Results 1 - 10 of 2970
Results 1 - 10 of 2970. Search took: 0.026 seconds
|Sort by: date | relevance|
[en] An estimation of the dehydration kinetics of monohydrated D-glucose with the use of the Bayesian spectral source separation algorithm is described. The dehydration experiment was probed with the terahertz time domain spectroscopy (THz-TDS). Contrary to the widely used peak-area method, our approach to the quantitative analysis takes into account the full spectral information. The obtained concentration profiles at different temperatures were processed in order to measure the kinetics of the dehydration process. Our investigation shows that the proposed method may be used to estimate the evolution of concentration despite the overlapping peaks and multiple spectral sources in the observed spectra.
[en] Scientific and technical studies on the intensification of removal moisture from dispersed materials and their simultaneous dispergation in the hollow heating element of a thermo-vacuum apparatus isresearched. Continuous thermo-vacuum dehydration and dispergation process of zirconium hydroxide, brown coal, graphite, sawdust, biological materials is considered. Based on conducted studies was made conclusions about perspective to use this technology. Thermo-vacuum technology is different from the other by low-temperature heating, low time processing,humidity indicators controlling and nano-dispersion grinding. (Author)
[en] Artisanal fresh cheese is a type of cheese from Hispanic origin and one of the most consumed; however, its shelf life is short due to of its pH is close to neutrality, high aw and low salt content. The fluidized bed drying was employed as an efficient alternative to fresh cheese; however, in order to achieve the desired shelf life in a product, it is necessary to study different packaging and storage conditions that will depend on the specific characteristics of the product. A design of factorial experiments 23 was adopted, the storage study was carried out for 90 days, studying two qualitative variables: type of packaging and type of atmosphere in the packaging, and one quantitative variable: drying temperature. (Author)
[en] Dehydration is widely involved in tobacco processing such as tobacco leaf curing, tobacco trip redrying and cut tobacco drying, which plays a key role due to its effect on the physical and chemical quality of tobacco. The current drying methods in tobacco processing mainly use heat conduction, heat convection or their combination to dehydrate tobacco materials. However, radiation heat transfer as one of basic heat transferways has not been investigated in the tobacco drying. In the present work, infrared radiation dryer was designed to explore the tobacco infrared radiation drying characteristics. The effect of radiation heat transfer conditions and vacuum on the drying kinetics and temperature of tobacco leaves was investigated. Diffusion coefficient of middle tobacco leaves C2F is between 0.848×10-10 1.597×10-10 m2/s. At the same time, the pore structure andpetroleum ether tobacco extracts in dried tobacco were also analyzed in order to explore the different effects of infrared radiation drying and traditional drying technology on tobacco quality. (Author)
[en] Vibration is a promising way to intensify the drying process through heating-updue to viscous dissipation, activation of internal liquid transfer and increase of external transfer. To better assess the possible contribution of these effects, we choose a multiscale approach. This paper is focused on the pore scale, simulated by a capillary tube partially filled with water subjected to sinusoidal vibrations. We studied the displacement of water inside this tube through image analysis. This configuration mimics the moisture transfer inside the pores of aporous media during drying. The experimental device developed in this study is applicable to a wide range of configurations, such as symmetrical or asymmetrical vibrations. (Author)
[en] The aim of this work was to verify the influence of drying on physical and chemical characteristics of residues from rice milk production. Residues were from the production of white, red and black rice. They were dehydrated in an oven with air circulation at 60oC for 8h. Characterization of them were carried out by physical and chemical analyses. Residues have presented statistical difference for all parameters measured. Its characterization is necessary to justify its use in other process or application on new products.The residues from rice milk production have high content of nutrients and phenolic compounds, even after dehydration. (Author)
[en] Ulexite is one of the boron minerals, which include a respectable amount of hydration water. It can be used as a raw material in the production of boron compounds. Some part of water in the composition of ulexite can be removed from the solid matrix applying dehydration treatment, and a porous structure can be obtained to increase the reaction rate. In the present study, the effect of dehydration temperature on dissolution kinetics of ulexite in ammonium sulfate solutions was researched in a batch reactor utilizing the parameters of solution concentration, solid-to-liquid ratio, stirring speed and reaction temperature. It was determined that the dissolution rate of calcined material increased with increasing solution concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was attained with the sample calcined at 150 °C. It was found that the dissolution rate fit to the first order pseudo-homogeneous model. The activation energy of the dissolution process was estimated to be 42 kJ·mol−1.
[es]La ulexita es uno de los minerales de boro, que incluye una cantidad considerable de agua de hidratación. Se puede usar como materia prima en la producción de compuestos de boro. Una parte del agua existente en la composición química de la ulexita puede eliminarse de la matriz sólida aplicando tratamiento de deshidratación que permite obtener una estructura porosa, que aumenta la velocidad de reacción. En el presente trabajo, se estudió el efecto de la temperatura de deshidratación sobre la cinética de disolución de ulexita en soluciones de sulfato de amonio, en un reactor discontinuo estudiando los parámetros de concentración de solución, relación sólido/líquido, velocidad de agitación y la temperatura de reacción. Se determinó que la velocidad de disolución del material calcinado aumentaba al aumentar la concentración de la solución y la temperatura de reacción y con la disminución de la relación de sólido/líquido. La velocidad de disolución más alta se alcanzó con la muestra calcinada a 150 °C. Se encontró que la velocidad de disolución se ajusta al modelo pseudohomogéneo de primer orden. La energía de activación del proceso de disolución se estimó en 42 kJ·mol−
[en] Conversion of cyclohexanol has been used to investigate the deactivation modes of the HZSM-5, AIPO4-5 and MnAPSO-5. Conversion of cyclohexanol as a test reaction was used to evaluate the activity of these catalysts