Calibration Of Calorimeter Research Articles

Dynamic calibration of a sensor gas calorimeter for measurement of heat generation rates during kinetic of adsorption experiments

A procedure for dynamic calibration of a sensor gas calorimeter, resulting with a calibration transfer function, instead with a calibration line, is presented. The main factors influencing the calibration transfer function have been assessed. The calibration transfer function enables measurement of the heat generation rates during adsorption, necessary for obtaining a complete picture about adsorption kinetics.

Calibration of isothermal heat conduction calorimeters: case of flow calorimeters

In this article, the calibration of an isothermal heat conduction calorimeter used to measure the energy produced when mixing two liquids is carried out. A small amount of parameters that represents adequately the performance of the instrument has been obtained. In this sense, it has been proposed a simple model that offers a Transfer Function with two poles. The heat capacity of the injected liquids per time unit will be used as a parameter defining the validity limits of the calibration. It is shown a procedure for calibrating which consists in realizing some electrical and chemical calibrations with different pure liquids, different injection flows and mixtures with different behaviours, in order to determine the parameters of the model. This calibration is valid for the studied instrument and the used procedure is applicable to other similar thermal measuring instruments. With the calibration carried out, the studied calorimeter provides thermal measures with an uncertainty of 3%.

An adiabatic calorimeter for small samples: The solid–liquid system naphthalene–durene

The construction and calibration of an adiabatic calorimeter for samples of about 0.4g is described. The calorimeter works between 10 and 420K, the accuracy is 0.5% for heat capacity measurements and 0.2% for latent energy effect like the enthalpy of fusion. The solid–liquid phase diagram of the system naphthalene–durene is presented. The phase diagram has been determined by three measurements, the interrupted way of measuring in adiabatic calorimetry was used to calculate the liquid composition at different enthalpy levels. The phase diagram is an example of an almost ideal eutectic system. The excess Gibbs energy of the liquid phase at 360K was found to be in the order of 100Jmol−1 for the equimolar mixture.

Calibration and reconstruction performances of the KLOE electromagnetic calorimeter

The main aim of the KLOE experiment at DAΦNE, the Frascati φ-factory, is to study CP violation in the K 0– K ̄ 0 system. Requirements on shower detection are very stringent. An hermetic, lead-scintillating fiber sampling calorimeter has been chosen and built. A review of the methods used to calibrate and reconstruct energy and timing is reported in this paper. Emphasis is given to the calibration procedures developed using the 2.4 pb −1 collected in 1999. An energy resolution of 5.7%/ E/ GeV is achieved together with a linearity in energy response better than 1% above 50 MeV. A time resolution of ∼54 ps / E/ GeV is also measured on samples of radiative Bhabha and Φ decays.

Temperature, heat and heat flow rate calibration of scanning calorimeters in the cooling mode

The current publication continues the series of recommendations of the ‘Calibration’ Working Group of the German Society for Thermal Analysis (GEFTA) for temperature, heat and heat flow rate calibration of scanning calorimeters. It deals with calibration in the cooling mode. The procedures to be applied are essentially identical to those applied in the heating mode. Due to the general occurrence of supercooling for first-order phase transitions during cooling, liquid crystals and substances with higher-order phase transitions are recommended for temperature calibration. Substances with weak supercooling or substances for which the temperature dependence of the transformation enthalpy is known are recommended for heat calibration. The thermodynamic fundamentals relevant to the temperature dependence of phase transition enthalpies and phase transition temperatures are discussed. Detailed examples make it easy to follow the recommendations.

The electromagnetic calorimeter of the HERA-B experiment

The electromagnetic calorimeter of the HERA-B experiment is described. The main features of the calorimeter calibration procedure are also reported. Finally the first physics signals detected by the calorimeter in recent data taken during the commissioning of the installed HERA-B detector are described.

