Showing papers on "Calorimeter published in 1999"
01 Jan 1999
301 citations
TL;DR: In this paper, a mathematical model based on the previously proposed mechanism was developed in order to calculate self-heating rate profiles, which reproduce qualitatively the experimentally measured trends, suggesting the reaction kinetics are correctly represented by the model.
Abstract: Accelerating rate calorimeter (ARC) results for mesocarbon microbead electrodes in electrolyte and a reaction mechanism to qualitatively understand the results have been previously reported in the preceding companion paper. Here, a mathematical model, based on the previously proposed mechanism, is developed in order to calculate self‐heating rate profiles. The calculated self‐heating rate profiles reproduce qualitatively the experimentally measured trends. The mathematical model for the self‐heating of this anode material in electrolyte can be used to calculate differential scanning calorimeter (DSC) profiles. Using adjustable parameters, determined and fixed by comparisons to ARC experiments, the calculated DSC profiles approximate the measured DSC profiles, suggesting the reaction kinetics are correctly represented by the model. © 1999 The Electrochemical Society. All rights reserved.
164 citations
01 Jul 1999
TL;DR: In this paper, the authors present a survey of heat flux measurement techniques available for specific applications and a guide to the appropriate selection of a heat flux sensor according to the demands of response, sensitivity, temperature of operation, heat flux intensity, manufacturing constraints, commercial availability, cost, thermal disturbance and acceleration capability for vibrating, rotating and reciprocating applications.
Abstract: Heat flux measurement is used in the field of fluid mechanics and heat transfer to quantify the transfer of heat within systems. Several techniques are in common use, including: differential temperature sensors such as thermopile, layered resistance temperature devices or thermocouples and Gardon gauges; calorimetric methods involving a heat balance analysis and transient monitoring of a representative temperature, using, for example, thin-film temperature sensors or temperature sensitive liquid crystals; energy supply or removal methods using, for example, a heater to generate a thermal balance; and, finally, by measurement of mass transfer which can be linked to heat transfer using the analogy between the two. No one method is suitable to all applications because of the differing considerations of accuracy, sensitivity, size, cost and robustness. Recent developments including the widespread availability and application of thin-film deposition techniques for metals and ceramics, allied with advances in microtechnology, have expanded the range of devices available for heat flux measurement. This paper reviews the various types of heat flux sensors available, as well as unique designs for specific applications. Critical to the use of a heat flux measurement technique is accurate calibration. Use of unmatched materials disturbs the local heat flux and also the local convective boundary layer, producing a potential error that must be compensated for. The various techniques in common use for calibration are described. A guide to the appropriate selection of a heat flux measurement technique is provided according to the demands of response, sensitivity, temperature of operation, heat flux intensity, manufacturing constraints, commercial availability, cost, thermal disturbance and acceleration capability for vibrating, rotating and reciprocating applications.
110 citations
01 Jan 1999-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the authors review the physical properties of scintillation from liquid rare gas, including decay time constants and attenuation lengths, and present status of development of liquid Kr/Xe homogeneous SCI calorimeters by using reflected light.
Abstract: Scintillation from liquid rare gases has a fast decay component with a high photon yield which is comparable to that of NaI(Tl), although the wavelength is in the vacuum ultraviolet. On the basis of these properties, many investigators have tried to realize liquid rare gas scintillation detector. In particular, liquid Xe is expected to be an excellent detector medium for γ-rays because of its fast response, its large atomic number, and high density. However, it is very difficult to achieve sufficient light collection as scintillator, because the light emission are in vacuum ultraviolet. Recently, some groups have reported liquid Xe/Kr homogeneous scintillation calorimeters for high-energy γ-rays using reflectors method, but their energy resolution was not as high as expected. In this situation it seems that the realization of liquid rare gas detectors may not be easy. In this paper, we review the physical properties of scintillation from liquid rare gas, the scintillation yields, the decay time constants and attenuation lengths. We summarize the results obtained with liquid rare gas scintillation detector. The present status of development of liquid Kr/Xe homogeneous scintillation calorimeters by using reflected light is described. A new device which observes only direct light is proposed as high-energy γ-ray detector or homogeneous electromagnetic shower calorimeters for γ-rays.
