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The effect of stoichiometry on the pyrolytic decomposition, oxidation and ignition behaviour of synthetic violarite and pentlandite has been established. These minerals, of general formula (Fe,Ni)(subscript)3S(subscript)4 and (Fe,Ni)(subscript)9S(subscript)8 respectively, may vary considerably in Fe:Ni ratio. Pentlandite can also show some variation in metal:sulfur ratio. A series of samples, ranging in stoichiometry from Fe(subscript)0.96Ni(subscript)1.97S(subscript)4 to Fe(subscript)0.20Ni(subscript)2.72S(subscript)4 and Fe(subscript)5.80Ni(subscript)3.15S(subscript)8 to Fe(subscript)3.40Ni(subscript)5.55S(subscript)8, were synthesised and characterised using wet chemical analysis, electron probe micro-analysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer, Emmett and Teller (BET) surface area analysis.The thermal behaviour of these sulfides was examined using simultaneous Thermogravimetry-Differential Thermal Analysis (TG-DTA) at different heating rates and in different atmospheres. Partially reacted samples were collected at various temperatures and analysed using XRD, EPMA, SEM, optical microscopy (OM), and Fourier transform infrared (FTIR) spectroscopy. The endmembers of the violarite and pentlandite series were examined in detail to determine the effect of stoichiometry on the reaction mechanism. In this study the reaction mechanism refers to the sequence of reactions occurring during pyrolytic decomposition or oxidation of the sulfide minerals. Samples were sieved into four particle size fractions, 125-90, 90-63, 63-45 and 45-20 gm, to determine the effect of particle size on the reaction mechanism.When violarite was heated in an inert atmosphere at 10 degrees celsius min(subscript)-1, it initially decomposed to a monosulfide solid solution (mss), (Fe,Ni)(subscript)1-xS, and vaesite, (Ni,Fe)S(subscript)2, indicated by a ++ / sharp endothermic peak in the DTA trace. The decomposition temperature was found to be linearly dependent on the iron:nickel ratio, decreasing from 495 degrees celsius to 450 degrees celsius as the iron:nickel ratio decreased from 0.49 to 0.07. This was followed by a broader endothermic peak coinciding with a rapid mass loss, which was associated with the decomposition of vaesite to mss with the loss of sulfur. Between 615-805 degrees celsius the mss was converted to a high temperature form of heazlewoodite, (Fe,Ni)(subscript)3+/-S(subscript)2 melted incongruently at 835 degrees celsius and 805 degrees celsius for Fe(subscript)0.96Ni(subscript)1.97S(subscript)4 and Fe(subscript)0.20Ni(subscript)2.72S(subscript)4 respectively, with further loss of sulfur vapour forming a central sulfide liquid of general formula (Fe,Ni)(subscript)1+xS.Under similar experimental conditions, pentlandite pyrolytically decomposed forming mss and heazlewoodite with no associated loss of sulfur. The decomposition temperature decreased as the iron:nickel ratio deviated from the ideal value of 1:1. A maximum decomposition temperature of 610 degrees celsius was found at an iron:nickel ratio of 1.00, decreasing to 580 degrees celsius at a ratio of 1.84 and 0.61. Sulfur was evolved slowly at temperatures in excess of 760 degrees celsius as mss was converted to heazlewoodite, indicated by a gradual mass loss. The heazlewoodite then melted incongruently in excess of 840 degrees celsius indicated by a sharp endothermic peak, resulting in a further loss of sulfur.The oxidation of violarite and pentlandite was investigated at a heating rate of 10 degrees celsius min(subscript)-1 in an air atmosphere. The oxidation of violarite was initiated by decomposition to mss resulting in a rapid mass loss associated with the evolution of sulfur vapour, and an exothermic peak due to the gas phase oxidation of ++ / the sulfur. The iron sulfide component of the mss was then preferentially oxidised to iron(II) sulfate between 485-575 degrees celsius, upon which the sulfate decomposed and the remaining iron sulfide was preferentially oxidised to hematite. The mss core was then converted to (Fe,Ni)(subscript)3+/-xS(subscript)2 between 635-715 degrees celsius, resulting in the loss of further sulfur which was oxidised. The sulfide core, which consisted of predominantly Ni(subscript)3+/-xS(subscript)2 with a minor amount of iron still remaining in solid solution, incongruently melted at a constant temperature of 795 degrees celsius regardless of the initial stoichiometry of the violarite sample. This was followed by the rapid oxidation of the liquid sulfide resulting in a sharp exothermic peak in the DTA trace.For pentlandite, the TG-DTA curve exhibited an initial mass gain commencing at approximately 400 degrees celsius, which was attributed to the preferential oxidation of iron. Evidence from SEM indicated that iron migrated towards the oxygen interface, where it was oxidised to hematite. During this process the metal: sulfur ratio decreased and pentlandite was converted to mss. The iron sulfide component of the mss phase was then preferentially oxidised to hematite as indicated by a major exotherm, which occurred in the temperature range 575-665 degrees celsius, forming an oxide product layer around a nickel sulfide core. The oxidation of the remaining nickel sulfide followed the same reaction sequence to that of violarite.By increasing the heating rate to 40 degrees celsius min(subscript)-1, and carrying out the oxidation in pure oxygen, the tendency of the sulfides to ignite was established. Ignition was characterised by a highly exothermic reaction which coincided with a rapid mass loss over a short