1. Environmental impact assessment of organic rankine cycle using waste heat from the aluminium industryMonika Dokl, Gaja Strajnar, Annamaria Vujanović, Jan Puhar, Zdravko Kravanja, Lidija Čuček, 2025, original scientific article Abstract: Waste heat recovery technologies play an important role in enhancing energy efficiency and supporting sustainable energy production. This study investigates the utilization of waste heat from aluminium production through an Organic Rankine Cycle (ORC) system to generate electricity and heat simultaneously. Based on operational data from an aluminium plant, the system is firstly optimized from both the thermodynamic and economic perspectives. To maximize performance and to identify optimal configurations, a mathematical model is developed and solved using GAMS, capturing the complex interdependencies between the operational, economic and thermodynamic parameters. The environmental impact of the optimized scenarios is subsequently evaluated using a Life Cycle Assessment (LCA), considering a broad range of impact categories. The results indicate a maximum power output of 830.9 kW and a maximum net present value (NPV) of 51.71 M€, confirming the system’s technical and economic viability. The environmental assessment demonstrates the potential of ORC systems as sustainable energy solutions, with significant environmental unburdening under optimized operating conditions (up to -606.0 kg CO2 eq./h). A sensitivity analysis indicates that the greatest environmental benefits occur under the optimal thermodynamic scenario, achieved through the utilization of higher-energy flue gas streams (up to -515.0 kg CO2 eq./h), and under the optimal economic scenario by balancing the electricity and heat prices optimally for simultaneous heat and power production (up to -696.7 kg CO2 eq./h). These findings highlight the importance of the thermal input quality and availability in maximizing ORC performance. With the ability to prioritize electricity, heat, or both, the optimized ORC systems support flexible energy solutions tailored to specific applications and environmental conditions, offering a promising pathway for unburdening the environment through the efficient utilization of industrial waste heat. Keywords: waste heat recovery, aluminium production, organic rankine cycle, environmental impact, life cycle assessment, sustainable energy solutions Published in DKUM: 13.06.2025; Views: 0; Downloads: 5
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2. Improving electricity generation during the product reaction loop and the use of exhaust gas for co-product production using polyethylene waste and flue gas or woodAnita Kovač Kralj, 2022, original scientific article Abstract: More energy-efficient industries could reduce the problems of pollution, global warming,
energy security, and fossil fuel depletion, including processing waste into raw materials and more
efficient energy cogeneration. This research project considers the novelties of the upgraded electricity
cogeneration technique, including one open gas turbine during the high-pressure product reaction
loop and a second turbine during the exhaust gas for co-product production with only one compressor.
The upgraded electricity cogeneration was carried out in two steps and based on the productive use of
otherwise useless polyethylene waste, flue gas, and wood. The first step can simulate the simulation
model from the existing product production with well-known technology and process units using
the Aspen Plus® simulator. The maximum available electricity cogeneration can previously be
determined from the thermodynamics of the products and co-products, and an existing energy unit’s
characteristic capacity. In the second step, conventional natural gas can be replaced with waste
as the raw materials by using the same simulated model from the first step, including electricity
cogeneration using the gas turbines during the high-pressure reaction loop, and the exhaust gas as the
co-product with only one compressor. This research on electricity generation is based on processes
that include the pressure drop during the product reaction loop. This approach is illustrated using an
existing methanol production process, using wastes as sustainable raw materials, including electricity
cogeneration during the reaction loop and exhaust gas, generating a possible increase in annual profit
of 7.28 MEUR/a. Keywords: waste recovery, cogeneration, exothermic reactor, gas turbine, exhaust gas, combined compressor Published in DKUM: 15.05.2025; Views: 0; Downloads: 0
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3. Real-life application of a wearable device towards injury prevention in tennis : a single-case studyIztok Kramberger, Aleš Filipčič, Aleš Germič, Marko Kos, 2022, original scientific article Abstract: The purpose of this article is to present the use of a previously validated wearable sensor
