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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Portable Heat Kit : Explorative research on application of heat as a comfort material in day

Damitha Gunawardena, Suresh January 2022 (has links)
Heat is an essential aspect of personal comfort. However, designing for heat as a comfort material is difficult due to the subjective nature of materials in combination with differing human perceptions and preferences. This paper presents the results of an explorative design project, where a heat kit consisting of three design probes was developed through self-exploration and participatory design with five participants. Field studies with this heat kit enabled the participants to interact with heat as a comfort material in their day-to-day lives. This allowed exploration of the contexts where heat is considered a comfort material, use cases stemming from these contexts, and usability considerations in designing with heat as a comfort material. As a result, two significant paradigms of using heat for comfort emerged: discomfort-avoidance behavior and comfort-seeking behavior. In addition, the degree of flexibility for users, importance of material with differing use cases, controllability of heat, and comfort in social interactions emerged as key design considerations when developing artifacts with heat as a comfort material. / Värme är en viktig aspekt när det gäller personliga bekvämligheter. Att skapa en design där värme är ett bekvämlighetsmaterial är dock svårt på grund av materialets subjektiva natur och människors multipla preferenser. Denna artikel presenterar resultaten av ett utforskande designprojekt, där ett värmekit bestående av tre designsonder utvecklades genom självutforskning och fem deltagares design. Fältstudier med detta värmekit gjorde det möjligt för deltagarna att interagera med värme som ett bekvämlighetsmaterial i deras dagliga liv, vilket gjorde det möjligt att utforska de sammanhang där värme anses vara ett bekvämlighetsmaterial, användingsfall som kommer från dessa kontext samt omständigheter för användaren som kommer från att designa efter värme som ett bekvämlighetsmaterial. Som ett resultat uppstod två betydande paradigm för att använda värme för komfort: beteende som undviker obehag och beteende som söker komfort. Dessutom framträdde graden av flexibilitet för användarna, vikten av material med olika användningsfall, reglerbarhet av värme och komfort i sociala interaktioner som viktiga designöverväganden vid utveckling av artefakter med värme som komfortmaterial.
62

Implementation of BECCS in a polygeneration system : - A techno-economic feasibility study in the district heating network of Stockholm

Linde, Linus January 2017 (has links)
The combination of Biomass Energy with Carbon Capture and Storage (BECCS) can reduce the level of CO2 in the atmosphere. It is, therefore, seen as an interesting tool in the CO2 abatement portfolio. In a Swedish context, BECCS could contribute to the goal of CO2 neutrality by 2045. This thesis aims to investigate the application of BECCS in the district heating system of Stockholm region with a case study at the energy utility Fortum Värme. The focus of the study is the technical and economic feasibility of such an application. The applicability of Fortum Värme´s plants to implement carbon capture is investigated together with costs and technical implications on each applicable plant and the district heating system as a whole. Three plants are deemed feasible for carbon capture with a cost of about 45€/tonne of captured CO2 (not including transport or storage). A model for transport of CO2 to promising storage sites in Sweden, Norway, and Denmark is constructed for transport by pipeline and ship. Ship transport is estimated to be the most cost-efficient option in all scenarios. The total cost for BECCS is calculated at 70-100€/tonne depending on size of emissions and distance to storage locations. Furthermore, the total cost is calculated to decrease by 10-25% if some current promising technologies for carbon capture reach maturity, a market for transport services of CO2 evolves, and a number of actors are sharing the costs for storage.Calculated costs are on a similar price level as other CO2 abatement strategies such as CCS in industries, biogas, and biodiesel in the vehicle fleet. If the cost is applied directly to the heat price, without any subsidies, it would increase the price of heat by 14-21%.The major challenge of BECCS in combined heat and power production, compared to other studies based on power production, is the seasonality of heat demand. The capacity of the carbon capture system will be oversized during the summer, or undersized during the winter. This is an optimization challenge which has to be further studied.
63

