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A refining model is developed to analyses the refining process’s energy efficiency based on the refining variables. A simulation model is obtained for longer-term refining energy analysis by further developing the MATLAB Thermo-Mechanical Pulping Simulink toolbox. This model is utilized to predict two essential variables for refining energy efficiency calculation: refining motor-load and generated steam. The conventional variable for presenting refining energy efficiency is refining specific energy consumption (RSEC), which is the ratio of the refining motor load to throughput and does not consider the share of recovered energy from the refining produced steam. In this study, a new variable, corrected refining specific energy consumption (CRSEC), is introduced and practiced for better representation of the refining energy efficiency. In the calculation process of the CRSEC, recovered energy from the refining generated steam is considered useful energy. The developed model results in 160% and 78.75% improvement in simulation model determination coefficient and error, respectively. Utilizing the developed model and hourly district heating demand for CRSEC calculation, results prove a 22% annual average difference between CRSEC and RSEC. Findings confirm that the wintertime refining energy efficiency is 27% higher due to higher recovered energy in the heat recovery unit compared to summertime.
Behnam Talebjedi; Timo Laukkanen; Henrik Holmberg; Esa Vakkilainen; Sanna Syri. Energy Efficiency Analysis of the Refining Unit in Thermo-Mechanical Pulp Mill. Energies 2021, 14, 1664 .
AMA StyleBehnam Talebjedi, Timo Laukkanen, Henrik Holmberg, Esa Vakkilainen, Sanna Syri. Energy Efficiency Analysis of the Refining Unit in Thermo-Mechanical Pulp Mill. Energies. 2021; 14 (6):1664.
Chicago/Turabian StyleBehnam Talebjedi; Timo Laukkanen; Henrik Holmberg; Esa Vakkilainen; Sanna Syri. 2021. "Energy Efficiency Analysis of the Refining Unit in Thermo-Mechanical Pulp Mill." Energies 14, no. 6: 1664.
In the pulping industry, thermo-mechanical pulping (TMP) as a subdivision of the refiner-based mechanical pulping is one of the most energy-intensive processes where the core of the process is attributed to the refining process. In this study, to simulate the refining unit of the TMP process under different operational states, the idea of machine learning algorithms is employed. Complicated processes and prediction problems could be simulated and solved by utilizing artificial intelligence methods inspired by the pattern of brain learning. In this research, six evolutionary optimization algorithms are employed to be joined with the adaptive neuro-fuzzy inference system (ANFIS) to increase the refining simulation accuracy. The applied optimization algorithms are particle swarm optimization algorithm (PSO), differential evolution (DE), biogeography-based optimization algorithm (BBO), genetic algorithm (GA), ant colony (ACO), and teaching learning-based optimization algorithm (TLBO). The simulation predictor variables are site ambient temperature, refining dilution water, refining plate gap, and chip transfer screw speed, while the model outputs are refining motor load and generated steam. Findings confirm the superiority of the PSO algorithm concerning model performance comparing to the other evolutionary algorithms for optimizing ANFIS method parameters, which are utilized for simulating a refiner unit in the TMP process.
Behnam Talebjedi; Ali Khosravi; Timo Laukkanen; Henrik Holmberg; Esa Vakkilainen; Sanna Syri. Energy Modeling of a Refiner in Thermo-Mechanical Pulping Process Using ANFIS Method. Energies 2020, 13, 5113 .
AMA StyleBehnam Talebjedi, Ali Khosravi, Timo Laukkanen, Henrik Holmberg, Esa Vakkilainen, Sanna Syri. Energy Modeling of a Refiner in Thermo-Mechanical Pulping Process Using ANFIS Method. Energies. 2020; 13 (19):5113.
Chicago/Turabian StyleBehnam Talebjedi; Ali Khosravi; Timo Laukkanen; Henrik Holmberg; Esa Vakkilainen; Sanna Syri. 2020. "Energy Modeling of a Refiner in Thermo-Mechanical Pulping Process Using ANFIS Method." Energies 13, no. 19: 5113.
