Browsing by Department "Energiatekniikan laitos"
Now showing 1 - 20 of 299
Results Per Page
Sort Options
Item Accomplishing rural electrification for over a billion people: Approaches towards sustainable solutions(Aalto University, 2014) Rahman, Mizanur Md.; Paatero, Jukka, Dr., Aalto University, Department of Energy Technology, Finland; Energiatekniikan laitos; Department of Energy Technology; Energy Economics and Power Plant Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandAccess to electricity appears to be a prerequisite to materialize social, economic, and human development in the underprivileged rural areas. However, 1.1 billion rural people in the world, almost all of them living in developing countries, still do not have access to electricity. Although the rural electrification process poses more challenges than urban electrification, rural areas are blessed with abundant and relatively evenly distributed renewable energy resources. To facilitate electricity access to this huge population, it is essential to deal with the rural electrification task by considering its challenging features and the potential merits of renewable resources. The objective of this thesis is to present policy and techno-economic frameworks for sustainable and accelerated rural electrification for over a billion people in developing countries. This thesis considers grid expansion as the primary option for rural electrification, and renewable resource based off-grid options were considered as the alternative where grid expansion is not feasible. Grid-based rural electrification policies were examined by focusing on one case program (the Bangladesh rural electrification program) in light of challenges that are generic for developing countries. The assessment of the potentials and techno-economic viability of renewable resources were performed by utilizing analytical methodologies and well-established computer tools (HOMER and RETScreen). The evaluation of choices among rural electrification alternatives has been illustrated with the help of the Stochastic Multicriteria Acceptability Analysis (SMAA) tool. The evaluation methods and tools are illustrated by employing case data obtained mainly from Bangladesh. This thesis observed that some key policy elements influence the performance of a grid-based rural electrification program. These policy elements guide the rural electrification program towards success through addressing distinct rural electrification challenges. Agricultural residues have the potential to generate electricity to meet household-level demands in rural areas of many developing countries. Hybrid biogas and solar resources can serve both clean-cooking and electricity loads in rural households with achieving benefit (saving) more than the cost. The multicriteria decision support technique enables a rural electrification program to choose decision options from different alternatives based on sustainability criteria.Item The acoustic design of office buildings as a part of the construction project and concurrent engineering(2008) Mäkinen, Sari Johanna; Liljeström, Kimmo; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Sirèn, KaiItem Acoustic simulation of a tractor engine exhaust system(2013) Rodriguez, Alvaro; Kaario, Ossi; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Larmi, MarttiThis thesis focuses on the acoustic simulation of an agricultural engine. Its aim was to modify the noise emissions of a tractor diesel engine by making parameter changes on the exhaust line. Research about acoustic emissions from engines and a suitable software tool, available to simulate acoustics of the exhaust line is also included. Noise legislation existing today for tractors does not present big challenge for tractors having a cabin so the principal goal for developing the acoustics in the present study focuses on satisfy driver comfort and customer demand. A simulation model of the VALTRA N-Series 4-stroke, 4-cylinder, 4.9L has been built taking into account the intake and exhaust system. Whole simulation was carried out by way of I-D fluid dynamics utilizing the software GT ·Power 7.3. The turbo model was scaled from a 3.5L engine due to the exact engine turbo map was not available. The tractor model was validated by means of experimental data measured along the intake and the exhaust system using high frequency pressure sensors and at the exhaust outlet utilizing a microphone. Elementary modifications like exhaust pipe diameter, length and bend variations were analysed. Furthermore the acoustic damping effect of the existing components in the exhaust pipe was determined and new components like resonators were included. Acoustical performance of the system is presented in terms of sound pressure level emitted by the exhaust outlet. The results of this study show that the importance of exhaust pipe design on noise emissions and how the model behaves to elementary changes. In particular exhaust pipe diameter has a critical influence on the acoustic emissions and it was the only parameter which produced significant variations at the low frequency range.Item Advanced heat transfer modelling with application to internal combustion engine CFD simulations(2011) Nuutinen, Mika; Kaario, Ossi; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Larmi, MarttiAt present, majority of the detailed modelling related to engine performance, gas flow, combustion, and emissions is performed with Computational Fluid Dynamics (CFD) simulations. The Reynolds Averaged Navier Stokes (RANS) turbulence models are most widely utilized due to turbulent flow conditions, complex geometries, and complicated sub models. Although Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) are more accurate than RANS models, their application