Evaluation of the lubrication mechanism at various rotation speeds and granule filling levels in a container mixer using a thermal effusivity sensor

To research the detailed mechanism of the lubrication process using the thermal effusivity sensor, the relationships of the lubrication progress with the pattern of powder flow, the rotation speed and the filling level were investigated. The thermal effusivity profile was studied as a function of the number of rotations at various rotation speeds. It was observed that at lower rotation speeds, the profiles of the lubrication progress were almost the same, regardless of the rotation speed. In this region, the highest speed was defined as the critical rotation speed (CRS), which was found to be one of the important factors. The CRS had close relations with avalanche flow in the blender. The first and the second phases were observed in the lubrication process. The first phase was influenced by the CRS and the filling level in the blender. The second phase was influenced by the rotation speed. The mechanism of two-phase process was proposed as a macro progression of the dispersion of the lubricant (first phase) and micro progression of the coating of the powder particles with lubricant (second phase). The accurate monitoring by the thermal effusivity sensor was able to help a better understanding in the lubrication process.     

Effects of lubricant-mixing time on prolongation of dissolution time and its prediction by measuring near infrared spectra from tablets

The relationship between lubricant-mixing time and dissolution time was investigated, and we established a calibration model to predict dissolution time by near infrared (NIR) spectroscopy and the rationale of the prediction. The bulk powder consisted of theophylline, lactose, and potato starch were pre-mixed. After magnesium stearate (Mg-St) was added, the material was mixed for up to 180?min. The mixed powders were compressed to tablets and dissolution tests were performed. From each dissolution curve, 50% dissolution time (T50) was calculated. The NIR spectra of each tablet’s upper surface was measured and a chemometric analysis was conducted. With the extension of mixing time, T50 was prolonged. The Mg-St widely covered the surface of each particle of the bulk powder after material mixing. This coating effect may decrease the wettability of the particles and cause the prolongation of dissolution time. The T50 was predicted by NIR spectroscopy with chemometrics and a calibration model was established. The regression vector showed typical peaks derived from ?CH group of Mg-St, and it is suggested that those peaks, which were caused by the thin layer extension of Mg-St particles over the particle surfaces of other materials, contributed to the prediction of T50 prolongation. These studies show the usefulness of NIR measurements to control the effect of a lubricant in the process of raw powder material mixing.     

A feasibility study of real-time monitoring techniques for scale deposition thickness in pneumatic conveying pipelines

In this study, the feasibility of two techniques for real-time monitoring of scale deposition thickness were evaluated. Traditional pressure drop measurements and a variant of the heat pulse monitoring technique which was developed in this study were tested and compared in a lab scale experiment. Measurements were performed on test pipes while transportation air was led through the conveying system. Coating layers of different thicknesses were applied to the inner walls of the test pipes to simulate scaling. Prediction models were calibrated from the experimental data by multivariate methods and were used to assess the performance of the techniques. It was found that the heat pulse method provided the most accurate predictions for scale thickness. The pressure drop method did not give acceptable results for the application considered in this paper. Results show that the heat pulse method is somewhat sensitive to changes in the feed air temperature. However, it will still provide reliable results for online monitoring of industrial applications in which the conveying air temperature is relatively stable.     

Evaluation of thermal spike due to exothermic reaction in curing process of carbon fiber-reinforced plastic pressure accumulators for hydrogen stations

In the curing process of fiber-reinforced plastic accumulators, a thermal spike appears due to the exothermic reaction of the resin. It is necessary to accurately evaluate this thermal spike to guarantee quality and avoid using a trial and error approach to control the temperature. Thus, we developed a curing process simulator that is able to accurately evaluate the thermal spike of the thermosetting resin. A simplified mesoscale finite element model with the definite separation of fiber and resin is used in the simulation. In this study, the newly developed simulation system was examined by comparing its results with the experimental results from the curing process of fiber-reinforced plastic accumulators.     

Breakage behavior of two different coal types in a grinding process and importance for thermal power stations

This study investigates the effect of changes in coal properties in thermal power plants (TPPs) due to the breakage behavior of coal in the grinding stage. A grinding process is carried out in a stirred mill for different periods of time to determine the specific breakage rate. Two different types of coal with different properties and similar calorific values are used to compare their breakage rates. The results of the stirred mill grinding are presented in a comparative manner. Furthermore, washing tests are performed on the coal to determine the solid fossil fuel structure. It is shown that the solid fossil fuel structure affects linear and non-linear movement that results in different breakage behaviors.     

A method and instrument for measuring the thermal properties of samples of a regenerative product in a matrix when they are heated by a constant heat flux

A mathematical model of a method of measuring the thermal properties of new regenerative products is developed. The construction of a measuring instrument is proposed. Experimental data on the thermal conductivity and volume heat capacity of regenerative products in a matrix are obtained. Translated from Izmeritel’naya Tekhnika, No. 5, pp. 49–53, May, 2009.