1,567 research outputs found
Thermodynamic balancing of the humidification dehumidification desalination system by mass extraction and injection
No full textHumidification dehumidification (HDH) is a promising technology for small scale seawater desalination and has received widespread attention in recent years. The biggest roadblock to commercialization of this technology is its relatively high energy consumption. In this paper, we propose thermodynamic balancing of the humidifier or the dehumidifier through mass extraction and injection as a potential means of reducing the energy consumption of these systems. Balancing minimizes the entropy generation caused by imbalance in driving temperature and concentration differences. We outline a procedure to model the system, using on-design component variables, such that continuous or discrete extraction and-or injection of air from the humidifier to the dehumidifier or vice versa can be analyzed. We present an extraction profile (mass flow rate ratio versus non-dimensional position) in the dehumidifier and the humidifier for attaining close to complete thermodynamic reversibility in an HDH system with a 100percent effective humidifier and dehumidifier. Further, we have examined in detail the effect of having finite-sized systems, of balancing the humidifier versus the dehumidifier, and that of the number of extractions. © 2012 Elsevier Ltd. All rights reserved.Bejan A., 1996, ENTROPY GENERATION M; Bourouni K., 2001, DESALINATION, V137; Brendel T., 2003, THESIS RUHR U BOCHUM; Brendel T., 2003, German Patent, Patent No. [#DE10215079 (A1), 10215079]; Grune W., 1961, M AM SOC MECH ENG NE; Hou S., 2008, DESALINATION, V222, P5728; Hyland R.W., 1983, ASHRAE T, V89-IIa, P520; Lemmon E.W., 2007, STANDARD REFERENCE D; McGovern R.K., APPL ENERGY IN PRESS; Miller J.A., 2011, THESIS MIT; Mistry KH, 2011, INT J THERM SCI, V50, P779, DOI 10.1016-j.ijthermalsci.2010.12.013; Muller-Holst H, 2007, NATO SCI PEACE SECUR, P215, DOI 10.1007-978-1-4020-5508-9_16; Muller-Holst H., 2002, THESIS TU BERLIN; Narayan G. P., 2012, THESIS MIT; Narayan G. P., 2011, P ASME JSME 8 THERM; Narayan GP, 2010, DESALIN WATER TREAT, V16, P339, DOI 10.5004-dwt.2010.1078; Narayan G.P., 2010, FRONTIERS HEAT MASS, V1, P1; Narayan GP, 2010, RENEW SUST ENERG REV, V14, P1187, DOI 10.1016-j.rser.2009.11.014; Narayan GP, 2012, ENERGY, V37, P482, DOI 10.1016-j.energy.2011.11.007; Narayan GP, 2010, INT J THERM SCI, V49, P2057, DOI 10.1016-j.ijthermalsci.2010.04.024; Schlickum T., 2007, European Patent, Patent No. [EP 1770068 A2, 1770068]; Shah R.K., 2003, FUNDAMENTALS HEAT EX; Sharqawy MH, 2010, DESALIN WATER TREAT, V16, P354, DOI 10.5004-dwt.2010.1079; Thiel GP, 2012, INT J HEAT MASS TRAN, V55, P5133, DOI 10.1016-j.ijheatmasstransfer.2012.05.014; Wagner W, 2002, J PHYS CHEM REF DATA, V31, P387, DOI 10.1063-1.1461829; Wessel D.J., 2001, ASHRAE FUNDAMENTALS, V2001; YOUNIS MA, 1993, DESALINATION, V94, P11, DOI 10.1016-0011-9164(93)80151-C; Zamen M, 2011, CHEM ENGINEER TRANS, V25, P1091, DOI 10.3303-CET1125182118
A conceptual model and rapid appraisal tool for integrated coastal floodplain assessments
No full textLow-lying coastal zones are high-risk areas threatened by flooding due to extreme coastal events and rising sea-levels. The coastal floodplain system includes elements such as near-shore waves and water levels, inter-tidal beaches and coastal habitats, natural and artificial sea defences and multiple inland floodplain features. Flood risk studies generally achieve an integrated assessment of these elements using multiple numerical models for different floodplain elements. However fundamental choices of floodplain description and the appropriate data, methods and models can vary widely between different sites and flood risk studies. A comprehensive conceptual model is needed to describe the floodplain system and help inform these choices in each site. However a descriptive conceptual model for coastal floodplain systems does not exist at present. There is a bias in flood risk studies towards the direct use of numerical models with limited use of conceptual models – existing models are implicit and do not describe the coastal floodplain system.This thesis addresses this gap by developing, applying and testing a rapid appraisal tool that conceptually describes the coastal floodplain as a system of interacting elements. The tool is developed in two parts – i) a quasi-2D Source– Pathway – Receptor (SPR) model that provides a comprehensive qualitative description of the floodplain; and ii) a Bayesian network model that uses this description to quantify individual elements as sources, pathways and receptors of flood propagation. The quasi-2D SPR is applied in 8 diverse coastal zones across Europe 4 of which include nested case-studies. It is an effective way of gathering and describing information about the floodplain from stakeholders across multiple disciplines. The Bayesian network model is applied to two contrasting floodplain systems in England – Teignmouth and Portsmouth. The network model is effective in pinpointing critical flood pathways and identifying key knowledge gaps for further analyses. The two models together provide a comprehensive understanding of the coastal floodplain system that can be used to inform and target the use of more detailed numerical models.Hence this thesis provides a conceptual model and tool to improve flood risk assessment. It makes conceptual understanding of the floodplain explicit and stratifies quantitative analysis by application of a rapid assessment tool before the use of detailed numerical models
A Critical Study of the Autobiographical Elements in the Fictional Works of R. K. Narayan
No full textNot availabl
Electron transport through single donors in silicon
No full text-Kavli Institute of Nanoscience DelftApplied Science
Investigating the source – pathway – receptor – consequence framework for coastal flood system analyses
No full textNew (Probabilistic) Derivation of Diaz-Metcalf and Pólya-Szegő Inequalities and Consequences
No full textClassical inequalities of Diaz - Metcalf and Pólya - Szegő are generalized to
probabilistic setting which covers the initial deterministic (both discrete and integral) variants.
