Working fluid selection and design of small-scale waste heat recovery systems based on organic Rankine cycles

Demand for the use of energy systems, entailing high efficiency as well as availability to harness renewable energy sources, is a key issue in order to tackling the threat of global warming and saving natural resources. Organic Rankine cycle (ORC) technology has been identified as one of the most promising technologies in recovering low-grade heat sources and in harnessing renewable energy sources that cannot be efficiently utilized by means of more conventional power systems. The ORC is based on the working principle of Rankine process, but an organic working fluid is adopted in the cycle instead of steam. This thesis presents numerical and experimental results of the study on the design of small-scale ORCs. Two main applications were selected for the thesis: waste heat re- covery from small-scale diesel engines concentrating on the utilization of the exhaust gas heat and waste heat recovery in large industrial-scale engine power plants considering the utilization of both the high and low temperature heat sources. The main objective of this work was to identify suitable working fluid candidates and to study the process and turbine design methods that can be applied when power plants based on the use of non-conventional working fluids are considered. The computational work included the use of thermodynamic analysis methods and turbine design methods that were based on the use of highly accurate fluid properties. In addition, the design and loss mechanisms in supersonic ORC turbines were studied by means of computational fluid dynamics. The results indicated that the design of ORC is highly influenced by the selection of the working fluid and cycle operational conditions. The results for the turbine designs in- dicated that the working fluid selection should not be based only on the thermodynamic analysis, but requires also considerations on the turbine design. The turbines tend to be fast rotating, entailing small blade heights at the turbine rotor inlet and highly supersonic flow in the turbine flow passages, especially when power systems with low power outputs are designed. The results indicated that the ORC is a potential solution in utilizing waste heat streams both at high and low temperatures and both in micro and larger scale appli- cations.

Kiinteistöautomaatio osana älykkäitä sähköjärjestelmiä

Työssä tarkasteltiin älykkäiden sähköverkkojen näkökulmasta, millaisia toiminnallisuuksia kiinteistöautomaatiojärjestelmiltä odotetaan ja miten markkinoilla olevat järjestelmät vastaavat näihin odotuksiin. Lisäksi arvioitiin, kuinka taloudellisesti kannattavia valittuihin automaatiojärjestelmiin kuuluvat energian käytön hallintaan liittyvät toiminnallisuudet ovat sähkönkäyttäjien näkökulmasta. Lopuksi tehtiin lyhyt katsaus kiinteistöautomaatiojärjestelmien tulevaisuuden näkymiin. Kiinteistöautomaatiolla voidaan vaikuttaa energian käytön tehokkuuteen ohjaamalla esimerkiksi valaistusta, ilmanvaihtoa, ilmastointia, lämmitystä ja sähkölaitteita. Eräs vaihtoehto on toteuttaa ohjauksen avulla markkinapohjaista kysyntäjoustoa, jossa kiinteistön sähköjärjestelmän toimintaa säädetään sähkön hinnan perusteella. Kiinteistössä tulee myös voida tehdä laitekohtaisia energiankulutuksen mittauksia, jotka antavat tietoa sähkönkäyttäjille eri laitteiden sähkönkulutuksesta. Kiinteistöautomaation ja sähkön pientuotannon yleistymisen myötä on myös etähallittavien virtuaalivoimaloiden toteuttaminen tulossa mahdolliseksi. Lisäksi laskettiin sähkönkäyttäjän kannalta lämmityksen, valaistuksen ja ilmanvaihdon ohjauksen kannattavuutta ja selvitettiin, että tutkituissa esimerkkijärjestelmissä suurin säästöpotentiaali on lämmityksen ohjauksessa.