A key challenge in prevention of global warming is how to increase energy efficiency, to be able to deal with increased fossil CO2 emissions from rising energy usage. Increasing energy efficiency will decrease energy usage and is in a key role in emission mitigation. The focus is the pulp and paper industry, which is energy-intensive. Development of industrial energy efficiency has been studied before but the role of industrial transformation is still mostly unknown. The knowledge must be improved, to be able to predict future developments in the most effective way. In this research, impact of various production unit closures and start-ups on energy efficiency of the Finnish pulp and paper industry were studied utilizing statistical analysis. Results indicate that about 20% of the Finnish pulp and paper industry energy efficiency improvement between 2011 and 2017 is caused by the major structural changes. The rest, 80% of the progress, was mainly due to improved technology and more optimal operational modes. Additional findings suggest that modern mill start-ups have a significantly greater potential to reduce energy consumption than old mill closures.
Satu Kähkönen; Esa Vakkilainen; Timo Laukkanen. Impact of Structural Changes on Energy Efficiency of Finnish Pulp and Paper Industry. Energies 2019, 12, 3689 .
AMA StyleSatu Kähkönen, Esa Vakkilainen, Timo Laukkanen. Impact of Structural Changes on Energy Efficiency of Finnish Pulp and Paper Industry. Energies. 2019; 12 (19):3689.
Chicago/Turabian StyleSatu Kähkönen; Esa Vakkilainen; Timo Laukkanen. 2019. "Impact of Structural Changes on Energy Efficiency of Finnish Pulp and Paper Industry." Energies 12, no. 19: 3689.
In this article, we show how a revised district heat network control strategy can be employed to utilize the storage capabilities of the network. An optimization problem is formulated, with minimum operating costs as the objective. Allowing the district heat supply temperature to vary freely within given boundaries results in approximately 2% reduction in annual heat provision costs, in comparison to a reference control scheme in a case study. The benefits of added heat storage functionality in the network are greatest when there is a large difference between district heat generation costs from the available heat sources. In general, supply temperature optimization results in increased operational hours of those plants, whose variable costs are the lowest.
Mikko Kouhia; Timo Laukkanen; Henrik Holmberg; Pekka Ahtila. District heat network as a short-term energy storage. Energy 2019, 177, 293 -303.
AMA StyleMikko Kouhia, Timo Laukkanen, Henrik Holmberg, Pekka Ahtila. District heat network as a short-term energy storage. Energy. 2019; 177 ():293-303.
Chicago/Turabian StyleMikko Kouhia; Timo Laukkanen; Henrik Holmberg; Pekka Ahtila. 2019. "District heat network as a short-term energy storage." Energy 177, no. : 293-303.
Energy system design is complex and the long utilization time of plants and the variance in economic parameters induce uncertainty into the outcome. In this article, different design objectives in a mid-sized district heating system design are evaluated. A mixed integer linear multi-objective optimization model is formulated and solved for maximum profit, minimum exergy losses, minimum CO2 emissions, minimum district heat primary energy factor and minimum district heat primary exergy (PeXa) factor. Energy system design should include metrics that take externalities into account. A combination of profit, CO2 and primary energy factor is recognized as a feasible set of design objectives. Exergy losses do not represent sustainability viewpoint well in energy system design — PeXa method expands it to fit system evaluation better. Optimization models such as this may provide relevant information for system operators, and for setting policy actions.
Mikko Kouhia; Timo Laukkanen; Henrik Holmberg; Pekka Ahtila. Evaluation of design objectives in district heating system design. Energy 2018, 167, 369 -378.
AMA StyleMikko Kouhia, Timo Laukkanen, Henrik Holmberg, Pekka Ahtila. Evaluation of design objectives in district heating system design. Energy. 2018; 167 ():369-378.
Chicago/Turabian StyleMikko Kouhia; Timo Laukkanen; Henrik Holmberg; Pekka Ahtila. 2018. "Evaluation of design objectives in district heating system design." Energy 167, no. : 369-378.
