Plastification Behaviour of Different Native Starches

Based on physical and thermal conservation laws a quantitative variable is introduced, which allows evaluation of the thermomechanical starch plastification much more independent of the transformation procedure. By that method, a comparison of plastification behaviour during extrusion of native potato, maize and wheat starch without any additives is realized for the first time. The complete energetical balance of the extrusion process supplemented by microscopical investigations leads to an essential better understanding of thermomechanical proceedings during extrusion of starch or compounding of other polymers. After optimization of extruder and screw configuration the resulting data for the energy needed for the plastification of starch, i.e. for the transformation of native starch granules into a thermoplastic melt by extrusion, have been measured under constant conditions. On these adequat extrusion conditions the native, laminated starch granules of all three used starches have been destroyed completely during its plastification by extrusion. The specific energy input needed for the plastification of potato starch was about 650 kJ/kg, for maize 380 and for wheat starch 435 kJ/kg. In comparison of these results the energy input for melting of polyethylene high density was about 585 kJ/kg under same conditions.     

Experimental investigation of velocity fluctuations in a radial diffuser pump

The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Doppler velocimetry(LDV) technique is successfully applied to measure the periodic flow field in a radial diffuser pump with low-specific speed, in order to investigate the velocity fluctuations caused by the impeller-diffuser interactions both in the impeller and diffuser regions. The velocity fluctuations in the impeller region are quantitatively examined at different radial positions, and the flow structure at the radial gap between two flow components is analyzed at different relative positions. In addition, the downstream effect on the diffuser flow is quantitatively and qualitatively assessed and compared with the turbulence effect.     

A new colorimetric method to quantify β-1,3-1,6-glucans in comparison with total β-1,3-glucans in edible mushrooms

Mushroom β-glucans are known for their activity as biological response modifiers and anticarcinogenic agents. β-1,3-1,6 Branched glucans with a triple helix tertiary structure are recognised as the most potent ones. In the present work, a colorimetric method for β-1,3-1,6-glucan quantification based on the dye Congo red is introduced. This method is specific for β-glucans with a triple helix. The β-1,3-1,6-glucan content of mycelia and fruiting bodies from various mushrooms was determined and compared with the total β-1,3-glucan content, measured by a fluorimetric method. The results show equal amounts of β-1,3-1,6- and total β-1,3-glucans in the analysed species but obvious differences between mycelia and fruiting bodies. On the average, 3% of mycelia and 8% of fruiting body dry mass consist of β-1,3-1,6-glucans. The average percentage of β-1,3-1,6-glucans in the total β-1,3-glucan content differs between mycelia (46%) and fruiting bodies (87%).     

Gemeinsame kondensation von harnstoff,melamin und formaldehyd. I. Einfluß der reaktionsparameter

The dependance of the simultaneous polycondensation of urea, melamine, and formaldehyde on reaction conditions was studied using chromatographic and spectroscopic methods. The results indicate an increase in the reactivity between urea and formaldehyde and also between melamine and formaldehyde with increasing acidity. A. controllable reaction involving simultaneously urea, melamine, and formaldehyde was possible only in neutral and basic media. An increasing proportion of urea in the reaction mixture increases the degree of polycondensation. A comparison of the three-component-resin with the UF-and MF-resins gives information pertaining to the formation of cocondensats consisting of urea and melamine. Acetone dilutability and turbidimetric measurements are in agreement with the results of chromatographic and spectroscopic methods.     

Kompetenzzentrum Wasserkraft

AktuellInnovatives Biomassekraftwerk

Erfolgreiches Pilotprojekt mit neuem Kraftwerkstyp     

Synthesis and Characterization of Novel Surfactants: Combination Products of Fatty Acids,Hydroxycarboxylic Acids and Alcohols

The reaction of hydroxycarboxylic acids, such as citric, malic and tartaric species with an excess of fatty acid chlorides produces the corresponding O-acylated hydroxycarboxylic anhydrides in one step and in a near quantitative yield. These molecules are excellent electrophiles which react readily with a variety of nucleophiles including alcohols, diols and polyols. Their reaction with triethylene glycol and triethylene glycol monomethyl ether leads to two series of novel anionic surfactants, which are unsymmetrical gemini surfactants. The determination of their properties (CMC, foaming, HLB) revealed that these molecules are—depending on the chain length of the fatty acid—excellent emulsifiers, and that they also display interesting antimicrobial activity. These novel functional surfactants are of interest for applications in food and personal care products and for the formulation of pharmaceuticals.     

Simulation of the efficiency of hydrogen recombiners as safety devices

Passive auto-catalytic recombiners (PARs) may be used in the future as safety devices inside confined areas for the removal of accidentally released hydrogen. In the presented study, it was investigated whether a PAR designed for hydrogen removal inside an NPP containment would principally work inside a typical surrounding of hydrogen or fuel cell applications. For this purpose, a hydrogen release scenario inside a garage – based on experiments performed by CEA in the GARAGE facility (France) – has been simulated with and without PAR installation. For modeling the operational behavior of the PAR, the in-house code REKO-DIREKT was implemented in the CFD code ANSYS-CFX. The study was performed in three steps: First, a helium release scenario was simulated and validated against experimental data. Second, helium was replaced by hydrogen in the simulation. This step served as a reference case for the unmitigated scenario. Finally, the numerical garage setup was enhanced with a commercial PAR model. The study shows that the PAR works efficiently by removing hydrogen and promoting mixing inside the garage. The hot exhaust plume promotes the formation of a thermal stratification that pushes the initial hydrogen rich gas downwards and in direction of the PAR inlet. The paper describes the code implementation and simulation results.     

Simulation of Agglomeration in Spray Drying Installations: The EDECAD Project

Spray drying is used for the manufacture of many consumer and industrial products such as instant dairy and food products, laundry detergents, pharmaceuticals, ceramics, and agrochemicals. During spray drying, agglomerates of powder particles are formed which determine the instant properties of the powder. Agglomeration during spray drying is considered to be a difficult process to control. The main cause of this is the complex interaction of the process variables: the atomization process, the mixing of spray and hot air, the drying of suspension droplets and the collision of particles which might lead to coalescence or agglomeration. As a consequence, agglomeration during spray drying is operated by trial-and-error. In an EC-sponsored project, named the EDECAD projects, an industrially validated computer model, using CFD technology, to predict agglomeration processes in spray drying machines is developed. An Euler-Lagrange approach with appropriate elementary models for drying, collision, coalescence and agglomeration of the dispersed phase is used. The main result of the EDECAD project is a so-called “Design Tool,” which establishes relations between the configuration of the drying installation (geometry, nozzle selection), process conditions, product composition and final powder properties. The Design Tool is being validated on pilot-plant scale and industrial scale. It will provide an advanced tool for improved design and optimization of spray drying and agglomeration equipment, to improve the quality of products and to increase the productivity of such equipment. This article introduces the background and approach of the project and some preliminary results.