Prosessilaitteen teräsrakenteen optimointi

Diplomityön tarkoituksena oli optimoida puukentän nosturin teräsrakenteiden kustannuksia ja selvittää halvemman valmistusmaan vaikutus nosturin kokonaiskustannukseen. Tavoitteena oli saada 15 % kokonaiskustannussäästö. Työn alussa perehdytään optimoitavan nosturin rakenteeseen ja mahdollisiin rakenteen optimoitaviin osiin. Teräsrakenteen optimointi alkoi kustannusrakenteen tarkalla selvittämisellä. Näin saatiin kuva nosturin kokonaiskustannuksesta ja mahdollisista säästökohteista. Uusien ideoiden kehittämisessä käytettiin hyväksi osatoimintojen pisteytystä ja ideamatriisia. Ideamatriisin lopputuloksena uudet rakenteet tarkastettiin nosturin kuormituksien suhteen ja valittiin kustannusten kannalta paras ratkaisu. Teräsrakenteeseen tehtiin muutoksia myös merirahdin konttien asettamien rajaehtojen mukaan. Kiinassa valmistettavalle teräsrakenteelle tehtiin rahtisuunnitelma, jossa selvitettiin optimaalinen rahtimuoto ja tarvittavien konttien lukumäärä. Tarjouskilpailun avulla saatiin halvin kuljetushinta valmistavalta tehtaalta työmaalle. Lopuksi nosturin optimoidun teräsrakenteen kustannuksia verrattiin työn alussa selvitettyyn kustannusrakenteeseen. Työn lopputuloksena päästiin 12 % potentiaaliseen kustannussäästöön, joka jäi kolme prosenttiyksikköä kustannussäästötavoitteesta.

Framework for Regional Heating Energy Efficiency Assessment

The aim of this project was to develop general framework for systematic assessment of energy efficiency of heating on regional level in Russia. The framework created during this project includes two main instruments, namely: general regional heating energy efficiency assessment model (REEMod) and general regional heating energy efficiency assessment criteria for housing areas (REECrit). Framework pays extreme attention to realization of energy saving, overall cost efficiency and comfortable indoor climate. Life-cycle ideology was applied during creation of the framework. Application of the framework can provide decision-making process with systematically collected and processed information on current state of areas energy efficiency. Such information will help decision makers to evaluate current situation of the whole energy chain, to compare different development scenarios and to identify the most efficient improvement methods, thus supporting realization of regions efficient energy management. Simultaneous pursuit of energy savings, cost efficiency and indoor air quality can contribute to development of sustainable community. Presented instruments should be continuously developed further as an iterative process based on knew experience, development of technology and overall understanding of energy efficiency issues.

Quantification of fecal estradiol and progesterone metabolites in Syrian hamsters (Mesocricetus auratus)

Alternative methods to the utilization of laboratory animal blood and its by-products are particularly attractive, especially regarding hamsters due to their small size and difficulties in obtaining serial blood samples. Steroid hormone metabolite quantification in feces, widely used in studies of free-ranging or intractable animals, is a non-invasive, non-stressor, economical, and animal saving technique which allows longitudinal studies by permitting frequent sampling of the same individual. The present study was undertaken to determine the suitability of this method for laboratory animals. Estradiol and progesterone metabolites were quantified by radioimmunoassay in feces of intact, sexually mature female Syrian hamsters during the estrous cycle (control) and in feces of superovulated females. Metabolites were extracted by fecal dilution in ethanol and quantified by solid phase radioimmunoassay. Median estrogen and progesterone concentrations were 9.703 and 180.74 ng/g feces in the control group, respectively. Peaks of estrogen (22.44 ± 4.54 ng/g feces) and progesterone (655.95 ± 129.93 ng/g feces) mean fecal concentrations respectively occurred 12 h before and immediately after ovulation, which is easily detected in this species by observation of a characteristic vaginal postovulatory discharge. Median estrogen and progesterone concentrations (28.159 and 586.57 ng/g feces, respectively) were significantly higher in superovulated animal feces (P < 0.0001). The present study demonstrated that it is possible to monitor ovarian activity in Syrian hamsters non-invasively by measuring fecal estradiol and progesterone metabolites. This technique appears to be a quite encouraging method for the development of new endocrinologic studies on laboratory animals.