in engineering simulations is often limited due to high computational costs. Available heat transfer modelling options utilized with RANS turbulence models comply poorly with engine flows. They are either completely inadequate for the particular flow conditions, or their validity requirements may multiply the problem size and computational costs. The work in this thesis concentrates on development of an accurate, engine flow compliant heat transfer I near wall modelling formalism within RANS framework. The model development yields reformulation of the whole near wall treatment, intrinsically improving the entire near wall accuracy of utilized turbulence models. Furthermore, the developed models are universal and by no means restricted to engine simulations alone. This thesis comprises a survey of the research field and three attached original publications. The first publication presents numerical wall function formalism designed to include effects of strong temperature gradient induced density variation on wall heat and momentum transfer models. The objective was to study conjugate heat transfer from charge gas to piston material in order to get estimates for piston surface temperatures and heat loss. The results indicated that the near wall density variation has a significant effect on peak surface temperature and overall heat transfer predictions. The following research indicated that the temperature gradient induced variations of charge gas viscosity, conductivity, and heat capacity affect the heat transfer prediction as well. Furthermore, this new formalism facilitates rigorous computation of the turbulence model source terms in the near wall region. These source terms affect the near wall turbulence level, strongly coupled with the heat and momentum transfer models. Following these ideas in two subsequent publications, advanced models were developed and implemented. A commercial CFD software, Star-CD, extensively utilized in internal combustion engine CFD simulations, was used as a primary platform for model development and simulations. In addition, an in-house CFD solver was programmed for model testing and validation. This thesis contributes to the research field by providing a comprehensive theoretical approach to heat transfer related near wall modelling within RANS framework and complete theory based models directly applicable to engineering CFD simulations.Item Advances in Humidity Measurement Applications in Metrology(Aalto University, 2015) Sairanen, Hannu; Heinonen, Martti, Dr., VTT Technical Research Centre of Finland, Finland; Energiatekniikan laitos; Department of Energy Technology; Applied Thermodynamics; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandA significant part of the development of humidity measurement applications in metrology is carried out due to the climate change. Within this thesis metrology tools for humidity measurements in energy gases were developed. In addition, a new method and apparatus for radiosonde calibrations were developed and constructed to provide traceability to the System of Units (SI) and thus improve the quality of radiosonde measured humidity data. Metrology tools for humidity measurements of energy gases were developed by studying the water vapour enhancement factor for methane. A new hygrometer-based calibration method was developed and a set-up was assembled for calibrations of liquid microflows from syringepumps. Metrological validation for the set-up including uncertainty analysis was carried outfor flow rates from 0.1 ul min-1 to 10 ul min-1. The set-up was applied in development and construction of a novel apparatus to measure the enhancement factor. The apparatus was metrologically validated by air and methane measurements for pressures up to 6 MPa and dew/frost-point temperatures from -50 °C to +15 °C. Utilising this apparatus, new experimental enhancement factor data was measured. Along with literature data on equilibrium states of water vapour in methane, new literature-based enhancement factors were calculated. The experimental and the calculated data were combined and an equation expressed as a function of pressure and dew-pointe temperature was fitted to the data. The equation covers dew/frost-point temperature range from -23 °C to +20 °C and pressures below 7 MPa and its expanded uncertainty (k = 2) is 0.23 in the whole range. Radiosondes operate over a wide range of humidity, temperature and pressure values and thus their calibrations should also cover these conditions. However, calibrations performed with traditional methods at cold temperatures and low humidity require a lot of time and therefore a customized apparatus was developed and constructed. The new apparatus enables significantly shorter calibration times within the temperature range from -80 °C to +20 °C and the dew/frost-point temperature range between -90 °C and +10 °C. The apparatus fulfils the requirements set by Global Climate Observing System (GCOS) and its GCOS Reference Upper-Air Network (GRUAN).Item Affecting the carbon footprint of an office building with energy efficient design(2013) Paakkari, Jesse; Husu, Timo; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, RistoThe carbon footprint of an office building is a sum of many different aspects. The most important aspect is generally the energy use. Energy use in office buildings consists of heating, cooling and electricity use. Different fields of energy use can be affected by many different design solutions. Affecting the carbon footprint of an office building is easier at the beginning of the building project and gets more difficult towards the end of the project. In this thesis, I studied the ways of reducing the life cycle carbon footprint of an office building. I studied the effects