Heat transfer between different processes or inter-plant heat integration can be seen as an efficient way to cost-efficiently improve the energy efficiency of a system of different processes. Nanofluids are a new type of heat transfer fluids, in which particles with size of 1-100 nm are suspended in a liquid. Nanosized particles can cause considerable enhancement in convective heat transfer performance of the base fluid, although at the same time they increase the viscosity of the fluid, thus enhancing the needed pumping power. In this work we study the effect of using nanofluids in streams transferring heat from different processes by optimizing the total annual cost of a heat exchanger network. These costs include the cost of hot and cold utilities, heat exchanger investment costs and pumping costs. A modified version of the well-known Synheat superstructure is used as the optimization model in comparing the different fluids (water and five nanofluids) in two examples. Some key parameters (electricity price and annuity factor) are varied in these two examples. The results show that nanofluids can in some cases save total annual costs and especially if electricity prices are low compared to other factors. This is true especially for MgO1.0% which outperformed water and the other nanofluids in normal price conditions. But altogether it is evident that most, and in some cases all, of the benefits provided by nanofluids to improved heat transfer is canceled out by the increased pressure drops.
Timo Laukkanen; Ari Seppälä. Interplant heat exchanger network synthesis using nanofluids for interplant heat exchange. Applied Thermal Engineering 2018, 135, 133 -144.
AMA StyleTimo Laukkanen, Ari Seppälä. Interplant heat exchanger network synthesis using nanofluids for interplant heat exchange. Applied Thermal Engineering. 2018; 135 ():133-144.
Chicago/Turabian StyleTimo Laukkanen; Ari Seppälä. 2018. "Interplant heat exchanger network synthesis using nanofluids for interplant heat exchange." Applied Thermal Engineering 135, no. : 133-144.
Nugroho Agung Pambudi; Timo Laukkanen; Mochamad Syamsiro; Indra M. Gandidi. Simulation of Jatropha curcas shell in gasifier for synthesis gas and hydrogen production. Journal of the Energy Institute 2017, 90, 672 -679.
AMA StyleNugroho Agung Pambudi, Timo Laukkanen, Mochamad Syamsiro, Indra M. Gandidi. Simulation of Jatropha curcas shell in gasifier for synthesis gas and hydrogen production. Journal of the Energy Institute. 2017; 90 (5):672-679.
Chicago/Turabian StyleNugroho Agung Pambudi; Timo Laukkanen; Mochamad Syamsiro; Indra M. Gandidi. 2017. "Simulation of Jatropha curcas shell in gasifier for synthesis gas and hydrogen production." Journal of the Energy Institute 90, no. 5: 672-679.
Thomas Kohl; Moises Teles; Kristian Melin; Timo Laukkanen; Mika Järvinen; Song Won Park; Reinaldo Giudici. Corrigendum to “Exergoeconomic assessment of CHP-integrated biomass upgrading” [Appl. Energy 156 (2015) 290–305]. Applied Energy 2016, 181, 590 -591.
AMA StyleThomas Kohl, Moises Teles, Kristian Melin, Timo Laukkanen, Mika Järvinen, Song Won Park, Reinaldo Giudici. Corrigendum to “Exergoeconomic assessment of CHP-integrated biomass upgrading” [Appl. Energy 156 (2015) 290–305]. Applied Energy. 2016; 181 ():590-591.
Chicago/Turabian StyleThomas Kohl; Moises Teles; Kristian Melin; Timo Laukkanen; Mika Järvinen; Song Won Park; Reinaldo Giudici. 2016. "Corrigendum to “Exergoeconomic assessment of CHP-integrated biomass upgrading” [Appl. Energy 156 (2015) 290–305]." Applied Energy 181, no. : 590-591.
The production of precipitated calcium carbonate (PCC) from steel slag has been proposed as a potential method of simultaneously reducing the CO2 emissions from the steelmaking process and turning its waste stream into a valuable product. On average the production of one ton of steel results in two tons of CO2 emissions and 600 kg of slag. Globally, more than 400 Mt of steel slag are produced annually. If all the slag were used for the production of PCC, 64 Mt CO2 could be utilized and 145 Mt of calcium carbonate would be produced. In 2014 the research group Energy Engineering and Environmental Protection at Aalto University in Finland has designed, constructed and tested the world’s first mineral carbonation pilot plant test facility that converts steel slag and CO2 into PCC. In batch mode the pilot plant can handle up to 20 kg of solid steel slag and 190 L of liquid solvent, and it can produce about 10 kg of calcium carbonate. The solvent can be regenerated and reused in the calcium extraction stage, which makes the process economically more feasible. Almost 80% of the calcium in the slag was extracted, while more than 70% of the CO2 was utilized and converted into PCC. In high temperature carbonation tests, ammonia gas was detected from the flue gases. At 60 °C more than 2 vol.% of NH3 was detected in the flue gas, and at 50 °C it was 0.65 vol.%, while at 45 °C the NH3 concentration in the flue gas was only 0.11 vol.%. To avoid ammonia evaporation, aragonite PCC can be produced at 45 °C by optimizing the CO2 flow rate. The paper presents the process design as well as the early results achieved from the pilot plant. The paper also presents technical challenges that occurred during the scale-up work and experiments.
