Linköping Electronic Conference Proceedings
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Dropwise CondensationWater Drainage Model
Get PDFModeling of condensation is important to estimating the residual water in small channels. The residual water that forms becomes a water source for permeable materials such as wooden structure or insulation. A model has been implemented in Modelica that will predict the amount of residual moisture after a period of water build up. This model includes parameters to relate droplet physics to a control volume. The parameters provide an macroscopic means of varying droplet adhesion force, droplet velocity, and drainage dynamics. Using CFD data as an example of real world data, this model has been correlated to demonstrate the effects of the parameters
PNRG – A Library for Modeling Variable Structure Energy Grids in Modelica using Energetic Petri Nets
Get PDFOperating energy grids with a high share of renewable energy sources (RES) requires system reconfiguration as a response to environmental condition changes. To understand them better, simulations are needed and Modelica is an excellent choice for that. Energy grids with event-based reconfigurations are an instance of variable structure systems (VSS). However, the full support of VSS in Modelica is challenging and topic of ongoing research. Petri nets (PNs) offer a formalism for modeling VSS. The capability to simulate PNs in Modelica gives an opportunity to model VSS in Modelica. This paper presents an approach to utilize PNs in Modelica for modeling variable structure energy grids. Therefore, we introduce energetic Petri nets, a special type of PNs and an experimental library called PNRG for PN-based energy system modeling is presented. Furthermore, possibilities and limits of modeling VSS energy grids are discussed and an outlook how to develop this technique is provided
Performance assessment of a photovoltaic/thermal-powered absorption chiller for a restaurant
Get PDFIn recent years the demand for cooling in buildings has grown steadily due to factors such as climate change and increased use of technology in Sweden. The increase of cooling demand occurs mainly during peak demand periods, where there is limited cooling capacity combined with limited distribution capacity in the district cooling network. Sweden has experienced considerable growth in the solar energy market in recent years, though its utilization has been mostly limited to power generation. To fulfill the cooling demand increase, solar driven cooling is a viable solution alternative to traditional cooling methods. The use of solar cooling is still in its early stages in Sweden. The aim of this work is to design a simulation model of a solar absorption cooling system for a full-service restaurant prototype building. The system layout consists of photovoltaic/thermal collector, storage tank, single-effect absorption chiller, auxiliary heater, and cooling tower. The results revealed the system ability to meet the cooling load while delivering sufficient hot water for the establishment. Higher solar fraction confirmed that using photovoltaic/thermal collector is more competitive than solar thermal collectors based on restaurant operational activities. A levelized cost of cooling of 0.164 €kWh⁄ indicated the system cost-effectiveness in comparison to similar setups in other favorable European locations for solar energy utilization
Numerical Investigation on Performance of Gas Turbine Blade: Effects of simulation Models and Blade Geometry
Get PDFWith a significant impact on turbomachinery blade performance, surface curvature distribution becomes one of the essential factors in the design of high-efficiency blades. This study focuses on applying computational fluid dynamics (CFD) to evaluate turbine rotor blade performance. The main aim is to analyze the influence of incidence and geometry shape on the performance of a gas-turbine blade in two dimensions. To achieve this, an investigation was conducted to identify a suitable turbulence model for this case, with two turbulence models combined with two different solvers explored in ANSYS Fluent: Realizable k-ε model in pressure and density based solver; k-ω shear stress transport (SST) model in pressure and density based solver. The blade total pressure loss across different blade exit Mach numbers is the comparison factor, with validation against experimental data. Subsequently, the chosen pressure-based k-ω SST model mode is used to study the performance of various air inflow incidence angles and compare two different blade geometries. In this paper, two geometries, Geometry 1 and Geometry 2, were designed by setting two different exit blade angles, β2=79.5° and β2=70° respectively, while the inlet blade angles have the same value, β1=48.8°. Furthermore, the effect of varying air inflow incidence angles between -48.8° and 10° on the blade performance distribution is also investigated. Within the studied range, the inflow incidence angle of 10° is found to have the best performance in terms of turbine work output. On the other hand, the blade performance of Geometry 2 appears superior to Geometry 1