of different design solutions on the carbon footprint of an example building. The example building was the headquarters of Granlund Ltd. in Malmi, Helsinki. The energy simulations were executed with RIUSKA program developed by Granlund Ltd. and the carbon footprint from the construction phase was computed with ILMARI calculation tool developed by VTT and Pöyry Ltd. The reference case was the building with the systems according to the national building code of Finland. The results from this case were then compared to the results from the following cases in which the energy efficiency of the building was improved in some way. The cases following the reference case were structural improvements, lowering the energy intensity of the lighting, variable air volume in ventilation, several energy efficiency improvements combined (structural improvements, lower energy intensity of lighting and lower specific fan power in ventilation) and harnessing geothermal heat for heating and cooling. In every case the energy use was responsible for over 64 % of the life cycle carbon footprint of the building. The second biggest sector was manufacturing and transporting of the materials and products. The share of this sector was 18.5 - 21.6 % depending on the case. Thus it can be established that affecting the carbon footprint of an office building is most effectively done by improving the energy efficiency of the building. The biggest reduction in the carbon footprint was achieved by harnessing geothermal heat for heating and cooling and assuming that the building is located outside district heating area. The reduction in this case was 14.2 %. By using the geothermal heat, the energy used for heating was reduced by 61 %. However when the building is located in district heating area, smaller carbon footprint is achieved by using district heating. By combining several improvements in energy efficiency, the carbon footprint of the building was reduced by 12.4 %. Structural improvements and variable air volume in ventilation resulted in same reduction of carbon footprint, 6.6 % compared to the reference case. Lowering the energy intensity of lighting resulted in lowest reduction of carbon footprint, 4.5 %. In all cases the carbon footprint was reduced at least several percent. It can be concluded that even single improvement in energy efficiency can result in moderate reductions in carbon footprint of the building. However if the carbon footprint must be considerably reduced, one must consider the heat source of the building or combine several improvements in the energy efficiency of the building. In reality each office building is individual and the measures that are effective in this particular building aren't necessarily effective in all office buildings.Item Air heating system's effect on energy efficiency and thermal comfort in residential building(2012) Sipilä, Harri; Hurme, Minna; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Sirén, KaiFinnish building code was updated in July 2012 as a part of the European Union's Energy Performance of Buildings Directive. The new requirements will focus on total energy consumption which will lead to better energy efficiency and notes environmental impacts of different forms of heating. The thesis examines the impact of the new building code on the choice of air heating system. Different air heating systems were compared with the new E-factor. Thermal comfort was tested with simulations and with temperature measurements in existing air heating systems. By using air heating there's no need to install radiators under the windows. Air heating systems air flows must be calculated individually for every room to meet the need of heating power. To avoid cold convective air flows it's recommended to avoid large window surfaces. Windows should be airtight and energy efficient. Air heating system doesn't reduce the need for heating. Air heating reacts rapidly to temperature changes which will reduce overheating. Room or zone control keeps room temperatures more accurate on its set point when compared to single controlled system. Air heating doesn't cause significant vertical temperature change when warm air is lead to upper part of the room. There's no big difference in thermal comfort between systems with electrical or hot water heaters. Energy performance calculations made in this thesis shows that system with electric heaters exceeds the limit value of the new building code updated in July 2012. The envelope of the building should be more energy efficient than the building code requires in case of electrical heating. Air heating is suitable heat distribution system for residential building when hot water heaters are used.Item Air-conditioning system planning effects on life-cycle cost of a flexible building(2010) Honkavaara, Tuukka; Hämäläinen, Aimo; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Sirén, Kai-ErikThe aim of this thesis is to study how air-conditioning system effects on life-cycle costs of a flexible building. The work concentrates also on resolving the different factors influencing energy efficiency for air handling units and duct systems. Flexible building theory is presented at the beginning of the thesis. Effects of different building space-area changes on air-conditioning systems are also presented. The most commonly used air-conditioning systems are presented in outline. The systems studied are concentrated and decentralized air- conditioning. The energy efficiency of air handling unit components and duct systems are clarified using literature references. The components viewed are fans, fan motors, heating and cooling coils, heat recovery systems and air filters. Life-cycle costs of air-conditioning systems are presented generally. Also the factors that build