Calorimeter

About: Calorimeter is a research topic. Over the lifetime, 5878 publications have been published within this topic receiving 77157 citations.

Study of the Hydrogenation of Selected Nitro Compounds by Simultaneous Measurements of Calorimetric, FT-IR, and Gas-Uptake Signals

Abstract: The hydrogenation of nitrobenzene (NB) and ethyl-4-nitrobenzoate (NEE) over a Pd/carbon (1 wt % Pd) catalyst has been studied using a new small-scale, pressure-resistant reaction calorimeter (CRC.v4) fitted with an integrated infrared−attenuated total reflection (FT-IR−ATR) probe. This new calorimeter exploits the principles of power compensation and heat balance in combination with IR spectroscopy and on-line gas-uptake measurements. Thus, the reactions can be followed by three independent signals based on different properties of the chemical components. It was shown that, in the temperature and pressure range studied, all three simultaneous measurements of the NB hydrogenation can be described by a simple empirical kinetic model. The presence of an electron acceptor substituent like that in NEE leads to a consecutive hydrogenation with the accumulation of the corresponding hydroxylamine as an intermediate. The different information content of the simultaneously measured signals allow a quantitative desc...

Surface thermocouples for measurement of pulsed heat flux in the divertor of the Alcator C-Mod tokamak.

Abstract: A novel set of thermocouple sensors has been developed to measure heat fluxes arriving at divertor surfaces in the Alcator C-Mod tokamak, a magnetic confinement fusion experiment. These sensors operate in direct contact with the divertor plasma, which deposits heat fluxes in excess of ~10 MW/m(2) over an ~1 s pulse. Thermoelectric EMF signals are produced across a non-standard bimetallic junction: a 50 μm thick 74% tungsten-26% rhenium ribbon embedded in a 6.35 mm diameter molybdenum cylinder. The unique coaxial geometry of the sensor combined with its single-point electrical ground contact minimizes interference from the plasma/magnetic environment. Incident heat fluxes are inferred from surface temperature evolution via a 1D thermal heat transport model. For an incident heat flux of 10 MW/m(2), surface temperatures rise ~1000 °C/s, corresponding to a heat flux flowing along the local magnetic field of ~200 MW/m(2). Separate calorimeter sensors are used to independently confirm the derived heat fluxes by comparing total energies deposited during a plasma pulse. Langmuir probes in close proximity to the surface thermocouples are used to test plasma-sheath heat transmission theory and to identify potential sources of discrepancies among physical models.