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: 19
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2. When technology meets sustainability: microplastic removal from industrial wastewater, including impact analysis and life cycle assessmentJan Puhar, Michael Toni Sturm, Erika Myers, Dennis Schober, Anika Korzin, Annamaria Vujanović, Katrin Schuhen, 2025, original scientific article Abstract: Microplastics (MPs) that are ubiquitous in aquatic environments and industrial wastewater streams have been identified as key hotspots of MP contamination. It is significantly more effective to remove MPs at these points before they enter municipal wastewater streams. This study is an environmental assessment of a novel pilot plant for the removal of MPs and the chemical oxygen demand (COD) from wastewater with a high MP contamination from a plastics manufacturer in Germany. MP removal is based on physical–chemical agglomeration–fixation by organosilanes. Formed agglomerates are separated using a belt filter. The COD is removed by an adsorption process. The resulting MP removal was 98.0 ± 1.1% by mass and 99.9987 ± 0.0007% by particle count, while the COD was reduced by 96 ± 2.7%. The system’s sustainability is evaluated using the Life Cycle Assessment methodology, evaluating system construction, operation, and end-of-life considerations. The current pilot plant is also compared to an optimized circular and sustainable upgrade, where drivers of environmental burdens are eliminated and collected MPs are reused. Significant reductions in environmental impact categories are achieved and the global warming potential is reduced by 96%. This study provides a sustainability assessment of a novel technology and circular solution to remove MPs from highly polluted industrial wastewater.
Keywords: microplastics, life cycle assessment, impact analysis, removal technology, sustainable process design, carbon footprint, water quality, circular economy
Published in DKUM: 14.03.2025; Views: 0; Downloads: 4
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3. Analiza proizvodnega procesa za trajnostno proizvodnjo formalina : magistrsko deloJan Puhar, 2022, master's thesis Abstract: Formalin je pomembna kemikalija, ki se proizvaja v velikih količinah, njegova proizvodnja pa je energetsko zahteven proces. Zmanjšanje porabe energije procesa bi prispevalo tako k ekonomskim prihrankom kot tudi k zmanjšanim okoljskim vplivom in bi omogočilo bolj trajnostno proizvodnjo formalina kot vmesnega ali končnega produkta.
Cilj magistrskega dela je izboljšanje trajnosti proizvodnega procesa formalina preko reformiranja metana z analizo energetskega, ekonomskega in okoljskega vidika. Na simuliran proces je bila uvedena toplotna integracija, ki je bila izvedena s pomočjo uščipne metode in matematičnega programiranja, kjer smo uporabili pretovorjevalni optimizacijski model. Za izvedbo toplotne integracije smo uporabili sekvenčni pristopom, pri čemer smo najprej minimirali stroške pogonskih sredstev, nato smo minimirali število toplotnih prenosnikov ter nazadnje sintetizirali omrežje toplotnih prenosnikov. Za procesa pred in po toplotni integraciji smo izvedli ekonomsko analizo na osnovi investicijskih in obratovalnih stroškov, kjer smo uporabili faktorsko metodo. Izvedena je bila tudi analiza življenjskega cikla, s katero smo ocenili okoljske vplive procesa pred in po toplotni integraciji.
Rezultati kažejo, da toplotna integracija procesa zmanjša porabo pogonskih sredstev za 39 %, kar posledično vodi do 11 % prihrankov v investicijskih stroških. Toplotna integracija izboljša proces tudi z okoljskega vidika, kjer so okoljski vplivi zmanjšani za 7 do 22 % v izbranih kategorijah vpliva. Študija v magistrskem delu služi kot izhodišče za nadaljnje raziskave izboljšanja trajnosti proizvodnje formalina.
Keywords: Proizvodni proces formalina, toplotna integracija, zmanjšanje porabe energije, ekonomska analiza, okoljska analiza.
Published in DKUM: 08.06.2022; Views: 911; Downloads: 103
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4. Simulacija razpenjalnika s programskima orodjema Scilab in GAMSJan Puhar, 2018, undergraduate thesis Abstract: V diplomski nalogi je prikazan opis procesa ravnotežne destilacije z modeli različnih kompleksnosti: kot problem s sistemom linearnih enačb, sistemom nelinearnih enačb in sistemom DAE (diferencialno-algebrskih enačb). Delo obsega prikaz sistema enačb, potrebnega za rešitev vsakega od problemov in razvoj matematičnega modela za rešitev problemov v programskih orodjih Scilab in GAMS.
Namen diplomskega dela je bil z obema programskima orodjema izdelati ustrezen model. Ugotovili smo, kako predstaviti probleme z modelom ter prikazali smo izpisane rezultate za posamezen primer in ustrezno kodo v Scilabu in GAMS-u.
Keywords: ravnotežna destilacija, model, Scilab, GAMS, sistem enačb
Published in DKUM: 13.09.2018; Views: 1125; Downloads: 178
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