Showing papers on "Calorimeter published in 1988"
TL;DR: In this article, the enthalpies of fusion and transition together with heat capacities in both solid and liquid phases have been measured on LiNO3, NaNO3 and KNO3 with a high accuracy by differential scanning calorimetry (DSC).
Abstract: Enthalpies of fusion and transition together with heat capacities in both solid and liquid phases have been measured on LiNO3, NaNO3, and KNO3 with a high accuracy by differential scanning calorimetry (DSC). Polynomial expressions of heat capacities are given.
101 citations
01 Mar 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the relationship among the speed of response, the signal-to-noise ratio and the charge collection time in ionization chamber calorimeters is analyzed, and it is shown that a dominant limiting factor to the response is the charge transfer time from the electrodes to the amplifier determined by the electrode capacitance CD and the inductance of connections.
Abstract: Relations among the speed of response, the signal-to-noise ratio and the charge collection time in ionization chamber calorimeters are analyzed. A dominant limiting factor to the speed of response is the charge transfer time from the electrodes to the amplifier determined by the electrode capacitance CD and the inductance of connections Ls. The time parameter L s C D sol1 2 has to be at least an order of magnitude smaller than the required length of the overall calorimeter response. The charge collection time plays a secondary role in determining the speed of response, while together with the charge yield it affects the signal-to-noise ratio.
86 citations
TL;DR: In this paper, the authors measured the thermal diffusivity, specific heat capacity, and density of mixtures of alkaline carbonate salts, as well as measured these properties using an adiabatic scanning calorimeter.
Abstract: The purpose of this study is to develop measuring methods for the thermal diffusivity, the specific heat capacity, and the density of molten salts, as well as to measure these properties of mixtures of alkaline carbonate salts. The thermal diffusivity is measured by the stepwise heating method. The sample salt is poured into a thin container, and as a result, a three-layered cell is formed. The thermal diffusivity is obtained from the ratio of temperature rises at different times measured at the rear surface of the cell when the front surface is heated by the stepwise energy from an iodine lamp. The specific heat capacity is measured using an adiabatic scanning calorimeter. The density is measured by Archimedes' principle. Thermal conductivity is determined from the above properties. Measured samples are Li2CO3-K2CO3 (42.7–57.3, 50.0-50.0, and 62.0-38.0 mol%).
80 citations
TL;DR: All three of the blue phases of the liquid-crystal cholesteryl nonanoate are thermodynamically stable and that all the phase transitions observed are first order.
Abstract: An adiabatic scanning calorimeter has been used to study the thermal behavior of the liquid-crystal cholesteryl nonanoate in a temperature range covering all phase transitions involving the three different blue phases occurring in this substance. Results for the temperature dependence of the enthalpy and the heat capacity are reported. It is found that all three of the blue phases are thermodynamically stable and that all the phase transitions observed are first order.
78 citations
TL;DR: An adiabatic calorimeter for a vapor-deposited sample was newly constructed, and thermal properties of amorphous butyronitrile were studied in detail as mentioned in this paper.
Abstract: An adiabatic calorimeter for a vapor-deposited sample was newly constructed, and thermal properties of amorphous butyronitrile were studied in detail. The cryostat was cooled down to 10 K with a built-in refrigerator. The sample vapor was introduced through a filling tube into a calorimeter cell. During the deposition, the temperature of the cell was kept as low as possible by making mechanical-thermal contact with a refrigerant tank, while that of the tube was kept higher than the dew point of the vapor. A special device was made in order to minimize the heat flow from the tube to the cell. Butyronitrile vapor was deposited at 67 and 40 K in the first and the second experiments, respectively. Another kind of vitreous sample was prepared by rapidly cooling the liquid in comparison with the vapor-deposited vitreous samples. Heat capacities of the samples were measured in the temperature range from 15 to 175 K with an imprecision of about ±0.5%. Both the vapor-deposited and the liquid-quenched samples exhibited heat capacity jump characteristics of the glass transition of the same temperature, viz. 97 K. A large heat evolution amounting to 1.3 kJ mol −1 in total was observed in the case of vapor-deposited solid over a wide range of temperatures between the deposition temperature and the glass transition temperature. The microscopic picture for this heat evolution is discussed on the basis of the concept of the cluster structure for a liquid.
73 citations
TL;DR: In this paper, a microcalorimeter was proposed to measure the energy released in the absorption of a single photon by sensing the rise in temperature of a small absorbing structure, which can in principle be made as low as 1 eV.