Temperature, heat and heat flow rate calibration of differential scanning calorimeters

This contribution discusses basic problems and fundamental requirements for a universally applicable, unified and metrologically correct calibration of differential scanning calorimeters (DSC). The essential features of previously published recommendations of the German Society for Thermal Analysis (GEFTA) [see Höhne et al., Thermochim. Acta 160 (1990) 1–12; Cammenga et al., Thermochim. Acta 219 (1993) 333–343; Sarge et al., Thermochim. Acta 247 (1994) 129–168; J. Thermal Anal. 49 (1997) 1125–1134] developed for a correct and instrument-independent calibration of temperature, heat and heat flow rate of DSC, are outlined.

Calibration of the Setaram high-temperature calorimeter for determination of heat capacity of phases in the Sr–Cu–O system

A high-temperature Setaram calorimeter was calibrated to measure the heat capacities of Sr–Cu–O phases. The indicated temperature was calibrated through the solidification points of pure metals (ITS-90). Powdered CuO having similar emissivity and heat conductivity to the measured materials was used as a standard for caloric calibration. Two different methods of measurement were examined. Working in continuous scanning mode, the ‘classical’ three-step method of heat flow rate calibration was used, while for the discontinuous method the respective peak areas were calibrated. The sensitivity calibration curve for the discontinuous method was evaluated from two successive runs carried out on the reference material. The calibrated calorimeter was used for determination of temperature dependences (473–1133 K) of heat capacity of the SrCuO 2, Sr 2CuO 3 and Sr 14Cu 24O 41 phases. Obtained C p,m 0 data measured by the step-by-step procedure were evaluated by two different methods. In the first method, the mean value of C p,m 0 was obtained by dividing the enthalpy change attributed to a given change of temperature by a corresponding Δ T. The second method consisted of summing the individual enthalpy contributions and subsequent differentiation of the resulting temperature dependence of enthalpy. Both these approaches yielded comparable results with relative standard deviations of 2–3% from the standard polynomial fit C p,m 0 = a + bT + cT −2. The temperature dependences of heat capacity of measured phases were compared with the low-temperature data taken from the literature as well as with the estimated curves. Our results exhibit a systematic shift to lower C p,m 0 values.

NIST and standards for calorimetry

The present article describes briefly some of NISTs more recent work on calorimetric standards. New reference-quality measurements of the enthalpy of solution of aqueous sodium chloride, obtained with an adiabatic solution calorimeter, are presented and compared to a previous equation of state for NaCl(aq). Other calorimetric standards that are discussed are potassium chloride used for solution calorimetry and reference materials used for calibration of enthalpy-increment and heat-capacity calorimeters, namely synthetic sapphire (α-Al 2O 3) and copper.

Calibration of a fixed-cell temperature-scanning calorimeter to measure precise solution heat capacities from 275 to 398 K at 0.35 MPa

A procedure was developed to calibrate the Calorimetry Sciences Corporation Models 5100 and 6100 Nano-DSCs to measure more precisely volumetric heat capacities of liquids and solutions. These calorimeters are small-volume, twin fixed-cell, power-compensation, differential-output instruments that can scan temperature upward or downward between 263 and 398 K at pressures up to 0.4 MPa. The calibration procedure leads to volumetric heat capacities that have a relative precision and accuracy of 3 × 10 −6 to 5 × 10 −5 for aqueous solutions at concentrations between ca. 0.001 and 1 mol kg −1. The Nano-DSCs operate on the principle that the volumetric heat capacity of a solution or liquid is proportional to the difference between the calorimetric outputs for two separate experiments: one when both the cells contain a reference liquid (usually water), and one when the reference cell contains the reference liquid and the sample cell contains the solution or some other liquid of interest. The volumetric heat capacity of the reference liquid must be known precisely and accurately at the temperatures and pressures of the experiment. The calibration constant is determined from measurements on a second reference liquid whose volumetric heat capacity is also known precisely and accurately: 1-mol kg −1 NaCl(aq). Results of calibration and other experiments are used as examples to illustrate the advantages of the calibration procedure described in this paper.

