M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology / Corrosion responses of some carbon steels, stainless steel and copper alloys in the presence of a culture of bacteria (referred to as SRB-Sulphate-reducing bacteria) found in industrial heat exchangers, was studied to recommend best alloys under this service condition, with techno-economic consideration. Water from cooling towers in three plants in a petrochemical processing complex were analysed for SRB presence. Two of the water samples showed positive indication of SRB presence. The mixed cultures obtained from plant one were grown in prepared media and incubated at 35 °C for 18 days. Potentiodynamic polarisation studies in anaerobic conditions were done on the selected alloys in aqueous media with and without the grown SRB. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were then used to study the corrosion morphology and corrosion products formation. The voltamograms show higher icorr for alloys under the SRB compared to the control media, indicating the SRB indeed increased the corrosion rates. The surface analysis showed pitting on steel alloy ASTM A106-B. Localised attack to the grain boundaries on a selective area, was seen on ASTM A516-70 dislodging the grains, and intergranular corrosion was seen throughout the exposed area of ASTM A179. Copper alloys showed pitting on ASTM B111 grade C71500 (70-30), and denickelification on ASTM B111 grade C70600 (90-10), and is a good alternative material for use apart from carbon steel alloys, recording a low corrosion rate of 0.05 mm/year. The EDS analysis supported the findings showing higher weight percent of iron and sulphur on surface of the alloys after exposure to the SRB media. This implies that the presence of the sulphur ion indeed increased the corrosion rate. ASTM A516-70 carbon steel was chosen as a suitable alternative material to the stainless steel in this environment. The Tafel plot recorded a corrosion rate of 1.08 mm/year for ASTM A516-70 when exposed to SRB media.

Zur Kühlung von Prozessströmen kommen aufgrund hoher Leistungsdichten häufig Verdunstungskühltürme zum Einsatz. Um die Übertragungsfläche für Wärme und Stoff zu vergrößern, werden in diesen Kühltürmen Struktureinbauten integriert. Die Weiterentwicklung von Kühlturmeinbauten und die Untersuchung der den Kühlprozess beeinflussenden Faktoren erfolgt empirisch, was eine Vielzahl von Versuchen notwendig macht. Eine numerische Simulation des Kühlprozesses kann diese Messungen unterstützen und so helfen eine Vielzahl an Versuchen einzusparen. Des Weiteren können bei versuchsbegleitender Simulation mit einem geeigneten Modell weitere Untersuchungen durchgeführt und Erkenntnisse gewonnen werden, die bei Messungen am Versuchskühlturm verborgen bleiben. In dieser Arbeit werden zwei Ansätze der numerischen Simulation eines Verdunstungskühlturms betrachtet. Es werden eine CFD-Simulation und ein vereinfachtes Modellkonzept hinsichtlich der Anwendbarkeit auf diese Problemstellung untersucht. Schwerpunkt der vorliegenden Arbeit ist die methodische Entwicklung eines solchen vereinfachten mathematischen Modells. Dieses beruht auf der physikalisch deterministischen Beschreibung der im Kühlturm ablaufenden Prozesse der Wärme- und Stoffübertragung unter Berücksichtigung des Stoffverhaltens. Aufgrund der Nichtlinearität des Stoffverhaltens und der erforderlichen Inkrementierung des Berechnungsgebiets ist ein methodisches Vorgehen erforderlich, um die Erstellung der Modellgleichungen und deren Lösung überhaupt realisieren zu können. Hierfür wird auf allgemeine Methoden der gleichungsorientierten Simulation technischer Systeme zurückgegriffen. Das entwickelte Modellkonzept wird für die Modellierung und Simulation eines Versuchskühlturms angewandt. Mit den so ermittelten Messdaten wird das Modell kalibriert und validiert. Es zeigt sich, dass mit dem erstellten Modell quantitativ und qualitativ valide Ergebnisse erzielt werden können. / Due to the high power density, the cooling of process streams is often done bei evaporative cooling towers. To enlarge the exchange area for the heat and mass transfer, these cooling towers contain integrated structural fills. The future development of cooling tower fills and the research regarding the cooling process and its influencing parameters will be carried out empirically, resulting in a large number of required experiments. A numeric simulation of the cooling process can support theses measurements and reduce the vast number of needed experiments. Furthermore, with the use of test-related simulations and adapted models, it will be possible to gain knowledge and do research in areas which are omitted during regular measurements on cooling towers. In this study it is looked to two different approaches of numeric simulation of a evaporative cooling tower. There will be an examination of a CFD-Simulation and a simplified model concept regarding their respective applicability for this problem. This work is focussed on the systematic developement of such simplified mathematical models, based on the physical deterministic description of the occurring processes of heat and mass transfer in cooling towers considering the stock behaviour. Due to the non-linearity of the stock behaviour and the required incrementation of the calculation area, a systematic approach is needed to model equations and their respective solutions. For this purpose it is necessary to access general techniques of equation-based simulations of technological systems. The developed model concept will be applied for the modelation and simulation of an experimental cooling tower. The model will be calibrated and validated with data from this experimental tower. It shows, that the results from this model are qualitatively and quantitatevily valid.