90 citations
TL;DR: In this article, the thermal plasma powers measured with a calorimeter in the chamber of PWK3 are presented, leading to thepossibility to determineefe ciencies, when the power was varied, two discrete operational transitions were observed.
Abstract: Thedesignoftheplasmawindtunnel (PWK3),itsinductivelyheatedplasmagenerator (IPG3),andexperimental results using O 2 and CO2 as operational gases are described. Various operational conditions (mass e ow rate, frequency) were applied. The thermal plasma powers measured with a calorimeter in the chamber of PWK3 are presented, leading to thepossibility to determineefe ciencies. When thepowerwas varied, two discrete operational transitions were observed. The simultaneous differences in the discharge behavior of IPG3 are represented by sudden changes of parameters such as calorimetric powers and local heat e uxes measured with a stationary heat e ux probeinthechamberofthefacility. Additionally,thecoolingpoweroftheIPG3plasmatubeispresented.Here, a plasma stabilization effect appearing with the second operational transition was observed when the tube cooling power decreased suddenly despite the simultaneous increase of the plasma power in the chamber. An imaging spectrometer measuring the radial intensity of the plasma through an axial optical window of IPG3 was used. Both the operational behavior, in particular the stabilization effect, and the heat e ux measurements show that PWK3 enables high-enthalpy tests for both basic thermal protection material tests and atmospheric entry simulation of spacecrafts.
83 citations
TL;DR: In this paper, temperature-modulated differential scanning calorimetry of first-order transitions has led to many new observations, some of which involve non-linear processes or deal with transformations of practically instantaneous response.
81 citations
TL;DR: In this paper, the properties of a new class of integrated circuit calorimeters (IC calorometers) are discussed, which are constructed on the basis of micro-sized silicon chips with integrated thermopile and heater, and the applicability of IC calorimetric purposes strongly depends on their sensitivity and on an optimized area of the sensitive sphere.
Abstract: In the present paper the properties of a new class of calorimeters, so called integrated circuit calorimeters (IC calorimeters) are discussed IC calorimeters are constructed on the basis of micro-sized silicon chips with integrated thermopile and heater The applicability of integrated circuits for calorimetric purposes strongly depends on their sensitivity and on an optimized area of the sensitive sphere Thus the sensitivity has to be much higher than that of the heat power transducers of conventional calorimeters The parameters of different integrated circuits are compared corresponding to their use in calorimeters Different constructions of IC calorimeters are possible: batch and flow-through calorimeters operating at isoperibol or temperature scanning mode As an example a batch type IC calorimeter for liquid samples with a resolution in heat measurement of >100µJ is described in more detail The applications of this calorimeter are represented in the paper with the investigation of enzyme catalysed reactions, ie the hydrolysis of urea and the oxidation of glucose catalysed by the enzymes glucose oxidase and catalase
77 citations
Abstract: A new calorimeter has been designed to measure isosteric heats of adsorption from gaseous mixtures with simultaneous measurements of loading and composition. The combined measurements at a single r...
60 citations
21 Mar 1999-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the energy calibration of jets observed with the DO detector at the two p p center-of-mass energies in the transverse energy and pseudorapidity range ET>8 ǫ and |η|
Abstract: The DO detector is used to study p p collisions at the 1800 and 630 GeV center-of-mass energies available at the Fermilab Tevatron. To measure jets, the detector uses a sampling calorimeter composed of uranium and liquid argon as the passive and active media, respectively. Understanding the jet energy calibration is not only crucial for precision tests of QCD, but also for the measurement of particle masses and the determination of physics backgrounds associated with new phenomena. This paper describes the energy calibration of jets observed with the DO detector at the two p p center-of-mass energies in the transverse energy and pseudorapidity range ET>8 GeV and |η|
58 citations
01 Jan 1999
TL;DR: In this paper, the authors describe the signal processing system of the Astro-E XRS instrument and describe the operation of pulse detection, Pulse height analysis, and counting rate dependence.
