Dynamic volumetric measurements

Dynamic volumetric measurements monitoring of the resin volume kinetics during the curing process... 

Compared to other biomolecular systems, lipid bilayer membranes and lyotropic lipid mesophases in general have been shown to respond most sensitively to hydrostatic pressure. The methods used in the high pressure studies have mainly included X-ray and neutron diffraction, fluorescence, IR and Raman spectroscopy, light transmission and volumetric measurements. Only a small amount of work has been performed using NMR techniques combined with high-pressure, a field which was pioneered by Jonas and co-workers " although the method is very powerful, non-invasive and allows the study of a series of structural and dynamic properties of the systems in detail and with atomic resolution. 

Ammoniation was carried out in a dynamic volumetric adsorption apparatus, as described elsehwere [3]. The ammonia uptake was measured volumetrically, whereas the surfce chlorine concentration was determined argentometrically [5]. Extreme care was taken to prevent the samples from hydrolysis, by handling them in a Na glove box or in vacuo. The total chlorine concentration was determined argentometrically after direct hydrolysis of the modified surface following reaction. 

The IGC is a dynamic volumetric method that can be used to measure the activity coefficient at infinite dilution y of volatile liquids in IL. Figure 9.4 shows the setup of an IGC installation. The temperature of the GC column is kept constant by an air oven (1) with controlled temperature (TIC). The chromatographic column (2) usually is a simple stainless steel tube. It is packed with SILP particles including the IL but without the catalyst. The pressure drop over the column can be measured by two pressure gauges (PIR). The volatile sample can be inserted at the injection block (3). The sample is taken through the column by the carrier gas hehum (4). The volume flow rate of the carrier gas is measured at the oven outlet and controlled at the oven inlet flow meter (FIC). The sample is detected at the column outlet by a two-way thermal conductivity detector (HR). On the reference side, it is perfused by the pure carrier gas. The difference in the thermal conductivity is recorded. 

Two parameters must be measured to apply the BET equation, the pressure at the sample and the amount adsorbed at this pressure. There are tlnee conmron methods for measuring the amount of gas adsorbed, called the volumetric method, the gravimetric method and the dynamic method, of which the volumetric method is the connnonest [21],... 

Response time. In the literature, response time is usually specified as the time taken for the electrode to reach > 90% of the output. Typical response times are around 30 sec. A fast response time is critical when one is measuring transient phenomena such as oxygen respiration rates in tissue or suspended cells and dynamic measurements of the volumetric mass transfer coefficient in bioreactors. 

The consequences of this type of activated physical adsorption is not only that the quantity adsorbed can lie off the isotherm but also that the measured quantity of adsorption is far less than the equilibrium value. No experiments have been conducted to illustrate whether or not the quantity adsorbed lies within the hysteresis loop. The occasional failure of the vacuum volumetric method to agree with the dynamic method, which is not subject to any pressure overshoot, may in part be attributed to this phenomenon. 

By the dynamic method, the oxygen concentration was measured as shown in Figure P7.6. The static volume of a fermentation broth, the flow rate of air, and the cell concentration were 11,1.51 min", and 3.0 g-dry cell 1 , respectively. Estimate the oxygen consumption rate of the microbes and the volumetric mass transfer coefficient. 

Vapour and gas sorption measurements can be performed with static or dynamic methods, either of which can provide information on equilibrium behaviour. Furthermore, the measurements can be performed using gravimetric or volumetric based instrumentation. The most common flow methods are inverse gas chromatography (IGC) [1] for volumetric studies and dynamic gravimetric instrumentation [2]. 

Taguchi, H. and A. E. Humphrey, "Dynamic Measurement of Volumetric Oxygen Transfer Coefficient in Fermentation Systems," /. Ferment. 7ec/ z.(Jap.) 44 (1966) 881-889. 

This effect can be forecast on the basis of the retention time distribution function in continuous tank reactors, which represents the simplest approach to the analysis of reactor dynamics. In its cumulative form, this function represents, for any time t, the fraction of the exit volumetric flow rate characterized by a residence time smaller than t and can be measured experimentally by submitting the reactor to a step forcing input in the entering stream. Whereas for the ideal tank reactor, the following... 

There have been several different 3D-3C (or volumetric) PIV techniques for macro-scaled flow measurement. Among them, holographic PIV (HPIV), defocusing PIV (DPIV), and tomographic PIV (TPIV) are the three that inherently measure all the three components of velocity field in a 3D volume. Other PIV techniques available to obtain a 3D velocity field, such as scanning PIV, dynamic PIV, that are based on some indirect algorithms to reconstruct a 3D velocity field, will be mentioned in the later sections. 