Ohuiden päällystyskerrosten applikointi puukuitupohjaisille materiaaleille

Työn aiheena oli tutkia vaahdon soveltuvuutta ohuiden päällystyskerrosten applikointiin paperin tai kartongin pinnalle. Paperia ja kartonkia päällystetään teollisessa mittakaavassa eri menetelmillä, mutta niille kaikille yhteistä on päällystyspastan laimentaminen vedellä ennen applikointia ja laimennusveden haihduttaminen applikoinnin jälkeen päällysteen asettamiseksi. Laimennus on tärkeää pastan komponenttien tasaisen levittämisen vuoksi, mutta veden haihduttaminen kuluttaa valtavasti energiaa. Tekstiiliteollisuudessa on saavutettu merkittäviä säästöjä kuivausenergiassa korvaamalla laajalti vedellä laimentaminen vaahdottamisella. Diplomityön kirjallisessa osassa käytiin läpi vaahdon kemiallisia ja fysikaalisia ominaisuuksia sekä selvitettiin mitä kemikaaleja ja laitteita vaahdotukseen käytetään. Lisäksi luotiin katsaus vaahtoprosessien käyttöön tekstiiliteollisuudessa ja muilla aloilla. Kokeellinen osa koostui esikokeista, joissa selvitettiin pastan koostumuksen vaikutuksia vaahtoamiseen, ja pilot-mittakaavan koeajoista, joissa esikokeiden tuloksia hyödynnettiin. Esikokeissa huomiota kiinnitettiin varsinkin eri polyvinyylialkoholien (PVA) seosten erinomaiseen vaahtoavuuteen. Pilot-koeajoissa vaahtopäällystys vaikutti lupaavalta menetelmältä, joskaan täysin tyydyttävää päällystystulosta ei saavutettu. Suurimpana ongelmana esiintyi ilman pääseminen pohjapaperin ja päällysteen väliin ja siitä seuraava huono päällystejälki. Toisen ongelmakokonaisuuden muodostivat päällysteeseen jäävät reiät. Vaahtopäällystys vaikuttaa lupaavalta tekniikalta ohuiden päällystekerrosten applikointiin, mutta pastareseptejä tulee optimoida ja ratkaista päällysteen alle pääsevän ilman ongelma.

Green welding in practice

Efficient production and consumption of energy has become the top priority of national and international policies around the world. Manufacturing industries have to address the requirements of the government in relation to energy saving and ecologically sustainable products. These industries are also concerned with energy and material usage due to their rising costs. Therefore industries have to find solutions that can support environmental preservation yet maintain competitiveness in the market. Welding, a major manufacturing process, consumes a great deal of material and energy. It is a crucial process in improving a product’s life-cycle cost, strength, quality and reliability. Factors which lead to weld related inefficiencies have to be effectively managed, if industries are to meet their quality requirements and fulfil a high-volume production demand. Therefore it is important to consider some practical strategies in welding process for optimization of energy and material consumption. The main objective of this thesis is to explore the methods of minimizing the ecological footprint of the welding process and methods to effectively manage its material and energy usage in the welding process. The author has performed a critical review of the factors including improved weld power source efficiency, efficient weld techniques, newly developed weld materials, intelligent welding systems, weld safety measures and personnel training. The study lends strong support to the fact that the use of eco-friendly welding units and the quality weld joints obtained with minimum possible consumption of energy and materials should be the main directions of improvement in welding systems. The study concludes that, gradually implementing the practical strategies mentioned in this thesis would help the manufacturing industries to achieve on the following - reduced power consumption, enhanced power control and manipulation, increased deposition rate, reduced cycle time, reduced joint preparation time, reduced heat affected zones, reduced repair rates, improved joint properties, reduced post-weld operations, improved automation, improved sensing and control, avoiding hazardous conditions and reduced exposure of welder to potential hazards. These improvement can help in promotion of welding as a green manufacturing process.

