<p>The aerodynamic drag force acting on a circular cylinder clad with knitted wool and polyester textiles has been investigated in wind tunnel experiments in this study. Particle image velocimetry (PIV) was utilized to determine the flow field, both around the separation point and a wake profile in the close wake. The drag forces and the characteristic CD curves were determined over a range of Reynolds numbers expected to contain flow transition, for a number of knitted textiles having different surface roughness characteristics. The effects of knitting parameters and type of yarn on the flow field were investigated. The parameters of interest to be examined were critical Reynolds number, separation point, growth of the wake and wake profile. The wool and polyester textiles examined showed dissimilar effects on the flow field. Both were clearly adding surface roughness, and hence tripping transition to turbulence at a lower Reynolds number than for the smooth cylinder. The wool textile did however turn out be a more effective turbulence trigger than expected.</p>

<p>Energi til romoppvarming og til produksjon av varmt forbruksvann utgjør en stor del av den totale energibruken i bygninger, og fossil energi eller elektrisitet blir ofte benyttet. Bruk av fossil energi og elektrisitet produsert av fossile kilder bidrar til global oppvarming, og det er derfor ønskelig å redusere bruken av både fossil energi og elektrisk energi. Det er da aktuelt å bruke fornybar varme, og et solvarmeanlegg som dekker deler av varmebehovet i bygninger kan være et godt alternativ. Det ble derfor gjort et litteraturstudie over mulighetene for å utnytte soloppvarming av vann i Norge, med fokus på steder med et klima tilsvarende Oslo-klima. Det ble også gjort en analyse av mulighetene for å utnytte et solvarmeanlegg i et spesifikt kontorbygg i Oslo som skal bygges ut. Kontorbygget bruker nå fjernvarme til vann- og romoppvarming, men andre alternativer undersøkes. For å undersøke mulighetene for å utnytte et solvarmeanlegg i kontorbygget ble det gjort simuleringer i to simuleringsprogram, utført en økonomisk analyse, og en kort analyse av potensiell reduksjon av klimagassutslipp. Til slutt ble det gjort en kort analyse av et nytt solvarmeanlegg for oppvarming av varmtvann i et grendesenter i Oslo, med blant annet en barnehage, skole, og en flerbrukshall. Analysen av grendesenteret er basert på temperaturmålinger fra solvarmeanlegget. Litteraturstudiet indikerer at solvarmeanlegg passer generelt best for bygninger med et stort varmtvannsbehov, og bygninger med et stort varmtvannsbehov i forhold til totalt varmebehov. Dette medfører at idrettshaller og lavenergiboliger og passivhus er best egnet for solvarmeanlegg. For kontorbygg vil et solvarmeanlegg ikke kunne dekke noen særlig stor andel av totalt varmebehov. Det vil imidlertid kunne bidra til at krav i nye standarder og forskrifter blir oppfylt. I tillegg vil et solvarmeanlegg kunne bidra til en bra energimerking av kontorbygg og bygg generelt. Hvis det skal bygges et solvarmeanlegg i tilknytting til kontorbygget i Oslo anbefales det å bygge et solvarmeanlegg for vann- og romoppvarming med solfangere på taket. Solvarmeanlegget som anbefales har et solfangerareal på 100 m2 og en lagringskapasitet på 5000 liter. Solvarmeanlegget bruker en god vakuumrørsolfanger som er vendt mot sør og har en helningsvinkel på 60 °. Solvarmeanlegget gir en årlig varmeproduksjon på 13,9 % av årlig energibehov til vann- og romoppvarming. Resultatene fra den økonomiske analysen av solvarmeanlegget til kontorbygget er usikker. Resultatene er avhengig av hva levetiden til solvarmeanlegget blir og hvor stor kostnaden knyttet til planlegging og oppføring av solvarmeanlegget er. Hvis levetiden til solvarmeanlegget er 20 år og kostnad knyttet til planlegging og oppføring av solvarmeanlegget er 39 % av total investeringskostnad vil anbefalt solvarmeanlegg gi et tap på omtrent 209 328 kr, det trengs da en støtte på 2,2 kr/kWh produsert fornybar varme for at solvarmeanlegget skal gå i null. Hvis levetiden til solvarmeanlegget er 20 år og kostnad knyttet til planlegging og oppføring er 20 % av total investeringskostnad vil solvarmeanlegget gi en gevinst på omtrent 53 766 kr. Hvis levetiden til solvarmeanlegget er 30 år og kostnad knyttet til planlegging og oppføring er 39 % av total investeringskostnad vil anbefalt solvarmeanlegg gi et tap på omtrent 65 421 kr, det trengs da en støtte på 0,7 kr/kWh produsert fornybar varme for at solvarmeanlegget skal gå i null. Hvis levetiden til solvarmeanlegget er 30 år og kostnad knyttet til planlegging og oppføring er 20 % av total investeringskostnad vil solvarmeanlegget gi en gevinst på omtrent 197 673 kr. Anbefalt solvarmeanlegg vil redusere årlig klimagassutslipp fra kontorbygget med omtrent 8924 kg CO2-ekvivalenter. Dette tilsvarer omtrent å fjerne 1,5 biler fra veiene i året. Resultatene viser at det er mulig å bruke solvarmeanlegg som kan ta en del av varmebehovet i kontorbygninger i et klima tilsvarende Oslo-klima. Om solvarmeanleggene er lønnsomme kommer an på hvor lang levetid solvarmeanleggene får og hvor stor investeringskostnaden blir. Mange av de simulerte systemløsningene for solvarmeanlegg i kontorbygget ble aldri lønnsomme, selv med lang levetid og optimistisk investeringskostnad. Det er derfor viktig å gjøre en grundig analyse før en bygger store solvarmeanlegg for kontorbygninger. Beregninger indikerer at solvarmeanlegget på Storøya Grendesenter har produsert varme tilsvarende 5,8 % av totalt energibehov til oppvarming av varmtvann i perioden anlegget har blitt analysert. Beregningene er basert på temperaturmålinger fra og med uke 11 til og med uke 14, og fra og med uke 18 til og med 28. mai i uke 21. Beregningene er svært usikre siden de bare er basert på temperaturmålinger, men de indikerer at solvarmeanlegget ikke fungerer optimalt.</p>