For laboratory-scale modification, distinction has to be made between static and dynamic adsorption procedures. In a static procedure, the substrate is contacted with a known volume of gas at a well-defined pressure. The modifying gas may be stationary or circulating in a closed loop. Modification in a static gas adsorption apparatus allows the careful control of all reaction parameters. Temperature and pressure can be controlled and easily measured. Adsorption kinetics may be determined by following the pressure as a function of the reaction time. Figure 8.13 displays a volumetric adsorption apparatus, in which mercury is used, as a means to change the internal volume and for pressure measurement. 

Adsorbed amounts can easily be measured with high accuracy by means of the conventional volumetric (49, 50) and gravimetric (50) techniques. For static measurements the desorption temperature is increased by certain increments and the desorption carried out at constant temperature. Thermogravi-metric analysis (TGA) is a dynamic method by which the weight loss is detected by a balance while heating the catalyst continuously. The same type of information can be obtained as with the static methods, provided the heating rate is sufficiently low to attain the characteristic irreversibly adsorbed amount at any temperature. 

The many different procedures which have been devised for the determination of the amount of gas adsorbed may be divided into two groups (a) those which depend on the measurement of the amount of gas removed from the gas phase (i.e. gas volumetric methods) and (b) those which involve the measurement of the uptake of the gas by the adsorbent (e.g. direct determination of increase in mass by gravimetric methods). Many other properties of the adsorption system may be related to the amount adsorbed, but since they require calibration they will not be discussed here. In practice, static or dynamic techniques may be used to determine the amount of gas adsorbed. 

The volumetric, elastic and dynamic properties of internally and externally plasticised PVC were studied and compared with those of unplasticised PVC. The glass transition temperature for the plasticised samples was markedly lowered and this decrease was more important for the externally plasticised ones. The positions of the loss peaks from dielectric alpha-relaxation measurements confirmed the higher efficiency of the external plasticisation. However, the shape of the dielectric alpha-relaxation function was altered only for the internally plasticised samples. The plasticisation effect was linked with a decrease in the intensity of the beta-relaxation process but no important changes in the activation energy of this process were observed. The results were discussed. 47 refs. 

Apparatus and Procedure. It was necessary to design more definitive tests to further evaluate the better candidate surfactants. This was accomplished by means of a multi-phase dynamic-fiow test that consists of a small packed bed through which surfactant solution can be passed followed by gas to produce in situ foam. The pressure drop through the column is measured as the fiuid is drawn through the column at a constant volumetric fiow rate. From the recorded data, relative mobilities of the liquid and gas phases may be calculated. The change in gas mobility due to the presence of the surfactant is very closely related to the effectiveness of that surfactant for mobility control in oil core studies. A schematic drawing of the apparatus is shown in Figure 2. 

The viscosities we have been using in this section are conventional dynamic viscosities with units of poises or Pas. They are to be distinguished from kinematic viscosities which have units in stokes and equal the dynamic viscosity divided by the density of the liquid. The latter are widely used in technology where the mass flow rate is measured in preference to the volumetric flow rate of Eq. (3-60). 

Pressure Swing Adsorption (PSA) unit is a dynamic separation process. In order to create a precise model of the process and thus an accurate design, it is necessary to have a good knowledge of the mixture s adsorption behaviour. Consequently, the dilAision rates in the adsorbent particles and the mixture isotherms are extremely vital data. This article intends to present a new approach to study the adsorption behaviour of isomer mixtures on zeolites. In a combined simulation and experimental project we set out to assess the sorption properties of a series of zeolites. The simulations are based on the configurational-bias Monte Carlo technique. The sorption data are measured in a volumetric set-up coupled with an online Near Infra-Red (NIR) spectroscopy, to monitor the bulk composition. Single component isotherms of butane and iso-butane were measured to validate the equipment, and transient volumetric up-take experiments were also performed to access the adsorption kinetics. 

The volumetric air sampler, which provides active measurement of viable contaminants by mechanical aspiration and dynamic inoculation of process air. 

While TMA is one of the older and simpler forms of thermal analysis, its importance is in no way diminished by its age. Advances in DSC technology and the appearance of dynamic mechanical analysis (DMA) as a common analytical tool have decreased the use of it for measuring glass transitions, but nothing else allows the measurement of CTE as readily as TMA. In addition, the ability to run standardized material test methods at elevated temperatures easily makes TMA a reasonable alternative to larger mechanical testers. As the electronic, biomedical, and aerospace industries continue to push the operating limits of polymers and their composites, this information will become even more important. During the last 5 years a major renewed interest in dilatometry and volumetric expansion has been seen. Other thermomechanical techniques will also likely be developed or modernized as new problems arise. 

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