Showing papers on "Calorimeter published in 1982"
01 Nov 1982
TL;DR: In this paper, a new bench-scale rate of heat release calorimeter utilizing the oxygen consumption principle has been developed for use in fire testing and research, which is capable of higher accuracy than existing instruments and yet to be simple to operate and moderate in construction cost.
Abstract: A new bench-scale rate of heat release calorimeter utilizing the oxygen consumption principle has been developed for use in fire testing and research. Specimens may be of uniform or composite construction and may be tested in a horizontal, face-up orientation, or, for those which do not melt, in a vertical orientation. An external irradiance of zero to over 100 kW m−2 may be imposed by means of a temperature-controlled radiant heater. The rate of heat release is determined by measuring combustion product gas flow and oxygen depletion, while the mass loss is also recorded simultaneously. The instrument has been designed to be capable of higher accuracy than existing instruments and yet to be simple to operate and moderate in construction cost. The instrument is thermed a ‘cone calorimeter’ because of the geometric arrangement of the electric heater.
464 citations
TL;DR: In this article, a new bench-scale rate of heat release calorimeter utilizing the oxygen consumption principle has been developed for use in fire testing and research, which is capable of higher accuracy than existing instruments and yet to be simple to operate and moderate in construction cost.
Abstract: A new bench-scale rate of heat release calorimeter utilizing the oxygen consumption principle has been developed for use in fire testing and research. Specimens may be of uniform or composite construction and may be tested in a horizontal, face-up orientation, or, for those which do not melt, in a vertical orientation. An external irradiance of zero to over 100 kW m−2 may be imposed by means of a temperature-controlled radiant heater. The rate of heat release is determined by measuring combustion product gas flow and oxygen depletion, while the mass loss is also recorded simultaneously. The instrument has been designed to be capable of higher accuracy than existing instruments and yet to be simple to operate and moderate in construction cost. The instrument is thermed a ‘cone calorimeter’ because of the geometric arrangement of the electric heater.
454 citations
TL;DR: In this article, the authors developed general formulas for the heat release rate by oxygen consumption from which the formulas for specific applications can be easily derived, and the experimental choices or constraints include open or closed systems, paramagnetic or high temperature oxygen analyzers, CO analyzers or CO traps.
Abstract: The calculation of heat release rate by oxygen consumption is based on the assumption that all materials release approximately the same amount of heat per unit mass of oxygen consumed. This technique is now being employed to determine the heat release rate of materials in various heat release rate calorimeters. Other uses include the heat release rate of assemblies in the fire endurance furnaces and the total heat release rate in room fire tests. These different applications lead to different experimental procedures which require different formulas. The experimental choices or constraints include open or closed systems, paramagnetic or high temperature oxygen analyzers, CO analyzers or CO traps, and the use of a gas burner whose heat release rate must be deducted from the total. Various assumptions about CO levels in the exhaust duct and vitiation and humidity in the incoming air are made. General formulas for the heat release rate by oxygen consumption are developed in this paper from which the formulas for specific applications can easily be derived.
252 citations
TL;DR: A Tektronix-31 programmable calculator interfaced to a Perkin Elmer differential scanning calorimeter, model 2, substantially improves the accuracy of measuring the time-dependent development of the degree of crystallinity (× 10) and hence improves the quality of the rate data as mentioned in this paper.
133 citations
TL;DR: In this article, the molar heat capacities and enthalpies of the odd linear alkanoic acids, ranging from heptanoic up to and including nonadecanoic, were determined.
73 citations
TL;DR: Two calibrated thermistors sandwiched between two insulative polyethylene films were immersed in a 30 cm cube of water having a low thermal diffusivity and Calculations showed that conductive heat transfer produced a negligible effect at the position of measurement along the beam axis.
Abstract: Two calibrated thermistors sandwiched between two insulative polyethylene films were immersed in a 30 cm cube of water having a low thermal diffusivity. The product of the specific heat of water and temperature rise gave the combined effect of the local absorbed dose and any heat defect at a position along a temperature profile produced by cobalt-60 irradiation. The dose rate was near 18 mGy/s and exposure times were 3 min. The standard deviation for a daily set of measurements was about 0.6 percent. Calculations showed that conductive heat transfer produced a negligible effect at the position of measurement along the beam axis. Tests showed the absence of convection. Temperature drifts before irradiation were quickly controlled by changing the power dissipated in the water between two immersed electrodes. Reproducible measurements were obtained in distilled water supplies that had a wide range of impurities. Measurements, after saturating the water with nitrogen or oxygen, showed no difference. A difference of 0.6 percent would have been easily detectable. Tests with several chemicals added to water showed some unexpected results and changes in the measured absorbed dose rate versus accumulated dose. The measured absorbed dose rate in distilled water under the conditions described was 3.5 percent higher than that determined from measurements with a graphite calorimeter.
