Calorimeter

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

Thermodynamic properties of magnesium oxide and beryllium oxide from 298 to 1,200 °K

Abstract: As a step in developing new standards of high-temperature heat capacity and in determining accurate thermodynamic data for simple substances, the enthalpy (heat content) relative to 273 deg K, of high purity fused magnesium oxide, MgO, and of sintered beryllium oxide, BeO, was measured up to 1,173 deg K. A Bunsen ice calorimeter and the drop method were used. The two samples of BeO measured had surfaceto-volume ratios differing by a factor of 15 or 20, yet agreed with each other closely enough to preclude appreciable error attributable to the considerable surface area. The enthalpies found for MgO are several percent higher than most previously reported values. The values are represented within their uncertainty (estimated to average plus or minus 0.25%) by empirical equations. Values of enthalpy, heat capacity, entropy, and Gibbs free-energy function are tabulated from 298.15 to 1,200 deg K. (auth)

Development of a large-scale biocalorimeter to monitor and control bioprocesses.

Abstract: Calorimetry has shown real potential at bench-scale for chemical and biochemical processes. The aim of this work was therefore to scale-up the system by adaptation of a standard commercially available 300-L pilot-scale bioreactor. To achieve this, all heat flows entering or leaving the bioreactor were identified and the necessary instrumentation implemented to enable on-line monitoring and dynamic heat balance estimation. Providing that the signals are sufficiently precise, such a heat balance would enable calculation of the heat released or taken up during an operational (bio)process. Two electrical Wattmeters were developed, the first for determination of the power consumption by the stirrer motor and the second for determination of the power released by an internal calibration heater. Experiments were designed to optimize the temperature controller of the bioreactor such that it was sufficiently rapid so as to enable the heat accumulation terms to be neglected. Further calibration experiments were designed to correlate the measured stirring power to frictional heat losses of the stirrer into the reaction mass. This allows the quantitative measurement of all background heat flows and the on-line quantitative calculation of the (bio)process power. Three test fermentations were then performed with B. sphaericus 1593M, a spore-forming bacterium pathogenic to mosquitoes. A first batch culture was performed on a complex medium, to enable optimization of the calorimeter system. A second batch culture, on defined medium containing three carbon sources, was used to show the fast, accurate response of the heat signal and the ability to perfectly monitor the different growth phases associated with growth on mixed substrates, in particular when carbon sources became depleted. A maximum heat output of 1100 W was measured at the end of the log-phase. A fed-batch culture on the same defined medium was then carried out with the feed rate controlled as a function of the calorimeter signal. A maximum heat output of 2250 W was measured at the end of the first log-phase. This work demonstrates that real-time quantitative calorimetry is not only possible at pilot-scale, but could be readily applied at even larger scales. The technique requires simple, readily available devices for determination of the few necessary heat flows, making it a robust, cost-effective technique for process development and routine monitoring and control of production processes.

Heat Capacity of CoCl2·2H2O between 7 and 120°K and its Anomaly Associated with Magnetic Transition

Abstract: A small adiabatic calorimeter is described, which is capable of measuring the solid heat capacities between 5° and 300°K continuously. The heat capacities of CoCl 2 ·2H 2 O were measured between 7° and 120°K. A lambda-shaped anomaly in the heat capacity, due apparently to a transition between antiferromagnetic and paramagnetic states, occurs below 20°K with the peak at 17.20°K. An analysis of the experimental heat capacity curve was made in the light of the series expansion method through help of the experimental heat capacities of CoCl 2 ·6H 2 O at the low temperatures in a semi-empirical way. This result gives the exchange interactions | J |/ k =10.8°K in the direction of the chain of the coordinated Co 2+ ions and | J '|/ k =2.03°K between Co 2+ ions in the neighboring chains. The total entropy of the transition is 1.39 cal/deg mole and about 37% of this is acquired in the temperature region above 17.20°K.

An Improved Shashlyk Calorimeter

Abstract: Shashlyk electromagnetic calorimeter modules with an energy resolution of about 3 % / E ( GeV ) for 50 – 1000 MeV photons have been developed, and a prototype tested. Details of these improved modules, including mechanical construction, selection of wave shifting fibers and photo-detectors, and development of a new scintillator with improved optical and mechanical properties are described. How the modules will perform in a large calorimeter was determined from prototype measurements. The experimentally determined characteristics of the calorimeter prototype show energy resolution of σ E / E = ( 1.96 ± 0.1 ) % ⊕ ( 2.74 ± 0.05 ) % / E , time resolution of σ T = ( 72 ± 4 ) / E ⊕ ( 14 ± 2 ) / E ( ps ) , where photon energy E is given in GeV units and ⊕ means a quadratic summation. A punch-through inefficiency of photon detection was measured to be e ≈ 5 × 10 - 5 ( Θ beam > 5 mrad ) .