Linköping Electronic Conference Proceedings
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Design optimization of small-scale ORC cycles for fluctuating heat source
Get PDFOrganic Rankine cycles (ORC) are efficient technologies for waste heat recovery (WHR) at low to mid temperatures. For the design of ORC power cycles, several thermodynamic parameters should be considered. A challenge related to small scale (<50 kW) ORC cycles is to define the optimal process given frequent variability in a heat source. Many relevant applications require robust ORC systems to perform under varying heat source loads. This is an area where the body of knowledge must be further developed.
In this work, the design of small-scale ORC cycles with varying heat source conditions is addressed by means of system modelling, simulation, and optimization. A framework is presented that consists of multi-scale optimization for the design of small-scale ORC systems considering seasonal and hourly heat source variations. The framework is developed as a flexible tool allowing to include fit-for-purpose models of key elements of the cycle, such as expander and heat exchanger, to suitably simulate off-design performance.
The optimization framework has been tested on a case study representing a woodchips-fired micro-cogeneration unit via ORC. The case study is representative of an existing unit operating at the Czech Technical University (CTU) in Prague. The results indicate that the tool delivers an ORC design that has a 5 % larger accumulated power production with the hourly variation of the heat source during one year than the original ORC solely optimized at the design heat source condition. The optimal ORC system also shows a 33 % smaller nominal capacity and size of heat exchangers than the ORC at the reference design, indicating a potential reduction in the capital cost
Modeling and analysis of secondary oil recovery with water flooding from a heterogeneous reservoir through advanced wells.
Get PDFOil and gas will remain the most important source of energy for the foreseeable future according to DNV’s Energy Transition Outlook 2021, and there is an urgent need to improve oil and gas recovery with less carbon footprint to meet the future energy demands. For the extraction of oil from the reservoir, horizontal drilling is being applied due to its higher recovery rate. These horizontal wells are advanced wells equipped with downhole Flow Control Devices (FCDs), sand screens, zonal isolation as well as monitoring and control systems, etc. FCDs are the key elements of advanced wells. The main objective of this paper is to modelling and simulation of secondary oil recovery with water flooding from a heterogeneous reservoir through advanced wells completed by main types of FCDs. In this paper, a computational study of oil recovery from a black oil reservoir is performed through modelling and simulation using the Petrel© software. The modified ‘Egg Model’ is used which is a synthetic heterogeneous reservoir model consisting of an ensemble of relatively small three-dimensional realizations of a channelized oil reservoir produced under water flooding conditions. A comparative analysis of reservoir models with vertical open hole wells and horizontal open hole wells is presented where it is found that the horizontal well produces 23% more oil. Also, horizontal open-hole wells are further equipped with ICDs which have reduced the water production by 91.4% and have also delayed the water breakthrough in comparison to open-hole horizontal wells
Influence on the fluidization pattern of a freely bubbling fluidized bed with different modes of air supply
Get PDFBubbling fluidized bed (BFB) reactors are extensively used in several process applications like gasification, pyrolysis, drying, and combustions due to their excellent mixing properties and good temperature control. The bubble dynamic and particle movement in the reactor is primarily responsible for uniform heat and mass transfer and mixing. The properties of bubbles in BFB are governed by the gas distribution inside the reactor or supply of the fluidizing gas. This work investigates the influence on the fluid dynamic behaviour of the BFB reactor at different fluidizing gas injection systems using the Computational Particle Fluid dynamic model. Three different modes of fluidizing gas injection include uniform injection, air injection via twenty-five nozzles, and air supply via side nozzles along the reactor height in a gasification reactor of 10.04 cm diameter. Air is used as the fluidizing gas and silica sand as the bed material. The CPFD model is developed in Barracuda Virtual reactor 20.01. The CPFD model is validated against the experimental data obtained from the Electrical Capacitance Tomography (ECT) sensors. The result depicts the better fluidization quality of the bed with uniform air supply as flow boundary and air injection via twenty-five nozzles located at the bottom of the reactor. With air injection via two side nozzles along the reactor height, the bed is fluidized with large bubbles and particle entrainment in the freeboard zone of the reactor. A method is proposed to improve the fluidization quality of the bed while using side nozzles as inlet flow Boundary Conditions (BC) for air injection. The proposed method includes addition of four nozzles along the reactor wall instead of two which improves the fluidization quality of the bed in terms of smaller size bubbles without particle entrainment in the freeboard region
