Showing papers on "Calorimeter published in 1997"
28 Apr 1997
TL;DR: In this article, the authors summarize the advances in high temperature reaction calorimetry and present examples of specific applications to problems of transition metal oxide chemistry, high pressure geophysics, melt and glass energetics, and metastable materials relevant to the earth sciences.
Abstract: High temperature reaction calorimetry has seen considerable advances over the past twenty years. New and more sensitive calorimeters, improved sample handling techniques, and better control of the final dissolved state has made solution calorimetry and drop solution calorimetry, using molten lead borate and other solvents, very versatile and reliable techniques. This paper summarizes these advances and presents examples of specific applications to problems of transition metal oxide chemistry, high pressure geophysics, melt and glass energetics, and metastable materials relevant to the earth sciences.
477 citations
TL;DR: In this paper, a new method that fits the whole temperature response of a heat-pulse calorimeter for heat capacity is developed, which is capable of measuring heat capacity regardless if the sample is adiabatically or nonadiabatically isolated.
Abstract: A new method that fits the whole temperature response of a heat-pulse calorimeter for heat capacity is developed. Analyzing the thermal response of a heat-pulse calorimeter on a model that was used by the relaxation method, the authors derived some useful relations and further utilized the numeric method of the general linear least squares to determine the heat capacity of a sample. Absolute accuracy of the proposed method was verified by determining the heat capacity of a 0.249 76 g copper sample (purity 99.999%) on a self-designed and fully automated calorimetric system from 4.5 to 80 K. Comparing the result with the literature, the deviation in average was 1.2% from 4.5 to 20 K and 2.0% from 20 to 80 K. It is found that the proposed method is capable of measuring heat capacity regardless if the sample is adiabatically or nonadiabatically isolated. The size of the specimen is not critical for the application of the method and the temperature range of measurement can be expanded. It also deals with the τ...
238 citations
TL;DR: In this paper, a fully automated calorimeter for rapid measuring the heat capacity of solids in the temperature region from ∼3 to ∼350 K and in magnetic fields from 0 to 10 T is given.
Abstract: A description of a fully automated calorimeter for rapid measuring the heat capacity of solids in the temperature region from ∼3 to ∼350 K and in magnetic fields from 0 to 10 T is given. A comprehensive mathematical analysis of the semiadiabatic heat pulse technique for heat capacity measurements on solid materials resulted in the development of the necessary formal algorithms for the complete automatization of the data collection process. Simultaneously a procedure for the on-line evaluation of uncertainties in the measured heat capacity data is developed. An approach which eliminates the need for a separate temperature sensor(s) attached to an adiabatic heat shield(s) used to maintain semiadiabatic conditions during heat pulse heat capacity measurements has been proposed and tested. The sensorless technique provides reliable control of the heat transfer inside a vacuum chamber and results in accurate heat capacity data. The calibration results show that the heat capacity can be measured with an average ...
97 citations
TL;DR: In this article, a thin-film differential scanning calorimetry technique has been developed that has extremely high sensitivity of 0.2 nJ. By combining two calorimeters in a differential measurement configuration, the heat capacity and melting process of Sn nanostructures formed via thermal evaporation with deposition thickness down to 1 A.
Abstract: We have developed a new thin-film differential scanning calorimetry technique that has extremely high sensitivity of 0.2 nJ. By combining two calorimeters in a differential measurement configuration, we have measured the heat capacity and melting process of Sn nanostructures formed via thermal evaporation with deposition thickness down to 1 A. The equivalent resolution of the calorimeter is 1 nanogram in mass or 0.4 A in thickness. We have observed a decrease of up to 120°C in the melting point of Sn nanostructures.
79 citations
TL;DR: In this article, the quantitative performance of differential scanning calorimeters is reviewed and temperature calibration is discussed in terms of an isothermal correction plus a contribution from thermal lag, this can be derived from individual curves and is valid in both, heating and cooling, and it is emphasised that baselines that are drawn to thermal events, such as melting and transition phenomena, must have thermodynamic significance.
78 citations
TL;DR: A flow mixing unit using a SETARAM C-80 calorimeter, developed for measuring the enthalpy of solution of two fluids, has been used to measure enthalpies of absorption of carbon dioxide in a 30 wt.% aqueous solution of methyldiethanolamine (MDEA) at three temperatures 313.15, 353, 393, and three pressures 2.0, 5.0 and 10.0 MPa as mentioned in this paper.
