Chemical Engineering Department
The Chemical Engineering Group works on subjects related to fluid mechanics, rheology, polymers and processing. In most cases the projects pertain to a direct technological area associated with processing and the work usually involves a combination of both modelling and experimental studies. Rheology and processing The research encompasses different problems of rheology of non-Newtonian liquids like suspensions, polimer solutions and melts or rubber compounds. The investigations are focused on characterisation and description of flow processes in various industrial situations like flow of polymer melts through granular beds and mesh packages, thixotropic behaviour of muds in a long distance transport, rubber mixing and mixing dependent rheology. The group has excellent facilities for the characterisation of rheologically complex fluids. The equipment includes
Process rheometry Over the last three decades successful works have been carrying out on a novel design of different types of rheometers including so called process rheometers. The last, unlike the ordinary ones, are suitable for continuous measurement of rheological properties of fluids by the on-line methods and can be used for monitoring and control of various industrial processes, during which viscosity changes are indicators of the process, and consequently, its product quality. We have designed several new geometries of the rheometrical measuring systems, fulfilling the essential requirements of fast and adequate monitoring of the current state of the medium samples collected in the process. Particularly, the systems present a new approach to investigation of the fast sedimenting suspensions. Complete, innovative rheometers are also constructed. Multiphase flows The general theme of our research in this field is the flow of and mass transfer in two- or multiple-phase mixtures in situations that occur in process plants. Particularly, we investigate the hydrodynamics of two-phase flows systems : non-Newtonian liquid-gas in horizontal pipes. The optimal conditions for occurring of distinct flow patterns and formulae for pressure drop have been determined. Full scale industrial plant has been designed and implemented for a long distance transport of highly concentrated carbonatation mud. Also, the hydrodynamics and the mass transport in air-lift columns are investigated. The influence of physical properties of liquids, the geometry of column and the gas velocity on the re-circulation rate, gas holdup and the mass rate coefficient have been established. Polymer and material science The research concerns various aspects of characterisation of new polymers and polymer composites. This includes polymer dispersion and reorientation in liquid crystals, PDLC systems (investigation of their morphology, relaxation times, electro- and thermo-optical analysis), biodegradable properties of composites containing bio-polymers with application to the environmental protection methods (e.g. paper coating with polymer mixtures containing chitosan, starch or dibutyrylchitin), rheological properties of chitosan solutions and its mixtures with water soluble polymers. Calorimetric and thermoanalitic investigations of amorphous sorts of sulphur and selenium are carried out. The relationship between the molecular chains and rings content on one hand and the crystallization rate on the other, has been established. The group has excellent equipment, including
Novel numerical schemes based on the finite element method (FEM) are developed, particularly for viscoelastic fluids flows simulations in conjunction with moving boundaries and random free surface generation. Original approach to the flow analysis in the Lagrangian framework has been used involving step-wise distortion and recovery of computational meshes and meshes rotation, for successful coping with generally known instability problems encountered during numerical simulation of hyperbolic type differential equations. The methods are particularly aimed at simulations of rubber mixing process and the optimal mixer design. The original software package, created in co-operation with Loughborough University (UK) has capability of polymer processing simulation in arbitrary geometry and operating conditions. We also have a commercial FEM package FIDAP for complementary analysis and graphical post-processing. The problems currently solved, beside the mentioned above, include the velocity profile formation at the entrance regions, flow patterns inside the rheometrical measuring systems, the die swell and contraction phenomena, simulation of flows in granular beds, cross-flow filtration, diffusion processes and dispersion of effluents in rivers and estuaries. A Silicon Graphics computer Power Challenge (4 processors, 192 MB memory, 1.5 GFlops) is available in the Campus. visit on this page since 8th November 96 rjz 29.10.96 |