Comparison of Model-Based Flow Rate Estimation Methods in Frequency-Converter-Driven Pumps and Fans

Fluid handling systems such as pump and fan systems are found to have a significant potential for energy efficiency improvements. To deliver the energy saving potential, there is a need for easily implementable methods to monitor the system output. This is because information is needed to identify inefficient operation of the fluid handling system and to control the output of the pumping system according to process needs. Model-based pump or fan monitoring methods implemented in variable speed drives have proven to be able to give information on the system output without additional metering; however, the current model-based methods may not be usable or sufficiently accurate in the whole operation range of the fluid handling device. To apply model-based system monitoring in a wider selection of systems and to improve the accuracy of the monitoring, this paper proposes a new method for pump and fan output monitoring with variable-speed drives. The method uses a combination of already known operating point estimation methods. Laboratory measurements are used to verify the benefits and applicability of the improved estimation method, and the new method is compared with five previously introduced model-based estimation methods. According to the laboratory measurements, the new estimation method is the most accurate and reliable of the model-based estimation methods.

Analyzing and Computing the Sustainability Gains of Building Automation

Smart home implementation in residential buildings promises to optimize energy usage and save significant amount of energy simply due to a better understanding of user's energy usage profile. Apart from the energy optimisation prospects of this technology, it also aims to guarantee occupants significant amount of comfort and remote control over home appliances both at home locations and at remote places. However, smart home investment just like any other kind of investment requires an adequate measurement and justification of the economic gains it could proffer before its realization. These economic gains could differ for different occupants due to their inherent behaviours and tendencies. Thus it is pertinent to investigate the various behaviours and tendencies of occupants in different domain of interests and to measure the value of the energy savings accrued by smart home implementations in these domains of interest in order to justify such economic gains. This thesis investigates two domains of interests (the rented apartment and owned apartment) for primarily two behavioural tendencies (Finland and Germany) obtained from observation and corroborated by conducted interviews to measure the payback time and Return on Investment (ROI) of their smart home implementations. Also, similar measures are obtained for identified Australian use case. The research finding reveals that building automation for the Finnish behavioural tendencies seems to proffers a better ROI and payback time for smart home implementations.

Development of an Ecology-Oriented Software-Defined Networking Framework

ICT contributed to about 0.83 GtCO2 emissions where the 37% comes from the telecoms infrastructures. At the same time, the increasing cost of energy has been hindering the industry in providing more affordable services for the users. One of the sources of these problems is said to be the rigidity of the current network infrastructures which limits innovations in the network. SDN (Software Defined Network) has emerged as one of the prominent solutions with its idea of abstraction, visibility, and programmability in the network. Nevertheless, there are still significant efforts needed to actually utilize it to create a more energy and environmentally friendly network. In this paper, we suggested and developed a platform for developing ecology-related SDN applications. The main approach we take in realizing this goal is by maximizing the abstractions provided by OpenFlow and to expose RESTful interfaces to modules which enable energy saving in the network. While OpenFlow is made to be the standard for SDN protocol, there are still some mechanisms not defined in its specification such as settings related to Quality of Service (QoS). To solve this, we created REST interfaces for setting of QoS in the switches which can maximize network utilization. We also created a module for minimizing the required network resources in delivering packets across the network. This is achieved by utilizing redundant links when it is needed, but disabling them when the load in the network decreases. The usage of multi paths in a network is also evaluated for its benefit in terms of transfer rate improvement and energy savings. Hopefully, the developed framework can be beneficial for developers in creating applications for supporting environmentally friendly network infrastructures.