70 citations
TL;DR: In this article, the Pitzer ion-interaction model was used to derive the volumetric and heat capacities of aqueous solutions of HCL at molalities from 0.1 to 6.0 mol·kg−1, temperatures from 298.15 K to 623 K, and pressures of 10 MPa and 28 MPa with a vibrating tube flow densimeter.
66 citations
18 May 1997
TL;DR: In this article, the design and construction of a double chamber calorimeter (DCC) that can be used for measurement of harmonic losses of a 7.5 kW cage induction motor is discussed.
Abstract: Direct measurement of electric machine losses using the principle of the calorimetric method is described in this paper. The design and construction of a double chamber calorimeter (DCC) that can be used for measurement of harmonic losses of a 7.5 kW cage induction motor is discussed. The advantages of this approach are highlighted as compared with a single chamber type calorimeter. Conducted heat leakage through the calorimeter walls is estimated accurately by developing a simple thermal model and compared with the experimental results. Accuracy and reliability is investigated by performing experimental tests using a known heater. Limits for the air flow rate and temperature rise inside and across calorimeter chambers are derived, The calorimeter is capable of measuring a heat loss up to 1 kW corresponding to the 7.5 kW machine with an overall accuracy of /spl plusmn/15 W. This provides a high resolution required for measurement of motor harmonic losses caused by distorted waveforms.
64 citations
TL;DR: In this article, a simple mathematical model for modulated differential scanning calorimetry in the form of an ordinary differential equation is derived and the model is analysed to find the effect of a kinetic event in form of a chemical reaction.
Abstract: Reading and co-workers introduced a new technique a few years ago called Modulated Differential Scanning Calorimetry or MDSC. Here the first part of a theoretical analysis for this technique is given. A simple mathematical model for modulated differential scanning calorimetry in the form of an ordinary differential equation is derived. The model is analysed to find the effect of a kinetic event in the form of a chemical reaction. Some possible sources of error are discussed. A more sophisticated version of the model allowing for spatial variation in a calorimeter is developed and it is seen how it can be reduced to the earlier model. Some preliminary work on a phase change is also presented.
54 citations
TL;DR: In this paper, a two-dimensional, air-filled enclosure containing discrete internal heat sources and an internal baffle is examined, and a modified procedure for calculating the temperature distributions on the window surface improves the predicted results and yields good agreement with measured data.
50 citations
TL;DR: Using computer simulations of the radiolysis of water, it is shown that the observed behavior can be explained if, in the gas mixtures, the amount-of-substance of H2 and of O2 differed significantly from 50 %.
Abstract: Domen developed a sealed water calorimeter at NIST to measure absorbed dose to water from ionizing radiation. This calorimeter exhibited anomalous behavior using water saturated with gas mixtures of H2 and O2. Using computer simulations of the radiolysis of water, we show that the observed behavior can be explained if, in the gas mixtures, the amount-of-substance of H2 and of O2 differed significantly from 50 %. We also report the results of simulations for other dilute aqueous solutions that are used for water calorimetry-pure water, air-saturated water, and H2-saturated water. The production of H2O2 was measured for these aqueous solutions and compared to simulations. The results indicate that water saturated with a gas mixture containing an amount-of-substance of H2 of 50 % and of O2 of 50 % is suitable for water calorimetry if the water is stirred and is in contact with a gas space of similar volume. H2-saturated water does not require a gas space but O2 contamination must be guarded against. The lack of a scavenger for OH radicals in "pure" water means that, depending on the water purity, some "pure" water might require a large priming dose to remove reactive impurities. The experimental and theoretical problems associated with air-saturated water and O2-saturated water in water calorimeters are discussed.
Patent•
07 Apr 1997
TL;DR: In this paper, a calorimeter for measuring flammability parameters of materials using only milligram sample quantities is described, and the thermochemical and thermophysical processes associated with the flaming combustion of solids are reproduced in the device through rapid anaerobic pyrolysis in a thermogravimetric analyzer.
Abstract: A calorimeter for measuring flammability parameters of materials using only milligram sample quantities. The thermochemical and thermophysical processes associated with the flaming combustion of solids are reproduced in the device through rapid anaerobic pyrolysis in a thermogravimetric analyzer. Volatile anaerobic thermal decomposition products are swept from the pyrolysis chamber by an inert gas and combined with excess oxygen in a combustion chamber maintained at several hundred degrees Centigrade to simulate the combustion reactions which occur in a well ventilated diffusion flame. Mass loss is measured continuously during the process and heat release rate is calculated from the oxygen consumed from the gas stream.