up the costs are demonstrated. The main purpose of this thesis is to calculate how the flexible building influences on air-conditions systems life-cycle costs. Calculations and simulations of space-area changes are done using the office building example with three different implementation plans. One concentrated and two decentralized air-conditioning systems were selected for calculations and simulations. The calculations demonstrate that the biggest influence on lowering the costs of space-area changes is that air handling units and duct systems are big enough. Concentrated air-conditioning system is the cheapest solution when utilization rate of the building is 100 %. Decentralized air-condition systems are competitive when utilization rate of the building is lower than 100%. Also paying attention to energy efficiency and outages of air-conditioning system make decentralized systems a good alternative to he most commonly used concentrated system. The sensitivity analysis shows that the escalation of energy price has a strong impact on life-cycle costs of air-conditioning systems.Item Alternative design models for areal development - perspective of energy and eco-efficiency(2012) Tulamo, Marko-Joonatan; Matilainen, Pellervo; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Sirén, KaiThe climate change and the transformation of the energy sector have resulted in an international effort to save energy in all sectors. Buildings and construction sector cause about 40 per cent of the energy end-use and carbon dioxide emissions. Due to this buildings have an essential role in preventing the climate change. The purpose of this research is to find the essential factors that impact on energy efficiency and carbon dioxide emissions of areal development. The other purpose of this study was to develop an energy and Eco efficiency evaluation model for areal development. The research was conducted using three different computer programs. The subject of the research was Skanska's areal development located in Härmälänranta Tampere. In addition to the Master plan, six alternative design models were formed. Areal diversity, building massing, energy production, demand side management and low-energy buildings were studied in perspective of energy and eco-efficiency and life cycle costs. According to the results total energy consumption can be significantly reduced through energy efficiency measures. Energy production systems can also reduce the total energy consumption, but the results will depend on efficiency, politically defined energy form factors as well as the renewable energy produced by distributed systems. The areal diversity and massing had smaller impact on reducing the total energy consumption. The demand side management systems slightly increased the total energy consumption due to the energy storage losses. According to the research carbon dioxide emissions caused by energy consumption could be reduced best by the energy production systems as well as the demand side management systems. The energy production systems influenced the amount of energy purchased from which carbon dioxide emissions were calculated. The demand side management systems prevented high carbon energy consumption peaks. According to the research areal diversity was the most profitable option in life-cycle analysis where low energy buildings, building massing as well as diversity were studied. The result must be viewed critically because areal diversity can't be considered itself as a factor that reduces life-cycle costs. Primarily the factors that influence the areal diversity are social factors. The changes in building massing were economically viable option. However low-energy buildings weren't economically viable option because energy cost savings didn't compensate additional investments made in the case. In the life-cycle analysis where energy production systems were studied, geothermal was the most profitable option after five years. Solar energy system was more profitable option than the base scenario after 24 years. The Demand side management systems weren't economically viable option because savings made with peak energy costs didn't compensate the energy storage investment, maintenance and operating costs.Item Analysis of active solar heating systems in cold climate urban areas(2009) Johansson, Anna; Hyvönen, Martti; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Pirilä, Pekka|Lahdelma, RistoThe effects and advantages of solar energy have been known to mankind for a long time. With the progress of modern research the systems developed for taking advantage of the solar heat have been improved and solar collectors can now be used for gathering solar heat for both domestic hot water and space heating purposes. Some problems still remain with the technical solutions and experiences from use in cold climate are scarce as solar heating systems in Finland are still rare. This thesis aims at evaluating and analyzing the experiences from the solar heating project in Eco-Viikki, Helsinki and at discussing the critical success factors for future solar heating projects in urban areas in a cold climate. The theoretical part of the thesis consists of a literature review that defines the general principles of solar heating systems. In the empirical part the solar heating systems in EcoViikki are evaluated in detail and the experiences are compared to two cases set in similar circumstances. The conclusions are formed as a synthesis of the literature review and of the comparison between the experiences from the three cases studied. The conclusion also includes recommendations for similar future projects. Problems perceived in the Eco-Viikki solar heating systems include overheating of the systems, constructional problems and