Lämmöntuotannon energiatehokkuuden parantaminen Sotek-säätiön rakennuksissa

Diplomityössä tarkastellaan lämmöntuotannon energiatehokkuuden parantamista neljässä Sotek- säätiön rakennuksessa. Työssä oli tarkoitus selvittää, minkälainen lämmitysjärjestelmä on juuri kyseiseen kiinteistöön järkevin ja investointikustannuksiltaan kannattava. Työssä käydään läpi polttoaineita, lämmöntuotanto- ja lämmönjakotapoja, sekä mietitään kannattaako rakennuksia lisäeristää. Työssä verrataan vanhojen järjestelmien hiilidioksidipäästöjä valittujen uusien järjestelmien hiilidioksidipäästöihin. Kiinteistöjen lämmitys tuottaa Suomessa noin 30 % kaikista hiilidioksidipäästöistä. Se on siis merkittävä alue, josta päästöjä voitaisiin vähentää. Tehtävänä oli laskea kaikille kiinteistöille tarkat lämmitystarpeet ja lämmitystehontarpeet käyttäen apuna Suomen rakennusmääräyskokoelmaa. Työn perusteella lämmöntuotannon energiatehokkuuden parantaminen kohteissa on järkevää ja taloudellisesti kannattavaa muuttamalla lämmöntuotanto pääosin lämpöpumpuille. Täystehoiset järjestelmät eivät tulleet investoinnillisesti kannattavaksi, eikä se ilmalämpöpumpuissa ollut edes mahdollista. Tulosten perusteella lämmitysenergian kustannuksia saatiin vähennettyä parhaiten mitoittamalla kohteisiin osatehoiset lämpöpumput. Lisälämmöneristäminen kohteissa ei taloudellisesti tullut kannattavaksi, vaikka lämmitystarve väheni. Lämmöntuotannon hiilidioksidipäästöt vähenisivät kohteissa keskimäärin noin 50 %.

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.

Determination of potential value drivers by identifying customer expectations and perceived value

The purpose of this exploratory research is to identify the potential value drivers regarding a new service offering. More specifically, the aim is to build understanding of customer expectations and perceived value of energy efficiency solutions in the building’s sector. The knowledge is then used in defining potential value drivers. The research is conducted from the customer’s perspective in a business-to-business context. The theory part of the master’s thesis focuses on discussing the antecedents of customer expectations and customer value. The theory gives implications how to determine value drivers and develop value propositions as well as conduct value assessment. The empirical part is based on the qualitative research method. The research was conducted as a single-case study, and the primary data was collected through semi-structured interviews with potential customers. The results of the research revealed that the customer expectations are connected to being able to define value drivers. In addition, the research revealed generic themes relating to the offering and customer-supplier relationship, which help in the process of identifying potential value drivers. The results were discussed in terms of product-, service-, price- and relationship-related value drivers for the new service. Based on the data analysis the dominant value drivers are elaborated in terms of identified customer benefits and customer sacrifices (costs). Finally, some implications of value proposition and value assessment to support the value delivery were given.

Benchmark of routing protocols regarding green considerations

In Mobile Ad-hoc Networks (MANET) the participating nodes have several roles such as sender, receiver and router. Hence there is a lot of energy consumed by the nodes for the normal working of the network since each node has many different roles. Also in MANET the nodes keep moving constantly and this in turn consumes a lot of energy. Since battery capacity of these nodes is limited it fails to fulfil the high demand of energy. The scarcity of energy makes the energy conservation in mobile ad-hoc networks an important concern. There is several research carried out on the energy consumption of mobile ad-hoc networks these days. Some of this research suggests sleep mode, transmission power control, load balancing etc. In this thesis, we are comparing various proposed energy efficient models for some of the ad-hoc protocols. We compare different energy efficient models for Optimised Linked State Algorithm (OLSR) and Ad-hoc On Demand Distance Vector (AODV). The routing protocols are compared for different parameters such as average remaining energy, number of nodes alive, payload data received and performance with different mobility speed. The simulation results helps in benchmarking the various energy efficient routing models for OLSR and AODV protocols. The benchmarking of the routing protocols can be based on many factors but this thesis concentrates on benchmarking the MANET routing protocols mainly based on the energy efficiency and increased network lifetime.