Abstract: Thermal detectors for X-ray spectroscopy combining high spectral resolution and quantum efficiency have been developed. These microcalorimeters measure the energy released in the absorption of a single photon by sensing the rise in temperature of a small absorbing structure. The ultimate energy resolution of such a device is limited by the thermodynamic power fluctuations in the thermal link between the calorimeter and isothermal bath and can in principle be made as low as 1 eV. The performance of a real device is degraded due to noise contributions such as excess 1/f noise in the thermistor and incomplete conversion of energy into phonons. The authors report some recent advances in thermometry, X-ray absorption and thermalization, fabrication techniques, and detector optimization in the presence of noise. These improvements have resulted in a device with a spectral resolution of 17 eV FWHM, measured at 6 keV. >
59 citations
TL;DR: In this article, the thermal energy transferred to noncombusting gases by a spark at pressures from 1 to 7 atmospheres was measured using a pressure-rise calorimeter, and the energy transfer efficiency (from electrical to thermal energy) was determined for conventional coil ignition systems, a plasma jet ignitor, and an ultra short pulse (USP) ignitor.
Abstract: The thermal energy transferred to noncombusting gases by a spark at pressures from 1 to 7 atmospheres was measured using a pressure-rise calorimeter. The energy transfer efficiency (from electrical to thermal energy) was determined for conventional coil ignition systems, a plasma jet ignitor, and an ultra-short pulse (USP) ignitor
47 citations
TL;DR: A pressure-scanning calorimeter operating in the pressure range from 0.1 to 400 MPa at temperatures from 303 to 503 K is described in this article, with a computer and a stepping motor.
40 citations
TL;DR: In this paper, two types of isoperibolic mixing calorimeters are presented, which allow to determine directly the enthalpy of mixing of liquid alloys as a function of concentration and temperature.
Abstract: High temperature calorimetric methods used in metallurgy are discussed. Two types of isoperibolic mixing calorimeters are presented. They allow to determine directly the enthalpy of mixing of liquid alloys as a function of concentration and temperature and to measure the derivative as a function of concentration for temperatures up to 1300 K and 2000 K, respectively. A high temperature solution calorimeter in which a liquid metal or alloy is used as the bath (maximum temperature 1800 K) can be used to determine the heat of formation of solid alloys and to measure the partial enthalpy of mixing at infinite dilution. With a drop calorimeter it is possible to measure the thermodynamic properties of highly reactive alloy systems. Thermodynamic measurements of high melting refractory metals and alloys for temperatures up to 4000 K can be achieved with levitation calorimetry.
38 citations
15 Mar 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a test with a lead-copper calorimeter in liquid argon is presented, and the electromagnetic energy resolution obtained is 10%/√E. For hadronic showers the software weighting technique is demonstrated to work.
Abstract: Results from a test with a lead-copper calorimeter in liquid argon are presented. The electromagnetic energy resolution obtained is 10%/√E. For hadronic showers the software weighting technique is demonstrated to work. A hadronic energy resolution of 50%/√E is found.
29 citations
TL;DR: In this article, a laboratory scale polymerization calorimeter was developed to measure heatflux of the reaction independently from heat transfer coefficient through reactor wall which often changes during the course of polymerization.
TL;DR: In this paper, the enthalpy increments of Cs 2 MoO 4 were measured from 415 to 700 K in a drop calorimeter, and the temperature and the entropy of transition were determined by DSC.
TL;DR: In this article, a basic study is made of determination of the effect of the heating rate selected in calorimetry working in the scanning mode on the values obtained for the kinetic parameters.
TL;DR: In this article, the instrumental parameters of a heat-flux DSC are now determined at two temperatures whereby the accuracy of the results is improved, and the method also allows a more exact determination of fusion temperature.
TL;DR: A differential twin-cell heat flow calorimeter has been constructed for the measurement of the enthalpy changes of the reaction of hydrogen gas with intermetallic compounds as a function of their hydrogen contents.
Abstract: A differential twin-cell heat flow calorimeter has been constructed for the measurement of the enthalpy changes of the reaction of hydrogen gas with intermetallic compounds as a function of their hydrogen contents. It was designed especially for use with those intermetallic compounds which form very stable hydride phases; therefore prior to the calorimetric studies it must be possible to evacuate the sample in situ at elevated temperatures to remove all of the hydrogen resulting from the activation procedure. The calorimeter was employed in this research for the determination of the thermodynamics of the reaction of H 2 with ErFe 2 H x over the range of hydrogen contents x = 0.4. ErFe 2 H is a multiplateau system; the enthalpy change for hydride formation corresponding to the plateau near x = 3 is more exothermic than that corresponding to the preceding plateau near x = 2. In addition to the calorimetric determination of the enthalpies of reaction, the free energies were determined simultaneously from the equilibrium hydrogen pressures. Using these free energy and enthalpy data the entropies were also obtained over a range of hydrogen contents.