Analysis of Energy Saving Proposals at St. Louis County Jail

Lillesve, Peter January 2010 (has links)
<p>The goal of this project was to evaluate three main proposals, by the Property Management Department (PMD) of St. Louis County, which the department hoped would reduce energy consumption at their Duluth Jail facility. This particular facility was opened in 1995 and houses approximately 170 inmates. Despite its relatively new construction, the building produces some of the highest utility bills of all of the County’s buildings.</p><p>The proposals put forth by the PMD were the following: to reduce natural gas consumption by using solar water heating for the domestic hot water; to reduce heating and cooling costs by enclosing a light well which is currently open to the sky with a transparent, insulated roof; and to utilize a white roof to reduce cooling demand during the summertime.</p><p>The solar water heating proposal was evaluated by determining the energy the solar system could provide annually and comparing these energy- and monetary savings to the cost of the system. Two solar options were evaluated; one system with 20 collectors and another with 50. Both systems also included condensing boilers to provide supplementary heating during times of low solar output. The annual savings of the 20- and 50 collector systems were 128 and 173 MWh, respectively. This led to a payback period of approximately 17 years for the 20 collector system and 16 years for the 50 collector system.</p><p>Enclosing the open light well, which is an open area inside the perimeter of the building which is designed to give rooms on the inside of the building natural daylight, was evaluated by performing an energy flow analysis comparing the existing condition with one in which a roof topped the well. This involved calculating the U-values of the walls before the skyroof and then using heating and cooling degree days to determine the heat flows through the walls. The enclosed light well was evaluated by performing an energy balance on the well to determine the temperature of the enclosed well. This temperature could then be used to calculate the heat flow through the enclosed light well’s walls. The difference in these heat flows between the two options was then converted to an economic cost to evaluate a payback period. Two grades of Kalwall-brand insulation were evaluated; the “Nanogel” grade and a mid-range grade. The Nanogel-enclosed light well reduced the heating demand by 16 MWh but increased the cooling load by 9 MWh, while the mid-grade enclosed well decreased the heating load by 11 MWh but increased the cooling load by 4 MWh. These added up to net annual savings of $650 for the Nanogel roof and $470 for the mid-grade skyroof. However, the investment costs were so high that the payback periods were between 450 and 550 years.</p><p>Two white roofing options were considered and corresponded to a newly installed roof and one that had weathered for 3 years, thereby reducing its reflectivity. These options were evaluated by determining the mean monthly roof temperatures throughout a typical year and calculating the heat flows through the roofs based on these temperatures. The temperatures were determined by performing a heat balance on the roofs’ surfaces and considering the solar radiation incident on the roofs. The heat flows with the existing black colored roof and the proposed white roofs were thencompared and converted into heating and cooling costs. The white roofs led to summertime air-conditioning savings but created more wintertime heat losses and therefore caused net annual energy cost increases of $560 and $240 for the new and weathered roofs, respectively.</p><p>The recommendations therefore were to implement the solar thermal system but not the other two proposals. Other areas which might benefit from additional investigations include lighting efficiency improvements, water use reductions, and replacement of the existing boilers with either more efficient natural gas units or wood-pellet/biomass boilers.</p>
64

