system was referred to as the "Dry
Method".
Isoperibol (Isothermal)
calorimeter:
With an isoperibol calorimeter a water jacket
surrounds the bucket in which the vessel sits. The
surrounding water jacket is controlled to be at a constant temperature.
When a sample is fired, the heat from the vessel is transferred to the
water in the bucket and the temperature rise of the bucket water is
measured to determine the calorific value of the sample.
"Dry"
Static Jacket (Isothermal) calorimeter (DDS - CAL2k, ECO and
e2K):
The "dry" static jacket
isothermal method has no water inside the calorimeter. An aluminium sleeve that
is an integral part of the vessel replaces the bucket. The sleeve
transfers the heat from the combustion process rapidly and evenly around
the outside shell of the vessel. The temperature sensors are located
between the combustion vessel and the sleeve. The temperature rise of the
vessel is measured to determine the calorific value of the sample. The
surrounding water jacket is replaced by polystyrene that is insulated from
the outside environment by an aluminium box. The timing of the
determination and the quality of the insulation is such that the
environment has negligible effect on the
determination. |