TL;DR: In this paper, the influence of the electric field on specific heat, thermal conductivity and pyroelectric coefficient is described by means of a flux calorimeter and the behavior of other properties, such as thermal diffusivity and electrocaloric coefficient, is deduced.
Abstract: Simultaneous measurement of the influence of the electric field on specific heat, thermal conductivity and pyroelectric coefficient is described as a summary of previous papers. From these coefficients, which are determined by means of a flux calorimeter, the behaviour of other properties, such as thermal diffusivity and electrocaloric coefficient, is deduced.
TL;DR: The multifrequency calorimeter developed in this laboratory has been designed to measure the frequency spectrum of the enthalpy fluctuations, thus allowing us to estimate thermodynamic parameters as well as relaxation times.
Abstract: A multifrequency calorimeter has been designed to measure the amplitude and time regime of the enthalpic fluctuations associated with structural or conformational transitions in biological macromolecular systems. The heat capacity function at constant pressure is directly proportional to the magnitude of the enthalpic fluctuations in a system. Biological macromolecules undergo thermally induced transitions of different kinds. Within the transition region, these systems exhibit relatively large enthalpy fluctuations that give rise to the characteristic peaks observed by conventional differential scanning calorimetry. The multifrequency calorimeter developed in this laboratory has been designed to measure the frequency spectrum of the enthalpy fluctuations, thus allowing us to estimate thermodynamic parameters as well as relaxation times. This information is obtained from the attenuation in the amplitude or phase-angle shift of the response of the system to a periodic temperature oscillation. This instrument has been used to study the gel-liquid crystalline transition of phosphatidylcholine bilayers. The frequency-temperature response surface for large dimyristoyl phosphatidylcholine vesicles has been measured in the frequency range 0.04-1 Hz. The data are consistent with two enthalpic relaxation processes with time constants on the order of 3.8 s and 80 ms at the midpoint of the main gel-liquid crystalline transition.
TL;DR: In this article, a series of large pool fires has provided temperature and heat flux data for a large, thermally massive object, where tower temperatures were obtained at 4 elevations.
TL;DR: In this article, the temperature dependence of the isobaric heat capacities and the temperatures and enthalpies of physical transitions of 4-methylcyclohexene, glycollide, and 1,1,3, 3,5,5-hexaethylcyclotrisiloxane have been studied between 13.4 and (330 to 400) K in adiabatic and vacuum-adiabatic calorimetric cryostats within about 0.2 per cent.
01 Dec 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a test was performed in t9 beam at the CERN-PS (proton synchrotron) with incoming electron energies of 2, 4 and 6 GeV and it was found that in the investigated radial region, the structure of the lateral shower development has two components.
Abstract: In order to find the optimal granularity of the electromagnetic section of a hadronic calorimeter, with tungsten or uranium absorbers, lateral shower extension is to be defined. A test was performed in t9 beam at the CERN-PS (proton synchrotron) with incoming electron energies of 2, 4 and 6 GeV. It was found that in the investigated radial region, the structure of the lateral shower development has two components.
TL;DR: In this paper, the specific heat of samples of Y1−xPrxBa2Cu3O7−y for x = 0.5 has been measured from 4.5 to 65 K using a quasi-adiabatic calorimeter.
01 Mar 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: A review of experimental studies carried out by the SICAPO collaboration at CERN on Si/W and Si/U sandwich calorimeters is presented in this paper, where results on the response of sensed energy versus incoming electron energy and depleted layer width, of the longitudinal and lateral development of electromagnetic showers and of the energy resolution are compared with data from Hamburg (Si/Pb) and Tokyo(Si/W) calorimeter.
Abstract: A review of experimental studies carried out by the SICAPO collaboration at CERN on Si/W and Si/U sandwich calorimeters is presented. Results on the response of sensed energy versus incoming electron energy and depleted layer width, of the longitudinal and lateral development of electromagnetic showers and of the energy resolution are given and compared with data from Hamburg (Si/Pb) and Tokyo (Si/Pb and Si/W) calorimeters. The performance of the electromagnetic section of a large Si/U hadronic calorimeter is also described.
TL;DR: In this article, a computer program for the determination of solution and reactions in a quasi-adiabatic calorimeter has been presented, which is made up of the following steps: (1) calibration curve; (2) cooling curve, (3) reaction curve; and (4) equilibrium temperature.