time period. Overheating of the samples above the programmed furnace ++ / temperature was also observed. Violarite exhibited ignition behaviour while pentlandite did not.Both sulfides were subjected to shock heating conditions (heating rate = 1500 - 5000 degrees celsius min(subscript)-1, oxygen atmosphere) using isothermal thermogravimetry (TG). This method produces heating rates analogous to those which are experienced in the reaction shaft of an industrial flash smelter. The effect of stoichiometry on ignition temperature and extent of oxidation for the entire series of synthetic violarites and pentlandites was determined. Partially ignited and ignited products were collected from isothermal TG experiments and were examined by OM, SEM and EPMA to establish the ignition mechanism.Both violarite and pentlandite ignited using the isothermal TG technique. A clear relationship was found between the stoichiometry of violarite and pentlandite and the ignition temperature, with an increase in the iron:nickel ratio causing a decrease in the ignition temperature. The ignition temperature also decreased as the size of the particles decreased.The extent of oxidation increased as the iron:nickel ratio increased, and also increased as the particle size decreased.

<p>This thesis involves a study the fabrication and characterization of photon radiation detectors. The focus has been to develop and improve the performance of optical measurement systems, but also to reduce their cost. The work is based on the study of two types of detectors, the position sensitive detector and the thermal detector.</p><p>Infrared detectors are usually subcategorized into photonic detectors and thermal detectors. In the thermal detectors, heat generated from the incident infrared radiation is converted into an electrical output by some sensitive element. The basic structure of these detectors consists of a temperature sensitive element connected to a heat sink through a thermally isolating structure. Thin membranes of Silicon and Silicon nitride have been commonly used as thermally insulation between the heat sink and the sensitive elements. However, these materials suffer from relatively high thermal conductivity, which lowers the response of the detector. The fabrication of these membranes also requires rather advanced processing techniques and equipment. SU-8 is an epoxy based photoresist, which has low thermal conductivity and requires only standard photolithography. A new application of SU-8 as a self-supported membrane in a thermal detector is presented. This application is demonstrated by the fabrication and characterization of both an infrared sensitive thermopile and a bolometer detector. The bolometer consists of nickel resistances connected in a Wheatstone bridge configuration, whereas the thermopile uses serially interconnected Ti/Ni thermocouple junctions.</p><p>The position sensitive detectors include the lateral effect photodiodes and the quadrant detectors. Typical applications for these detectors are distance measurements and as centering devices. In the quadrant detectors, the active region consists of four pn-junctions separated by a narrow gap. The size of the active region in these detectors depends on the size of the light spot. In outdoor application, this spot size dependence degrades the performance of the four-quadrant detectors. In this thesis, a modified four-quadrant detector having the pn-junctions separated by a larger distance has been fabricated and characterized. By separating the pn-junctions the horizontal electric filed in the active region is removed, making the detector spot size insensitive.</p><p>Linearity of the lateral effect photodiodes depends on the uniformity of the resistive layer in the active region. The introduction of mechanical stress in an LPSD results in a resistance change mainly due to resistivity changes, and this affects the linearity of the detector. Measurements and simulations, where mechanical stress is applied to LPSDs are presented, and support this conclusion.</p>

<p>This is a report written for an examination project C-level, on the subject of energy. The examination project is a product of the FVB Sweden AB (district heating bureau). It started with a meeting with Stefan Jonsson FVB Sweden AB, were he explained the content of the project, and from this a presentation of the problem was made. The problem that needed to be solved was how they could control the valves in the system to provide heating to everyone in the system. The valves are often oversized so the pump in the heating plant would have to be enormous to be able to provide enough flow to be sufficient, if everyone in the system had there valves fully opened.</p><p> </p><p>I came up with two solutions to the problem, one was a wireless network that could keep track of the valves and the other solution was an extra sensor that was placed on the radiator. The purpose for that was to open the valve if the temperature dropped more than one degree inside. With the help of a program called IDA it was calculated that, if the temperature drop five degrees, they would have sixteen hours at the heating power plant to open the flow before the sensor open the valves.</p><p> </p><p>After careful consideration I came up with the conclusion that the wireless network must be the best solution. Mostly because you can monitor all the clients in the system from the heating power plant and that will make it easier to discover faults and temperature differences.</p><p>Wireless networks is already a well tested solution in form of wireless controlled electricity meters so it shouldn’t be to much of a problem connecting these sensors to it either.</p>