11 Nov 1997-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the results of beam tests with high-energy (8-375 GeV) electrons, pions, protons and muons of a sampling calorimeter based on the detection of Cherenkov light produced by shower particles are presented.
Abstract: We present the results of beam tests with high-energy (8–375 GeV) electrons, pions, protons and muons of a sampling calorimeter based on the detection of Cherenkov light produced by shower particles. The detector, a prototype for the very forward calorimeters in the CMS experiment, consists of thin quartz fibers embedded in a copper matrix. Results are given on the light yield of this device, on its energy resolution for electron and hadron detection, and on the signal uniformity and linearity. The signal generation mechanism gives this type of detector unique properties, especially for the detection of hadron showers: narrow, shallow shower profiles and extremely fast signals. These specific properties were measured in detail. The implications for measurements in the high-rate, high-radiation Large Hadron Collider (LHC) environment are discussed.
TL;DR: In this article, a fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (d.s.c.) was used to measure heat capacities of NaCl(aq) at T = (283.15 to 393.15)K and at p = 0.3 5 MPa.
TL;DR: In this paper, the authors proposed a method for temperature-modulated differential scanning calorimeters (TMDSC) to calculate heat-flow rate and sample temperature directly from the quantities measured.
TL;DR: In this article, a double twin microcalorimeter is used for the study of solid-vapor interactions, and the flow rate of the vapor is governed by diffusion through the tube between the vessels, and using information from both chambers the heat of sorption may be calculated as a function of equilibrium vapor pressure.
Abstract: A calorimetric method for the study of solid-vapor interactions is described. In one calorimetric chamber a vapor evaporates; in a second calorimetric chamber the vapor is absorbed by a sample. The two chambers are connected by a tube and form part of a double twin microcalorimeter. As vapor is sorbed by the sample the vapor pressure in the sorption chamber will increase from a low value to near saturation. The flow rate of the vapor is governed by diffusion through the tube between the vessels. From the thermal power measured in the vaporization calorimeter it is possible to evaluate the sorption isotherm, and using information from both calorimeters the heat of sorption may be calculated as a function of equilibrium vapor pressure. By conducting experiments with different sized samples it is also possible to study the kinetics of the sorption process. The paper describes some recent improvements of the technique and gives examples of its use.
TL;DR: In this article, the heat capacities for sapphire-filled and empty aluminum calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured.
Abstract: The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on strict symmetry of the twin calorimeter. This symmetry is of particular importance for temperature-modulated DSC (TMDSC) since positive and negative deviations from symmetry cannot be distinguished in the most popular analysis methods. The heat capacities for sapphire-filled and empty aluminum calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured. In addition, the positive and negative signs of asymmetry have been explored by analyzing the phase-shift between temperature and heat flow for sapphire and empty runs. The phase shifts change by more than 180° depending on the sign of the asymmetry. Once the sign of asymmetry is determined, the asymmetry correction for temperature-modulated DSC can be made.
Patent•
19 Dec 1997
TL;DR: In this paper, a method of simultaneously measuring thermal conductivity and heat capacity of a fluid, using a heat conduction calorimeter having a reference fluid in a first cell and a sample fluid in another cell, is presented.
Abstract: A method of simultaneously measuring thermal conductivity and heat capacity of a fluid, using a heat conduction calorimeter having a reference fluid in a first cell and a sample fluid in a second cell includes the steps of calibrating the calorimeter using a standard fluid having known thermal conductivity and heat capacity over a range of temperatures and the reference fluid to determine a set of sensitivity parameters, {a n ij }, of the calorimeter, wherein the a n ij are functions of the calorimeter, temperature and the reference fluid; applying a square wave heat pulse to the calorimeter containing said sample fluid and said reference fluid; measuring the thermal response curve to the square wave heat pulse, wherein the thermal response curve is a function of time, temperature of the measurement, thermal properties of the sample fluid, and thermal properties of the reference fluid; reducing the response curve to a set of discrete characteristic parameters, {p n } wherein each pn is a function of time, temperature of the measurement, thermal properties of the sample fluid and thermal properties of the reference fluid; calculating the thermal conductivity and heat capacity of the sample fluid from the {p n } for the sample fluid and the {a n ij } for the calorimeter.
TL;DR: In this paper, the thermal properties of a lithium secondary battery are calorimetrically studied using a twin-type heat conduction calorimeter and its accuracy was determined by the specific heat capacity measurement of a standard material, synthetic sapphire.