Analysis of Energy Saving Proposals at St. Louis County Jail

Lillesve, Peter January 2010 (has links)
The goal of this project was to evaluate three main proposals, by the Property Management Department (PMD) of St. Louis County, which the department hoped would reduce energy consumption at their Duluth Jail facility. This particular facility was opened in 1995 and houses approximately 170 inmates. Despite its relatively new construction, the building produces some of the highest utility bills of all of the County’s buildings. The proposals put forth by the PMD were the following: to reduce natural gas consumption by using solar water heating for the domestic hot water; to reduce heating and cooling costs by enclosing a light well which is currently open to the sky with a transparent, insulated roof; and to utilize a white roof to reduce cooling demand during the summertime. The solar water heating proposal was evaluated by determining the energy the solar system could provide annually and comparing these energy- and monetary savings to the cost of the system. Two solar options were evaluated; one system with 20 collectors and another with 50. Both systems also included condensing boilers to provide supplementary heating during times of low solar output. The annual savings of the 20- and 50 collector systems were 128 and 173 MWh, respectively. This led to a payback period of approximately 17 years for the 20 collector system and 16 years for the 50 collector system. Enclosing the open light well, which is an open area inside the perimeter of the building which is designed to give rooms on the inside of the building natural daylight, was evaluated by performing an energy flow analysis comparing the existing condition with one in which a roof topped the well. This involved calculating the U-values of the walls before the skyroof and then using heating and cooling degree days to determine the heat flows through the walls. The enclosed light well was evaluated by performing an energy balance on the well to determine the temperature of the enclosed well. This temperature could then be used to calculate the heat flow through the enclosed light well’s walls. The difference in these heat flows between the two options was then converted to an economic cost to evaluate a payback period. Two grades of Kalwall-brand insulation were evaluated; the “Nanogel” grade and a mid-range grade. The Nanogel-enclosed light well reduced the heating demand by 16 MWh but increased the cooling load by 9 MWh, while the mid-grade enclosed well decreased the heating load by 11 MWh but increased the cooling load by 4 MWh. These added up to net annual savings of $650 for the Nanogel roof and $470 for the mid-grade skyroof. However, the investment costs were so high that the payback periods were between 450 and 550 years. Two white roofing options were considered and corresponded to a newly installed roof and one that had weathered for 3 years, thereby reducing its reflectivity. These options were evaluated by determining the mean monthly roof temperatures throughout a typical year and calculating the heat flows through the roofs based on these temperatures. The temperatures were determined by performing a heat balance on the roofs’ surfaces and considering the solar radiation incident on the roofs. The heat flows with the existing black colored roof and the proposed white roofs were thencompared and converted into heating and cooling costs. The white roofs led to summertime air-conditioning savings but created more wintertime heat losses and therefore caused net annual energy cost increases of $560 and $240 for the new and weathered roofs, respectively. The recommendations therefore were to implement the solar thermal system but not the other two proposals. Other areas which might benefit from additional investigations include lighting efficiency improvements, water use reductions, and replacement of the existing boilers with either more efficient natural gas units or wood-pellet/biomass boilers.
65

Potentiell koppling mellan elektrolys och landbaseradfiskodling : En analys av behov och tillgång på syrgas och värme

Hansen, Per January 2021 (has links)
Det kommer ske en stor utbyggnad av elektrolys för produktion av vätgas i Sverigeoch övriga världen. För att sänka produktionskostnaden och därmed göra vätgasenbilligare analyserar denna rapport vilket behov av syrgas och värme som en landbaserad fiskodling har, samt hur mycket syrgas och värme fiskodlingen skulle behövaköpa från en elektrolysör. Analysen visar att de arter som används i studien - tilapia(Oreochromis, Oreochromis,. Alcolapia), regnbåge (Oncorhynchus mykiss) och lax(Salmo salar) - i en odling som producerar 40 ton fisk om året skulle förbruka cirka1,16 procent av syrgasen och cirka 0,35 procent av värmen från en 3 MW PEMelektrolysör. Försäljningsvärdet av syrgasen och värmen från en 3 MW elektrolysörberäknas till cirka 695 000 SEK/år för syrgasen och cirka 1 830 000 SEK/år för värmen. Den genomsnittliga kostnaden för syrgas och värme för arterna i studien i enodling på 40 ton/år beräknas till 8900 SEK/år för syrgasen och 6400 SEK/år förvärmen i en landbaserad fiskodling. / There will be a major expansion of electrolysis for production of hydrogen in Sweden and the rest of the world. To reduce production costs and thus make hydrogencheaper, this report analyzes how much oxygen and heat a fish farm consumes andtherefore would need to buy from an electrolyser. The analysis shows that the species used in the study - tilapia (Oreochromis, Oreochromis, Alcolapia), rainbow(Oncorhynchus mykiss) and salmon (Salmo salar) - in a farm that produces 40 tonsof fish per year would consume 1.16 percent of the oxygen and 0,35 percent of theheat produced from a 3 MW PEM electrolyzer. The value of the oxygen and theheat from a 3 MW electrolyser is calculated at SEK 694,939/year for the oxygenand SEK 1,829,813/year for the heat. The average cost for the species in the studyin a 40 tonne/year fish farm is calculated at SEK 8,900/year for the oxygen and SEK6,400/year for the heat in a land-based fish farm.
66