<p>This thesis presents a study of the cooling process of a solid block performed by a turbulent air flow channel. The study focuses on the turbulent flow and its influence in the heat transfer of the block.</p><p>The first part of the thesis is an analysis of the different turbulent model and their adaptation on the necessities of this study. Once the turbulent model has been confirmed it makes a study of the behavior of the cooling process by CFD (Computational Fluid Dynamics), and an analysis of the numerical accuracy of this computational study.</p><p>When the procedure of the study of the cooling process is defined it proposes some different variations in the initial solution to improve this process. The study concentrates in variations of the turbulence and the geometry of the studied block.</p><p>Finally, the different improving are discussed analyzing parameters as the heat transfer, pressure drop, time consuming or energy consuming.</p>

<p>This project has been developed at the company Gavlegardarna. The companyowns a large part of the buildings of Gävle and two of them are the objective ofthe project. Gavlegardana is highly concerned about the environment; for thisreason, they cooperate on the subject with the energy management from theirtechnical department.</p><p>Gävle is one of the Swedish cities where the DH (district heating) network isdistributed, arriving to most of the dwellings, industries and commercialbuildings. As DH uses environmentally friendly sources of energy,Gavlegardana is introducing it in its buildings.</p><p>Electrical radiators and boilers were installed in the buildings when the price ofelectricity was more affordable than nowadays. The price of the electricity canbe considered 1,23 SEK/kWh while the DH price is 0,45 SEK/kWh.</p><p>Consequently, this is another reason why the objective of the company at thepresent time is to replace electrical space heating systems by means of districtheating.</p><p>The energy balance of the buildings is analysed in order to study their currentenergy situation. This entails the consideration of heat gains and lossesinvolved. The heat gains of the building are the heat from solar radiation whicharrives at the building trough the windows, the heat internally generated (bypersons, lighting and other devices) and the heat supplied. The heat losses are composed by the transmission trough walls and windows, the infiltrations, the heat used for hot tap water and the ventilation losses.</p><p>An important part of the work required to calculate the energy balance hasconsisted of the collection and organization of all the data (areas, types ofmaterial, electrical devices, lighting, number of employees, opening hours...).This data comes from the drawings of the buildings provided by the companyand from the information gathered during the visits to the installation. In addition, the ventilation flows were measured in-situ using the tools provided by Theorells.</p><p>Gavle Energi, the DH distributor company, has been contacted in order to fixthe cost and other details related to the district heating connection. The heatexchanger models, selected from Palmat System AB, are TP20 for Building Aand TP10 for Building B. TP20 provides 100 kW of heating and 0,4 l/s of hot tap water and TP10 provides 50 kW and 0,31 l/s respectively. The capital cost is 187500 SEK which includes the heat exchangers and the connection cost.</p><p>As the secondary circuit is not currently installed because the existing system iscomposed by electrical radiators, the installation of the piping network in thebuilding has been designed. The radiators’ power is calculated taking intoaccount the need of heat in each room which is estimated as the transmissionlosses. This need of heat calculated is higher than the energy currently supplied which means that the thermal comfort is not achieved in all the rooms of the buildings.</p><p>In spite of using more energy for space heating, the change of heat sourceentails a lower energy cost per year. The selected radiators are from Epeconand the investment cost (including the installation) is 203671 SEK. The brand of the selected pipes is Broson and the investment cost of the total piping system is 66000 SEK.</p><p>The initial investment of the new installation is 457171 SEK, considering the DHconnection, heat exchangers, radiators and pipes. If the initial investment istotally paid in cash by the company the payback will be fulfilled in 6 years. Incase of borrowing the money from the bank (considering an interest rate of 5%), two possibilities can be considered: paying back the money in annual rates over 15 years or 30 years of maturity. The paybacks are 11 and 8 years respectively.</p><p>After designing the DH piping system in the buildings, estimating the total costs of the investment and studying the project’s feasibility by suggesting different payment options, some possible energy savings are recommended.</p><p> </p><p>The first of the options refers to the transmission losses trough the windowswhose values’ are considerably high. Using a glass with a lower U-value, theselosses can decrease until 66% (with triple glass windows). Consequently, thepower required for space heating can also be reduced until 26%.</p><p>Regarding the ventilation, rotating heat exchangers are currently used, whichentails the problem of smells mixture detected by the users of the buildings. By changing them with flat-plate heat exchangers, the problem is solved and the efficiency is increased from 66% to 85%. The new heat exchanger cost is340387 SEK and it has a payback of 10 years.</p>