Modelling Energy Consumption of a Switch using Fuzzy-Rule Classifier

The energy consumption of IT equipments is becoming an issue of increasing importance. In particular, network equipments such as routers and switches are major contributors to the energy consumption of internet. Therefore it is important to understand how the relationship between input parameters such as bandwidth, number of active ports, traffic-load, hibernation-mode and their impact on energy consumption of a switch. In this paper, the energy consumption of a switch is analyzed in extensive experiments. A fuzzy rule-based model of energy consumption of a switch is proposed based on the result of experiments. The model can be used to predict the energy saving when deploying new switches by controlling the parameters to achieve desired energy consumption and subsequent performance. Furthermore, the model can also be used for further researches on energy saving techniques such as energy-efficient routing protocol, dynamic link shutdown, etc.

Electromagnetic and thermal design of a multilevel converter with high power density and reliability

Electric energy demand has been growing constantly as the global population increases. To avoid electric energy shortage, renewable energy sources and energy conservation are emphasized all over the world. The role of power electronics in energy saving and development of renewable energy systems is significant. Power electronics is applied in wind, solar, fuel cell, and micro turbine energy systems for the energy conversion and control. The use of power electronics introduces an energy saving potential in such applications as motors, lighting, home appliances, and consumer electronics. Despite the advantages of power converters, their penetration into the market requires that they have a set of characteristics such as high reliability and power density, cost effectiveness, and low weight, which are dictated by the emerging applications. In association with the increasing requirements, the design of the power converter is becoming more complicated, and thus, a multidisciplinary approach to the modelling of the converter is required. In this doctoral dissertation, methods and models are developed for the design of a multilevel power converter and the analysis of the related electromagnetic, thermal, and reliability issues. The focus is on the design of the main circuit. The electromagnetic model of the laminated busbar system and the IGBT modules is established with the aim of minimizing the stray inductance of the commutation loops that degrade the converter power capability. The circular busbar system is proposed to achieve equal current sharing among parallel-connected devices and implemented in the non-destructive test set-up. In addition to the electromagnetic model, a thermal model of the laminated busbar system is developed based on a lumped parameter thermal model. The temperature and temperature-dependent power losses of the busbars are estimated by the proposed algorithm. The Joule losses produced by non-sinusoidal currents flowing through the busbars in the converter are estimated taking into account the skin and proximity effects, which have a strong influence on the AC resistance of the busbars. The lifetime estimation algorithm was implemented to investigate the influence of the cooling solution on the reliability of the IGBT modules. As efficient cooling solutions have a low thermal inertia, they cause excessive temperature cycling of the IGBTs. Thus, a reliability analysis is required when selecting the cooling solutions for a particular application. The control of the cooling solution based on the use of a heat flux sensor is proposed to reduce the amplitude of the temperature cycles. The developed methods and models are verified experimentally by a laboratory prototype.

Kartonkikoneen tuoreveden käytön vähentäminen kemiallisesti puhdistettua jätevesikirkastetta hyödyntäen

Tämän diplomityön tarkoituksena oli tutkia mahdollisuutta hyödyntää kemiallisesti puh-distettua jätevettä prosessivetenä. Vedensäästöpotentiaalin perusteella tutkimuskohteeksi valittiin kartonkikone 4. Tutkimuksen tavoite oli tuoreveden käytön ja jätevesipäästöjen vähentäminen Stora Enso Imatran tehtailla. Työn kirjallisuusosa keskittyy kemialliseen jätevedenkäsittelyyn, kartonkikoneen veden käyttöön ja prosessiveden laatuun vaikuttaviin tekijöihin. Työn kokeellisessa osassa laa-dittiin vesitase tuoreveden käyttökohteiden ja veden tarpeen määrittämiseksi. Kemialli-sesti puhdistetun jäteveden ja prosessiveden ominaisuudet määritettiin, jotta saatiin sel-ville ne ominaisuudet, jotka voisivat estää jätevesikirkasteen hyötykäytön. Laboratoriomääritykset osoittivat, että hyötykäytön esteenä ovat jätevesikirkasteen kiin-toaine-, sulfaatti- ja karbonaattipitoisuus sekä mikrobitaso ja väri. Metallien ja suolaionien haittavaikutusten selvittäminen vaatii lisätutkimusta. Lisäpuhdistusmenetelmien avulla, kuten käänteisosmoosi, jätevesikirkasteen laatu saataisiin vastaamaan prosessiveden tasoa ja hyötykäyttö olisi mahdollista myös kartonkikone 4:n ulkopuolella.