From these two inequalities, by the probabilistic derivation method further well -
known inequalities are obtained (that ones by Kantorovich, Rennie and Schweitzer)
The electrons are waves: impossible interview to C.J. Davisson (1881-1958) and G.P. Thomson (1892-1975)
No full textThe author imagines to interview the Nobel Laureates in Physics of the year 1937, who turned upside-down modern physics, demonstrating the wave nature of matter. The answers of C. Davisson and G.P. Thomson are based on
the Nobel Lectures they delivered during the Nobel Prize Award Ceremony
Evaluatierapport “Powered by you”: Ontwikkeling Sustainable Energy Floor- energieopwekkende vloer
No full textOp weg naar rendabele energieopwekking door lopen. Er was een voorsprong in kennis en ervaring aangaande de techniek die nodig was een energie genererende loopvloer (de Sustainable Energy Floor – SEF) te realiseren. Specifieke aanpassingen moesten echter ontwikkeld worden in verband met de andere bewegingsvorm, de schaal die vele malen groter is en de andere installatie- en logistieke eisen. Het doel was om een pilot te doen op één of meer aansprekende locaties. Het project moest een belangrijke stap zijn op weg naar rendabele energieopwekking door lopen. Samen met de TU Delft, faculteit Industrieel Ontwerpen en Rinnic Vaude is onderzoek gedaan naar de haalbaarheid van het ontwikkelen van SEF, zijn prototypes en een pilotvloer gerealiseerd, tests gedaan en presentaties en demonstraties gegeven aan vele partijen en een breed publiek in Delft en Rotterdam. Vanwege technische knelpunten gedurende het project en de praktische haalbaarheid is er niet één grote pilot voor een langere periode gedaan, maar zijn er meerdere kortdurende pilots en tests gedaan. Het voordeel hiervan was dat we op basis van de analyses, tests en de feedback van gebruikers op verschillende versies prototypes, het ontwerp steeds verder konden verbeteren. Tenslotte heeft dit geresulteerd in het bouwen van de pilotvloer, waarmee de eindtest in De Kuip is uitgevoerd naar tevredenheid van alle betrokken partijen. Het project is succesvol afgerond en de doelstellingen zijn gehaald binnen het gestelde budget. Het project is uitgevoerd met steun van het programma Kansen voor West, wat valt onder het Europese Fonds voor Regionale Ontwikkeling.Industrial Design Engineerin
Decay of turbulence at high Reynolds numbers
No full textUsing the unique capabilities of the Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization, we investigated virtually homogeneous and isotropic grid turbulence over a wide range of Reynolds numbers, , between and . The choice of pressurizable Sulfur Hexafluoride as a working gas makes it possible to reach extremely high Reynolds numbers without changing boundary conditions. Indeed, the Reynolds number we reached were higher than any previous classical grid wind-tunnel experiment. In this talk, we focus on the fundamental question of how fast turbulent energy decays once it has been created, and show that the Reynolds number plays no important role in setting the decay rate if it is high enough
Wall to wall optimal transport
No full textThe calculus of variations is employed to find steady divergence-free velocity fields that maximize transport of a tracer between two parallel walls held at fixed concentration for one of two constraints on flow strength: a fixed value of the kinetic energy or a fixed value of the enstrophy (the mean square rate of strain in this situation). The optimizing flows realize upper limits on convective transport in this scenario. We interpret the results in the context of buoyancy-driven Rayleigh–Bénard convection problems that satisfy the flow intensity constraints, enabling us to investigate how optimal transport scalings compare with upper bounds on Nu expressed as a function of the Rayleigh number Ra
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