<p>Helt fra 25 år tilbake har issørpe som ny teknologi for å bedre kjølebetingelsene for fisk fått mye oppmerksomhet. Etter nesten 30 år med kontinuerlig innsats fra forskere og produsenter, har issørpe etablert seg som en anerkjent og meget god kjøleteknologi på dette området, samt et egnet medium for konservering. Når det gjelder håndtering av issørpen ombord på fiskebåter, er det kjent at på de fleste fiskebåter benyttes issørpen til direkte kjøling av fisk og annen fangst. Issørpen blir da produsert av sjøvann ombord på båtene, og når fangsten tas inn blir den blandet med issørpe i beholdere. Ulik håndtering av issørpen ble prøvd ut gjennom praktiske forsøk. Basert på målinger av kjernetemperatur i modellprodukt ble kjøleeffekten i fire ulike metoder for bruk av issørpe sammenlignet. De ulike metodene bestod av tre ulike tilfeller med hensyn til drenering av issørpen, hhv. uten drenering, kontinuerlig drenering og forhåndsdrenering (større iskonsentrasjon enn uten drenering). I tillegg ble en siste metode med luftinnsprøyting i bunn av issørpebeholderen prøvd ut som et tiltak for å bedre varmeovergangen. Issørpen ble også sammenlignet med tradisjonell kjøling med flak-is. Kjøleprosessene ble modellert i MATLAB og simuleringer kjørt i forsøk på å tallfeste kjøleeffekten i form av et varmeovergangstall. Det ble ved siden av modellproduktene utviklet et system beregnet for studering av interaksjonen mellom issørpe og produkt ved hjelp av et termisk kamera. Temperaturmålinger i modellprodukt bekreftet en langt større kjølekapasitet ved bruk av issørpe sammenlignet med tradisjonell flak-is. Issørpe ga raskere nedkjøling enn flak-is uansett håndtering, men sammenligning av temperaturmålinger og varmeovergangstall viste at hvordan issørpen benyttes er avgjørende. Lav iskonsentrasjon medførte temperaturstigning i beholderen og modellproduktene nådde ikke kjernetemperaturer under 0 °C. Høyere iskonsentrasjon ga raskere nedkjøling og lavere slutttemperatur. Luftinnsprøyting i issørpen for å skape omrøring viste seg å gi en vesentlig økning i varmeovergangstallet. I tillegg opprettholdes issørpens lave temperatur også inne ved produktoverflaten, i motsetning til de øvrige kjøletilfellene hvor denne temperaturen opplevde en stigning etter forsøksoppstart, for så å etterhvert gå ned igjen. Konseptet for lufttilførsel i issørpen bør derfor jobbes videre med, ettersom det har en potensiell gevinst i produktkvalitet som følge av raskere nedkjøling og konstant lav overflatetemperatur hos produkt uten at frysing oppstår.</p>

