Digital Data Systems (dds)
The CAL2k bomb calorimeter systems
are the most advanced fully automatic "dry" static jacket isothermal
bomb calorimeter systems available today. A quality product which
produces accurate results.
The
calorimeters can operate as either a stand alone unit or via a PC. The
cooler reduces the temperature of a fired vessel by having its hot junction
of the peltier elements cooled down by a continous trickle of mains water
supply. The filling station fills the vessel with oxygen to 3000Kpa (3Mpa)
at a controlled pace, so as not to disturb the sample inside the crucible.
The vessel is the heart of the calorimeter systems. It has an isothermal design with a
microprocessor in its base. The vessel also has a number of temperature sensors within its
cylindrical walls, ensuring absolute accuracy.
The
CAL2k bomb calorimeters with their easy maintenance
and compact size are a must for
any calorimetry application.
What is Bomb
Calorimetery? Bomb calorimetry - a procedure
which determines the heat of combustion or calorific
value of solid and liquid materials which are burned as fuels.
It is a primary test of
great importance to the following industries: coal production, coal analysis, fuel analsyis
power stations, animal feed research (measuring calorific content of feed), food industry (measuring calofric
content of food) educational institutes, waste product incineration, safety
applications, heat ignitable explosives, propellants, scientific research, commercial
analytical laboratories, by-product analysis, building materials etc.
Theory
of "dry isothermal" cv determinations. The Conventional Way:The CV (Calorific Value) of a substance is
measured by burning it in a controlled environment. The resulting heat
released by this combustion i.e. the net temperature rise, is proportional
to the calorific value.
A problem, however,
occurs in that during the determination period (Approx.
10min) some energy
may be gained from or lost to the environment.
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.
The
Isothermal bomb 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.
The
Modified Conventional Way: Prior to development of the CP500, over
a 5-year period, it was demonstrated by "dds" that a polystyrene jacket,
which has very little thermal mass and negligible heat conductivity, could
replace the water jacket. This system was used in the
AMPC.
The Dry
Method:In the conventional way a
vessel is placed in a water container and the water temperature is measured.
Since the water quantity and container are part of the effective heat
capacity, great care must be taken not to change the capacity. Equally
important is that the water acts as a heat sink and a temperature transfer
medium to the sensor.
In the dry
vessel, the water and container are replaced by a highly temperature
conductive aluminium jacket which is shrunk over the stainless steel body at
a very high pressure and forms an integral part of the vessel. The
temperature sensors are equally spaced around the vessel body in between the
aluminium jacket and the stainless steel body. This method eliminates all
the problems with water and results in very fast temperature equilibrium,
with a fixed heat capacity.
Since the
vessel was that much faster, the environment could affect the measurement 5
times less than conventionally.
Also, a warm
vessel is not placed in cold water to achieve equilibrium. The CAL2k-2
solid-state cooler reduces the temperature from warm to ambient, after which
the vessel would be ready for firing again.
The vessel
design was the result of a computer aided process and extensive computer
simulations to predict its temperature behaviour. The vessel is tested and
certified to international material and test requirements.
From the
operator's point of view, the vessel is lighter, easier to handle and plated
on the exterior, for easy cleaning.
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Updated: 16 February 2011