Banks of Gaussian Process Sensor Models for Fault Detection in Wastewater Treatment Processes
Get PDFThe harsh operating environment in a wastewater treatment process (WWTP) makes sensor faults commonplace. Detecting these faults can be challenging due to the complex process dynamics, unknown inputs, and general noise in the process and measurements. Comparing sensor readings against predictions from a physics-based or data-driven model of the WWTP is a common strategy for detecting such faults. In this work sensor measurements are directly modelled using Gaussian process (GP) regression, a data-driven multivariate approach. These GP sensor models are, with a generalised product of experts, combined into a dedicated fault isolation scheme resembling traditional observer bank methods. The residuals are monitored with a multivariate exponentially weighted moving average chart which is used for fault detection and isolation. The method is evaluated using simulated data generated with the Benchmark Simulation Model No. 1 WWTP. Fault detection performance is reported using several standard metrics such as false alarms, missed detections, time to detection, and successful fault isolations, with emphasis on reporting across a wide range of sensors and faults to provide a point of comparison for future studies. The proposed approach performs well across these metrics. Given sufficient data representative of normal operation, this approach can easily be adapted across a wide variety of plant configurations and can be used to create operatorfriendly diagnostics resembling classical control charts
Green production of dimethyl ether (DME) - indirect conversion of synthesis gas produced from biomass
Get PDFIn the transition to a fossil-free transport sector, the use of Dimethyl ether (DME) can be an environmentally friendly alternative. DME is a synthetically produced alternative to fuels like diesel or liquified petroleum gas (LPG), and has lower emissions of CO2, NOx and particles compared with diesel. To be a green renewable alternative, DME needs to be produced from carbon neutral resources such as biomass. DME can be produced from synthesis gas produced by gasification of biomass. The synthesis gas can be used to produce either DME directly in a single stage process with a bi-functional catalyst, or in a twostep process in which methanol is produced in the first step and converted to DME via dehydration in the second step. In this study process simulations of the DME synthesis from methanol is assessed. The paper involves assessment of process parameters and energy improvement of the DME synthesis. The study evaluates the effects of different thermodynamic models like PRSV, NRTL, WILSON and UNIQUAC in Aspen Hysys. Conversion reactor and Gibbs reactor configurations, and sensitive analysis of process parameters is studied. Heat integration is evaluated for energy resource management and cost estimation. The Gibbs reactor with the UNIQUAC model and internal heat integration resulted in an increase in DME production of 0.5% and a reduction in energy demand of 46%
A preliminary study on methods for risk analysis in system of system- A case study on the Västmanland 2014 forest fire
No full textCrisis management in the twenty-first century is facing new challenges, due to the increasing complexity of contemporary society. To mitigate a societal crisis, it is often necessary for a collection of independent systems, people, and organizations to cooperate. These collaborating entities constitute an interconnected socio-technical system of systems (SoS) based on information exchange. An important question is how a crisis management SoS should be constructed to accurately handle a crisis and to minimize the risk of failure. SoS pose new challenges regarding how risk during interactions is analysed, due to their complex nature as they are interconnections of independent systems. Additionally, SoS are dynamic and evolve as the crisis unfolds. Available traditional risk analysis methods focus on individual systems. We believe that this does not work well for the SoS specific characteristics. To test this, we applied one of those methods to an SoS case, to learn what specific improvements are needed. The objectives were to find characteristics that cause risk during interactions in a SoS and to evaluate the usefulness of an existing risk analysis method in the context of crisis management. Applying STAMP (System-Theoretic Accident Model and Processes), a widely used risk analysis method, we analysed the system of system put together to handle the 2014 Västmanland forest fire by systematically analysing many existing investigations on that event. We documented this as a preliminary approach to creating a risk management process. Initial results show that in our study, STAMP was able to isolate characteristics that included inadequate preparedness, and insufficient capability, among others. However, the method was limited in identifying characteristics of risk related to dynamic SoS structure, and latent risks or existing characteristics only triggered as risk, during an operation. Thus, risks in SoS could arise from emergent behaviour and requires a different approach to risk analysis. 