Details of calibration of a scanning calorimeter of the triple heat bridge type

It was shown that traditional procedure of measurement of heat capacity by the triple heat bridge method causes systematic error tied with a non-compensated asymmetry of a device. Two variants of calibration of triple heat bridge scanning calorimeters based on a ratio of signals from two cells are examined and compared to the conventional procedure of heat capacity measurements with DSC. Efficiency of calibration has been tested in experiments with rubidium nitrate and potassium chloride.

The temperature calibration on cooling of differential scanning calorimeters

The procedure for the calibration of differential scanning calorimeters (DSC) has been addressed by several authors. Most of the work published on this subject dealt mainly with the calibration on heating. For calibration on cooling, Menczel and Leslie suggested the use of thermally stable liquid crystals, for which the isotropic to nematic or cholesteric to isotropic transitions do not exhibit hysteresis on cooling. In this work, a new method is proposed to calibrate differential scanning calorimeters on cooling. It is suggested that the calibration on heating, with standard metals, may also be used to perform the calibration on cooling. The onset of the nematic to isotropic transition on heating (and vice-versa on cooling) will be used to support the method and to quantify the errors, which are of similar magnitude to those obtained by Menczel and Leslie with thermally stable high purity liquid crystals. Results of the change in the indium and lead crystallisation onset temperatures with the cooling rate are presented. Using as an example the non-isothermal crystallisation of polyethylene, the errors obtained with the standard calibration of the DSC and the new calibration on cooling are discussed.

Reference materials for calorimetry and differential thermal analysis

This publication is the result of the efforts of the ICTAC working group “thermochemistry” 1 during 1997–1998. It deals with reference materials (in abbreviated form: RM) for calorimetry and differential thermal analysis. It represents the updated version of two previous documents produced by the IUPAC Commission “Physicochemical Measurements and Standards”: the first was published in Pure and Applied Chemistry in 1974 [1] and the second in the book entitled “Recommended Reference Materials for the Realization of Physicochemical Properties” [2]. Calorimetry and differential thermal analysis are applicable to a wide range of scientific and technological research fields involving physical, chemical and biological processes. Calorimetry usually yields highly reproducible results which may, however, be inaccurate because of faulty calibration of the measurement system. Calibration is a fundamental requirement for every thermoanalytical study. It requires the establishment of a quantitatively defined relationship between the value indicated by the measuring instrument and the correct value. The calibration of a modern calorimeter is achieved by the quantification of the produced

Thermodynamic Properties of the KCl+H2O System

The thermodynamic properties of the KCl+H2O system were examined in order to provide: (1) an improved equation for the osmotic coefficient as a function of molality and temperature for purposes of isopiestic measurements, (2) a determination of the thermodynamic properties of the standard-state solution process, and (3) a test of the accuracy of the enthalpy of solution values for KCl(cr), a calorimetric standard. New equations that describe the thermodynamic properties of the KCl+H2O system were obtained from previously published measurements for this system. The measured values included in the fitted equations spanned the range of temperature from approximately 260 to 420 K for KCl(aq) and 1.5 K to 1033.7 K for KCl(cr). New equations and/or values for the following properties are given in the present work: (1) thermal properties of KCl(cr) from 0 K to the melting point, 1045 K, (2) the change in chemical potential for both KCl and H2O in KCl(aq) as a function of temperature, and molality, valid from 260 to 420 K, and (3) standard-state properties for the aqueous solution process. The effect of heat treatment on the determination of enthalpy of solution values was also examined. This examination indicated that the NIST recommendation of heating Standard Reference Material 1655, potassium chloride, at 800 K for a minimum of 4 h prior to its use in calorimeter calibration, should probably not be followed. The heat treatment recommended by the NIST certificate appears, at this point, to have a higher probability of corrupting the sample than improving the accuracy of the measurement.

Calibration of the DELPHI HPC calorimeter during the LEP2 programme

The readout chambers of the DELPHI HPC calorimeter are affected by large ageing which results in a module-dependent loss of gain. The calorimeter response thus needs to be tuned on a module-by-module basis. During the LEP operation phase at energies close to the Z resonance (LEP1), the tuning was based on the high available statistics of Z→e +e − events. In the high energy operation phase (LEP2), no such clear monochromatic physics channel is available with high statistics. A monitoring of the analog response of the readout chambers of each module is provided by the periodic calibration with radioactive 83 m Kr; using this information to account for module-dependent effects ensures the stability of the energy resolution throughout the LEP2 programme.