Arshe Said; Timo Laukkanen; Mika Järvinen. Pilot-scale experimental work on carbon dioxide sequestration using steelmaking slag. Applied Energy 2016, 177, 602 -611.
AMA StyleArshe Said, Timo Laukkanen, Mika Järvinen. Pilot-scale experimental work on carbon dioxide sequestration using steelmaking slag. Applied Energy. 2016; 177 ():602-611.
Chicago/Turabian StyleArshe Said; Timo Laukkanen; Mika Järvinen. 2016. "Pilot-scale experimental work on carbon dioxide sequestration using steelmaking slag." Applied Energy 177, no. : 602-611.
Highlights•An exergy-based energy efficiency method called PeXa is developed.•PeXa combines exergy analysis and primary energy analysis.•PeXa uses exergy analysis inside a process and primary energy based factors for the surrounding society.•In some cases exergy analysis and PeXa will give different results assuming that the objective is to consider the primary energy effects of society. AbstractImproving energetic performance is a key factor in making societies more sustainable. One way to analyze energetic performance is to use methods based on the second law of thermodynamics. Exergy analysis is such a method. With exergy analysis thermodynamic losses of the studied system can be found. For a specific process decreasing the exergy losses decreases the need for exergy inputs and production costs. Exergy analysis can also be used to analyze the life cycle of a process or product, but then it is necessary to model the total production system. For this reason, it is important to have efficiency analysis methods that can simultaneously analyze the studied system or process and the surrounding environment around this system. The objective of this article is to present such a method where the whole energy chain needs not to be modeled, but still the effect of an energy improvement or change in a studied process can be analyzed with respect to the whole energy chain. This method is called PeXa and it combines exergy analysis and primary energy analysis. In this work we show that also the system environment affects the benefit of exergy savings in the system level depending what production does this exergy saving replace. A district heating (DH) network with different DH producing units having different exergy efficiencies is used to show the concept. It is shown that in some cases basic exergy analysis and PeXa will give different results assuming that the objective is to consider the primary energy effects of society. By considering this broader concept of environment in exergy analysis companies and societies can direct limited resources into investments that maximize primary exergy savings.
Timo P. Laukkanen; Thomas Kohl; Mika P. Järvinen; Pekka Ahtila. Primary exergy efficiency—Effect of system efficiency environment to benefits of exergy savings. Energy and Buildings 2016, 124, 248 -254.
AMA StyleTimo P. Laukkanen, Thomas Kohl, Mika P. Järvinen, Pekka Ahtila. Primary exergy efficiency—Effect of system efficiency environment to benefits of exergy savings. Energy and Buildings. 2016; 124 ():248-254.
Chicago/Turabian StyleTimo P. Laukkanen; Thomas Kohl; Mika P. Järvinen; Pekka Ahtila. 2016. "Primary exergy efficiency—Effect of system efficiency environment to benefits of exergy savings." Energy and Buildings 124, no. : 248-254.
Thomas Kohl; Moises Teles; Kristian Melin; Timo Laukkanen; Mika Järvinen; Song Won Park; Reinaldo Giudici. Exergoeconomic assessment of CHP-integrated biomass upgrading. Applied Energy 2015, 156, 290 -305.
AMA StyleThomas Kohl, Moises Teles, Kristian Melin, Timo Laukkanen, Mika Järvinen, Song Won Park, Reinaldo Giudici. Exergoeconomic assessment of CHP-integrated biomass upgrading. Applied Energy. 2015; 156 ():290-305.