Komplexa händelseutvecklingar - Att vända strömmen: Att använda megaspel
No full textTill viss del kommer framtidens kriser, och därmed skadeplatser, karakteriseras av den långsamma förändring som pågår i och med de klimatförändringar som pågår. Hur dessa kommer att se ut, vilka samhällsaktörer som påverkas och medverkar och vilka som drabbas kommer att ske genom komplexa orsakssamband.
Ett sätt att visualisera och skapa förståelse för denna typ av händelser är att använda megaspel, storskaliga sociala spel där deltagarna agerar utifrån givna roller och på så sätt kan utforska olika perspektiv och händelseutvecklingar.
Megaspel låter brädspel, simulering och rollspel mötas i ett format där stora mängder deltagare involveras, ofta mellan 30 och 500 personer. Megaspel kan använda som lärspel, här för att skapa en bättre förståelse för hur energisystemet påverkar förutsättningarna för en hållbar framtid och hur olika aktörer påverkar varandra, direkt och indirekt. Spelet omfattar produktion, distribution, och konsumtion av energi tillsammans med politik, näringsliv och medborgare som ska försöka skapa en hållbar utveckling i förhållande till Agenda 2030-målen. Spelarna hanterar tre faser: teamfas (aktörsintern planeringstid), orderfas (förhandling med andra aktörsgrupper) och uppsamlingsfas (då rundan sammanfattas). En runda motsvarar fem år, således kan en uppsnabbad tidsutvecklig visa på konsekvenser av handlingsval som annars kan ta årtionden innan de blir reella.
Deltagarnas intressen och målsättningar omsätts i spelhandlingar, vilka testas mot en simulering av klimatpåverkan som återkopplas till deltagarna. Interaktion som uppstår mellan deltagarna analyseras och långsiktiga effekter utvärderas, som till exempel attityder och föreställningar om energisystemet i förhållande till samhälle, miljö och klimat.
En konkret upplevelse av komplexiteten i systemet tillsammans med att deltagarna får en ökad förståelse för hur de påverkar varandra bidrar till en insikt om vad som behöver göras för att energisystemet drastiskt ska kunna minska sitt koldioxidutsläpp. En iakttagelse från de första genomförda spelen är att megaspelsformatet bidrar till en ökad förståelse för de beroenden som finns mellan olika aktörer. Vidare kan megaspelet fungera som ett krisövningsformat för att inte bara hantera konsekvenser av klimatförändringar såsom naturkatastrofer, utan även bidra till att förstå och hantera orsakerna till dessa.
Projektet finansieras av Energimyndigheten och är ett samarbete mellan Linköpings universitet, Högskolan i Skövde och Jönköpings Universitet
PDV-händelsen i Vetlanda
No full textPDV-händelsen i Vetlanda
Onsdagen den 3 mars inkom det första samtalet till larmnumret 112, angående en knivattack i Vetlanda. En person hade blivit knivskuren i magen utanför Vetlanda resecentrum och befann sig inne på Pressbyrån. Flera samtal inkom från personer som sett knivdådet. Initialt var det ett oklart läge om hur många skadade det rörde sig om. De första fem inkomna samtalen tolkades som en och samma knivskurna person. Under en och en halv minut inkom fem telefonsamtal rörande händelsen vid Vetlanda resecentrum. Under tiden larmades tre ambulanser ut till händelsen tillsammans med polis, samtidigt fortsatte gärningsmannen sin promenad mot Storgatan. Sju personer knivskars under de 21 minuter som händelsen pågick innan gärningsmannen oskadliggjordes av polis. Föredraget ger en beskrivning och en tidsresa under knivattentatet i Vetlanda 3 mars 2021
SMOTIES: Scenario-building for creative future solutions in remote places
Get PDFThis paper introduces a scenario-building design methodology used in setting up a four-year Creative Europe Program project co-funded by the European Union. The project addresses an emerging field of action that aims to explore how small and remote places can benefit from the design of cultural and creative innovations within public spaces and in collaboration with local stakeholders. The paper describes how a common ground of scenarios has been designed for the development of project trajectories by defining future visions of action within small and remote places in Europe. This methodology is currently being applied and tested in ten pilot projects for the development of innovative creative solutions that address the specific needs of depopulated and relationally remote places considered to be depositories of material and immaterial culture that risks being undervalued, not consolidated, not handed down, and hence lost