Benefits of gas driven ground source heat pump systems

This thesis studies energy efficiencies and technical properties of gas driven ground source heat pumps and pump systems. The research focuses on two technologies: gas engine driven compressor heat pump and thermally driven gas absorption heat pump. System consist of a gas driven compressor or absorption ground source heat pump and a gas condensing boiler, which covers peak load. The reference system is a standard electrically powered compressor heat pump with electric heating elements for peak load. The systems are compared through primary energy ratios. Coefficient of performances of different heat pump technologies are also compared. At heat pump level, gas driven heat pumps are having lower coefficient of performances as compared with corresponding electric driven heat pump. However, gas heat pumps are competitive when primary energy ratios, where electricity production losses are counted in, are compared. Technically, gas heat pumps can potentially achieve a slightly higher temperatures with greater total energy efficiency as compared to the electric driven heat pump. The primary energy ratios of gas heat pump systems in relation to EHP-system improves when the share of peak load increases. Electric heat pump system's overall energy efficiency is heavily dependent on the electricity production efficiency. Economy as well as CO2-emissions were not examined in this thesis, which however, would be good topics for further study.

Feasibility of industrial implementation of laser cutting into paper making machine

Laser cutting implementation possibilities into paper making machine was studied as the main objective of the work. Laser cutting technology application was considered as a replacement tool for conventional cutting methods used in paper making machines for longitudinal cutting such as edge trimming at different paper making process and tambour roll slitting. Laser cutting of paper was tested in 70’s for the first time. Since then, laser cutting and processing has been applied for paper materials with different level of success in industry. Laser cutting can be employed for longitudinal cutting of paper web in machine direction. The most common conventional cutting methods include water jet cutting and rotating slitting blades applied in paper making machines. Cutting with CO2 laser fulfils basic requirements for cutting quality, applicability to material and cutting speeds in all locations where longitudinal cutting is needed. Literature review provided description of advantages, disadvantages and challenges of laser technology when it was applied for cutting of paper material with particular attention to cutting of moving paper web. Based on studied laser cutting capabilities and problem definition of conventional cutting technologies, preliminary selection of the most promising application area was carried out. Laser cutting (trimming) of paper web edges in wet end was estimated to be the most promising area where it can be implemented. This assumption was made on the basis of rate of web breaks occurrence. It was found that up to 64 % of total number of web breaks occurred in wet end, particularly in location of so called open draws where paper web was transferred unsupported by wire or felt. Distribution of web breaks in machine cross direction revealed that defects of paper web edge was the main reason of tearing initiation and consequent web break. The assumption was made that laser cutting was capable of improvement of laser cut edge tensile strength due to high cutting quality and sealing effect of the edge after laser cutting. Studies of laser ablation of cellulose supported this claim. Linear energy needed for cutting was calculated with regard to paper web properties in intended laser cutting location. Calculated linear cutting energy was verified with series of laser cutting. Practically obtained laser energy needed for cutting deviated from calculated values. This could be explained by difference in heat transfer via radiation in laser cutting and different absorption characteristics of dry and moist paper material. Laser cut samples (both dry and moist (dry matter content about 25-40%)) were tested for strength properties. It was shown that tensile strength and strain break of laser cut samples are similar to corresponding values of non-laser cut samples. Chosen method, however, did not address tensile strength of laser cut edge in particular. Thus, the assumption of improving strength properties with laser cutting was not fully proved. Laser cutting effect on possible pollution of mill broke (recycling of trimmed edge) was carried out. Laser cut samples (both dry and moist) were tested on the content of dirt particles. The tests revealed that accumulation of dust particles on the surface of moist samples can take place. This has to be taken into account to prevent contamination of pulp suspension when trim waste is recycled. Material loss due to evaporation during laser cutting and amount of solid residues after cutting were evaluated. Edge trimming with laser would result in 0.25 kg/h of solid residues and 2.5 kg/h of lost material due to evaporation. Schemes of laser cutting implementation and needed laser equipment were discussed. Generally, laser cutting system would require two laser sources (one laser source for each cutting zone), set of beam transfer and focusing optics and cutting heads. In order to increase reliability of system, it was suggested that each laser source would have double capacity. That would allow to perform cutting employing one laser source working at full capacity for both cutting zones. Laser technology is in required level at the moment and do not require additional development. Moreover, capacity of speed increase is high due to availability high power laser sources what can support the tendency of speed increase of paper making machines. Laser cutting system would require special roll to maintain cutting. The scheme of such roll was proposed as well as roll integration into paper making machine. Laser cutting can be done in location of central roll in press section, before so-called open draw where many web breaks occur, where it has potential to improve runability of a paper making machine. Economic performance of laser cutting was done as comparison of laser cutting system and water jet cutting working in the same conditions. It was revealed that laser cutting would still be about two times more expensive compared to water jet cutting. This is mainly due to high investment cost of laser equipment and poor energy efficiency of CO2 lasers. Another factor is that laser cutting causes material loss due to evaporation whereas water jet cutting almost does not cause material loss. Despite difficulties of laser cutting implementation in paper making machine, its implementation can be beneficial. The crucial role in that is possibility to improve cut edge strength properties and consequently reduce number of web breaks. Capacity of laser cutting to maintain cutting speeds which exceed current speeds of paper making machines what is another argument to consider laser cutting technology in design of new high speed paper making machines.

