Browsing by Author "Beukes, H. T."
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- ItemThe development of a generic simulation model of citrus packing lines(Stellenbosch : Stellenbosch University, 2011-10) Beukes, H. T.; Schutte, C. S. L.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.ENGLISH ABSTRACT: The design of a citrus packhouse is a time-consuming process and the construction of such a facility is extremely expensive. Most packhouses, however, consist of identical operations. It has been proposed that a generic simulation model can be developed in order to assist engineers in decision-making and evaluation during the design or redesign of citrus packhouses. This project is concerned with the development of such a model. The report consists of five major phases, namely the problem identification phase, the solution approach identification phase, the solution development phase, the verification and validation phase and the recommendation and conclusion phase. The problem identification phase is focused on the formulation of the problem and a discussion of the major functions and operations within a citrus packhouse. Simulation modelling has been identified as an appropriate tool to develop the solution and a roadmap for the development of such a model has been identified. The solution development phase entails the construction and computerization of the simulation model according to the proposed roadmap. The techniques employed to ensure the validity of the model are described in the verification and validation phase. The recommendations and conclusion phase entails a discussion of how the model can be used to perform experiments and the final remarks regarding the model are discussed. The model developed during the course of this project can be used to assist engineers to evaluate proposed designs and evaluate the effect of certain parameters on the system. The model is generic and can be used to represent almost any citrus packhouse.
- ItemOpportunities for solar thermal process heat integration in South African sugar mills(Stellenbosch : Stellenbosch University, 2016-03) Beukes, H. T.; Brent, Alan C.; Hess, S.; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT: The sugar milling sector is one of the major agro-processing industries in the South African economy. This sector, however, is under pressure to remain profitable under strenuous economic conditions. In order to enhance the competitive advantage of the industry, stakeholders are investigating opportunities to reduce the input costs of raw sugar production as well as alternative income streams, such as the production of bagasse by-products or the cogeneration of electricity. Since the production of raw sugar is characterised by a significant demand for thermal energy, this study has been conducted to identify opportunities for the integration of solar thermal process heat into this process. Potential solar heat integration points have been identified by considering all of the heat sinks and input streams within a generic raw sugar factory. The suitability of each of the integration points have been assessed in terms of the heat demand and expected impact of solar heat integration. Integration opportunities that conserve bagasse and coal or enhance the potential for electricity cogeneration have been prioritised. The sugar production process consists of various processes, such as sugarcane preparation and juice extraction, clarification, evaporation, crystallisation and drying of the raw sugar. Although there are numerous potential solar heat integration points within these processes, only six have been found to be potentially feasible in terms of the abovementioned criteria. The major opportunities for solar process heat integration into the sugar production process have been found to be the parallel production of live and exhaust steam, the drying of bagasse and sugar, the preheating of boiler feed water and, to a lesser extent, the heating of mixed juice. Basic integration concepts have been developed for the abovementioned integration points in order to assess the potential solar gains. Rudimentary energy yield simulations have been used to estimate the expected solar gains of the proposed concepts and the collector fields have been pre-dimensioned according to the mean thermal loads of the processes. According to this preliminary study, solar thermal process heat can potentially supply between 10 and 27 % of the respective processes’ heat demand without thermal storage. According to a basic economic assessment, the levelised cost of heat (LCOH) of the particular integration concepts is expected to be between R 0.43 and R 1.72 /kWh1. Although this study is only a preliminary evaluation of the potential of solar heat integration into the sugar milling industry, it has been shown that there are feasible integration points within the production process and that solar process heat integration can be considered as technically and financially feasible. However, owing to the intricacies of the heat supply and distribution network of a typical sugar factory, detailed studies should be conducted to optimise the integration of solar heat into the industry.