Households’ willingness to engage in demand response in the Finnish retail electricity market: an empirical study

If electricity users adjusted their consumption patterns according to time-variable electricity prices or other signals about the state of the power system, generation and network assets could be used more efficiently, and matching intermittent renewable power generation with electricity demand would be facilitated. This kind of adjustment of electricity consumption, or demand response, may be based on consumers’ decisions to shift or reduce electricity use in response to time-variable electricity prices or on the remote control of consumers’ electric appliances. However, while demand response is suggested as a solution to many issues in power systems, actual experiences from demand response programs with residential customers are mainly limited to short pilots with a small number of voluntary participants, and information about what kinds of changes consumers are willing and able to make and what motivates these changes is scarce. This doctoral dissertation contributes to the knowledge about what kinds of factors impact on residential consumers’ willingness and ability to take part in demand response. Saving opportunities calculated with actual price data from the Finnish retail electricity market are compared with the occurred supplier switching to generate a first estimate about how large savings could trigger action also in the case of demand response. Residential consumers’ motives to participate in demand response are also studied by a web-based survey with 2103 responses. Further, experiences of households with electricity consumption monitoring systems are discussed to increase knowledge about consumers’ interest in getting more information on their electricity use and adjusting their behavior based on it. Impacts of information on willingness to participate in demand response programs are also approached by a survey for experts of their willingness to engage in demand response activities. Residential customers seem ready to allow remote control of electric appliances that does not require changes in their everyday routines. Based on residents’ own activity, the electricity consuming activities that are considered shiftable are very limited. In both cases, the savings in electricity costs required to allow remote control or to engage in demand response activities are relatively high. Nonmonetary incentives appeal to fewer households.

From protein structure to function with bioinformatics

It has long been known that amino acids are the building blocks for proteins and govern their folding into specific three-dimensional structures. However, the details of this process are still unknown and represent one of the main problems in structural bioinformatics, which is a highly active research area with the focus on the prediction of three-dimensional structure and its relationship to protein function. The protein structure prediction procedure encompasses several different steps from searches and analyses of sequences and structures, through sequence alignment to the creation of the structural model. Careful evaluation and analysis ultimately results in a hypothetical structure, which can be used to study biological phenomena in, for example, research at the molecular level, biotechnology and especially in drug discovery and development. In this thesis, the structures of five proteins were modeled with templatebased methods, which use proteins with known structures (templates) to model related or structurally similar proteins. The resulting models were an important asset for the interpretation and explanation of biological phenomena, such as amino acids and interaction networks that are essential for the function and/or ligand specificity of the studied proteins. The five proteins represent different case studies with their own challenges like varying template availability, which resulted in a different structure prediction process. This thesis presents the techniques and considerations, which should be taken into account in the modeling procedure to overcome limitations and produce a hypothetical and reliable three-dimensional structure. As each project shows, the reliability is highly dependent on the extensive incorporation of experimental data or known literature and, although experimental verification of in silico results is always desirable to increase the reliability, the presented projects show that also the experimental studies can greatly benefit from structural models. With the help of in silico studies, the experiments can be targeted and precisely designed, thereby saving both money and time. As the programs used in structural bioinformatics are constantly improved and the range of templates increases through structural genomics efforts, the mutual benefits between in silico and experimental studies become even more prominent. Hence, reliable models for protein three-dimensional structures achieved through careful planning and thoughtful executions are, and will continue to be, valuable and indispensable sources for structural information to be combined with functional data.