<p>The panel bed filter (PBF) is a granular filter patented by A. M. Squires in the late sixties. PBFs consist of louvers with stationary, granular beds. Dust is deposited in the top layers and on the bed surface when gas flows through. PBFs are resistant to high temperatures, variations in the gas flow and hot particles. The filter is cleaned by releasing a pressure pulse in the opposite direction of the bulk flow (a puff back pulse). A new louver geometry patented by A. M. Squires is the filter tray louvers. The new design is believed to reduce the pressure drop and the number of louvers, and to make the filter more compact. We have designed and built a laboratory scale PBF with filter tray louvers based on the patent. Experiments with the prototype show that the new louver can be cleaned with a puff back pulse. A PBF system for a hypothetical biomass combustion plant has been designed. The heat from the flue gas will be used for district heating. The proposed PBF system design consists of double-sided modules with 46 filter tray louvers on top of each other. Five modules are mounted together in module columns, sharing the same clean gas duct and puff back pipe. The granular medium chosen is Sintered Bauxite 20/40 (SB). The module columns are placed in an enveloping house. SB and dust fall into bins in the bottom of the enveloping house during puff back cleaning. A vacuum pneumatic conveying system brings the dust and SB to the top of the filter. Dust and SB are separated in a sieve. Dust is deposited, and SB is transported back to the modules. NTNU is currently involved in the BioSOFC project. The objective of this project is to increase efficiency in energy production from biomass by using producer gas from a biomass gasification plant in a Solid Oxide Fuel Cell. Field tests will be performed at a plant in Güssing, Austria. A PBF will be used for gas filtration. The operating temperature will be 500 °C to avoid tar condensation. We have performed heating experiments on the BioSOFC filter system. The results were not satisfactory, as the temperature in the filter ranged from 384 to 625 °C. The filter system was due to be shipped, and new tests could not be performed. This work proposes that modifications to the heating cable circuits are made, and new heating tests are performed before the field testing.</p>

<p>It is clear that society worldwide must immediately begin to mitigate its environmental damage in order to sustain life on Earth. In this regard, researchers all over the global are exploring new energy efficient alternatives to power everything from cars to cell phones. The following brief describes research conducted on Microbial Fuel Cells (MFC) and its ability to utilize bacteria to produce electricity from biological masses for low energy consumer products While structurally the MFC is very similar to a Conventional Fuel Cell, the two systems have inherent differences that change the reactions, inputs and energy output. Currently, we have found MFC to produce only a fraction of the power (~1A/cm2 vs ~1mA/ cm2 ) produced by a conventional CFC, however, its versatility keeps MFCs as a promising fuel source potential. A Multi-disciplinary University Research Initiative has organized to examine and test the potential of MFC. The team is divided into three teams based on industry domains and expertise: microbiology, chemistry and electrochemistry, and engineering and modeling. The followin master thesis research was part of the engineering and modeling team lead by Professor Ronney XX. The goal of our team was to construct a first version of a computational model simulating the MFC system. The computational model is be based on combustion kinetics and a diffusion-reaction system theories, and is manipulated to immatate a biological system that can maximize its energy output. The model has been constructed in Fluent. Starting out with a 1D model, and consequently moved on to a 2D version. The final model is a diffusion-reaction system with 6 different species, a 3-step reaction, including a bacterial anodic oxidation, a cathodic reduction, and a possibility of taking into account a counteracting anodic reaction for oxygen crossover through the membrane. While the model has been proven to correlate well with lab tested experimental results, the team will continue to identify conditions to maximize the MFC’s efficiency and energy output.</p>