<p>Detta arbete beskriver hur Herons ångkula fungerar och hur den har byggts.</p><p>Ånkulan konstruerades för ca 2000 år av Heron.</p><p>Meningen var att få fram en verkningsgrad eftersom denna var okänd. Verkningsgraden blev aldrig konstaterad. Endast en teoretisk beräkning för verkningsgraden gjordes. Kulan sattes inte i rotation av ångtrycket som byggdes upp när det eldades under denna.</p><p>Anledningen var troligen att det var för mycket friktion i tätningen som skulle tillföra matarvatten in i kulan. Värmeöverföringen mellan gaslågan och kulkroppen var inte heller den mest optimala.</p><p>Kulan med tillhörande kringutrustning byggdes under dec-07/jan-08 efter eget tycke och utan någon existerande ritning. Den byggdes för att efterlikna originalet så mycket som möjligt. Dessutom hade en mindre ångkula byggts några år tidigare och denna hade visat sig fungera. Denna något större ångkula fick därför samma utseende.</p><p>Eftersom ångkulan inte orkade rotera råder det inga tvivel om hur ineffektiv denna tidiga reaktionsmotorn är.</p><p>Den fick ingen praktisk betydelse för 2000 år sedan, och det har den inte idag heller.</p><p>En framräknad verkningsgrad finns redovisad och denna blev mycket låg.</p><p>Det var stimulerandel att bygga Herons ångkula men konstruktionen i sig tillhör inte de mest lyckade.</p> / <p>This work describes how the Herons steam ball was built and how it works. It was constructed by Heron 2000 years ago. The purpose was to determine the efficiency of the steam ball because it was unknown. The efficiency was never determined. It was only theoretically determined by calculations. The steam pressure never gave the steam ball rotation when heat was added underneath the construction. A possible reason was that friction in the sealing for supplying feed water into the steam ball was too high.</p><p>The heat transfer was also a reason that the construction did not rotate.</p><p>The steam ball and necessary equipment was fabricated in dec-07/jan-08. It was built without any drawings. The goal was to make it look like the original as much as possible. A smaller steam ball was built some years before. This one did rotate and therefore was the same design given to the bigger one.</p><p>Because of the lack of rotation there was no doubt if the steam ball was a sucsess or not.</p><p>It was not used for any real purpose 2000 years ago and this has not changed.</p><p>A calculated figure of the efficiency was documented in this rapport, and it was very low.</p><p>It was amusing to design and build the steam ball but the construction was clearly no success.</p>

Improved methods of determining temperature transients in reactor systems are desired because of recent interest in Pressurized Thermal Shock (PTS) issues. The research presented herein was performed in support of the Nuclear Regulatory Commission's effort to re-evaluate its existing PTS rules. These rules are particularly important to the re-licensing of aging nuclear power plants. The much advanced computational power available to industry may offer a tool that allows the accurate calculation of temperatures inside the reactor vessel while not being inaccessibly expensive. It is proposed that an off-the-shelf Computational Fluid Dynamic (CFD) code, STAR-CD, can be a competitive tool in solving the thermal hydraulic domain of a reactor system. A comparison of the methodology and accuracy of the code types that have been previously used in PTS and one that has not been used extensively, CFD, is provided. A review of the literature shows that computer codes have been validated for solving PTS scenarios. The highly specialized program, REMIX, has been utilized extensively from 1986 to 1991 to interpret accident scenarios in reactor systems. Other programs are also available that can calculate downcomer temperatures including system and CFD type codes. Three codes representing the three different types of programs available are described in detail in the literature review section. Data appropriate for assessing a program's ability to calculate the response of a system to a PTS scenario is available from the current matrix of PTS tests being completed at the APEX-CE facility of the Oregon State University Nuclear Engineering department. The facility is a reduced scale integral test facility originally built for modeling the then-proposed AP-600 plant designed by Westinghouse. For the current test series, the facility was modified to model the Palisades nuclear power plant, a Combustion Engineering Pressurized Water Reactor (PWR). Two of the tests were chosen for their PTS typical conditions to compare with calculations of STAR-CD, REMIX, and RELAP. The computer models in each of the programs were either created, modified from a previous version, or the calculations for the comparisons were contributed. The downcomer temperatures at several locations and cold leg temperature gradients, where available, were extracted from the data and calculations and compared. Comparisons are presented in chapter 5 with graphs, along with some interpretation of the comparisons. It was found that STAR-CD agreed best with the data set in the downcomer and is the only program that calculated the temperature gradient in the cold legs. The agreement of STAR-CD with the cold leg data is also very good. REMIX and RELAP calculations agreement with data for downcomer temperatures are found to be good for all comparisons made, qualitatively more than quantitatively when contrasted with the STAR-CD calculations. / Graduation date: 2002