CFD Design of Waste Heat Boiler Burner in the Education System of Masters Heat Engineering Specialties

Modern CFD methods for calculating combustion processes make it possible to take into account changes in temperatures, heat loads, rates of coolants, as well as further changes in fuel quality. To develop the skills of CFD design and understanding of combustion processes among future specialists in thermophysical specialties, work was carried out to simulate the burner device of a waste heat boiler. For the study, the design of the gas burner of the waste heat boiler RB-70-4.0-440, which operates as a part of the power unit at the LLC “Rubezhansky Cardboard and Container Plant” in the city of Rubezhnoe, was selected. When constructing a geometric model, the hydraulic resistance to the flow of the supply and distribution manifolds was taken into account. To simplify the calculations, the problem was carried out in a two-dimensional, axisymmetric formulation. Analyzing the computational combustion models, the Non-Premixe Combustion model was chosen, which made it possible to take into account the entry of fuel and oxidizer into the reaction zone by two different flows, as well as turbulent diffusion flame propagation. Six variants of models were investigated: the first three variants with a flame tube with a solid disc with diameters of 32, 48, 56 mm, the next three variants, had a burner with a discontinuous disk 32 mm in diameter at a distance of 6, 16, 32 mm from the flame tube. As a result of the research, the optimal shape of the burner was chosen, which corresponds to model 4, and provides a high-quality combustion process, as evidenced by the high temperature of the torch and the lowest temperature at the disk. The conducted research gives future masters the skills of modeling combustion processes in power equipment.

Heat Exchange and Hydrodynamic Characteristics of Unified Package of Cold Layer of RAH

Heating the air in the boiler air heater with the heat of fuel combustion products performs the functions of increasing the fuel combustion temperature, increasing the temperature level of gases in convective heating surfaces, improving ignition and fuel combustion conditions, increasing boiler efficiency by utilizing waste gas heat, improving fuel quality due to its preliminary supply, etc. However, the peculiarities of the process of heating the air in the air heaters do not allow to achieve a decrease in the temperature of the exhaust gases. This is due to the unfavorable ratio of heat capacities of flue gases and air, as well as corrosion and contamination of the heating surfaces of air heaters. The research of heat transfer processes and hydraulic resistance of unified package of cold layer of RAH is depicted at this work. The graphic dependence of the change in the coefficient of hydraulic resistance and Nu number for unified packages with single line of sheets and simplified profile with corrosion resistance enamel from the Reynolds number for different values of the length of the replaced areas was constructed. The unified packing of the simplified profile has increased by 1.17 times equivalent diameter and is characterized by good operational parameters and takes into account the risk of contamination of heating surfaces due to the enamel coating.

Dynamic Load Cycle Effects on PEMFC Stack CO Tolerance under Fuel Recirculation and Periodic Purge

This work presents first experimental evidence on the effects of dynamic load cycle on PEM fuel cell system CO tolerance, a topic which to date has not been comprehensively investigated. The experiments were performed with a 1 kW fuel cell system employing components, design, and operation conditions corresponding to automotive applications. To distinguish between the load cycle and other factors affecting the CO tolerance, the experiments were repeated with static and dynamic load cycles, as well as with pure and CO contaminated fuel. The measurement data showed that dynamic load cycle improves the CO tolerance in comparison to static load with the same average current density. Moreover, the cell voltage deviation data indicated that the difference could be explained by higher electrochemical CO oxidation rate under the dynamic load cycle. These results allow us to estimate the effect of the load cycle on CO tolerance and understand its origins, thus giving valuable input for fuel quality standardization and fuel cell system development work.

THE APPLICATION OF FUZZY AHP – VIKOR HYBRID METHOD TO INVESTIGATE THE STRATEGY FOR REDUCING AIR POLLUTION FROM DIESEL POWERED VESSELS

The negative impact of air pollution on human health had become a vital issue as a result of the increasing use of fossil fuels in recent years. In this context, maritime transportation is one of the most contaminant sectors by using much more fossil fuels. Ships which have a major role in maritime transport, directly affect human health via its emissions, especially in marine areas close to the land such as around the ports, canals, and straits. In this study, strategies were gathered by evaluating International Maritime Organization (IMO) regulations, European Union (EU) recommendations and the applications of the ship owner companies to reduce air pollution stem from ships, and considering the priority perception of these strategies, the effect level of the strategies at the marine areas where ships are approaching the land was analysed by the Fuzzy Analytic Hierarchy Process-Visekriterijumska Optimizacija I Kompromisno Resenje (AHP- VIKOR) hybrid method. As a result of the study, the most effective strategies appeared as “Forbiddance of Heavy Fuel Oil (HFO) usage on Ships” and “Detection of Low Sulphur Fuel Usage by the help of Remote Detector Systems”, and it was seen that these strategies would be most effective in canal or strait passing of the ships. It was also revealed that the relevant expert opinions and IMO regulations meshed together, and it was pointed out the applications for increasing fuel quality.