Chicago/Turabian StyleThomas Kohl; Moises Teles; Kristian Melin; Timo Laukkanen; Mika Järvinen; Song Won Park; Reinaldo Giudici. 2015. "Exergoeconomic assessment of CHP-integrated biomass upgrading." Applied Energy 156, no. : 290-305.
Henrik Holmberg; Sari Siitonen; Timo Laukkanen; Mari Tuomaala; Tuomas Niskanen. Comparison of Indirect CO2-emissions of Different Renewable Transport Fuels. Energy Procedia 2015, 72, 19 -26.
AMA StyleHenrik Holmberg, Sari Siitonen, Timo Laukkanen, Mari Tuomaala, Tuomas Niskanen. Comparison of Indirect CO2-emissions of Different Renewable Transport Fuels. Energy Procedia. 2015; 72 ():19-26.
Chicago/Turabian StyleHenrik Holmberg; Sari Siitonen; Timo Laukkanen; Mari Tuomaala; Tuomas Niskanen. 2015. "Comparison of Indirect CO2-emissions of Different Renewable Transport Fuels." Energy Procedia 72, no. : 19-26.
Thomas Kohl; Timo Laukkanen; Mika Järvinen; Carl-Johan Fogelholm. Corrigendum to “Energetic and environmental performance of three biomass upgrading processes integrated with a CHP plant” [Appl. Energy 107 (2013) 124–134]. Applied Energy 2015, 145, 374 -375.
AMA StyleThomas Kohl, Timo Laukkanen, Mika Järvinen, Carl-Johan Fogelholm. Corrigendum to “Energetic and environmental performance of three biomass upgrading processes integrated with a CHP plant” [Appl. Energy 107 (2013) 124–134]. Applied Energy. 2015; 145 ():374-375.
Chicago/Turabian StyleThomas Kohl; Timo Laukkanen; Mika Järvinen; Carl-Johan Fogelholm. 2015. "Corrigendum to “Energetic and environmental performance of three biomass upgrading processes integrated with a CHP plant” [Appl. Energy 107 (2013) 124–134]." Applied Energy 145, no. : 374-375.
Thomas Kohl; Timo Laukkanen; Mika Järvinen. Integration of biomass fast pyrolysis and precedent feedstock steam drying with a municipal combined heat and power plant. Biomass and Bioenergy 2014, 71, 413 -430.
AMA StyleThomas Kohl, Timo Laukkanen, Mika Järvinen. Integration of biomass fast pyrolysis and precedent feedstock steam drying with a municipal combined heat and power plant. Biomass and Bioenergy. 2014; 71 ():413-430.
Chicago/Turabian StyleThomas Kohl; Timo Laukkanen; Mika Järvinen. 2014. "Integration of biomass fast pyrolysis and precedent feedstock steam drying with a municipal combined heat and power plant." Biomass and Bioenergy 71, no. : 413-430.
Thomas Kohl; Timo Laukkanen; Mari Tuomaala; T. Niskanen; Sari Siitonen; Mika Järvinen; Pekka Ahtila. Comparison of energy efficiency assessment methods: Case Bio-SNG process. Energy 2014, 74, 88 -98.
AMA StyleThomas Kohl, Timo Laukkanen, Mari Tuomaala, T. Niskanen, Sari Siitonen, Mika Järvinen, Pekka Ahtila. Comparison of energy efficiency assessment methods: Case Bio-SNG process. Energy. 2014; 74 ():88-98.
Chicago/Turabian StyleThomas Kohl; Timo Laukkanen; Mari Tuomaala; T. Niskanen; Sari Siitonen; Mika Järvinen; Pekka Ahtila. 2014. "Comparison of energy efficiency assessment methods: Case Bio-SNG process." Energy 74, no. : 88-98.
José Tamayo Vera; Timo Laukkanen; Kai Sirén. Multi-objective optimization of hybrid photovoltaic–thermal collectors integrated in a DHW heating system. Energy and Buildings 2014, 74, 78 -90.
AMA StyleJosé Tamayo Vera, Timo Laukkanen, Kai Sirén. Multi-objective optimization of hybrid photovoltaic–thermal collectors integrated in a DHW heating system. Energy and Buildings. 2014; 74 ():78-90.