53 citations
TL;DR: In this paper, a Picker flow calorimeter was used to determine the heat capacities of organic liquids and liquid mixtures, and the procedure of measurement was improved to obtain greater accuracy.
48 citations
TL;DR: An adiabatic calorimeter was constructed for heat capacity measurement between 13.8 and 350 K as discussed by the authors, which was produced by a cryo-refrigerator built into the cryostat.
40 citations
TL;DR: In this article, the energy of the reaction between F2g and UPd3(c) to give Pd(PdF6)(c), about 15 mass per cent Pdc and UF6(g), has been measured in a bomb calorimeter.
29 citations
TL;DR: A differential ac calorimeter has been developed to investigate the phase transition behavior of liquids of biological interest, especially suspensions of liposomes and other model membranes, and results are presented for heating, cooling, and quasi-isothermal studies of the main phase transition in dimyris-toylphosphatidylcholine liposome.
29 citations
TL;DR: In this paper, a technique for measuring the enthalpy change during isothermal aging of polystyrene polymers has been proposed, based on the output of a scanning calorimeter not only during steady heating but also during the transients at the beginning and end of a heating scan.
Abstract: Techniques for measuring the enthalpy change during isothermal aging of polymer glasses are discussed. Critical analysis of conventional scanning calorimetry reveals that its accuracy may be suspect under certain circumstances due to the thermal lag inherent in a temperature scanning experiment. An additional problem is that the conventional technique is restricted to certain kinds of paths for reaching the aging temperature. It is proposed that both problems can be overcome by analyzing the output of a scanning calorimeter not only during steady heating but also during the transients at the beginning and end of a heating scan. This data analysis method represents an extension of a method used previously by others in accurate measurements of the much larger heat of fusion of crystalline polymers. Practical feasibility of the improved technique is demonstrated by preliminary measurements of enthalpy relaxation during aging of well-characterized polystyrene at 80°C. In particular, the initial departure from equilibrium of a glass prepared by 5°C/min cooling from the liquid state is found to be 6.9 ± 0.6 J/g. This measured value agrees with a value calculated on the basis of the glass transition temperature corresponding to 5°C/min cooling and heat-capacity data from the literature.
TL;DR: In this paper, the UNIQUAC associated solution theory was used to predict the excess enthalpy data at 298.15 K for ternary mixtures of methanol-p-xylene, ethanol-pxylene and cyclohexane.
TL;DR: In this article, a method to measure very small heat capacities at low temperatures (0.06 K to 3 K) is described, which allows the detection of heat capacities of less than 10 −9 J K −1 at 0.1 K.
TL;DR: In this article, the authors describe the development of a total automation and cheap data acquisition system for a high temperature Calvet calorimeter or an isoperibolic Calorimeter with a Commodore 3032 microcomputer.
TL;DR: In this article, the difference in hadron response between a fine grain ("electromagnetic") lead calorimeter and a coarser ("hadron") iron calorimeters is compared.
Abstract: At wide angles in a storage ring environment, a substantial part of the energy seen by a hadron calorimeter can be in the form of very low momentum particles such as jet fragments or resonance cascade decay products. Data are presented on the deviations from Gaussian resolution and linear response for such low momentum particles. The differing responses to incident e-, μ-, π+-, K+-, p and at momenta below 10 GeV/c are also compared. In addition, we discuss the significance of angle effects for a 4π calorimeter, and the problems of combining data from calorimeters with different physical characteristics. Experimental data are presented on the difference in hadron response between a fine grain ("electromagnetic") lead calorimeter and a coarser ("hadron") iron calorimeter, and on the dependence of the response on the energy sharing between the two calorimeters.
TL;DR: In this paper, the anomalous specific heat at the phase transition point of a ferroelectric CsH2PO4 and CsD2P4 was measured using an AC calorimeter.
Abstract: For ferroelectric CsH2PO4 and CsD2PO4 the specific heat has been measured using an AC calorimeter. The singularity of the specific heat at the phase transition point is logarithmic. The most characteristic feature of the behaviour is the existence of an anomalous specific heat over the wide temperature region from Tc-60K to Tc+60K. This anomalous specific heat is considered to be due to the one-dimensional fluctuation of the polarisation in these materials. The authors also compare the experimental results with the pseudo-one-dimensional Ising model.