planning deficiencies that affect the optimal operation of the system. The study confirms that the use of a solar heating system in an urban area in combination with district heating in a Country with cold climate is a method for reducing energy consumption in real estate. It is stated that the complicated system planning of the Eco-Viikki solar heating systems is partly responsible for the defective condition of some of the solar heating systems in use. The use of solar heat for both domestic hot water and space heating must thus be carefully thought through. A contributing reason for the operational problems and the low efficiencies of the systems in Eco-Viikki are the house managing agencies' lack of knowledge about the maintenance and the operation of the systems. The thesis also emphasizes that careful monitoring of the systems is needed to achieve optimal performance of the system.Item Analyzing and modelling electricity consumption in blocks of flats(2009) Haulio, Mikko; Paatero, Jukka; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Pirilä, PekkaTässä tutkimuksessa on mallinnettu kerrostalojen kotitaloussähkönkulutus bottom-up menetelmään perustuvalla tietokoneohjelmalla ja tarkistettu tulosten oikeellisuutta. Bottom-up menetelmällä tarkoitettiin kotitalouksien kuormituskäyrien mallintamista laitetasolta alkaen. Tutkimuksessa tuli osoittaa, kuinka tuntimitattua energiatietoa voidaan hyödyntää huomattavasti nykyistä enemmän sähkönkulutuksen analysoinnissa ja mallintamisessa. Laitetason parametrit arvioitiin julkisista tilastoista kerättyihin yleisimpien kotitalouslaitteiden kulutusta ja käyttöä koskevien mittaustulosten perusteella. Tulokset validoitiin vertaamalla mallinnettua kulutustietoa ja tutkimusta varten kerättyä ja analysoitua kerrostalojen tuntimitattua kulutustietoa. Aineisto käsitti 28 pääkaupunkiseudun ja 31 Tampereen alueen kerrostaloyhtiön sähkönkulutuksen energia- ja taustatiedot. Yksittäisiä huoneistoja pääkaupunkiseudun näytteessä oli 1796 ja Tampereella 1760. Tuloksia tarkasteltiin keskeisimpien sähkönkulutukseen vaikuttavien tekijöiden: vuodenajan, viikonpäivän ja vuorokaudenajan mukaisen vaihtelun kannalta. Viikonpäivissä tarkasteltiin erikseen sekä arkipäivien että viikonloppupäivien kulutusta. Tulosten perusteella ilmeni, että mallinnetun kuormituksen vaihtelu ajan funktiona ja kokonaistaso olivat lähellä tuntimitatulle aineistolle laskettuja arvoja. Vuorokauden tuntikohtaisen keskiarvon poikkeama vaihteli 0 %:n ja 7 %:n välillä. Tutkimuksessa havainnollistettiin lisäksi mallin käyttökelpoisuutta arvioimalla kulutuksen laiteryhmittäinen jakauma jokaiselle arkipäivän ja viikonlopun tunnille Bottom-up menetelmällä voidaan huomioida vain osa sähkönkulutukseen vaikuttavista tekijöistä. Tulokset osoittivat, että hyvään tarkkuuteen voidaan siitä huolimatta päästä. Tarkempien mallien luominen edellyttäisi laitekannan ja kulutuskäyttäytymisen yksityiskohtaisempaa tuntemista kerrostaloissa ja mallin yksityiskohtien kehittämistä.Item Applicability of absorption refrigeration in a smelter cooling system(2013) Takala, Tero Tuomas; Björklund, Peter; Jäfs, Mikael; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Lampinen, MarkkuThe absorption refrigeration technology was first introduced in the 1850s. However, it wasn't until a few decades ago that large-scale absorption refrigeration systems began to grow in popularity in industrial cooling. The utilization of industrial waste heat streams and the production of centralized cooling are just a few examples where the benefits of improved energy efficiency by absorption cooling can be exploited. Despite the fact that several industries already enjoy the benefits brought about by absorption cooling, the applicability of absorption refrigeration in smelter cooling is still a relatively uncharted research area. This master's thesis examines the applicability of absorption refrigeration in a smelter cooling system through a theoretical framework in a HSC-Sim flow sheet model. The simulated cooling system consists of a primary and a secondary cooling circuit as well as an integrated double-stage lithium bromide-water absorption cooling unit. The cooling water circuit of the absorption chiller unit is attached to an existing cooling tower whereas the chilled water circuit is connected to the primary cooling circuit via an additional heat exchanger. The first half of this work reviews the scientific literature on absorption cooling technology and revises the design, the theoretical performance and the limitations of absorption chillers. The review is followed by a detailed description of a five-part case study and simulation results of the HSC-Sim model. Finally, in addition to a technical feasibility analysis, a brief economic analysis based on the capital expenditure and operating expenditure of an absorption chiller is conducted. Based on the simulation results it was concluded that with the help of absorption refrigeration technology a desired smelter cooling water temperature can be maintained as long as an adequate amount of driving heat is available. Although a waste heat stream more often than not serves as a driving heat source for the chiller, providing a near zero-cost fuel, the overall operating costs of the smelter cooling system with an integrated absorption chiller generally increase due to greater evaporation losses of water in the cooling tower. Nevertheless, the suitability of absorption refrigeration in smelter cooling varies according to local climate and operating conditions. Moreover, the future potential of absorption technology for smelter cooling lies in the innovative utilization of high-temperature cooling sources combined with an absorption refrigeration system.Item An application of exergy analysis to commercial