Prospects for continued use and production of Swedish biogas in relation to current market transformations in public transport / Utsikter för fortsatt användning och produktion av svensk biogas i förhållande till pågående marknadsförändringar inom kollektivtrafiken

Hagstroem, Agnes January 2019 (has links)
Biogas is largely utilised as vehicle fuel in public bus transport in Sweden today. This study investigates opportunities and barriers for continued domestic use and production of biogas, in relation to the ongoing electrification of public bus transport. The analysis is based on interviews with actors in public transport and the biogas sector, experts on biogas systems, and representatives for alternative user segments. Three regions were chosen as case-studies for investigations of prospects in public transport, i.e. Stockholm, Västra Götaland and Skåne, though alternative uses were studied from a national perspective. In addition to public transport, considered uses include road transport, sea transport, industries, and electricity and heat production. The study identifies a broad agreement among stakeholders that renewable resources should be implemented where they provide most benefits from a system perspective. Therefore, electric public buses are valued in urban environments, while biogas solutions are found suitable for regional routes. Biogas is further viewed as environmentally beneficial in all user segments except continuous electricity and heat production, where it largely would replace renewable rather than fossil sources. Regarding costs and competitiveness, probable future uses are identified within light and heavy-duty road transport, and in consumer-oriented industries, i.e. the food industry. Economic support in policy instruments is further considered essential for continuous development of the Swedish biogas sector, though current influential instruments, e.g. the tax exemption, are described as short-term and unpredictable. The willingness to pay for the collected societal benefits of biogas further decrease in transitions from public to private consumers, and as biogas solutions simultaneously are linked with limited or uncertain competitiveness in these sectors, risks prevail that such transitions could imply stagnations and declines in biogas use and production, given today’s situation. / Idag används biogas till stor del som drivmedel för bussar inom kollektivtrafik i Sverige. Denna studie undersöker möjligheter och hinder för en fortsatt nationell användning och produktion av biogas, i samband med att bussar inom kollektivtrafiken nu elektrifieras. Analysen är baserad på intervjuer med aktörer inom kollektivtrafiken och biogassektorn, sakkunniga inom biogas, och alternativa användare av biogas. Tre regioner, Stockholm, Västra Götaland och Skåne, valdes som fallstudier för analys av möjligheter för fortsatt användning inom kollektivtrafiken. Alternativa användningar studerades istället ur ett nationellt perspektiv, och inkluderade vägtransporter, sjöfart, industri och el- och värmeproduktion. Studien visar att det råder enighet mellan intervjupersoner att förnybara resurser över lag ska användas där de medför störst samhällsnytta sett till samhället i stort. Inom kollektivtrafiken beskrivs elbussar därför som fördelaktiga i stadsmiljöer, medan biogas ses som lämpligt i regional trafik. Biogas framställs dessutom som miljömässigt fördelaktigt i alla alternativa användningsområden utom kontinuerlig el- och värmeproduktion, eftersom då främst förnybara och inte fossila resurser ersätts. Med hänsyn till kostnader och konkurrenskraft ses lätta och tunga transporter tillsammans med kundnära industrier, t.ex. livsmedelsindustrin, som troliga framtida användningsområden för biogas. Ekonomiskt stöd från styrmedel bedöms vara nödvändigt för en fortsatt utveckling av biogassektorn i Sverige, även om dagens styrmedel, t.ex. skattebefrielsen, beskrivs som kortsiktiga och oförutsägbara. Betalningsviljan för biogasens samlade samhällsnyttor minskar också vid en övergång från offentliga till privata kunder. Eftersom biogas därtill har en begränsad eller osäker konkurrenskraft jämtemot andra alternativ i de privata segmenten, identifierar denna studie risker för stagnation eller nedgång i användning och produktion av biogas vid en eventuell utfasning från den offentliga sektorn, givet dagens situation.
67