The production of biodiesel from plum waste oil using nano-structured catalyst loaded into supports

The present study was undertaken with aims to produced catalyst loaded on low-cost clay supports and to utilize plum waste seed oil for the production of biodiesel. For this purpose, Bentonite–potassium ferricyanide, White pocha-potassium ferricyanide, Granite-potassium ferricyanide, Sindh clay-potassium ferricyanide, and Kolten-potassium ferricyanide composites were prepared. Transesterification of plum oil under the different conditions of reactions like catalysts concentrations (0.15, 0.3 and 0.6 g), temperature (50, 60, 70 and 80 °C), reaction time (2, 4 and 6 h) and oil to methanol ratio (1:10) was conducted. The maximum biodiesel yield was recorded for Bentonite–potassium ferricyanide composite. This composite was subjected to calcination process to produce Calcinized bentonite–potassium ferricyanide composite and a further improvement in biodiesel amount was recorded. The fuel quality parameters of all biodiesel samples were in standard range. Gas chromatographic mass spectrometric analysis confirmed the presence of oleic and linoleic acids in the plum seed oil. The characterization of composite was done using FTIR, SEM and EDX. Two infrared bands are observed in the spectrum from 1650 to 1630 cm−1 indicates that the composite materials contained highly hydrogen bonded water. The presence of surface hydroxyls groups can also be confirmed from FTIR data. SEM image clearly show the presence of nano-rods on the surface of Granite-potassium ferricyanide and Kolten-potassium ferricyanide composites. Another interesting observation that can be recorded from SEM images is the changes in surface characteristic of Bentonite–potassium ferricyanide composite after calcination (at 750 °C, 1 atm for 4 h). Calcinized bentonite–potassium ferricyanide composite found to contain more nano rod like structures at its surface as compared to Bentonite–potassium ferricyanide composite which contained spherical particles. EDX data of Bentonite–potassium ferricyanide composite and Calcinized bentonite–potassium ferricyanide composite show that after calcination carbon and oxygen was reduced. The other lost volatile compounds after calcination were of Na, Mg, Al, Si, and S. The XRD spectrum of pure bentonite showed the average crystal size of 24.46 nm and calcinized bentonite of 25.59 nm. The average crystal size of bentonite and potassium ferricyanide composite and its calcinized form was around 33.76 nm and 41.05 nm, respectively.

Threats and prospects for the development of operators in the market of light petroleum products of Ukraine

The study of the market of light petroleum products of Ukraine made it possible to establish that the market is highly competitive and is growing at an average pace. The main operators on it are FPG "Privat" (gas station networks "Avias", "ANP", "Sentosa Oil", etc.), PJSC "Ukrnafta" (gas station network "UKRNAFTA"), PEG "Continental" (gas station network "WOG"), JSC "Concern "Galnaftogaz" (gas station network "OKKO"). These companies, as well as international gas stations networks, occupy the best competitive positions in the market. In the nearest future, the entry of new companies into the market is not forecasted. Oil refinery companies in Ukraine import oil and products of its processing, and their own oil and gas fields are not developed. Foreign companies that develop their own fields (for example, Russian corporations) have a significant competitive advantage. Also, competitive advantages for operators in the light petroleum products market are the geographical distribution of filling stations, the presence of a strong brand, additional service for consumers, and a significant number of loyal consumers. It was found that such factors as the presence of bureaucratic aspects in decision-making in cooperation with the state, unfair competition in the market from illegal gas stations, a gradual increase in the number of electric vehicles, global fluctuations in oil prices, legislative restrictions, inflation, potential devaluation of the hryvnia, as well as the low purchasing power of consumers have a threatening impact on the market. Among the weaknesses of the industry was the exhaustiveness of the planet's oil resources, and among the opportunities - the development of its own fields or the gradual diversification of production towards adjacent markets (for example, the renewable energy market). Based on the analysis of the light petroleum products industry, it was established that horizontal and vertical diversification strategies are promising for JSC "Concern Galnaftogaz". According to them, the main marketing solutions of this enterprise can be aimed at creating new types of products (in particular, related to renewable energy), building solar power plants and wind farms on the company's own land plots, and full access to the renewable energy market. The advantage of these strategies is the minimization of risk since the market is partially known (JSC "Concern Galnaftogaz" owns a façade solar power plant on the building of the head office and "green" filling stations (filling stations with solar panels on roofs) in areas with a high level of solar insolation. The implementation of the diversification strategy also consists in expanding the range of products offered by JSC "Concern Galnaftogaz", for example, by providing such a new service as testing fuel samples in mobile laboratories for individuals who would be able to carry out their own fuel quality check offered by various filling stations.

Valorization of Hemp Stalk Waste Through Thermochemical Conversion for Energy and Electrical Applications

The presented research aimed at finding new ways to value hemp by-products (stalks) from the cannabidiol industry through thermochemical conversion. Chemical and elemental composition of hemp biomass was investigated by successive chemical extractions and Scanning Electron Microscopy along with Energy-dispersive X-ray Spectroscopy. Proximate and elemental analyses completed the chemical characterization of the hemp biomass and its biochar. Thermogravimetric analysis of the hemp biomass allowed to understand its kinetic of decomposition during thermal conversion. The carbon structure and porosity of the biochar were assessed by Raman spectroscopy and CO2 gas adsorption. Properties of interest were the energy production measured through calorific values, and the electrical conductivity. Two ways of valorisation of the hemp biomass were clearly identified, depending mainly on the chosen pyrolysis temperature. Hemp biochar carbonized at 400–600°C were classified as lignocellulosic materials with a good potential for solid biofuel applications. Specifically, the resulting carbonized biochar presented low moisture content (below 2.50%) favourable for high fuel quality, low volatile matter (27.1–10.4%) likely to show lower particle matter emissions, limited ash content (6.8–9.8%) resulting in low risk of fouling issues during the combustion, high carbon content (73.8–86.8%) suggesting strong energy density, associated with high higher heating values (28.45–30.95 MJ kg−1). Hemp biochar carbonized at 800–1000 °C displayed interesting electrical conductivity, opening opportunities for its use in electrical purposes. The electrical conductivity was related to the evolution of the biochar microstructure (development of graphite-like structure and changes in microporosity) in regard with the thermochemical conversion process parameters. Graphical abstract