TL;DR: In this paper, two methods for the absolute calibration of flow calorimeters (used for measuring the differences in heat capacities of two fluids) have been investigated, and both methods give different results and leads to various methods of improving calorimeter construction and operation.
Abstract: Two methods for the absolute calibration of flow calorimeters (used for measuring the differences in heat capacities of two fluids) have been investigated. In the recommended method of calibration, a change in the flow rate of the fluids is used to minic a change in the heat capacity of the fluid. In the other method of calibration, heat loss is measured using a fluid of known heat capacity, and it is assumed this heat loss is constant. This calibration method is not recommended because the heat loss is, in general, not constant. For some calorimeters the difference between the two methods of calibration is negligible, while for others erros as high as 40% are caused by choosing the wrong method. A detailed analysis of the heat losses in this kind of calorimetry shows why the two calibration methods give different results and leads to various methods of improving calorimeter construction and operation. Because chemical standardization is far more convenient for routine use, the recommended absolute calibration method has been used to establish 3.00 mol-kg−1 aqueous NaCl as a chemical standard for temperatures between 325 and 600K at 17.7 MPa.
TL;DR: In this paper, an isothermal high-pressure flow calorimeter suitable for measuring enthalpy of mixing for endothermic and exothermic processes is described, which can be measured from 263 K to 343 K and up to 40 MPa.
TL;DR: In this article, an adiabatic high-pressure calorimeter was constructed for measurement under constant pressure up to 110 MPa and over the temperature range from 100 to 370 K.
Abstract: An adiabatic high-pressure calorimeter was constructed. The calorimeter cell was devised for minimization of the cell mass relative to the volume of the sample chamber. The pressure in the cell was controlled by joining the cell with a transmitting tube to a stabilized high-pressure system. The adiabatic conditions were achieved by temperature control of the transmitting tube as well as of adiabatic shields inside the cryostat. Procedures for the precise pressure control and for the determination of the molar volume and heat capacity with the correction for the mass transfer of pressure-transmitting liquid in a series of measurement were discussed. The apparatus is capable of measurement under constant pressure up to 110 MPa and over the temperature range from 100 to 370 K. The results on liquid 3-methylpentane which was used as the pressure medium proved satisfactory performance of this new-type calorimeter.
TL;DR: It is shown that variations in the air gap between the cell and cell holder can be a major source of error when the calorimeter is used to investigate the kinetics of a chemical reaction and the time for the heat to flow through the solution in the cell can be the dominant factor in determining the rise-time of the instrument.
TL;DR: In this article, an isothermal flow calorimeter was used to measure enthalpies of mixing for the binary gaseous system methane-carbon dioxide at temperatures of 293.15, 305.15 and 313.15 K, with mole fractions of methane ranging from approximately 0.2 to 0.8.
Abstract: Enthalpies of mixing for the binary gaseous system methane-carbon dioxide were measured by an isothermal flow calorimeter at temperatures of 293.15, 305.15, and 313.15 K, with mole fractions of methane ranging from approximately 0.2 to 0.8. For the first two isotherms, the measurements were made at pressures of 0.507, 1.115, and 1.520 MPa (5, 11, and 15 atm, respectively). For the third isotherm, measurements were made at pressures of 0.507, 1.013, 1.520, 2.533, 3.546, and 4.600 MPa (5, 10, 15, 25, 35, and 45.4 atm, respectively). The experimental results were compared with those already available in the literature, as well as with predictions based upon the following equations of state: Benedict-Webb-Rubln (BWR), Redllch-Kwong, and the Redllch-Kwong equation with the modifications proposed by Jacoby and Robinson.
TL;DR: In this paper, an adiabatic calorimeter has been modified for the measurement of heat capacities of small samples of radioactive materials over the temperature range 300 to 700 K. A major part of the modification is the use of transistorized temperature controllers.
TL;DR: In this paper, a systematic investigation of the heats of formation in the Pr-Sb system has been performed using a small-furnace, isoperibolic calorimeter.
Abstract: A systematic investigation of the heats of formation in the Pr-Sb system has been performed using a small-furnace, isoperibolic calorimeter. The compositions and the equilibrium states of the samples have been checked by metallographic and X-ray analyses. The following values have been found for the various compounds (kJ/g atom±2): Pr2Sb:-99; Pr5Sb3:-112; Pr4Sb3:-120; PrSb:-126; PrSb2:-97.
TL;DR: The heat capacities of diphenyl, p-terphenyl and p-quaterphenyl from 180 K to their melting points were measured with a Perkin-Elmer DSC 1B scanning calorimeter as mentioned in this paper.