The hadron calorimeter of EAS-TOP: operation, calibration and resolution

We describe and discuss the operation, calibration and stability of the EAS-TOP calorimeter (Campo Imperatore, National Gran Sasso Laboratories), a large area hadron and muon detector devoted to cosmic-ray physics. It consists of iron slabs (for a total thickness of 818 g cm −2) and Iarocci tubes as sensitive layers, operating in the streamer mode and the “quasi proportional” regime. Using a model describing the operation of the “quasi proportional” chambers, we derive a calibration curve in the energy range 50–5000 GeV, whose reliability has been indirectly checked through on-site measurements, by means of an accelerator beam run (up to≃600–700 GeV) and by comparing the model predictions on hadron shower transition curves with the data.

Calibration and performance of the E706 lead and liquid-argon electromagnetic calorimeter

We report on the calibration and performance of a large lead liquid-argon electromagnetic calorimeter used by experiment E706 at Fermilab. The reconstructed π 0 mass was used to calibrate the energy response of the calorimeter. The systematic uncertainty in the linearity and uniformity of the mean-energy response of the calorimeter after calibration was found to be less than ±0.5% for the sample of data analyzed. Detector characteristics, including sampling fluctuations and position resolution, are discussed.

Quality checks and first calibration of the KLOE electromagnetic calorimeter

The construction of the KLOE lead-scintillating fibres electromagnetic calorimeter has been completed. The final results of the extensive quality checks of all the calorimeter modules are presented here. The measurements have been done in the Frascati Laboratories at a cosmic ray test facility using minimum ionizing particles. The results show that all the calorimeter modules are well fulfilling the design specifications concerning time and energy resolutions. Furthermore, by using the same cosmic ray facility, all the calorimeter elements have been also pre-calibrated.

Electrical calibration and testing of calorimeters with simulated, time-variable reaction power

For calorimetric investigations where the reconstruction of the real heat-flow rate during the experiment is required, the usual electrical calibration with constant power is often not sufficient. However, the use of a chemical calibration is limited by the number of suitable and certified reactions showing a known dynamics of the heat-flow rate. Therefore, a computer controlled electrical calibration unit was developed capable of duplicating any simulated reaction power–time curve in the calorimetric cell. The calibration unit consists of a universal simulation software with an interface to a programmable precision current supply connected to the calibration heater inside the calorimetric vessel. The reliability of the electrical calibration was proved with a continuous titration calorimeter using different recommended test reactions (TRIS+HCl, dilution of aqueous KCl, NaCl and urea solutions).In order to test the electrical calibration procedure in the dynamic mode the heat-flow rate of a first-order equilibrium reaction during a continuous titration experiment was simulated. It is demonstrated that the combination of simulation software and electrical calibration hardware provides a very close adaptation of calibration and experiment, allows a more reliable estimation of experimental uncertainties, simplifies the verification of complex data analysis procedures and opens up new possibilities for the optimization of experimental parameters.

Temperature calibration of temperature-modulated differential scanning calorimeters

Calibration of differential scanning calorimeters (DSC) is essential because it is not possible to calculate heat-flow rate and sample temperature directly from the quantities measured. The question arises whether the calibration used in the conventional DSC mode is also valid for temperature-modulated DSC (TMDSC). To prove this, a well-defined transition is needed which does not disturb the temperature profile within the sample during the modulation, the response of the whole system (calorimeter, sample, transition) must be linear. Some low-energy liquid-crystal transitions behave in this way under certain conditions and can be used for temperature calibration in TMDSC. The procedure is demonstrated for a smectic-A—nematic transition in a cyanobiphenyl liquid crystal (8OCB). Limitations of the method are discussed — in particular, rate effects. The TMDSC measurements also give some information about the order of phase transitions (8OCB: SN — second-order; NI — first-order).