Optimization of comfort-related energy and thermal comfort for commuter trains : A case study of Stockholm commuter trains

Lidén, Jimmy January 2023 (has links)
Today, energy efficiency is an increasingly important question in which progress is accelerating. One of the high electricity demand energy users is public transport. In addition, passenger satisfaction with thermal comfort is an important parameter. Consequently, it is essential to consider thermal comfort in combination with the energy-saving measures of thermal-related functions. Unfortunately, there have not been a lot of investigations into improving the energy efficiency of the thermal-related functions on commuter trains, where most of the focus has been on traction energy. The first part consisted of a literature study to explore thermal-related functions, energy saving, and thermal comfort of commuter trains. At least three articles have utilized the methodology of evaluating energy measures in IDA ICE; however, none of them has considered door openings that are frequent on commuter trains. The literature study concluded which efficiency measures can be applicable for short-haul distance trains and typical approaches to evaluating thermal comfort. A commuter train is a complex and transient thermal environment, with passengers entering and leaving the train in short intervals, airflows, temperature fluctuations, and the train's movement. Simplifications of the model were made to simulate the average ambient conditions. To validate and adapt the IDA ICE model, experimental measurements were done during the winter season using a thermal camera, air speed, and temperature measurements. The model was validated through experimental measurements and data analysis. In addition, data analysis was used for evaluating some of the energy measures through available live and history-data of the train fleet. The energy efficiency measures, which are quantifiable, have been quantified using the simulation model in combination with the data-analysis. Three categories of energy-saving measures are proposed: easily implementable, medium, and measures that require physical changes of the train components. Parking mode has a lot of saving potential of 34 % of annual energy compared to baseline. With a reversible heat pump of 11 kW, heating energy saving of 43 %, and 40 % energy coverage could be obtained, with the potential for up to 100 % energy coverage but being in the category of hard to implement. Door opening reduction with a potential saving of 11 000 kWh per train in annual energy, as compared to the baseline simulated model, being in the category of easy to implement. Balancing temperature heating shutdown could save between 3 100 to 9 500 kWh per train. A setpoint temperature of 18°C could save 16.5 %, and a variable temperature setpoint curve was proposed with similar savings. Ventilation control was among those measures with the highest potential; recirculation, CO2 and temperature-controlled ventilation heating energy saving of 31 % was simulated. Thermal comfort was improved in the measures affecting thermal conditions. With a setpoint temperature of 18°C during winter and based on clothing values derived from the literature study, an improvement of thermal comfort was observed in the PMV scale for thermal comfort. With combined energy efficiency measures, the simulation results showed a reduction of heating energy of 59 %, and in addition the fan power consumption could be reduced in magnitude of up to 12 000 kWh per train and year. Finally, further suggestions on research within the area were proposed, mainly to make more long-time