Abstract: We describe the signal processing system of the Astro-E XRS instrument. The Calorimeter Analog Processor (CAP) provides bias and power for the detectors and amplifies the detector signals by a factor of 20,000. The Calorimeter Digital Processor (CDP) performs the digital processing of the calorimeter signals, detecting X-ray pulses and analyzing them by optimal filtering. We describe the operation of pulse detection, Pulse height analysis. and risetime determination. We also discuss performance, including the three event grades (hi-res mid-res, and low-res). anticoincidence detection, counting rate dependence, and noise rejection.
49 citations
TL;DR: In this paper, a rotating bomb combustion calorimeter specifically designed for the study of sulfur-containing compounds has been assembled and calibrated, and the energy of combustion of 1,3-dithiane has been determined.
TL;DR: In this paper, the sources of the intrinsic errors in the heat capacity near the first order phase transition temperature and the procedures to minimize them are discussed, and the experimental heat capacity data of Gd5(Si2Ge2) and ultra pure Dy, both of which exhibit first-order phase transition, are used to confirm the theoretical conclusions.
Abstract: The heat capacity measured in an adiabatic heat pulse calorimeter with nonzero heat capacity suffers from intrinsic errors in the vicinity of a first order phase transition. When these errors are carried over into the calculation of the magnetocaloric effect, the latter also suffers from large systematic errors. The sources of the intrinsic errors in the heat capacity near the first order phase transition temperature and the procedures to minimize them are discussed. The experimental heat capacity data of Gd5(Si2Ge2) and ultra pure Dy, both of which exhibit first order phase transition, are used to confirm the theoretical conclusions.
TL;DR: In this paper, the authors described experiments with temperature-modulated calorimetry, in which use is made of multiple modulation frequencies for the evaluation of the heat capacity, and showed that the extrapolation of heat capacity from the amplitudes of the first and higher harmonics of the Fourier-transforms of heat-flow rate and heating rate allowed the correct heat capacity to be obtained from a single experiment.
Journal Article•
TL;DR: In this article, the thermal decomposition behavior of the following plasticizers and uncured binders (diols for PUR-type elastomer binders) was investigated in solutions of toluene (with 10 mass% contents) by adiabatic self heating with an accelerating rate calorimeter.
TL;DR: In this article, a miniaturized flow-through calorimeter based on silicon integrated thermopile chips has been developed for the detection of volatile organic compounds as well as for the precise determination of heats of absorption of gases onto thin coatings.
01 Apr 1999-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The Small angle TIle Calorimeter (STIC) as mentioned in this paper provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider.
Abstract: The Small angle TIle Calorimeter (STIC) provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider. The structure of the calorimeters, built with a so-called “shashlik” technique, gives a perfectly hermetic calorimeter and still allows for the insertion of tracking detectors within the sampling structure to measure the direction of the showering particle. A charged-particle veto system, composed of two scintillator layers, makes it possible to trigger on single photon events and provides e–γ separation. Results are presented from the extensive studies of these detectors in the CERN testbeams prior of installation and of the detector performance at LEP.
TL;DR: In this article, an isothermal microcalorimetric study of the imidazole catalysed hydrolysis of triacetin is presented as an example of a solution phase medium term reaction.
Patent•
24 Sep 1999
TL;DR: In this paper, a single sample holder in thermal contact with a heat source is measured, and a temperature difference over mutually spaced locations along a heat flow path between sample (23 ) and heat source (1 ) is measured.
Abstract: A heat flow calorimeter comprises a single sample holder ( 5 ) in thermal contact with a heat source ( 1 ). A temperature difference over mutually spaced locations ( 11, 12 ) along a heat flow path between sample ( 23 ) and heat source ( 1 ) is measured. The measured signal ( 24, 25 ) is combined with a compensation signal from a signal source ( 34 ) to derive a compensated temperature difference signal representative of the net heat flow to sample ( 23 ), (FIG. 1).
24 Oct 1999
TL;DR: In this paper, the performance and application of PbWO/sub 4/ in electromagnetic calorimetry at energies far below 1 GeV has been continued, and the significantly improved optical and scintillation properties of 15 cm long Nb/La-doped crystals, optimized for the ECAL/CMS calorimeter, are documented.