TL;DR: In this paper, a linear, first order, constant coefficient system was used to recover the dynamic variation in heat production of animals, normally obscured when measured using indirect calorimeters, via deconvolution and methods were presented to do this.
Abstract: AN indirect calorimeter was shown to be adequately described as a linear, first order, constant coefficient system. Dynamic variation in the heat production of animals, normally obscured when measured using indirect calorimeters, could, therefore, be recovered via deconvolution and methods are presented to do this. These methods were applied in the measurement of activity related heat production of 40 kg swine. When the deconvolution methods were applied to measured data, a close correlation was found between observed behavior and the resulting changes in heat production. Results showed that, on average, heat production rate was increased 95% above the resting level during standing activity
15 Feb 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors discuss the possibilities opened up by a recently developed field effect transistor of large gate area, whose design has been tailored to the applications in front-end preamplifiers for calorimeters and other large capacitance detectors of frequent use in elementary particle physics.
Abstract: The achievement of adequate signal-to-noise ratios in the measurement of the energy released by ionizing particles in detectors of large capacitance such as, for instance, calorimeter cells, frequently relies upon transformer coupling between detector and preamplifier. Such a solution, however, may not be feasible if the detector is located in a strong magnetic field. This paper discusses the possibilities opened up by a recently developed field effect transistor of large gate area, whose design has been tailored to the applications in front-end preamplifiers for calorimeters and other large capacitance detectors of frequent use in elementary particle physics.
TL;DR: In this paper, a combined system of the Newsham vaporization calorimeter and the Pitzer gaseous heat capacity flow calorimeters was reconstructed with modifications, with deviations of 0.4% and 0.9%, respectively, with anomalies due to association noted.
Abstract: A combined system of the Newsham vaporization calorimeter and the Pitzer gaseous heat capacity flow calorimeter were reconstructed with modifications. Both calorimeters were calibrated with benzene, the liquid standard, and were found to be acceptable for measurements, with deviations of 0.4% and 0.9%, respectively. Heats of vaporization of pure ethanol under five pressures and binary mixtures of ethanol and benzene under normal pressure were determined. Gaseous molar heat capacities of pure ethanol under three pressures and of binary mixture of ethanol and benzene at two temperatures were also determined, with anomalies due to association noted. Association of ethanol molecules in the vapor phase was discussed and analyzed, with heats of association and entropy change of association calculated.
TL;DR: In this article, a microcalorimeter is designed for measuring the heat capacity of a 1- µl liquid sample, which can be determined within an accuracy of 1% with the help of light-irradiation-type ac calorimetry.
Abstract: Making the most of light-irradiation-type ac calorimetry, a microcalorimeter is designed for measuring the heat capacity of a 1- µl liquid sample. The heat capacity can be determined within an accuracy of 1%.
TL;DR: In this article, the specific heat capacity of 2-methylpentane was measured with an accuracy of ± 2 per cent with a high-pressure calorimeter for the pressure range 0.1 MPa to 756 MPa at the temperature 299 K.
TL;DR: In this paper, the construction and operation of a new fully automated microcalorimeter is described, which allows specific heat measurements to be performed on small samples in the 10 mg-range at low temperatures (10 K
Abstract: The construction and operation of a new fully automated microcalorimeter is described.This instrument allows specific heat measurements to be performed on small samples in the 10 mg-range at low temperatures (10 K
Patent•
28 Nov 1988
TL;DR: In this paper, a fast reacting, automated calorimeter includes a reaction vessel containing a chemically reacting mass, a fluid circulation system containing heat transfer fluid, and a circuit, preferably including a computer, responsive at least to the flow rate signal and generating a heat flow signal generally related to instantaneous rate of heat exchange between the reacting mass and the fluid.
Abstract: AUTOMATED CALORIMETER AND METHODS OF OPERATING THE SAME Abstract of the Disclosure A fast reacting, automated calorimeter includes a reaction vessel containing a chemically reacting mass, a fluid circulation system containing heat transfer fluid, a portion of the system passing the fluid through the reaction vessel for exchanging heat between the fluid and the reacting mass, a flow rate controller at least generally responsive to variations in temperature of the reacting mass to vary the flow rate of the fluid circulated through the reaction vessel portion of the circulation system, a flow rate signal generator generating a signal related to the varying flow rate of the fluid passing through the reaction vessel portion of the fluid circulation, and a circuit, preferably including a computer, responsive at least to the flow rate signal and generating a heat flow signal generally related to instantaneous rate of heat exchange between the reacting mass and the fluid. Heat transfer is measured and the reaction is controlled by varying, during the course of the reaction, the flow rate of heat transfer fluid fed into the reaction vessel at a predetermined temperature.