Assessment of Efficiency of Drying Grain Materials Using Microwave Heating

We present results of experimental work on studying the drying of a dense layer of grain using microwave heating. We investigated a series of techniques to supply heat to grain to assess energy efficiency of a microwave field. We studied the following ways of drying: a microwave method, a pulsating microwave method, a microwave-convective cyclic method with blow of a layer with heated air flow and air without preheating, simultaneous microwave-convective drying method.Studying the kinetics of drying in a microwave field showed that we can divide the process into heating periods (zero drying rate), constant (first drying rate) and falling (second drying rate). These periods are characteristic for drying of colloidal capillary-porous bodies at other methods of heat supply. We obtained empirical relationships for the drying rate and the average temperature of grain in the first period based on the generalization of experimental data on the study on drying of grain of buckwheat, barley, oats, and wheat. We presented kinetic dependences in a dimensionless form. They summarize data on the studied grains. The aim of comprehensive studies of various methods of heat supply during drying was determination of the optimal method and rational operational parameters, which ensure high intensity of the process and the required quality of the finished product with minimal energy consumption.All studies took place under identical conditions and for the same grain (oats) to ensure the accuracy of the comparison. We determined that the most preferable method is a simultaneous microwave-convective energy supply without air preheating, which minimizes specific energy consumption. Experimental studies on drying using a microwave field made possible to select the required process parameters: power, heating rate, mass, and form of loading. We plan to develop a technology for drying of grain using microwave energy based on the study dat

Assessment of Efficiency of Drying Grain Materials Using Microwave Heating

We present results of experimental work on studying the drying of a dense layer of grain using microwave heating. We investigated a series of techniques to supply heat to grain to assess energy efficiency of a microwave field. We studied the following ways of drying: a microwave method, a pulsating microwave method, a microwave-convective cyclic method with blow of a layer with heated air flow and air without preheating, simultaneous microwave-convective drying method.Studying the kinetics of drying in a microwave field showed that we can divide the process into heating periods (zero drying rate), constant (first drying rate) and falling (second drying rate). These periods are characteristic for drying of colloidal capillary-porous bodies at other methods of heat supply. We obtained empirical relationships for the drying rate and the average temperature of grain in the first period based on the generalization of experimental data on the study on drying of grain of buckwheat, barley, oats, and wheat. We presented kinetic dependences in a dimensionless form. They summarize data on the studied grains. The aim of comprehensive studies of various methods of heat supply during drying was determination of the optimal method and rational operational parameters, which ensure high intensity of the process and the required quality of the finished product with minimal energy consumption.All studies took place under identical conditions and for the same grain (oats) to ensure the accuracy of the comparison. We determined that the most preferable method is a simultaneous microwave-convective energy supply without air preheating, which minimizes specific energy consumption. Experimental studies on drying using a microwave field made possible to select the required process parameters: power, heating rate, mass, and form of loading. We plan to develop a technology for drying of grain using microwave energy based on the study dat

Simulation study of the link between molecular association and reentrant miscibility for a mixture of molecules with directional interactions

The reentrant liquid-liquid miscibility of a symmetrical mixture with highly directional bonding interactions is studied by Gibbs ensemble Monte Carlo simulation. The resulting closed loop of immiscibility and the corresponding lower critical solution temperature are shown to be a direct consequence of the dramatic increase in association between unlike components as the temperature is lowered. Our exact calculations for an off-lattice system with a well-defined anisotropic potential confirm the findings of previous theoretical studies.Dirección General de Investigación Científica y Técnica PB94-144

Synthesis of (cinnamate-zinc layered hydroxide) intercalation compound for sunscreen application

Background: Zinc layered hydroxide (ZLH) intercalated with cinnamate, an anionic form of cinnamic acid (CA), an efficient UVA and UVB absorber, have been synthesized by direct method using zinc oxide (ZnO) and cinnamic acid as the precursor. Results: The resulting obtained intercalation compound, ZCA, showed a basal spacing of 23.9 Å as a result of cinnamate intercalated in a bilayer arrangement between the interlayer spaces of ZLH with estimated percentage loading of cinnamate of about 40.4 % w/w. The UV–vis absorption spectrum of the intercalation compound showed excellent UVA and UVB absorption ability. Retention of cinnamate in ZLH interlayers was tested against media usually came across with sunscreen usage to show low release over an extended period of time. MTT assay of the intercalation compound on human dermal fibroblast (HDF) cells showed cytotoxicity of ZCA to be concentration dependent and is overall less toxic than its precursor, ZnO. Conclusions: (Cinnamate-zinc layered hydroxide) intercalation compound is suitable to be used as a safe and effective sunscreen with long UV protection effect