<p>This study investigates the behaviour of a vertically distributed source of buoyancy on the vertical stratification in a ventilated space, an important factor for determining indoor comfort when using displacement ventilation. A new theory describing the behaviour of this buoyancy source in a ventilated space was presented previous to this work, but experimental results were required in order to validate the theoretical and numerical modelling. The behaviour of this source of buoyancy on the stratification in a ventilated space is studied for a mechanically ventilated at steady-state and for a linearly stratified environment using salt water in a water scale model. The stratifications were measured using a traversing conductivity probe and then compared to theoretical predictions by numerically solving the plume equations for the new theory in Fortran. High quality measurements were produced, showing excellent repeatability for stratification measurements at steady-state with deviations of less than 1 %. Moreover, the linear stratifications had linear best fits up to R2 = 0.999 by using the double-bucket method. The theoretical predictions of the influence of the vertically distributed source correlate quantitatively with the mechanically ventilated experiments, showing good agreement to the strength of the ambient stratification, the position of the first front and the ventilation flow rate. The experimental results for the determination of the height of a horizontal intrusion of fluid into the linearly stratified environment were severely affected by the occurrence of gravity current at the ceiling of the ventilated space and comparisons to the new theory was not successful because of this. A two-layer stratification is observed where the upper layer had a weakly stratified density profile, instead of the multi-layer stratification predicted by previous researchers in their theoretical model. This discrepancy is due to smoothing and vertical turbulent mixing in the water scale model. It is recommended that the characteristic of the membrane that is used in the water scale model is investigated in relation to the gravity currents for future research.</p>

<p>It has been proposed to supply heat and power to Snøhvit Train II (STII) from onsite heat generation based on natural gas and power import from the power grid. Without carbon capture and storage, greenhouse gas (GHG) emissions from the combustion of natural gas in furnaces make a considerable contribution to the global warming potential (GWP) of this energy system. Depending on the interpretation of marginal power consumption, the power import also contributes to and increases this system’s GWP. A recent SINTEF report claimed that European CO2 emissions are reduced with additional renewable power production in Norway, and it has been suggested to invest in wind power in order to completely offset the GWP of the STII energy system. This paper provides investment analyses for the proposed energy system. A scenario approach was used, with six different scenarios covering two dimensions. The first dimension is the origin of the grid power, with three different interpretations of marginal power representing Cases A, B and C. The other dimension is the STII train size, with two different sizes being analyzed, namely 50 % and 70 % of the Snøhvit Train I design capacity. The proposed energy system was also analyzed with respect to security of supply. Improved reliability and transmission capacity, together with a stable, positive power balance, make a good foundation for security of power supply. The power demand of the two train sizes was estimated to 101 MW and 141 MW, with corresponding heat demand of 94 MW and 131 MW. These estimates were based on a combination of HYSYS simulations and data provided by StatoilHydro (SH), and provided input for both the GWP analysis and the investment analysis. The GWP impact of each scenario determined the share of power import from the grid that would have to be replaced by energy harnessed from wind. The applied capacity factor was 39.6 %, and the rated wind power requirement for the six different scenarios ranged from 101 MW for the A.50 scenario to 257 MW for the C.70 scenario. The break even (BE) energy prices were calculated for each of the six scenarios analyzed. If the power consumption is based solely on power import, with zero StatoilHydro (SH) share of grid reinforcements and no SH development of wind power, the BE power price would be 466 NOK/MWh. The inclusion of wind power development as part of the investment will increase the BE power price by up to 33 NOK/MWh. The additional SH share of grid reinforcement will add 86 NOK/MWh for the 50 % STII or 62 NOK/MWh for the 70 % STII. It was shown that the investment in wind power to offset the GWP of the energy system might also be a reasonable way of hedging against increases in the market price of electricity. It was found that the share of STII power demand that is provided by wind power is one of the parameters that have the least influence on the project’s net present value (NPV). A high share of wind power is an inexpensive investment in improving reputation and predictability of energy price.</p>