Ubiquitous digital health-related data: clarification of concepts
Get PDFThe increased development and use of ubiquitous digital services reinforce the trend where health-related data is generated everywhere. Data usage in different areas introduces different terms for the same or similar concepts. This adds to the confusion of what these terms represent. We aim to provide an overview of concepts and terms used in connection with digital twins and in a healthcare context
Autostrata: Improved Automatic Stratification for Coarsened Exact Matching
Get PDFWe commonly adjust for confounding factors in analytical observational epidemiology to reduce biases that distort the results. Stratification and matching are standard methods for reducing confounder bias. Coarsened exact matching (CEM) is a recent method using stratification to coarsen variables into categorical variables to enable exact matching of exposed and nonexposed subjects. CEM’s standard approach to stratifying variables is histogram binning. However, histogram binning creates strata of uniform widths and does not distinguish between exposed and nonexposed. We present Autostrata, a novel algorithmic approach to stratification producing improved results in CEM and providing more control to the researcher
Pilot Testing and Evaluation of Participatory Patient Record in Psychiatric Care
Get PDFThe PEPPPSY(Pilot Testing and Evaluation of Participatory Patient Record in Psychiatric Care) project is a new initiative from the Digital Health group of the Centre for Health Services Research in Brandenburg. PEPPPSY stands for “Pilot Testing and Evaluation of a Participatory Patient Record in Psychiatric Care”. The project is based on the United States-based initiative, OpenNotes[1], an international movement promoting and studying transparent communication in healthcare. The project is created with open communication in mind, as it aims towards giving patients insight into their treatments by accessing their psychiatric records. This will hopefully increase trust, engagement, and understanding of both themselves and the therapeutic process
Legal Issues Related to the Use of Twitter Data in Language Research
Get PDFTwitter data is used in a wide variety of research disciplines in Social Sciences and Humanities. Although most Twitter data is publicly available, its re-use and sharing raise many legal questions related to intellectual property and personal data protection. Moreover, the use of Twitter and its content is subject to the Terms of Service, which also regulate re-use and sharing. The first part of this paper provides an analysis of these issues, whereas the second part discusses two possible strategies to address them: using the new Academic Research product track, which enables authorized researchers to access Twitter API on a preferential basis, or relying on the new statutory copyright exception for Text and Data Mining for research purposes
ARCHE Suite: A Flexible Approach to Repository Metadata Management
Get PDFThis article presents an innovative approach to metadata handling implemented in the ARCHE Suite repository solution. It first discusses the technical requirements for metadata management and contrasts them with the shortcomings of existing solutions. Then, it demonstrates how the ARCHE Suite addresses those problems. After one year of use, we can assert that the approach implemented in the ARCHE Suite is viable and provides important benefits. We aim to establish the ARCHE Suite as an open-source repository solution to be used also by other parties
Enigma History and an Unexpected Treasure Trove
Get PDFDocumentary history of the Polish contribution to the Enigma breaking is convoluted, difficult to follow and heavily dominated by the narration based on the documents preserved in the American and British archives. Therefore, every new document of strictly Polish origin, in particular preserved beyond the US National Archives and Records Administration or the UK National Archives collections, attracts attention and, usually, presents new, so far unknown, aspects of this history. In this paper we present a sensational history of discovery and recovery of the part of the archive of Polish codebreaking service, and some basic remarks regarding its contents
Unicity Distance of the Zodiac-340 Cipher
Get PDFIn December 2020, David Oranchak, Jarl Van Eycke, and Sam Blake solved a 51-year old mystery: the Zodiac cipher of 340 symbols. Blake (2021) explains their solution. The correctness of their solution has not been seriously doubted, and here we give a further argument in its favor: the unicity distance of the cipher’s system is between 80 and 152