PROTECTIVE PROPERTIES OF ZN-MN COMPOSITE COATINGS

Galvanic and nanocomposite Zn-Mn(11 wt.%) alloy coatings are obtained from a simple sulfate bath at electrodeposition conditions. The nanocomposite coatings contain stabilized polymeric micelles – SPM - the latter added to the electrolytic bath in concentration of 0,1 wt.%. Some of the coatings are additionally treated in Cr3+-based solution for obtaining of surface conversion layer. The protective ability of the coatings is evaluated in a model corrosion medium of free aerated 3% NaCl solution by potentiodynamic polarization curves and polarization resistance measurements. The surface morphology of the coatings is investigated by SEM images. The results show the better corrosion resistance and greater protective ability of the nanocomposite Zn-Mn alloy coatings compared to the ordinary ones. The influence of the Cr3+-based conversion layers on the coating characteristics is also commented and discussed

INNOVATIVE PASSIVATION FILM ON GALVANIC ZINC COATINGS BASED ON TANNIN AND GELATIN

Steels are widely applied traditional materials in the transport industry as well as for buildings, bridges, railway facilities etc. However, their application often leads to significant financial expenses due to the need for increased protection against corrosion destruction. This protection can be realized by usage of additional passive films on the metal surface. Tannin and gelatin are well known environmentally friendly natural products, they are easily accessible and profitable from a financial point of view. The chemical interaction of tannin and gelatin with each other, as well as with metal ions ensure the possibility for bonding the layers with both the zinc base as well as the individual layers for each other to form a sandwich structure. Galvanized low-carbon steel with such a film has been placed in a 5% NaCl solution and its corrosion behavior was compared with that of the ordinary zinc coating. The results demonstrate the positive influence of the passive film on the protective characteristics of the zinc layer in chloride containing medium

COMPOSITE ZINC COATINGS WITH POLYMERIC MODIFIED CUO NANOPARTICLES AGAINST CORROSION AND BIOFOULING OF STEEL

Biofouling and corrosion are well-known problems in the marine industries. In this study, the role of copper oxide (CuO) nanoparticles on the biofouling and corrosion performance of composite (hybrid) zinc coating on steel is examined. A cationic polyelectrolyte polyethylenimine (PEI) is used to stabilize the CuO suspension before particles electrodeposition on a steel substrate. The size and charge density of the PEI coated CuO nanoparticles are followed using light scattering methods and microelectrophoresis. The polymeric modified CuO nanoparticles are electrodeposited on the steel (cathode) surface at pH 9.0 aiming to minimize the effect of aggregation in the suspension and dissolution of the CuO nanoparticles. Standard zinc coating is then electrodeposited on the CuO coated steel sample from a zinc sulfate solution at pH 4.5-5.0. Distribution of CuO nanoparticles at the steel surface and morphology of the composite zinc coating are studied by scanning electron microscopy. The protective properties of this system are investigated in a model corrosive medium of 5% NaCl solution by application of Potentiodynamic polarization (PDP) curves and Polarization resistance (Rp) measurements. The results obtained allow to conclude that the embedded polymeric modified CuO particles ensure better corrosion resistance and protective ability compared to the ordinary zinc

Surface Analysis and Electrochemical Behavior of Zinc Composite Layers, Incorporating Polymer Nano-Micelles

This study presents a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers on a steel substrate in 5% NaCl solution as a corrosion medium.Design and ConstructionCivil Engineering and Geoscience

Steel Corrosion in Mortar Specimens, Deteriorated by Chloride Ingress: Electrochemical Study Using AC and DC Methods and Microscopic Analysis of the Steel/Mortar Interface

Design and ConstructionCivil Engineering and Geoscience