Integroidun sähköhydraulisen energiamuuntimen sovellusmahdollisuuksia

Energian kulutuksen pienentäminen ja energiatehokkuuden parantaminen ovat nykyaikana tärkeässä osassa laitteita ja järjestelmiä suunniteltaessa. LUT:ssa kehitetty sähköhydraulinen energiamuunnin pyrkii vastaamaan tähän tarpeeseen hydraulisten järjestelmien osalta. Se on alunperin suunniteltu hybridityökoneita silmällä pitäen, ja tässä työssä selvitetään työkoneiden ohella, millä muilla sovellusalueilla sitä voisi hyödyntää. Lisäksi tarkoituksena on selvittää hybridityökoneiden tämänhetkistä kehitysastetta.

Converter-Fed Induction Motor Losses: Determination With IEC Methods

Energy efficiency is an important topic when considering electric motor drives market. Although more efficient electric motor types are available, the induction motor remains as the most common industrial motor type. IEC methods for determining losses and efficiency of converter-fed induction motors were introduced recently with the release of technical specification IEC/TS 60034-2-3. Determining the induction motor losses with IEC/TS 60034-2-3 method 2-3-A and assessing the practical applicability of the method are the main interests of this study. The method 2-3-A introduces a specific test converter waveform to be used in the measurements. Differences between the induction motor losses with a test converter supply, and with a DTC converter supply are investigated. In the IEC methods, the tests are run at motor rated fundamental voltage, which, in practice, requires the frequency converter to be fed with a risen input voltage. In this study, the tests are run on both frequency converters with artificially risen converter input voltage, resulting in rated motor fundamental input voltage as required by IEC. For comparison, the tests are run with both converters on normal grid input voltage supply, which results in lower motor fundamental voltage and reduced flux level, but should be more relevant from practical point of view. According to IEC method 2-3-A, tests are run at rated motor load, and to ensure comparability of the results, the rated load is used in the grid-fed converter measurements, although motor is overloaded while producing the rated torque at reduced flux level. The IEC 2-3-A method requires also sinusoidal supply test results with IEC method 2-1-1B. Therefore, the induction motor losses with the recently updated IEC 60034-2-1 method 2-1-1B are determined at the motor rated voltage, but also at two lower motor voltages, which are according to the output fundamental voltages of the two network-supplied converters. The method 2-3-A was found to be complex to apply but the results were stable. According to the results, the method 2-3-A and the test converter supply are usable for comparing losses and efficiency of different induction motors at the operating point of rated voltage, rated frequency and rated load, but the measurements do not give any prediction of the motor losses at final application. One might therefore strongly criticize the method’s main principles. It seems, that the release of IEC 60034-2-3 as a technical specification instead of a final standard for now was justified, since the practical relevance of the main method is questionable.