measurements and to improve the possibility of energy follow-up by improving the data channels and available information. / Idag är energieffektivitet en viktigare fråga där framstegen har accelererat. En av energiförbrukarna med hög efterfrågan på elektricitet är kollektivtrafiken. Passagerarnas tillfredsställelse av termisk komfort är en viktigt parameter. Följaktligen är det viktigt att analysera termisk komfort i kombination med energibesparingsåtgärder. Det har inte gjorts mycket tidigare forskning inom att förbättra energieffektivitet inom termiska funktionerna på pendeltåg i Sverige, främst har fokus varit på energi för framförandet av fordonen. Den första delen av projektet bestod av en litteraturstudie för att få en uppfattning av vilka typer av energibesparingsåtgärder som är lämpliga för kortdistanståg som också skiljer sig mycket från långdistanståg. Tre artiklar hittades som har använt IDA ICE för att utvärdera energiåtgärder på tåg, men ingen av dem har tagit hänsyn till dörräppningar som är väldigt frekventa på pendeltåg. Flera metoder undersöktes för att bedöma termisk komfort och för att bygga upp en modell och validera den.  Ett pendeltåf är en komplex och transient termisk miljö, där passagerarna går in och lämnar tåget i relativt korta tidsintervall jämfört med långdistanståg. Men det ansågs fortfarande tillräckligt långa tidsintervall för att kunna använda PMV för att bedöma termisk komfort. Jämfört med en byggnad, så sker det stora temperatur-fluktuationer, variationer i antal passagerare, och en kontinuerlig förflyttning av tåget med nya omgivningsförhållanden. För att validera och anpassa IDA ICE-modellen gjordes experimentiella mätningar under vintersäsongen med hjälp av värmekamera, lufthastighetsmätning och temperaturmätning. Modellen kunde valideras med till exempel yttertemperaturer, energisignatur från dataanalys, och hur långt tid det tar för modellen att tappa temperaturen jämfördes med ett liknande tåg, X61. Dessutom användes dataanalys för att utvärdera några av energiåtgärderna. Energieffektivitetsåtgärdena som är kvantifierbara, har simulerats för hur mycket energibesparingspotential som finns.  Tre kategorier av energibesparingsåtgärder föreslås, lätt genomförbara, medelsvåra, och svåra där fysiska förändringar av tågkomponenterna krävs. Parkeringsläge har stor energibesparingspotential på 34% av den årliga uppvärmningsenergin jämfört med bas-scenariot. Reversibel värmepump på 11 kW, har värmeenergibesparingspotential på 43% och 40% enegitäckning, med stor potential för upp till 100% energitäckning, men i kategorin svår att implementera. Manuellt öppningsbara dörrar på vintern har besparingspotential i värmeenergi på 11 000kWh per tåg, jämfört med bas-scenariot. Balanstemperatur har besparingspotential på 3100 till 9500 kWh per tåg. Börvärdetemperatur på 18 °C jämfört med 20°C kan spara 16.5% värmeenergi, samt så föreslogs en variabel temperaturkurva. Med en börvärdetemperatur på 18°C under vintern, baserat på bärden av isolering av kläder från litteraturstudien, observerades en föbättring av termiska komforten i PMV-skalan för termisk komfort. Med kombinerade energieffektivitetsåtgärder visade simuleringsresultaten en minskning av värmeenergi med 59%, och dessutom kunde fläktarnas energianvändning minskas i storleksordning om upp till 12 000 kWh per tåg och år.  Slutligen föreslogs ytterligare förslag på forskning inom området, främst att göra fler långtidsmätningar och förbättra möjligheten till energiuppföljning genom att förbättra datakanalerna och tillgänglig information.
68

A methodology to assess impacts of energy efficient renovation : a Swedish case study