Abstract: The study of the performance and application of PbWO/sub 4/ in electromagnetic calorimetry at energies far below 1 GeV has been continued. The significantly improved optical and scintillation properties of 15 cm long Nb/La-doped crystals, optimized for the ECAL/CMS calorimeter, are documented. The lineshape, energy and time response of a 5/spl times/5 matrix are tested with monoenergetic photons up to 790 MeV energy and compared to previous measurements. First attempts have been made to enhance the scintillation yield by suitable dopants (Mo,Tb) for applications at very low photon energies. As a first large scale project at medium energies, the proposed concept for a compact photon spectrometer to be implemented into the ANKE magnetic spectrometer at COSY (KFA Julich) is illustrated.
TL;DR: Only 7 pg of substance are needed to measure solid-solid phase transitions in n-alkanes with a new type of calorimeter, which corresponds to a transition heat of only 500 pJ.
Abstract: Only 7 pg of substance are needed to measure solid-solid phase transitions in n-alkanes with a new type of calorimeter (see schematic picture). This corresponds to a transition heat of only 500 pJ. The small time constant of the calorimeter additionally permits the observation of dynamic effects in the examined phase transitions.
TL;DR: This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the Electrical Properties of human muscle.
Abstract: Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for computing the power and/or temperature distributions. For the numerical simulations to be accurate, the electrical and thermal properties of the materials that form the phantom should be accurately characterized. This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the electrical properties of human muscle. Particularities of the two samples required the design of alternative measuring techniques for the specific heat and thermal conductivity. For the specific heat, a calorimeter method is used. For the thermal diffusivity, a method derived from the standard guarded comparative-longitudinal heat flow technique was used for both materials. For the 'muscle'-like material, the thermal conductivity, density and specific heat at constant pressure were measured as: k = 0.31 +/- 0.001 W(mK)(-1), p = 1026 +/- 7 kgm(-3), and c(p) = 4584 +/- 107 J(kgK)(-1). For the 'fat'-like material, the literature reports on the density and specific heat such that only the thermal conductivity was measured as k = 0.55 W(mK)(-1).
01 Jan 1999
TL;DR: In this paper, an improved form of air-cooled calorimeter is used to measure the stray load losses of induction machines, which can be used for either loaded or unloaded operation.
Abstract: Induction machine stray load losses have always been difficult to determine with precision, so it has been difficult to refine methods of their prediction. This paper provides further description of and results from an improved form of air-cooled calorimeter used to measure the stray load losses of induction machines. Losses may be determined for either loaded or unloaded operation. By adjusting the set mass flow rate of coolant, the calorimeter is capable of measuring losses ranging from 1.5 kW to 6 kW full scale. Absolute errors are 5W in measurement and resolution is to 0.1W with averaging. However, it is the total machine loss that is measured accurately. Stray load loss is then evaluated by loss segregation. This again imposes a particular “loss model” which may not be correct but is directly comparable to international standards.
TL;DR: In this article, a micro-combustion calorimeter was developed to measure combustion energies of very small samples, and the energy equivalent was determined by burning 2 mg of benzoic acid.
Abstract: A micro-combustion calorimeter was developed. The small energy equivalent (ca. 68 JK−1) of this calorimeter makes it possible to measure combustion energies of very small samples. The energy equivalent was determined by burning 2 mg of benzoic acid. The standard deviation of the mean energy equivalent was reduced to 0.014% in 5 experiments. The standard massic energy of combustion of salicylic acid and the standard deviation of the mean were determined to be −21871±5 J g−1, which agrees well with the literature values. The standard molar enthalpy of formation of salicylic acid was derived as −591.2±1.7 kJ mol−1.
22 Oct 1999
TL;DR: The XRS instrument has an array of 32 micro-calorimeters at the focal plane, which consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers as mentioned in this paper.