Kaukolämpöjohdon lämpöhäviöiden talteenotto lämpöpumpputeknologian avulla

Tämän tutkimuksen tavoitteena oli laatia tarkastelumalli, jonka perusteella pystyttäisiin analysoimaan tutkimuksessa tarkasteltavan kaukolämpöjohdon lämpöhäviöiden talteenot-toratkaisun taloudellista kannattavuutta yleisellä tasolla sekä sen mahdollisissa sovellus-kohteissa. Työssä tarkastellaan kaukolämpöjohtoa, jonka sisään on sijoitettu lämmönke-ruuputki. Lämmönkeruuputken on tarkoitus kerätä lämpöä kaukolämpöjohdon vaipasta sekä pitää vaipan lämpötilaa ympäristön lämpötilaa matalampana, jolloin johdon ulkopuo-lisia lämpöhäviöitä ei synny. Tarkastelumalli laadittiin perustuen lämpöpumppuprosessin ja kaukolämpöverkoston yleisiin mitoitusperiaatteisiin sekä ratkaisuun liittyvien järjestelmien osalta kerättyihin tarkas-teluhetkeä edustaviin kustannustietoihin. Tarkastelumallista laadittiin Excel-laskentataulukkona, jota voidaan tulevaisuudessa soveltaa järjestelmän sovelluskohdekoh-taiseen tarkasteluun sekä mitoitukseen. Lasketut takaisinmaksuajat osoittautuivat kaikissa tarkastelluissa tapauksissa järjestelmien arvioitua teknistä käyttöikää lyhyemmäksi. Järjestelmällä voisi olla tietynlaisissa sovellus-kohteissa myös strateginen, kaukolämpöliiketoiminnan riskejä vähentävä merkitys.

Pienjännitteisen tasasähkönjakelun hyödyntäminen ja siihen liittyvä tutkimus maailmalla

Tässä kandidaatintyössä selvitetään kirjallisuustutkimuksena, minkälaista tutkimusta maailmalla on tehty liittyen pienjännitteiseen tasasähkönjakeluun, sekä missä sovelluskohteissa sitä hyödynnetään. Työssä esitetään yleisimmät järjestelmärakenteet ja sovelluskohteet sekä organisaatiot, joiden on havaittu tutkivan tasasähkönjakelua kiinteistöissä, microgrideissä tai julkisessa sähkönjakelussa. Katsauksen perusteella havaittiin, että maailmalla on tehty erityisesti laskennallisia tutkimuksia ja simulointeja liittyen pienjännitteiseen tasasähkönjakeluun. Näkökulma on pääasiassa ollut kiinteistöissä ja microgrideissä, vähäisemmässä määrin myös julkisissa sähkönjakeluverkoissa. Pienjännitteistä tasasähkönjakelua hyödynnetään, tai ainakin voitaisiin hyödyntää näissä kohteissa. Pääasiassa konseptilla on pyritty hakemaan kustannussäästöjä ja toisaalta parantamaan hyötysuhdetta. Ympäri maailmaa on käynnissä pilottihankkeita sekä kiinteistöihin, että julkiseen sähkönjakeluun liittyen. Bipolaarinen ratkaisu näytti olevan yleisempi. Käytetyt ja tutkitut jännitetasot vaihtelivat riippuen sovelluskohteesta – kiinteistön sisällä oli käytössä tasot pienoisjännitteestä aina 350–400 VDC jännitetasoon asti, ja sama 350–400 VDC oli selvästi suosittu jännitealue myös jakeluverkossa, mutta myös korkeampia jännitteitä, kuten 700–750 VDC, oli käytössä.