Ramirez Villegas, Ricardo January 2017 (has links)
The European Union aims to reduce energy use and CO2-emissions by 40 % by the year 2030. The building sector has been identified as having a great potential to reduce emission of CO2 by increasing its energy efficiency. Also, there is a growing concern of the buildings environmental performance, that lead to the development of building environmental assessment tools. However, different types of energy sources and confusing environmental impacts affect the decision making when renovating for improved energy efficiency. This study develops and tests a methodology to help decision-makers when considering major renovation of their building stock when connected to adistrict heating system. The proposed methodology is applied and used to investigate how different renovation scenarios affects the building environmental impacts in terms of CO2 emissions and identify and discuss future improvements of the methodology. The novelty of the method is the expanded system boundaries that include both the distribution and production of district heating and the energy use at a building level. In this way it is possible to compare and weight measures made both at the energy system level and the building level. This work has limited its approach to energy use in buildings, but it is important to bring the life cycle thinking to the methodology. During the choice of the renovation methods it was noticed that the environmental impact of the production of some components in order to reduce the energy use of a building are not insignificant. Even if all the renovation measures considered in this case study are feasible, it is important to determine in which order they are desirable or achievable from an economic point of view. Uncertainty in the future development of energy, and limited economic resources can play an important role in the possibility of energy efficient renovation. / Den Europeiska Unionen har som målsättning att minska energianvändning och utsläpp av växthusgaser med 40 % till året 2030 jämfört med 1990. Byggnader har identifierats som ett område med stor potential för utsläppsminskningar om de energieffektiviseras. Användningen av olika energislag och olika sätt att värdera miljöpåverkan påverkar beslutsfattandet i samband med energieffektivisering. I studien utvecklas och testas en metodik som kan hjälpa beslutsfattare vid renovering med energieffektivisering inom fjärrvärmeområdet. Först utvecklades en översiktlig metodik vilken inkluderar både byggnadsenergisimulering och energisystemsimulering. Sen implementerades metodiken genom olika renoveringsscenarier och utsläppen av växthusgaser analyserades. Metodiken visar att det finns en möjlighet att utveckla ett verktyg som kan hjälpa beslutsfattare när energibesparingsstrategier ska implementeras vilka kan bli positiva för både byggnader och fjärrvärmesystemet. / REESBE
69

An investigation of friction graphs ranking ability regarding the galling phenomenon in dry SOFS contact : (Adhesive material transfere and friction)

Wallin, Harald January 2008 (has links)
The main purpose of this project is to investigate different tool steels in terms of their ability to withstand material transfer buildup, so-called galling, occurring in SMF (sheet metal forming) operations. The ability to withstand galling is vital to optimize cost-effectiveness and increase the work tool’s effective operational time. This investigation studies four different tool steels, including a TiN-coating, with the intention of evaluating the microstructures, chemical composition and hardness effect on galling resistance in dry conditions using a slider-on-flatsurface (SOFS) tribo-tester which measures the coefficient of friction during sliding. An OP (optical profilometer) was used to measure the size and geometry of lump growth on the tool and damage on the work sheet. A scanning electron microscope (SEM) was used to identify the interacting tribological mechanisms exhibited at different stages during the slide. The SEM figures confirmed three different types of characteristic patterns exhibited in the tracks after tribo- testing which were categorized as mild adhesive, abrasive and severe adhesive damage. A SEM figure that illustrates a ragged contact surface and an obvious change in the sheet materials plastic behavior is in this report regarded as a sign of severe adhesive contact, the characteristics could possibly be explained by local high temperature and high pressure followed by a sudden pressure drop and creation of hardened welds or solders between the two surfaces which increase the frictional input needed for further advancement. Friction coefficients observed in the initial 100% mild adhesive stage were, μ=0,22-0,26 succeeded by abrasive SEM characteristics often in association with mild adhesive contact and friction values between μ=0,25-0,4 which where sometimes followed by severe adhesive SEM characteristics in 100% of the contact zone with friction values between μ=0,34- 0,9 respectively. The tool material that performed best according to the friction detection criteria was Sv21 closely followed by Sleipner (TiN coated) and Va40 (HRC 63.3). Unfortunately was the friction criteria, a significant raise in friction for defining a sliding length to galling, not adequate for dry conditions due to immediate material transfer succeeded by cyclic changes between partial or 100% abrasive+mild adhesive and severe adhesive contact. The mechanism that change abrasive wear in association with mild adhesive contact, (moderate friction input), to sever adhesive wear, (higher friction input), is dependent on lump shape (lump geometry) and can appear at comparably low speeds 0,04-0,08 [m/s] and low friction energy input (μ=0,34), the magnitude of the change in friction is therefore not always significant and hardly detectable on the friction graph. This was quite unexpected but could be explained by concentration of friction energy rater than the absolute amount. The problem with using friction graphs for galling evaluation was increased even further when a very small lump size and low corresponding rate of material transfer to the tool surface caused a sustainable high raise in friction (μ≈0,3→0,6) on a TiN-coated tool steel called Sleipner. A hardly detectable or similar friction raise for Sv21 and Va40 showed much larger corresponding lump size and rate of material transfer. This means that friction graphs demonstrate a clear problem with quantifying lump size [m3] and rate of  material transfer [m3/s]. Another phenomenon called stick slip behavior, material transfer and lump growth followed by a sudden decrease in lump size and transfer of material back to the work sheet, is also not possible to detect on a friction graph. Because a drop in friction can easily be a change in contact temperature and lump attack angle due to a growing lump and not a decreasing lump.   The conclusion, a friction graph is not suited for galling evaluation and ranking in dry SOFS conditions. A ranking should primarily be based on dimensional OP measurements of the cross section of formed tracks and scratches or preferably by repeated OP measurements of the tool surface during a single test, the last revel the exact lump growth history and true lump growth even in the sliding direction. / civilingenjörsexamen
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HotHumiBox, ett provelement mellan två kammare / HotHumiBox, a test element between two chambers

