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Water Tanks (water + tank)
Selected AbstractsComputation of turbulent free-surface flows around modern shipsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2003Tingqiu Li Abstract This paper presents the calculated results for three classes of typical modern ships in modelling of ship-generated waves. Simulations of turbulent free-surface flows around ships are performed in a numerical water tank, based on the FINFLO-RANS SHIP solver developed at Helsinki University of Technology. The Reynolds-averaged Navier,Stokes (RANS) equations with the artificial compressibility and the non-linear free-surface boundary conditions are discretized by means of a cell-centred finite-volume scheme. The convergence performance is improved with the multigrid method. A free surface is tracked using a moving mesh technology, in which the non-linear free-surface boundary conditions are given on the actual location of the free surface. Test cases recommended are a container ship, a US Navy combatant and a tanker. The calculated results are compared with the experimental data available in the literature in terms of the wave profiles, wave pattern, and turbulent flow fields for two turbulence models, Chien's low Reynolds number k,,model and Baldwin,Lomax's model. Furthermore, the convergence performance, the grid refinement study and the effect of turbulence models on the waves have been investigated. Additionally, comparison of two types of the dynamic free-surface boundary conditions is made. Copyright © 2003 John Wiley& Sons, Ltd. [source] Energetic and exergetic analysis of a domestic water tank with phase change materialINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2008C. Solé Abstract Although water is a cheap and effective medium for thermal energy storage, other options are currently being studied, to increase the storage density or to reduce the cost of the storage. The authors have been developing a system which combines the advantages of stratified sensible heat storage and latent, phase change heat storage; i.e. a hot water storage tank with stratification where a phase change material (PCM) is included into a spiral tube installed in the top of the tank. The PCM used was a granular PCM,graphite compound of about 90 vol.% of sodium acetate trihydrate and 10 vol.% graphite. This paper presents the results of an experimental investigation of the performance of the new storage concept, and of a conventional hot water storage tank for comparison. The data are further analysed with respect to the energetic and exergetic performance of the two systems. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Complexity of External Acoustic Detection of Defects in Björk-Shiley Convexoconcave Heart ValvesARTIFICIAL ORGANS, Issue 1 2001Bas A. De Mol Abstract: Fractures in Björk-Shiley convexoconcave (BScc) heart valves have raised questions about the feasibility of early diagnosis of technical defects by means of acoustic assessment. Three laboratory tests were conducted. To establish acoustic fingerprints, 66 valves with a defect, such as single-leg fracture (SLF) or single-leg separation (SLS), or without a defect were connected with a contact sensor and excited by dropping a small metal ball onto the outlet strut. In the second test, we simulated the valve sound propagation within the thorax. In the third test, intact, SLF, and SLS valves were placed in a mock heart immersed in a large water tank. We observed a resonance frequency corresponding with valve size and presence of defects. The second test showed that both the chest wall and the lungs created numerous reflections. This led to a substantial overlap of the original pulse frequencies and the frequencies measured. The third test confirmed that submersion of the chest in water can significantly reduce chest wall reflections. Reliable noninvasive assessment of BScc valve clicks for the presence of defects of the outlet strut is hampered by complex sound propagation within the thorax and variability of valve excitation. Acoustic fingerprints to diagnose mechanical defects should be integrated in valve design. [source] An Ultrasonic Profiling Method for the Inspection of Tubular StructuresCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2007Francisco Gomez These graphs not only show the inner contour of the pipe but also integrate the intensity of the echoes employed to create the profile. The enhanced profile is generated by superimposing the peak intensity from the returning echoes at the calculated x, y, and z coordinates where it reflected from the pipe wall. The proposed method is capable of showing anomalous conditions, inside pipes filled with liquid, with dimensions smaller than the theoretical lateral and axial resolution of the transducer, in contrast to traditional methods where these kinds of defects are not disclosed. The proposed inspection method and its capabilities were validated through the realization of simulations and experiments. The presented approach was particularly developed with the aim of scanning internal sections of pipes filled with liquid using rotary ultrasonic sonars, but it is expected that this research could be expanded to the inspection of other submerged structures, such as water tanks, or pressurized vessels. [source] Performance analysis of a modified two-bed solar-adsorption air-conditioning systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009K. Sumathy Abstract This paper presents the description and operation of a solar-powered modified two-bed adsorption air-conditioning system with activated carbon and methanol as the working pair. A simple lumped parameter model is established to investigate the performance of this continuous adsorption cycle consisting of a twin adsorber immersed in water tanks, which is measured in terms of the temperature histories, gross solar coefficient of performance and specific cooling power. In addition, the influence of some important design and operational parameters on the performance of the system has been studied. Compared with the conventional system, it is found that the modified system can operate more cycles and at a higher efficiency. The parametric study also shows that the adsorbent mass and the solar collector area have significant effect on the system performance as well as on the system size. Finally, when the system uses gas heater as an auxiliary heat source, it is found that the system can provide a stable cooling effect for a longer period of operation. Copyright © 2008 John Wiley & Sons, Ltd. [source] To be and to continue being a cog: the conservation of the Bremen Cog of 1380INTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 1 2001Per Hoffmann The conservation project for the Bremen Cog of 1380 took 38 years from salvage to presentation of the ship to the public in the Deutsches Schiffahrtsmuseum in 2000. The ship was salvaged from the River Weser in about 2000 pieces, and stored in water tanks. A new museum was built, and the Cog reassembled from the waterlogged timbers. The ship was reconstructed with most of the weight being taken by the ceiling of the hall via a steel-rod hanging system. Then a conservation tank was built around the hull, and a novel two-step PEG-treatment applied, especially developed for the Cog. In two consecutive baths PEG 200 and PEG 3000 stabilized lesser degraded and heavily degraded wood against shrinkage, splitting, and warping. After cleaning, the wood looks dark brown, dry, and natural. The extraordinary project is regarded a success. [source] Integration of Solar Energy into Absorption Refrigerators and Industrial ProcessesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2010E. A. Tora Abstract Absorption refrigeration is gaining increasing attention in industrial facilities to use process heat for partially or completely driving a cooling cycle. This paper introduces a systematic approach to the design of absorption refrigeration systems for industrial processes. Three sources of energy are considered to drive absorption refrigerators: excess process heat, solar energy, and fossil fuels. To handle the dynamic nature of solar energy, hot water tanks are used for energy storage and dispatch. Thermal pinch analysis is performed to determine the amount of available excess heat and the required refrigeration duty. Next, a multiperiod optimization formulation is developed for the entire system. The procedure determines the optimal mix of energy forms (solar versus fossil) and the dynamic operation of the system. Three case studies are solved to demonstrate the effectiveness and applicability of the devised procedure. [source] | ||||||||||