Modelling of changes in electricity end-use and their impacts on electricity distribution

The electricity distribution sector will face significant changes in the future. Increasing reliability demands will call for major network investments. At the same time, electricity end-use is undergoing profound changes. The changes include future energy technologies and other advances in the field. New technologies such as microgeneration and electric vehicles will have different kinds of impacts on electricity distribution network loads. In addition, smart metering provides more accurate electricity consumption data and opportunities to develop sophisticated load modelling and forecasting approaches. Thus, there are both demands and opportunities to develop a new type of long-term forecasting methodology for electricity distribution. The work concentrates on the technical and economic perspectives of electricity distribution. The doctoral dissertation proposes a methodology to forecast electricity consumption in the distribution networks. The forecasting process consists of a spatial analysis, clustering, end-use modelling, scenarios and simulation methods, and the load forecasts are based on the application of automatic meter reading (AMR) data. The developed long-term forecasting process produces power-based load forecasts. By applying these results, it is possible to forecast the impacts of changes on electrical energy in the network, and further, on the distribution system operator’s revenue. These results are applicable to distribution network and business planning. This doctoral dissertation includes a case study, which tests the forecasting process in practice. For the case study, the most prominent future energy technologies are chosen, and their impacts on the electrical energy and power on the network are analysed. The most relevant topics related to changes in the operating environment, namely energy efficiency, microgeneration, electric vehicles, energy storages and demand response, are discussed in more detail. The study shows that changes in electricity end-use may have radical impacts both on electrical energy and power in the distribution networks and on the distribution revenue. These changes will probably pose challenges for distribution system operators. The study suggests solutions for the distribution system operators on how they can prepare for the changing conditions. It is concluded that a new type of load forecasting methodology is needed, because the previous methods are no longer able to produce adequate forecasts.

Control of multi-actuator system by an electrically driven hydraulic pump-motor

The awareness and concern of our environment together with legislation have set more and more tightening demands for energy efficiency of non-road mobile machinery (NRMM). Integrated electro-hydraulic energy converter (IEHEC) has been developed in Lappeenranta University of Technology (LUT). The elimination of resistance flow, and the recuperation of energy makes it very efficient alternative. The difficulties of IEHEC machine to step to the market has been the requirement of one IEHEC machine per one actuator. The idea is to switch IEHEC between two actuators of log crane using fast on/off valves. The control system architecture is introduced. The system has been simulated in co-simulation using two different software. The simulated responses of pump-controlled system is compared to the responses of the conventional valve-controlled system.

Relay protection in active distribution networks

Increasingly growing share of distributed generation in the whole electrical power system’s generating system is currently a worldwide tendency, driven by several factors, encircling mainly difficulties in refinement of megalopolises’ distribution networks and its maintenance; widening environmental concerns adding to both energy efficiency approaches and installation of renewable sources based generation, inherently distributed; increased power quality and reliability needs; progress in IT field, making implementable harmonization of needs and interests of different-energy-type generators and consumers. At this stage, the volume, formed by system-interconnected distributed generation facilities, have reached the level of causing broad impact toward system operation under emergency and post-emergency conditions in several EU countries, thus previously implementable approach of their preliminary tripping in case of a fault, preventing generating equipment damage and disoperation of relay protection and automation, is not applicable any more. Adding to the preceding, withstand capability and transient electromechanical stability of generating technologies, interconnecting in proximity of load nodes, enhanced significantly since the moment Low Voltage Ride-Through regulations, followed by techniques, were introduced in Grid Codes. Both aspects leads to relay protection and auto-reclosing operation in presence of distributed generation generally connected after grid planning and construction phases. This paper proposes solutions to the emerging need to ensure correct operation of the equipment in question with least possible grid refinements, distinctively for every type of distributed generation technology achieved its technical maturity to date and network’s protection. New generating technologies are equivalented from the perspective of representation in calculation of initial steady-state short-circuit current used to dimension current-sensing relay protection, and widely adopted short-circuit calculation practices, as IEC 60909 and VDE 0102. The phenomenon of unintentional islanding, influencing auto-reclosing, is addressed, and protection schemes used to eliminate an sustained island are listed and characterized by reliability and implementation related factors, whereas also forming a crucial aspect of realization of the proposed protection operation relieving measures.