buildings' HVAC system design(2010) Nikolaenko, Evgeny; Velev, Petko; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Sirén, KaiNowadays it is widely declared that the most important design determinations concerning building sustainability have to be made in early design stage. The integrated analysis of used energy consists of exergy analysis. The exergy analysis is an important tool to understand quality of energy flows in whole building HVAC systems and subsystems. During the last few years the International Energy Agency (IAE) was formed two research programs Annex 37 and Annex 49 to develop concepts for reducing the energy demand in the built environment by applying the exergy analysis methods. The research focuses on a detailed exergy analysis of HVAC systems. The results of exergy analysis give an opportunity to get information about qualitative performance of HVAC systems already on the early design stage. The main objective of this thesis is to apply the exergy analysis to the building HVAC system and to find out the possibilities for further improvements in energy utilisation in the overall building HVAC system. This research work analyses the possibilities to increase qualitative energy consumption efficiency in commercial buildings by applying the exergy analysis method. The investigation of building includes the energy and exergy balance equations. The exergy analysis is applied on the systems level as well as on the subsystems level. The exergy analysis provides the possibility to calculate and compare the different quality of energy demands in the building service systems. In this thesis a verification method for quality of performance of HVAC system in commercial buildings was developed. The model of exergy analysis of building HVAC system was created. The exergy analysis method of building HVAC is applied in reference commercial building. For HVAC systems the exergy efficiency and the rate of exergy destruction are quantified and illustrated. These calculations are made on the annual level and monthly under the steady-state conditions. Results gotten show that the integrated together the energy and exergy analyses can be used to evaluate the performance of HVAC system in commercial buildings.Item Applying experience curves to Finnish bioenergy production(2009) Metsäniemi, Tomi; Pirilä, Pekka; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Pirilä, PekkaUusiutuvien energiamuotojen tutkimus ja niiden käytön laajentaminen vaatii uusia kehityskeinoja. Tämän diplomityön tarkoitus on tutkia kokemuskäyriä, joita 2000-luvun vaihteesta lähtien on käytetty myös energiateknisessä tutkimuksessa. Kokemuskäyrien tarkoituksena on mallintaa kokemuksen kertymistä teollisuuden prosesseissa ja oppimisen tapahtumista prosessien kehittyessä. Energiatekniikan kokemuskäyrän tarkoituksena on antaa energiapolitiikan tutkijalle keinoja mallintaa energiatekniikoiden aiempien toimien vaikutuksia energiateknologioiden menestymismahdollisuuksiin. Kokemuskäyrien avulla voidaan myös mallintaa tulevaisuuden näkymiä tietyillä lähtöarvoilla. Tämä diplomityö keskittyy kokemuskäyrän malliin ja sen hyödyntämiseen Suomen bioenergian mallintamisessa. Tarkoituksena on kertoa kokemuskäyrän hyödyntämisestä ja kuinka se toimii. Työssä selvitetään myös kokemuskäyrän sovelluskohteita ja kuinka sitä voidaan soveltaa energiantuotannon poliittisen päätöksenteon tukivälineenä. Diplomityössä tutkittaan kokemuskäyrää kirjallisuuden ja tieteellisten julkaisujen avulla. Lisäksi käydään läpi uusiutuvien energialähteiden tulevaisuuden näkymiä sekä Euroopan Unionin alueella että Suomessa ja biopolttoainekattiloiden teoriaa. Diplomityön käytännön osuudessa kokeiltiin biopolttoainekattiloiden hintojen soveltamista kokemuskäyrän perusmalliin. Tulosten perusteella nähdään kokemuskäyrän soveltuvan paremmin pidemmän aikavälin mallintamiseen, koska liian lyhyillä mallinnusajoilla talouden ja kattiloiden komponenttien hintavaihtelut vaikuttavat liian paljon kokemuskäyrän tuloksiin. Tutkimuksen perusteella kokemuskäyrät soveltuvat moniin käyttökohteisiin ja ne voivat parhaimmillaan olla loistavia poliittisen päätöksenteon apukeinoja.Item Appropriate treatment processes for bio waste in the metropolitan area - Benchmarking of greenhouse gas emissions(2009) Virtavuori, Veera; Kouvo, Petri; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Fogelholm, Carl-JohanJätteenkäsittelyn säädöksiä uudistetaan parhaillaan. Valtioneuvoston kaatopaikkapäätöksen tavoitteena on mm. rajoittaa biohajoavien jätteiden kaatopaikkasijoitusta jätehuollon metaanipäästöjen vähentämiseksi. EU:n uusi jätedirektiivi ehdottaa jätteenkäsittelylle sovellettavaksi elinkaariajattelua. Biojätteet käsitellään pääkaupunkiseudulla kompostoimalla, mutta erilliskäsittelyn vaatimat prosessit aiheuttavat päästöjä. Tässä työssä vertaillaan pääkaupunkiseudun biojätteelle soveltuvien käsittelyketjujen aiheuttamia kasvihuonekaasupäästöjä. Käsittelyvaihtoehtojen KHK-päästötaseita laskettaessa on huomioitu myös prosesseissa syntyvien lopputuotteiden hyötykäytöllä saavutettavat KHK-päästöjen hyvitykset, jotka ovat seurausta fossiilisten polttoaineiden korvauksesta. Biojätteen erilliskäsittely- vaihtoehdoiksi on valittu kompostointi ja mädätys. Näiden lisäksi tarkastellaan biojätteen polttoa sekajätteen mukana. Tutkimuksessa on myös arvioitu biojätteen erilliskeräysjärjestelmän kattavuuden vaikutusta biojätteen keräyksestä ja kuljetuksesta aiheutuviin KHK-päästöihin. Biojätteen käsittelyvaihtoehdoista polton KHK-päästötase on negatiivisin, koska poltossa vapautuvalla energialla korvataan fossiilista energiaa ja saavutetaan kasvihuonekaasupäästöjä suuremmat päästöjen hyvitykset. Erilliskäsittelyn vaihtoehdoista mädätys on kompostointia suotuisampaa, sillä prosessissa vapautuva