Temperature compensated chambers for measuring the heats of reation of materials, heats of fusion, combustion, radio-nuclide decay, endo-exothermic heat releases, and biological thermogenesis. Heat releases to 0.1×10-6 Watts can be determined at temperatures from cryogenics to 600oC
Radioisotope Microcalorimeter Specs
The series CR-100 Microcalorimeters provide an accurate measurement of radioisotope heat release rates.
The thermal gradient calorimeter transfers all the heat developed in a reaction to its surrounding heat sink at a constant temperature. The calorimeter walls thermoelectrically transduce sample heat release into an electrical signal which is directly proportional to the energy release of the source. Transient as well as steady state energy releases may be measured.
Sample chamber volume range……….1 in3 to any required volume
The calorimeter walls are composed of a thin high temperature thermopile structure containing thousands of junctions. One set of junctions is in thermal contact with one wall surface, and the other set is in contact with the opposite surface. As heat flows through the walls (Fig. 1) a temperature difference is established between both sets of thermopile junctions, thus generating a voltage, which is directly proportional to the heat flow. The large number of thermopiles develop extreme sensitivity to minute heat flows.
Calorimeters are constructed in a range of designs incorporating large sample chambers for high heat fluxes (cover) or small sample chambers capable of measuring low heat releases (Fig. 2).
Each calorimeter is calibrated at a base temperature of 70°F by a known, electrical heat source in thermal equilibrium with the system.
The calibration constant is expressed in terms of wattage input versus millivolt output. A temperature correction curve is also supplied for use at elevated temperatures.
The CR-100 Series calorimeters are designed to measure both microcaloric and megaocaloric heat release from pure or mixed radioisotopes. The magnitude of the generated signal is linearily proportional to the mean intensities of the sample.
Other applications include: physical, chemical and biological thermogenesis, specific heats, heats of fusion and reaction.
To measure microwatt heat flow accurately, it is necessary to provide a stable, cooling environment. However, most constant temperature cooling baths exhibit small fluctuations, which may generate signals the same order of magnitude as those produced by the sample. To avoid this large noise to signal ratio, a temperature compensated enclosure has been developed (Fig. 4). This double cup system contains both an active and passive chamber having matched sensitivities in opposition. Thus, spurious, external temperature fluctuations are compensated for, and only the heat release from the sample source is detected.
COMPENSATED MICROCALORIMETER SPECIFICATIONS
Sample chamber series……….1″ – 8″ Dia. x 1″ – 72”
STANDARD MODELS, SINGLE CHAMBER
Models CR-100-1 and CR-100-2 are also available for 600 F operating temperature at reduced sensitivities.
OTHER ITI THERMAL INSTRUMENTS
Thermal Conductivity Apparatus, Heat Flux Meters, HEAT-PROBE™, Accelerator target Calorimeters, Radiometers, Thermal Flux Standards.