<p>This report presents opportunities for use of CO2 as refrigerant in the air conditioning system in public trains. The CO2 system shall provide cooling in the summer and heating in the winter. CO2 is a natural fluid which means that it exists naturally in the biosphere. Today 75% of the air conditioning systems in trains use R134a as refrigerant. The GWP of R134a is 1410 while CO2 used as refrigerant is 0. A replacement from R134a to CO2 gives possibilities of large environmental savings. Three different technical system solutions of the heat pump are presented, each with its own method of provide cooling and heating. Solution I changes between cooling and heating by change the direction of the refrigerant flow through the system. Solution II changes between cooling and heating by change the configuration of the air streams through the heat exchangers. In Solution III the refrigerant flow direction and the configurations of the air streams is always the same. The whole heat pump is placed on a rotatable unit and the change between cooling and heating is done by rotating the whole heat pump 180°. In all the three technical solutions there are separated heat exchangers for fresh and exhaust air. This gives an energy efficient system which recover heat from the exhaust air. Computer simulation shows that a system solution with one evaporation pressure and one stage compression is problematic for low ambient temperatures; the system must stand temperatures to 40 °C. A system solution with two levels on the evaporation pressure and a two stage compression showed to improves the COP from 1,7 to 3,2 when the ambient temperature at 40 °C. A railway coach need cooling when the ambient temperature is above 20 °C and heating below 15 °C. Norway is a country with cold climate. Weather statistic show that a train which drives in Oslo every day from 0600 to 1800 throughout a year will need cooling 3% of the time and heating 83% the time. This heating should be done by a heat pump and not with electrical heating as today. Results of the computer simulation shows that the annual energy consumption of heating the train will be reduced by 78 % if the designed CO2 heat pump is used in stead of electrical heating.</p>

<p>Vane pack demisters in the industry operate with natural gas at pressures up to 100 bara. A new vane pack has been compared with the traditional one used by the industry. The vane packs have been investigated through experiments and Computational Fluid Dynamics, CFD. The fluid flow inside a vane pack consist of turbulence and two fluid phases. The simulations were carried out with a Large Eddy Simulation model and a Scale-Adaptive Simulation model. Phenomena observed in the experiments were confirmed by CFD. A transient Discrete Phase Model,DPM, that should be capable of modeling the generation of a liquid film together with droplets was used. The DPM simulation gave a mist flow pattern that agreed with the one observed in the laboratory. Separation efficiency measurements of the two vane packs using Exxsol D60 as liquid and SF6 as gas were performed at different pressures, ranging from 1 to 8 barg. This corresponds to natural gas density ranging from 8 to 65 barg. Non of the experiments achieved the specification given by the oil and gas industry. The efficiency measurements did show that the pressure had a great influence on the performance. The low pressure measurements were the only experiments which had a efficiency above 97% at a k-value between 0.2 - 0.25 m/s.</p>

<p>A multiregional input-output model representing the world in the year 2000 was constructed based on statistical data, and combined with process specific data on a primary aluminium supply chain, to create a model of the global primary aluminium industry. Using input-output methodology, total emissions of eight substances due to primary aluminium production, their size and origins, were estimated and expressed in terms of global warming potential (GWP) and acidification potential (AP). Simulations from 2000 to 2030 were run based on final demand estimates from external GDP projections and three assumed development scenarios. The baseline, scenario 0, assumed no changes in technologies or relative production and trade patterns - only the model's response to the expected change in final demand was analyzed. By contrast, both scenarios 1 and 2 assumed that the additional aluminium production predicted by the baseline would be produced exclusively in China. Scenario 2 employed the added assumption that the Norwegian aluminium production would experience a steady decline from its 2000 level to zero by 2030. The baseline scenario showed rapidly increasing aluminium output towards 2030, following the expected GDP developments. Emissions followed the same trend, increasing about 3.3 times over the three decades. As for total cradle-to-gate impacts of primary aluminium production, the model showed large variations from one region to another. Emissions per ton of Chinese primary aluminium were high relative to most other regions, hence the total global GWP and AP from primary aluminium production rose more rapidly in scenarios 1 and 2 than in scenario 0. By 2030, the GWP in scenarios 1 and 2 were 11.4% and 12.5 higher than in the baseline, while AP were 50.0 and 51.9 higher.</p>