biokaasu käytetään joko sähkön- ja lämmöntuotannossa tai liikenteen polttoaineena. Molemmissa korvataan fossiilisia polttoaineita ja päästään päästöhyvityksiin, jotka aikaansaavat negatiiviseen KHK-päästötaseesen. Kompostointi on käsittelyvaihtoehdoista ainoa, joka jää kasvihuonekaasujen osalta päästöjä tuottavalle puolelle. Mädätyksessä ja kompostoinnissa syntyvää lopputuotetta on mahdollista käyttää multatuotteen raaka-aineena, jolloin keinolannoitteen ja turpeen korvauksesta syntyy kasvihuonekaasupäästöhyvityksiä. Nykyisen pääkaupunkiseudun biojätteen erilliskeräysjärjestelmän keräys- ja kuljetuspäästöjä olisi mahdollista vähentää rajaamalla pienet, alle 20 huoneistoa käsittävät kiinteistöt, järjestelmän ulkopuolelle. Tämä on seurausta siitä, että pieniltä kiinteistöiltä kerätty biojätemäärä on kuljetusrasitukseen suhteutettuna vähäinen.Item Assessing energy efficiency potential in the building stock: Method for estimating the potential for improvements and their economic effects(Aalto University, 2015) Tuominen, Pekka; Tuomaala, Mari, Dr., Gasum Ltd., Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandBuildings, representing more than a third of global energy consumption, have long remained one of the focal points for the efforts to increase energy efficiency. The residential sector in particular has had more energy-related policies put in place than any other sector in the IEA countries. Therefore, the question which policies will have the greatest effect over time is very relevant to the policymakers. The main objective of this thesis is to develop a method for calculating the en-ergy efficiency potential of the building stock and to assess the economic effects of the realization of the potential in terms of changes in GDP, employment and external costs. Even though the method is meant to be applicable to different building stocks, the Finnish building stock was mostly studied as the method was developed over time. Similar but more limited analysis was also conducted for a number of EU member states. During the course of the study, a calculation tool called REMA was developed based on the methods used. The purpose of REMA is to allow conducting similar analyses in the future with relative ease in a systematized way. REMA is a bottom-up engineering model of energy use in the building stock. Future developments are estimated using annual rates of new construction, renovations and removals from the building stock. The selected approach entails selecting representative building types, also called archetypes, for estimating the energy consumption in different segments of the building stock. The scenarios calculated concerning the Finnish case indicate that a few per-cent rise in annual construction and renovation investments can decrease total primary energy consumption 5–7% of the country by 2050 compared to a baseline scenario. On the short term a slight decrease in the level of GDP and employment is expected. On the medium to long term, however, the effects on both would be positive. Furthermore, a significant drop in harmful emissions and hence external costs is anticipated. Overall, a clear net benefit is expected from improving energy efficiency. For other EU countries studied, typically energy savings of about 20% were estimated to be achievable by 2030 with cost-effective renovation investments in the building stock analysed. Overall, major economically sound energy efficiency potentials were identified, but the realization of these potentials is rather slow due to the limited renewal rates present in building stocks.Item Assessing the uncertainties of climate policies and mitigation measures. Viewpoints on biofuel production, grid electricity consumption and differentiation of emission reduction commitments(VTT Technical Research Centre of Finland, 2012) Soimakallio, Sampo; Savolainen, Ilkka, Professor, VTT Technical Research Centre of Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Syri, Sanna, Professor, Energy Economics, Department of Energy Technology, School of Engineering, Aalto University, FinlandAmbitious climate change mitigation requires the implementation of effective and equitable climate policy and GHG emission reduction measures. The objective of this study was to explore the significance of the uncertainties related to GHG emission reduction measures and policies by providing viewpoints on biofuels production, grid electricity consumption and differentiation of emission reduction commitments between countries and country groups. Life cycle assessment (LCA) and macro-level scenario analysis through top-down and bottom-up modelling and cost-effectiveness analysis (CEA) were used as methods. The uncertainties were propagated in a statistical way through parameter variation, scenario analysis and stochastic modelling. This study showed that, in determining GHG emissions at product or process level, there are significant uncertainties due to parameters such as nitrous oxide emissions from soil, soil carbon changes and emissions from electricity production; and due to methodological choices related to the spatial and temporal system boundary setting and selection of allocation methods. Furthermore, the uncertainties due to modelling may be of central importance. For example, when accounting for biomass-based carbon emissions to and sequestration from the atmosphere, consideration of the temporal dimension is critical. The outcomes in differentiation of GHG emission reduction commitments between countries and country groups are critically influenced by the quality of data and criteria applied. In both LCA and effort sharing, the major issues are equitable attribution of emissions and emission allowances on the one hand and capturing consequences of measures and policies on