Abstract: The XRS instrument has an array of 32 micro-calorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices have demonstrated a resolution of 9 eV at 3 keV and 11 eV at 6 keV. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, operating temperature, thermistor size, absorber choice, and means of attaching the absorber to the thermistor bearing element. We will present representative performance data, though a more detailed presentation of the results of the instrument calibration is presented elsewhere in these proceedings. A silicon ionization detector is located behind the calorimeter array and serves to reject events due to cosmic rays. We will briefly describe this anti-coincidence detector and its performance in conjunction with the array.
TL;DR: In this article, a more realistic numerical implementation of the specific heat measurement is discussed, which mimics the interaction of the FPU system with a calorimeter, and it is found that there exists a "freezing" critical temperature below which the relaxation times to equilibrium between FPU systems and calorimeters become relevant, so that the system appears to vanish for vanishing temperatures.
Abstract: The specific heat of Fermi–Pasta–Ulam systems has until now been estimated through the energy fluctuations of a suitable subsystem, and opposite answers were apparently provided concerning its possible vanishing for vanishing temperatures. In the present paper a more “realistic” numerical implementation of the specific heat measurement is discussed, which mimics the interaction of the FPU system with a calorimeter. It is found that there exists a “freezing” critical temperature below which the relaxation times to equilibrium between FPU system and calorimeter become relevant, so that the system presents aging and hysteresis features very similar to those familiar in glasses and spin glasses. In particular, in the framework of such a point of view involving finite long times, the specific heat appears to vanish for vanishing temperatures.
TL;DR: In this paper, the authors developed a calorimeter with a sensitivity of better than 1 mW/m for measuring AC losses in HTS multi-strand conductors for superconducting power transmission lines over a temperature range of 64 K to 80 K.
TL;DR: In this article, a high-resolution AC microcalorimeter has been developed to measure the heat capacity of liquid samples using a very stable AC heat flux supplied to a sample by applying an AC electric current to a tubelike sample cell made of metal.
Abstract: A high-resolution AC microcalorimeter has been developed to measure the heat capacity of liquid samples A very stable AC heat flux is supplied to a sample by applying an AC electric current to a tubelike sample cell made of metal The fluctuation of the AC temperature of the cell caused by heat leakage from the cell to the surroundings is corrected using the phase of the AC temperature together with its amplitude Consequently, heat capacity can be measured with a precision of ±001%
TL;DR: In this paper, the optical lay-out and the mechanical design of the DLR high flux calorimeter SUNCATCH are described and various loss mechanism are evaluated and other important design parameter are discussed.
Abstract: After an introduction into the principle of black body calorimeters the optical lay-out and the mechanical design of the DLR high flux calorimeter SUNCATCH are described. The various loss mechanism are evaluated and other important design parameter are discussed. In addition to constructional parameters the performance of the data acquisition system (DAS) highly influences the accuracy of the calorimeter. Main features of the DAS and the sensors are outlined. From a detailed error analysis of the SUNCATCH a measurement uncertainty of about ±0.5% % at high fluxes can be expected. A comprehensive measurement campaign with SUNCATCH, the flux mapping system FATMES and a Kendall radiometer under flux in the DLR solar furnace is described. An excellent agreement was found between both fluxmeter with an RMS deviation of about±1%.
TL;DR: In this paper, the free radical polymerization of methyl methacrylate (MMA) has been studied and the existence of the ceiling temperature has been experimentally demonstrated in the laboratory with the Phi-Tec pseudo-adiabatic calorimeter.
Abstract: Adiabatic calorimetry is a technique that has been introduced as an important approach to hazard evaluation of exothermically reactive systems. In this paper the free radical polymerization of methyl methacrylate (MMA) has been studied. One of the most important aspects of MMA polymerization is its exothermicity and autoaccelerating behaviour, these characteristics can generate the occurrence of a runaway reaction. In a runaway situation the reacting system is close to adiabatic behaviour because it is unable to eliminate the heat that is being generated. An even worse situation can be reproduced in the laboratory with the Phi-Tec pseudo-adiabatic calorimeter. Process design parameters that are usually calculated from thermodynamic data or using semiempirical rules, such as adiabatic temperature rise or maximum attainable pressure, can be directly determined. The existence of the ceiling temperature has been experimentally demonstrated.