device, Armbeep, in a real-life application, to enhance a tennis player’s training by monitoring and
analysis of the time, physiological, movement, and tennis-specific workload and recovery indicators,
based on fused sensor data acquired by the wearable sensor—a miniature wearable sensor device,
designed to be worn on a wrist, that can detect and record movement and biometric information,
where the basic signal processing is performed directly on the device, while the more complex
signal analysis is performed in the cloud. The inertial measurements and pulse-rate detection of
the wearable device were validated previously, showing acceptability for monitoring workload and
recovery during tennis practice and matches. This study is one of the first attempts to monitor the
daily workload and recovery of tennis players under real conditions. Based on these data, we can
instruct the coach and the player to adjust the daily workload. This optimizes the level of an athlete’s
training load, increases the effectiveness of training, enables an individual approach, and reduces the
possibility of overuse or injuries. This study is a practical example of the use of modern technology
in the return of injured athletes to normal training and competition. This information will help tennis
coaches and players to objectify their workloads during training and competitions, as this is usually
only an intuitive assessment. Keywords: tennis, training, data-based coaching, shot recognition, wearable device, workload, recovery Published in DKUM: 31.03.2025; Views: 0; Downloads: 3
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4. On parsing programming languages with Turing-complete parserBoštjan Slivnik, Marjan Mernik, 2023, original scientific article Abstract: A new parsing method based on the semi-Thue system is described. Similar to, but with more efficient implementation than Markov normal algorithms, it can be used for parsing any recursively enumerable language. Despite its computational power, it is meant to be used primarily for parsing programming and domain-specific languages. It enables a straightforward simulation of a number of existing parsing algorithms based on context-free grammars. The list includes both top-down shift-produce methods (such as SLL and LL) and bottom-up shift-reduce methods (such as LALR and LR), as well as mixed top-down-and-bottom-up methods such as LLLR. To justify the use of the new parsing method, the paper provides numerous examples of how a parser can actually be made in practice. It is advised that the main part of the parser is based on some simple well-established approach, e.g., SLL(1), while syntactically more complicated phrases can be parsed by exploiting the full power of the new parser. These phrases may either be extensions to the original language or some embedded domain-specific language. In all such and similar cases, no part of the language is restricted to be context-free. In fact, context-sensitive languages can be handled quite efficiently. Keywords: Turing-complete parsing, context-sensitive, error recovery Published in DKUM: 14.02.2024; Views: 325; Downloads: 26
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5. Recovery study of gold nanoparticle markers from lateral flow immunoassaysTilen Švarc, Peter Majerič, Darja Feizpour, Žiga Jelen, Matej Zadravec, Timi Gomboc, Rebeka Rudolf, 2023, original scientific article Abstract: Lateral flow immunoassays (LFIAs) are a simple diagnostic device used to detect targeted analytes. Wasted and unused rapid antigen lateral flow immunoassays represent mass waste that needs to be broken down and recycled into new material components. The aim of this study was to recover gold nanoparticles that are used as markers in lateral flow immunoassays. For this purpose, a dissolution process with aqua regia was utilised, where gold nanoparticles were released from the lateral flow immunoassay conjugate pads. The obtained solution was then concentrated further with gold chloride salt (HAuCl4) so that it could be used for the synthesis of new gold nanoparticles in the process of ultrasonic spray pyrolysis (USP). Various characterisation methods including scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy and optical emission spectrometry with inductively coupled plasma were used during this study. The results of this study showed that the recovery of gold nanoparticles from lateral flow immunoassays is possible, and the newly synthesised gold nanoparticles represent the possibility for incorporation into new products. Keywords: gold nanoparticles, recovery, LFIA, ultrasonic spray pyrolysis, characterisation Published in DKUM: 09.02.2024; Views: 358; Downloads: 25