the other. As LCA and system level top-down and bottom-up modelling results are increasingly used to justify various decisions by different stakeholders such as policy-makers and consumers, harmonization of practices, transparency and the handling of uncertainties related to methodological choices, parameters and modelling must be improved in order to avoid conscious misuse and unintentional misunderstanding.Item Assessmant of the power production and district heating sectors' security of supply risk management tools in analyzing the current operational environment(2008) Länsimies, Anna-Maria; Jauhiainen, Matti; Leskelä, Jukka; Leskelä, Jukka; ; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Ahtila, PekkaHuoltovarmuustoiminnan tavoitteena on turvata yhteiskunnan toiminta kaikissa olosuhteissa, myös poikkeus-, häiriö- ja kriisitilanteiden aikana. Nopeasti muuttuva toimintaympäristö asettaa suuria haasteita sähkön ja kaukolämmön huoltovarmuuden ylläpitämiselle. Ajankohtaisia energiahuoltovarmuuden riskitekijöitä ovat esimerkiksi riittävä sähkön ja kaukolämmön tuotantokapasiteetin riittävyys, biopolttoaineiden käytön merkittävä lisääminen sekä teollisuuden, erityisesti metsäteollisuuden, rakennemuutos. Suomessa huoltovarmuustoiminta on perustunut aina viranomaisten ja elinkeinoelämän väliseen laajaan yhteistyöhön. Energiahuoltovarmuuden tason seuraamiseen on kehitetty kuusi erilaista mittaria tai analyysityökalua. Kolme työkaluista perustuu laskennallisiin taseisiin ja kolme analyysimenetelmää pohjautuu asiantuntijaryhmien kokoamiin tietoihin. Diplomityössä selvitetään, riittävätkö nykyiset analyysityökalut myös nykyisten melko nopeiden ja laajojen toimintaympäristömuutosten analysointiin. Case-tapausten perusteella voidaan todeta, että nykyisillä mittareilla ei voida tunnistaa ajankohtaisia huoltovarmuushaasteita kovin hyvin. Huoltovarmuuden arvioimiseen tarvitaan nykyistä joustavampia ja monipuolisempia työkaluja.Item Assessment and damage prevention in wind turbine rotor blades(2009) Leinonen, Jukka; Paludgnach, Pierre; Energiatekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Ahtila, PekkaTuulivoiman yleistyminen ja tuulivoimaloiden koon kasvu asettaa haasteita tuulivoimaloiden komponenteille. Roottorin lapojen koko on kahdenkymmenen vuoden aikana kasvanut moninkertaisesti. Vuonna 1985 roottorin halkaisija oli keskimäärin 15 metriä. Nykyään käytössä on roottoreita, joiden halkaisija on yli 120 metriä ja lapoja, joiden pituus on yli 60 metriä. Roottorin lapa on tuulivoimalan kallein yksittäinen komponentti ja niiden edellytetään kestävän jatkuvassa käytössä 20 vuotta. Roottorin lapojen valmistuksessa käytetään lasi- ja hiilikuituvahvistettuja muoveja ja valmistusmenetelmänä alipaineinjektiota. Näin on mahdollista valmistaa jopa yli 60 metriä pitkiä lapoja. Tämän kokoluokan lapojen valmistus vaatii huolellista manuaalista työtä ja modernit valmistuslaitteet. Valmistusvirheet voivat lyhentää roottorin lapojen käyttöikää huomattavasti. Lavat voivat vaurioitua myös kuljetuksen aikana tai esimerkiksi salamaniskusta. Vauriot voivat vaikuttaa heikentävästi lavan aerodynaamisiin ominaisuuksiin tai ne voivat heikentää lavan kantavia rakenteita. Vauriot tulisi havaita ja korjata mahdollisimman nopeasti niiden synnyttyä. Vaurioita voidaan havaita ilman teknisiä laitteita visuaalisesti tai kuuntelemalla lavan akustista kaikua. Teknisiä laitteita voidaan myös käyttää vaurioiden havaitsemisessa. Näitä ovat esimerkiksi venymäliuskat ja optiset kaapelit. Työssä on tarkasteltu tuulivoimalan lapojen kunnonvalvontaa ainetta rikkomattomin menetelmin. Työssä on tutkittu roottorin lapojen valmistuksessa käytettäviä materiaaleja sekä valmistusmenetelmiä. Lavan aerodynaamisia ominaisuuksia parantavia laitteita on myös tarkasteltu. Syitä, jotka aiheuttavat vaurioita roottorin lavoissa, on tarkasteltu. Näitä ovat esimerkiksi valmistusvirheet ja kuljetuksen tai pystytyksen aikana syntyvät vauriot. Työssä on tilastoitu käytössä olevien roottorin lapojen vaurioita ja annettu esimerkkejä vaurioiden korjauksista ja niiden kustannuksista.Item Atomic layer deposition of dense mixed ionic-electronic conducting membrane on porous tubular substrate for oxygen combustion(2012) Ristimäki, Ville; Mäkelä, Milja; Energiatekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Lampinen, MarkkuAtomic layer deposition thin film deposition technique was studied for producing robust and high performance mixed ionic-electronic conducting membranes for oxygen production. Non-functional dense thin films were deposited on the inner surface of a mesoporous tubular alumina substrate and experiments were also done to coat mesoporous substrate material conformally. Coating experiments were carried out with a flow type reactor, with modified forced flow for coating of tubular and porous substrate. Pressure and flow rate data for different coating processes were gathered and gas tightness of coated samples were measured. Gas tight coatings on the inner surfaces of mesoporous tubes and some conformal coating of mesoporous tube material were achieved in the experiments. Some signs of flow velocity inside the tube to have effect on the film growth were indicated. From electrical measurements it was derived that coating cross-sectional area on the inner surface of the tube was approximately three times larger than what could be derived from theoretical film growth rate and from the tube's inner diameter. Larger than expected cross sectional area of the coating is explained as uncontrolled film growth on the inner surface of the tube, or improved surface area of the coating resulting from thin film conform the rough inner surface of the tube. Suggestions to improve process control and conformal coating of porous tube material are also presented.