Lekic, Dragan January 2018 (has links)
HotHumiBox är en försöksutrustning som finns på Linnéuniversitetet och som ska ge bättre kunskap och förståelse om hur fukt och temperatur varierar i en provkropp monterad mellan två kammare där klimatet kan styras var för sig. Syftet med examensarbetet är att undersöka om HotHumiBoxen fungerar väl och huruvida den kan börja användas i undervisningen i olika kurser inom institutionen för byggteknik på Linnéuniversitetet, bl.a. i samband med demonstrationslaborationer vid föreläsningar om fukt. För att genomföra arbetet har mätningar med tre olika klimat utförts på ett provelement som motsvarar en yttervägg som kan finnas i nybyggda typhus. Resultatet av mätningar utförda med HotHumiBoxen presenteras i form av tabeller och diagram och jämförs slutligen med beräkningar av fukt- och temperaturtillstånd. Jämförelsen mellan mätningar och beräkningar visar att givarna som styr klimatet i båda kamrarna visar mycket bra resultat. Däremot visar majoriteten av givarna i provelementet antingen lite för höga eller för låga värden för att resultatet ska anses som tillfredställande. För att få en bekräftelse på att HotHumiBoxen fungerar väl rekommenderas därför att ytterligare mätningar görs. / HotHumiBox is an experimental equipment that is available at Linnaeus University and is supposed to provide better knowledge and understanding about the way moisture and temperature varies in a building element installed between two chambers in which the climate can be controlled separately. The purpose of this work is to investigate whether the HotHumiBox works well and whether it can be used at various courses at the Department of Building Technology at Linnaeus University, such as demonstration laboratory experiments at lectures on moisture. Measurements with three different climates were performed on a building element that corresponds to a wall that could be installed in modern houses. The results of the HotHumiBox measurements are being presented in tables and diagrams and are being compared with moisture and temperature calculations. The comparison between measurements and calculations shows that the sensors which control the climate in both chambers show very good results. On the other hand, the majority of the sensors in the test element show either too high or too low values for the result to be considered as satisfactory. Therefore, it is recommended that some more tests and measurements are done before it can be concluded that the HotHumiBox work well.

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