In the process industries, cooling capacity is an important enabler for the facility to manufacture on specification product. The cooling water network is an important part of the over-all cooling system of the facility. In this research a cooling water circuit consisting of 3 cooling towers in parallel, 2 cooling water pumps in parallel, and 11 heat exchangers in parallel, is modelled. The model developed is based on first principles and captures the dynamic, non-linear, interactive nature of the plant. The modelled plant is further complicated by continuous, as well as discrete process variables, giving the model a hybrid nature. Energy consumption is included in the model as it is a very important parameter for plant operation. The model is fitted to real industry data by using a particle swarm optimisation approach. The model is suitable to be used for optimisation and control purposes. Cooling water networks are often not instrumented and actuated, nor controlled or optimised. Significant process benefits can be achieved by better process end-user temperature control, and direct monetary benefits can be obtained from electric power minimisation. A Hybrid Non-Linear Model Predictive Control strategy is developed for these control objectives, and simulated on the developed first principles dynamic model. Continuous and hybrid control cases are developed, and tested on process scenarios that reflect conditions seen in a real plant. Various alternative techniques are evaluated in order to solve the Hybrid Non-Linear Control problem. Gradient descent with momentum is chosen and configured to be used to solve the continuous control problem. For the discrete control problem a graph traversal algorithm is developed and joined to the continuous control algorithm to form a Hybrid Non-Linear Model Predictive controller. The potential monetary benefits that can be obtained by the plant owner through implementing the designed control strategy, are estimated. A powerful computation platform is designed for the plant model and controller simulations. / Thesis (PhD)--University of Pretoria, 2019. / Electrical, Electronic and Computer Engineering / PhD / Unrestricted

There was solved reinforced concrete cooling tower in the diploma thesis. This is a rotationally symmetrical construction. The cooling tower is concrete shell on columns. The cooling tower was solved using the finite element method, computer program Midas FEA. The work includes: calculation using the program Midas FEA, comparison of load between eurocode and foreign literature, the design of shell and columns, drawings form

M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / In the present study, the removal of Ca2+ and Mg2+ from cooling tower water using Amberlite IR120 and Amberjet 1200 was studied by the application of one factor at a time method (OFAT) and response surface modelling (RSM). The effect of operational parameters such as contact time (min), pH, dosage (mL), concentration (mg/L) and temperature (K) were investigated using central composite design. The regeneration of the Amberlite IR120 and Amberjet were also studied. The purpose of the study was to apply OFAT and RSM to investigate and optimize the ion exchange operating parameters. Furthermore, the second-order empirical model that was developed, using the analysis of variance (ANOVA), presented a sufficient correlation to the ion exchange experimental data. The optimal ion exchange operating conditions for Amberlite IR120 and Amberjet 1200 were found to be: contact time was 120 min, dosage of 150mL, initial pH level of 2, concentration of 400mg/L and temperature of 343K. Regeneration of Amberlite IR120 and Amberjet 1200 using 0.5 M NaCl stripping solution initially showed an increase in % Ca2+ and Mg2+ removal, then a decrease in subsequent cycles. The correlation coefficients (R2) of Langmuir, Freudlich and Tempkin isotherms were found to range from 0.92 to 1 and this suggest that experimental data best described the models. However correlation coefficients (R2) for Dubinin–Radushkevich (D-R) model were found to range between 0.5 to 0.8 and this means that experimental data does not fit the model. Thermodynamic functions such as entropy (Δ𝑆𝑜), enthalpy (Δ𝐻𝑜) and change of free energy (Δ𝐺𝑜) were obtained from the gradient and intercepts of straight line graphs. The positive values of ΔG° were found meaning that the adsorption is not spontaneous and positive values of ΔH° were found meaning the endothermic type of adsorption which indicate the chances of physical adsorption.The correlation coefficient (R2) values of pseudo-first-order, pseudo-second-order and intraparticle models were found to range from 0.89 to 1 on both metals as shown in table 4.4. This observation clearly indicates that pseudo-first-order, pseudo-second-order and intraparticle diffusion models best describe the experimental data in the removal Ca2+ and Mg2+ from cooling tower water.

Thesis is concerning urbanistic treatment of a chosen part of Zábrdovice, a catastral disctrict in the city of Brno. Analyses problems of the area, searches for causes and solutions of problems regarding living there or going through the area. Offers a possible solution to make the area passable for pedestrians, car and cyclists, and to improve its continuity to the center of Brno and make it more attractive.

First of all, the work should point out the possibilities of activating the non-functioning post-industrial area. The aim is to remove the “wedge” into the center and to bring missing urban activities to the site. For this purpose, I suggest the completion of a city blocks with a housing function, a square with a food market, a city park, and a connection to the surrounding of industrial buildings. The aim is to integrate the site into the city through the completion and rehabilitation of industrial houses. The great creative challenge is to preserve the genius loci of this post-industrial landscape.

The diploma thesis deals with the future smart district at Špitálka in Brno - Zábrdovice. The smart district will serve as a pilot territory to verify the goal setting from the vision for the #brno2050 strategy. One of the main motives is the activation of the territory by means of relevant interventions, which can start the development not only of this area, but can also have a positive impact on the entire locality. The aim of the diploma thesis is to contribute to the preparations for the revitalization of the city district and to outline possible alternatives for the phasing of development, the method of activating the territory and temporary use during the realization process. Further contribute to the discussion about cooperation public sector with private, community planning in our environment and the possibility of alternative project financing. The proposed tactics correspond to the local significance, are based on current values and lead to a sustainable urbanization process of an evolving urban environment. The work is analytically based on the current criteria of the urban environment generated by the investments of capitalist society. The proposal focuses on areas related to performative planning or an experimental form of so-called bottom-up planning and supports the principles of Smart City.