Abstract: The heat capacities of diphenyl,p-terphenyl andp-quaterphenyl from 180 K to their melting points were measured with a Perkin-Elmer DSC 1B scanning calorimeter Anomalies were observed in the heat capacity curves forp-terphenyl (from 400 K to the melting point) andp-quaterphenyl (from 190 to 260 K, and from 450 to 540 K) It is assumed that the anomalies near the melting points of the compounds under consideration could be related both to modification of the motion of the phenyl rings (external or/and internal) and to change in the motion of the molecules as a whole (diffusion phase)
TL;DR: In this article, a high-temperature calorimeter of the twin conduction type was designed with the capability of measuring heats of adsorption of gases on solids in the temperature range RT to 700 K. A chromel-alumel thermopile was used as the detector and a volumetric adaption apparatus was equipped.
Abstract: A high-temperature calorimeter of the twin conduction type was designed with the capability of measuring heats of adsorption of gases on solids in the temperature range RT to 700 K. A chromel-alumel thermopile was used as the detector and a volumetric adsorption apparatus was equipped. Its calibration and preliminary experiments on heats of adsorption of ammonia on zeolites are described.
TL;DR: In this article, an isothermal flow calorimeter was used to measure enthalpies of mixing for the binary gaseous system methane-hydrogen sulfide at temperatures of 293.15, 305.15 and 313.15 K. For each isotherm, the measurements were made at pressures of 0.507, 1.013, and 1.520 MPa (5, 10, and 15 atm).
Abstract: Enthalpies of mixing for the binary gaseous system methane-hydrogen sulfide were measured by an isothermal flow calorimeter at temperatures of 293.15, 305.15, and 313.15 K. For each isotherm, the measurements were made at pressures of 0.507, 1.013, and 1.520 MPa (5, 10, and 15 atm, respectively). The experimental results were compared with those predicted from the equation of state of Benedict-Webb-Rubin and Redlich-Kwong and the Redlich-Kwong equation with the modifications proposed by Jacoby and Robinson.
Patent•
15 Jul 1982
TL;DR: In this article, an accurate calorimeter for determining thermokinetic data consisting of a reactor (1) with an agitator (5) and a regulated heater (6) is presented.
Abstract: A reactor calorimeter for determining thermokinetic data consists of a reactor (1) with an agitator (5) and a regulated heater (6). Isothermal conditions are maintained in the reactor during reactions. The necessary electrical energy is measured. It is a highly accurate calorimeter whose reference line or its variation is continuously recorded without access to the reaction event. The arrangement enables the thermal energy to be measured under strictly isothermal conditions. The reactor (1) is placed in an intermediate thermostatic chamber (2) at an intermediate temp. (To+delta.T20). The intermediate chamber (2) is contained in an outer thermostatic chamber (3) at a second temp. (To). The temp. differences between the reactor and the intermediate chamber and between the intermediate chamber and the outer chamber are held constant using heaters and sensors. The intermediate chamber heater is connected to a heating power measurement circuit.
TL;DR: In this article, a high pressure differential scanning calorimeter for investigations in the temperature range from 300 to 600 K and pressure from 10 to 6000 bar is described, and the calibration procedure for the temperatures and the heats of transition is discussed.
Abstract: A new high‐pressure differential scanning calorimeter for investigations in the temperature range from 300 to 600 K and pressure from 10 to 6000 bar is described. The calibration procedure for the temperatures and the heats of transition is discussed. Some results on diamantane are presented.
TL;DR: Using a high temperature Calvet calorimeter, the enthalpy of dissolution of vitreous albite, or those and their mixtures into a 2PbO+B 2 O 3 liquid bath at 970 K has been deduced.
TL;DR: The construction and performance of a 5·8 m3 heat-sink calorimeter for human use differs from previously published human calorimeters mainly in the use of a digital computer for realtime measurement and closed-loop temperature control.
Abstract: The construction and performance of a 5·8 m3 heat-sink calorimeter for human use is described. It differs from previously published human calorimeters mainly in the use of a digital computer for realtime measurement and closed-loop temperature control. In addition the computational abilities provide a completely automated system. The performance characteristics of the calorimeter are: (i) a linear response between 0 and 280W for both sensible and evaporative heat, (ii) a 24h stability of less than ±1W (s.d.); (iii) a precision for sensible and evaporative heat better than 1·5 and 2%, respectively, and (iv) time constants (95%) of 14 and 7·5 min for sensible and evaporative heat, respectively.