Chicago/Turabian StyleJosé Tamayo Vera; Timo Laukkanen; Kai Sirén. 2014. "Multi-objective optimization of hybrid photovoltaic–thermal collectors integrated in a DHW heating system." Energy and Buildings 74, no. : 78-90.
J. Tamayo Vera; Timo Laukkanen; K. Sirén. Performance evaluation and multi-objective optimization of hybrid photovoltaic–thermal collectors. Solar Energy 2014, 102, 223 -233.
AMA StyleJ. Tamayo Vera, Timo Laukkanen, K. Sirén. Performance evaluation and multi-objective optimization of hybrid photovoltaic–thermal collectors. Solar Energy. 2014; 102 ():223-233.
Chicago/Turabian StyleJ. Tamayo Vera; Timo Laukkanen; K. Sirén. 2014. "Performance evaluation and multi-objective optimization of hybrid photovoltaic–thermal collectors." Solar Energy 102, no. : 223-233.
Interactive multiobjective optimization methods have provided promising results in the literature but still their implementations are rare. Here we introduce a core structure of interactive methods to enable their convenient implementation. We also demonstrate how this core structure can be applied when implementing an interactive method using a modeling environment. Many modeling environments contain tools for single objective optimization but not for interactive multiobjective optimization. Furthermore, as a concrete example, we present GAMS-NIMBUS Tool which is an implementation of the classification-based NIMBUS method for the GAMS modeling environment. So far, interactive methods have not been available in the GAMS environment, but with the GAMS-NIMBUS Tool we open up the possibility of solving multiobjective optimization problems modeled in the GAMS modeling environment. Finally, we give some examples of the benefits of applying an interactive method by using the GAMS-NIMBUS Tool for solving multiobjective optimization problems modeled in the GAMS environment.
Vesa Ojalehto; Kaisa Miettinen; Timo Laukkanen. Implementation aspects of interactive multiobjective optimization for modeling environments: the case of GAMS-NIMBUS. Computational Optimization and Applications 2014, 58, 757 -779.
AMA StyleVesa Ojalehto, Kaisa Miettinen, Timo Laukkanen. Implementation aspects of interactive multiobjective optimization for modeling environments: the case of GAMS-NIMBUS. Computational Optimization and Applications. 2014; 58 (3):757-779.
Chicago/Turabian StyleVesa Ojalehto; Kaisa Miettinen; Timo Laukkanen. 2014. "Implementation aspects of interactive multiobjective optimization for modeling environments: the case of GAMS-NIMBUS." Computational Optimization and Applications 58, no. 3: 757-779.
Kari Alanne; Timo Laukkanen; Kari Saari; Juha Jokisalo. Analysis of a wooden pellet-fueled domestic thermoelectric cogeneration system. Applied Thermal Engineering 2014, 63, 1 -10.
AMA StyleKari Alanne, Timo Laukkanen, Kari Saari, Juha Jokisalo. Analysis of a wooden pellet-fueled domestic thermoelectric cogeneration system. Applied Thermal Engineering. 2014; 63 (1):1-10.
Chicago/Turabian StyleKari Alanne; Timo Laukkanen; Kari Saari; Juha Jokisalo. 2014. "Analysis of a wooden pellet-fueled domestic thermoelectric cogeneration system." Applied Thermal Engineering 63, no. 1: 1-10.
Sudip Kumar Pal; Timo Laukkanen; Loay Saeed; Mika Järvinen; Victor Karlsson. Simulation and analysis of a combined cycle heat and power plant process. International Journal of Sustainable Engineering 2014, 8, 268 -279.
AMA StyleSudip Kumar Pal, Timo Laukkanen, Loay Saeed, Mika Järvinen, Victor Karlsson. Simulation and analysis of a combined cycle heat and power plant process. International Journal of Sustainable Engineering. 2014; 8 (4-5):268-279.
Chicago/Turabian StyleSudip Kumar Pal; Timo Laukkanen; Loay Saeed; Mika Järvinen; Victor Karlsson. 2014. "Simulation and analysis of a combined cycle heat and power plant process." International Journal of Sustainable Engineering 8, no. 4-5: 268-279.