An adiabatic calorimeter in which automation of the control of the adiabatic condition and the thermogram recording is achieved
in a simple way has been designed for studies of both thermochemistry and thermokinetics. A new method for specific heat measurements
has been proposed and specific heats ofn-heptane were measured to test the reliability of this calorimeter.
This paper presents several applications of the PHI-TEC II that are not commonly associated with adiabatic calorimeters but which have proved to be extremely valuable. These include simulation of a deep oil well for enhanced oil recovery, isothermal calorimetry of a semibatch reaction, catalyst research using flow through reactors (both plug flow and CSTR) with controlled feeds of high pressure liquid and gas.
Authors:Zhi-Cheng Tan, Ji-Biao Zhang, and Meng Shang-He
A computerized adiabatic calorimeter for heat capacity measurements in the temperature range 80–400 K has been constructed.
The sample cell of the calorimeter, which is about 50 cm3 in internal volume, is equipped with a platinum resistance thermometer and surrounded by an adiabatic shield and a guard
shield. Two sets of 6-junction chromel-copel thermocouples are mounted between the cell and the shields to indicate the temperature
differences between them. The adiabatic conditions of the cell are automatically controlled by two sets of temperature controller.
The reliability of the calorimeter was verified through heat capacity measurements on the standard reference material α-Al2O3. The results agreed well with those of the National Bureau of Standards (NBS): within 0.2% throughout the whole temperature
region. The heat capacities of high-purity graphite and polystyrene were precisely measured in the interval 260–370 K by using
the above-mentioned calorimeter. The results were tabulated and plotted and the thermal behavior of the two materials was
discussed in detail. Polynomial expressions for calculation of the heat capacities of the two substances are presented.
A fully automated adiabatic calorimeter controlled on line by a computer used for heat capacity measurements in the temperature
range from 80 to 400 K was constructed. The hardware of the calorimetric system consisted of a Data Acquisition/Switch Unit,
34970A Agilent, a 7 1/2 Digit Nano Volt /Micro Ohm Meter, 34420A Agilent, and a P4 computer. The software was developed according
to modern controlling theory. The adiabatic calorimeter consisted mainly of a sample cell equipped with a miniature platinum
resistance thermometer and an electric heater, two (inner and outer) adiabatic shields, two sets of six junction differential
thermocouple piles and a high vacuum can. A Lake Shore 340 Temperature Controller and the two sets of differential thermocouples
were used to control the adiabatic conditions between the cell and its surroundings. The reliability of the calorimeter was
verified by measuring the heat capacities of synthetic sapphire (α-Al2O3), Standard Reference Material 720. The deviation of the data obtained by this calorimeter from those published by NIST was
within ±0.1% in the temperature range from 80 to 400 K.
An automatic pressure
tracking adiabatic calorimeter (APTAC) has been developed to obtain the thermokinetic
and vapor pressure data during runaway reactions. The heat onset temperature
is important data for estimating the thermal hazardous materials. DTBP(di-tert-butyl peroxide)/toluene was chosen for evaluating
the measurement values and the thermokinetic parameters. The relationships
between the sample mass and the heat onset temperature in the addition to
the maximum temperature were investigated to explain the heat of reaction
measured by the APTAC. The apparatus properties and the reliability of the
data obtained by the APTAC were examined on the basis of the experimental
Authors:X.-C. Lv, Z.-C. Tan, Z.-A. Li, Y.-S. Li, J. Xing, Q. Shi, and L.-X. Sun
The (R)-BINOL-menthyl dicarbonates,
one of the most important compounds in catalytic asymmetric synthesis, was
synthesized by a convenient method. The molar heat capacities Cp,m
of the compound were measured over the temperature range from 80 to 378 K
with a small sample automated adiabatic calorimeter. Thermodynamic functions
[HT–H298.15] and [ST–S298.15] were derived in the
above temperature range with a temperature interval of 5 K. The thermal stability
of the substance was investigated by differential scanning calorimeter (DSC)
and a thermogravimetric (TG) technique.
Authors:N. Kuratomi, O. Yamamuro, T. Matsuo, and H. Suga
Heat capacities of structure I and II trimethylene oxide (TMO) clathrate hydrates doped with small amount of potassium hydroxide (x=1.8×10−4 to water) were measured by an adiabatic calorimeter in the temperature range 11–300 K. In the str. I hydrate (TMO·7.67H2O), a glass transition and a higher order phase transition were observed at 60 K and 107.9 K, respectively. The glass transition was considered to be due to the freezing of the reorientation of the host water molecules, which occurred around 85 K in the pure sample and was lowered owing to the acceleration effect of KOH. The relaxation time of the water reorientation and its distribution were estimated and compared with those of other clathrate hydrates. The phase transition was due to the orientational ordering of the guest TMO molecules accommodated in the cages formed by water molecules. The transition was of the higher order and the transition entropy was 1.88 J·K−1(TMO-mol)−1, which indicated that at least 75% of orientational disorder was remaining in the low temperature phase. In the str. II hydrates (TMO·17H2O), only one first-order phase transition appeared at 34.5 K. This transition was considered to be related to the orientational ordering of the water molecules as in the case of the KOH-doped acetone and tetrahydrofuran (THF) hydrates. The transition entropy was 2.36 JK−1(H2O-mol)−1, which is similar to those observed in the acetone and THF hydrates. The relations of the transition temperature and entropy to the guest properties (size and dipole moment) were discussed.
Authors:W. Lin, S. Wu, G. Shiu, S. Shieh, and C. Shu
The highly reactive and unstable exothermal features of methyl ethyl ketone peroxide (MEKPO) have led to a large number of
thermal explosions and runaway reaction accidents in the manufacturing process. To evaluate the self-accelerating decomposition
temperature (SADT) of MEKPO in various storage vessels, we used differential scanning calorimetry (DSC) and vent sizing package
2 (VSP2). The thermokinetic parameters were, in turn, used to calculate the SADT from theoretical equations based on the Semenov
This study aimed at the SADT prediction value of various storage vessels in Taiwan compared with the UN 25 kg package and
UN 0.51 L Dewar vessel. An important index, such as SADT, temperature of no return (TNR) and adiabatic time maximum rate (TMRad), was necessary and useful to ensure safe storage or transportation for self-reactive substances in the process industries.
of thermodynamic property for this substance is necessary. In this study, the low-temperature heat capacities of this compound over the temperature range from 78 to 350 K were measured by an automated adiabaticcalorimeter. The thermodynamic functions