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  • Feed channel spacer characteristics and their optimisation
    (1998) Cao, Zhiyi
    Thesis
    The optimization of the spiral wound module design generally refers to the optimization of feed channel spacers, which is investigated in this thesis. The feed channel spacers serve to improve the mass transfer by promoting turbulence and provide passage for the fluid. However, the presence of spacers also significantly increases the channel pressure drop and consequently increases the energy costs of the process. The spacer design could therefore have a significant effect on process economics. The main aim of this work was to study spacer characteristics and test its major geometrical characteristics. To achieve this, custom designed spacers were developed in the laboratory and CFD simulations were used to visualize the flow management that spacer can achieve. Through experiments and CFD simulation, it was found that the transverse filament was one of the dominating factors in spacer design. Most of the pressure drop in the spacer filled channel was caused by the form drag introduced by the transverse filaments. The variation in transverse filament distance can greatly affect the number of transverse filaments in the channel and consequently affect the pressure drop and mass transfer in the channel. The experimental results showed that the diameter of the transverse filament also had a significant effect on channel pressure drop and mass transfer, especially at high flow rates. Increasing transverse filament diameter may result in a rapid increase in pressure drop and mass transfer caused by increased from drag and enhanced turbulence. Voidage alone was found not to be efficient for quantifying the geometrical properties of spacer filled channels. Two ratios, transverse filament diameter/channel height and transverse filament diameter/transverse distance, were established for quantifying the performance of the spacer filled channels. Novel spacers were developed as the result of this research. They provide similar mass transfer performance to the benchmark commercial spacer with lower pressure drop. Optimal novel spacer design was analysis based on economics analysis.
  • Blast furnace hearth drainage
    (1985) Tanzil, Wira Budi Utama
    Thesis
  • Synthesis of optimal energy recovery networks applying a flexible pinch design embedded in artificial intelligence
    (1991) Suaysompol, Kraisak
    Thesis
    Widespread concern about the impact of the emission of greenhouse gases on global climate is leading to proposals to reduce such emissions. As a result, this should provide a great stimulus to energy conservation, since it can achieve a reduction in energy consumption without dampening economic activity. During the 1980’s, considerable progress has been accomplished in developing improved design methods for process integration, of which the most widely known is pinch technology. While this technique is successful for determining targets in the predesign phase, it has been realised that the minimum approach temperature (AT^) constraint used in the pinch design method (PDM) is too rigid and inevitably limits the flexibility of the designer. In this research, the flexible pinch design method (FPDM) is developed by integrating the art of process design and the science of artificial intelligence (AI) for the synthesis of optimal energy recovery networks. The flexible pinch design can be applied on both free hand basis guided by FPDM Heuristics and computer basis automated by the software, named FLEXNET. FLEXNET employs the A* heuristic search algorithm to guide the problem-solving strategy. As a design philosophy, FPDM is not constrained by any global exchanger minimum approach temperature, instead, a variable approach temperature is used. Alternative designs are generated heuristically and tested by exploiting a hierarchy of decision systems implemented in FLEXNET. The design strategy combined with thermodynamic insights makes the FPDM flexible and efficient to apply to practical situations. The application of the FPDM is well-demonstrated by comparison with designs from eight published case studies, half of which are based on data from industrial processes. It was found that the heat exchanger networks (HENs) designed by the FPDM are not only simpler but also cheaper compared with those designed by currently available methods. It is experienced that for the same operating costs significant capital cost savings of up to 10-15 % are often achieved by applying the FPDM.