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6. An analysis of the responsibility for zero wasteIvana Tršelič, Daniel Rolph Schneider, Niko Samec, Filip Kokalj, 2019, original scientific article Abstract: European Union Directive 2008/98/EC sets the priority hierarchy of the prevention of waste, re-using waste, recycling waste, waste recovery, and waste disposal. Although every one of us is in daily contact with waste, we do not have the knowledge that can lead us to the sound management of waste from the beginning, before products are identified as waste. Zero waste is a fundamental concept of the sustainable community of the future. It is a phrase frequently used by politicians seeking to upgrade the municipal solid waste management systems in their communities. In this manner, the responsibility of zero waste is given to the waste management process instead of to householders. Householders then equate waste prevention with recycling and the proper waste management of the collectors, public services, or waste management company. In reality, zero waste starts with each one of us at home. Households should aim to reduce consumption and undertake repairs to extend the life span of products. Behaviour change can only start with knowledge. In reality, waste prevention does not include recycling. Recycling leads to a combined reduction of waste brought to landfill and raw material extraction. The present paper evaluates household waste to clarify the facts. It analyses the composition of three streams: municipal solid waste, separately collected packaging waste, and bulky waste in different regions of Slovenia. The research defines waste into five different categories. The first category is waste that can and should be avoided. The second category is waste that can be re-used. Further on, the research expands by researching the market of the third category that defines recyclables, which waste can be recycled; the last two categories are the waste that we are fighting with at the end of the waste management process, either to make it to the waste-to-energy process or to comply with landfill restrictions. At the end of the research, we summarize the situation of household waste in 2018. Our goal is to reduce the quantity of waste, making only waste that can be recycled. If we consider waste prevention to be a fight against waste, we can put our plan in place by taking the first step: getting to know our enemy. Keywords: municipal solid waste, zero waste, recycling, lightweight packaging waste, waste management, material recovery Published in DKUM: 05.12.2023; Views: 397; Downloads: 52
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7. HRSG system description and water-steam analysis at the HRSG cold start-upDušan Strušnik, 2021, original scientific article Abstract: The basic purpose of this paper is to present the HRSG system description in detail and possibility analysis of preventing the HRSH water-steam generated release into the atmosphere through the sky valves during the HRSG cold start-up. The steam released into the atmosphere by the cross sky valve is not an adequate solution for the following reasons: Noise prevention, water losses, thermal heat release into the environment, etc. In this paper, the possibilities and solutions are investigated in order to avoid the HRSG start-up sky venting. For this purpose, the steam quality data at HRSG cold start-up is analysed, and the possibility is examined of discharging the HRSG generated steam at the start-up via a new start-up pipeline into the existing dump condenser, or into the start-up flash tank or into the blowdown tank. The results show that, at the first 3 minutes of cold start-up, the HRSG generated only water, and this water should not be discharged into the HP or IP pipeline headers. The HRSG generates a mixture of water and steam only after 4 minutes from the start-up. For that reason it is not recommended to drain the water-steam mixture at the HRSG start-up into the new start-up pipeline, but it is recommended to drain the water and steam mixture formed during the HRSG start-up into the new start-up flash tank, or into the blowdown tank. The flash tank, and also the blowdown tank, should be appropriately dimensioned. Keywords: boiler, duct, flue gas, heat recovery, stack, steam generator, superheater Published in DKUM: 13.11.2023; Views: 427; Downloads: 36
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8. RFCS project methenergy+ methane recovery and harnessing for energy and chemical uses at coal mine sitesMatjaž Kamenik, Janez Rošer, Salvador Ordonez, 2022, original scientific article Abstract: Ventilation Air Methane emissions (VAM) from coal mines lead to environmental concern because of their high global warming potential and the loss of methane (CH4) resources. How to tackle methane harnessing and its use was studied and analysed in the scope of the RCFS project, which was performed from 2017 till 2020, and coordinated by the University of Oviedo in Spain within the scope of an international consortium of eleven entities from Poland, Spain, the United Kingdom, Czechia, Greece, Slovenia and Sweden, combining universities, research institutions and industry (mostly Polish mines and the Slovenian Velenje mine). The main challenge tackled in the project was the use of methane released from both operating and abandoned mines, which is an environmental and safety hazard and also a useful source of energy. Therefore, the effective extraction of methane, its enrichment, purification, separation, thermal or chemical upgrading, and its use, considering coal mine site specifics, was assessed. Despite good operational results, after in-depth economic analysis of the integration, CAPEX and OPEX calculation, there turned out to be a high economic dependence on the cost of adsorbent, since adsorption was the most promising technology for concentrating the methane in these emissions. Therefore, the economic viability depends on the development of materials that meet a minimum cost and performance. Within the scope of the project, a lot of activities were carried out in order to widen and exploit the results. Keywords: ventilation air methane, abandoned mine methane, coalmining, methane recovery, harnessing, thermal upgrading, chemical upgrading, adsorption-based technologies, materials development, thermal regenerative oxidizers, catalytic regenerative oxidizers, methanol, greenhouse gases Published in DKUM: 30.10.2023; Views: 507; Downloads: 138
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9. Off-design flow analysis of cogeneration steam turbine with real process dataDušan Strušnik, Igor Kuštrin, Jurij Avsec, 2022, original scientific article Abstract: This paper presents the concept of reconstruction of the existing coal-fired combined heat and power plant to comply with new European environmental policies. The existing coal-fired boiler will be replaced by two new dual pressure heat recovery steam generators, which will utilize the exhaust gas heat from two new gas turbines. The steam from the heat recovery steam generators will be fed to the existing steam turbine. After the reconstruction, the nominal turbine inlet steam mass-flow of 40 kg/s will be reduced to 30 kg/s. During periods of low heat demand, only one gas turbine and one heat recovery steam generator will be in operation and the live steam mass-flow may drop even to 12 kg/s. Prior to the reconstruction, dedicated tests of the existing steam turbine were carried out using the steam from the existing coal-fired boiler. The goal of the test was to verify the viability of operation with such an extremely low mass-flow. The results of tests show that such operation is possible but inefficient from a power generation point of view. Besides this, the turbine control algorithm needs to be accommodated to this extreme operating regime and additional measures like displacement of the extraction points and steam cooling will be required to control the temperature of the steam extractions. The novelty of this paper is using real prereconstruction process data for the assessment of feasibility and efficiency of the post-reconstruction operation of a combined heat and power turbine. Keywords: cogeneration, control valves, exhaust gas, heat recovery, steam turbine Published in DKUM: 30.10.2023; Views: 248; Downloads: 24
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10. Method of the best available technology and low carbon future of a combined heat and power plantDušan Strušnik, Marko Agrež, 2022, original scientific article Abstract: The low-carbon development strategy and ecological awareness of a combined heat and power (CHP) plant is the key factor that enables further development of such systems. CHP plants are subject to rigid European ecological guidelines, which dictate the pace of development of global thermal power engineering. For this purpose, the European Union issued a special Directive for the promotion of heat and power cogeneration, and is established with the best available technology (BAT) method. Even though the production of electricity using carbon-free technologies is on the rise, the production of electricity by fossil fuel combustion cannot be avoided completely. The meaning of the operation of the CHP plant is reflected particularly in the provision of tertiary services to the electric power system, regulation of the network frequency, particularly in winter months, when electricity production using carbon-free technologies is limited. In CHP systems, the low-carbon future is linked intricately to high investment costs and these impacts the final price of energy. Using the BAT method, the article presents the advantages of energy production in a combined heat and power plant, an example of the restructuring of a larger CHP system into a low-carbon plant and guidelines for further development. Keywords: alternative facilities, best available technology, combined plant, heat recovery, hydrogen, low-carbon, methanisation, natural gas, steam recovery Published in DKUM: 26.10.2023; Views: 331; Downloads: 50
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