TL;DR: A gas perfusion microcalorimeter, primarily designed for studies of plant tissue, has been equipped with light guides in order to allow studies under the influence of light (UV-vis), and with variations in gas phase composition.
TL;DR: In this article, the heat capacities of glassy toluene, ethylbenzene, and 3-methylpentane were measured with an adiabatic calorimeter.
Abstract: We have investigated the low-temperature heat capacities arising from the low-energy excitations in several molecular glasses. The heat capacities of glassy toluene, ethylbenzene, and 3-methylpentane were measured with an adiabatic calorimeter. The first two samples were doped with 10 mol % of benzene to prevent crystallization. The low-temperature heat capacities of the molecular glasses measured in this study and those measured previously were all reproduced well by the sum of a normal part represented by the Debye function and an excess one represented by the soft potential model. The peak energy of G(ω)/ω2 [G(ω): density of states, ω: energy] was found to be proportional to M−1/2 (M: molecular mass) for the hydrocarbon molecules but not for the alcohol molecules. Intermolecular hydrogen bonds in the alcohols may be responsible for the different behavior.
TL;DR: A Gill titration calorimeter is evaluated as an instrument to determine in one experiment the equilibrium constant and the enthalpy change of a biochemical reaction and a Monte Carlo approach is used to estimate the precision in the thermodynamic parameters of the reaction under study.
TL;DR: In this paper, the isochoric heat capacities of pure water and H 2 O+KNO 3 were measured as a function of temperature along the different isochores and on the coexistence curves.
TL;DR: In this article, a light-modulated calorimeter (or light-heating dynamic DSC) was constructed using heating through light to give heat-flow modulation to the sample.
TL;DR: Results from 24-h measurements in 10 subjects indicate that corrected heat emission is equivalent to (99.8 +/- 2.0%) corrected energy expenditure, suggesting a change in the energy stored as heat in the body.
Abstract: Rumpler, James L., and William V. Seale. Synchronous direct gradient layer and indirect room calorimetry.J. Appl. Physiol. 83(5): 1775–1781, 1997.—A dual direct/indirect room-sized calorimeter is u...
TL;DR: In this paper, the entropy, enthalpy relative to 0 K, and the heat capacity of crystalline sodium chloride and potassium bromide were calculated from these models and compared to previous measurements of the thermodynamic properties of the two materials.
Abstract: Enthalpy increments for sodium chloride and potassium bromide were measured from 4.5 K to 350 K with an adiabatic calorimeter. These measurements were combined with other selected values from the literature to generate models that represented the thermal properties of crystalline sodium chloride and potassium bromide to the melting points. The entropy, enthalpy relative to 0 K, and the heat capacity of sodium chloride and potassium bromide were calculated from these models. The new measurements and models were compared to previous measurements of the thermodynamic properties of crystalline sodium chloride and potassium bromide. Additionally, the equation for the thermodynamic properties of copper given by Martin (Rev. Sci. Instrum. 1987, 58, 639), which is useful for calibration of calorimeters for temperatures below 310 K, was adjusted for the difference of the International Temperature Scale of 1990 from the International Practical Temperature Scale of 1968.
21 Dec 1997-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the general purpose spherical nonmagnetic detector (SND) is now taking data at VEPP-2M e+e− collider in BINP (Novosibirsk) in the center of mass energy range of 0.2 − 1.4 GeV.
Abstract: The general purpose spherical nonmagnetic detector (SND) is now taking data at VEPP-2M e+e− collider in BINP (Novosibirsk) in the center-of-mass-energy range of 0.2 – 1.4 GeV. The energy calibration of the NaI(Tl) calorimeter of the SND detector with cosmic muons is described. Using this method, the energy resolution of 5.5% (σ) for 500 MeV photons was achieved.
TL;DR: In this article, the denaturation and aggregation of bovine β-lactoglobulin (50 g/l) at neutral pH was investigated by scanning calorimetry.
TL;DR: In this paper, the results of a thermochemical study of a purified ferrocene sample were carried out by combustion calorimetry and by differential thermal analysis, and the values of the standard molar combustion energy resulting from this study are: −(5925 ± 5) kJ mol−1 (obtained by classical combustion caloreimetry with a static bomb); − (5948 ± 5), and −( 5947 ± 5)-kJmol−1, respectively, by using the CRMT rocking calorimeter.
TL;DR: In this article, the enthalpy increment of CeN was measured in the temperature range 474-883 K using a drop calorimeter and the X-ray pattern of the sample was recorded at room temperature.