The thesis is focused on the design of a self-powered sensor for measurement of water flow rate and temperature in water pipelines. The key block of this thesis is the construction of an electric generator powered by excitation with turbulent flow. The generated voltage should power the sensor's circuits and allow water flow rate measurements. Throughout the development, three prototypes of generators powered by turbulent flow were created. Turbulences were not created by an insertion of a bluff body but by inner geometry of the pipeline elements. Maximum power of 10,66 uW was generated at flow rate of 8 m3/h. Afterwards, a prototype of water flow rate and temperature sensor was assembled. Energy self-sufficiency of the device at common flow rates was not achieved using the chosen procedure. The designed flow rate measurement method is suitable for an approximate flow rate estimation.

Predicting fatigue failure is a critical design element for many engineering components and structures subject to complex service conditions. In high-temperature and corrosive environments, many materials exhibit rate dependent phenomena that can significantly alter safe service life predictions. Existing cycle processing techniques such as Peak Counting, Simple Range, and the Rain Flow method are able to resolve complex service histories into sets of simple cycles, but these methods are unable to handle time-related parameters such as engage rate and cycle sequence. To address this, a cycle processor was written in FORTRAN 95 later termed the Multi-Algorithm Cycle Counter (MACC). This code was utilized as a platform to develop, test, and study various methods of extracting and interpreting rate parameters extracted from cycles defined by existing counting algorithms.

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<p> Drop sizes were measured photographically for water in kerosene and for water in methyl isobutyl ketone, at varying flow rates and levels of agitation. At high levels of agitation the data could be represented very approximately by the well known relationship of Hinze and others: d32= CONS(σ0.6)/ρ0.6E0.44) (where d32=mean drop diameter, σ= interfacial tension, p̂= mean density and E= power input per unit mass). However this equation was not satisfactory at low levels of agitation, and an alternative equation based on dimensional analysis and including effects of density difference and gravity has been proposed. Qualitative observations regarding drop formation, holdup and various operating phenomena are made. </p> / Thesis / Master of Engineering (MEngr)

No description available.

An examination of various methods for mass flow rate measurements was undertaken to evaluate their applicability for measuring refrigerant R-134a two-phase mass flow in refrigeration and air-conditioning equipment. An experimental apparatus was constructed to generate the required two-phase flow conditions. A turbine and a venturi flowmeter were used together with either a capacitance transducer or a gamma densitometer to determine the two-phase mass flow rate. The time-averaged void fraction was measured using a capacitance transducer and a gamma densitometer. Their measurements were in good agreement. Hence, for mass flow rate measurements, the capacitance transducer was used as the void fraction meter because of its ease of operation. A number of models were used to combine the output of either the turbine flowmeter or the venturi flowmeter, with the void fraction measurement to estimate the mass flow rate. It was found that, within the range of experimental data tested in the present work, the venturi flowmeter, in conjunction with Chisholm's model, provided the best agreement with the experimental results. / Thesis / Master of Engineering (MEngr)

Water conservation efforts have led to a decrease of flow rates in buildings, increasing water retention time (WRT) and sometimes opportunistic pathogens (OPs) growth. A novel experiment with replicated distal pipes operated at commonly used flow rates was designed to evaluate the effects of water age, flush frequency, flow rate, pipe diameter, water temperature, disinfectant residual presence, and microbial regrowth in hot and cold pipes. In cold water, total bacterial regrowth was a function of water age, plateauing after approximately 6 days at cell counts 20 times higher than influent water with minimal disinfectants. In warm (40 °C) water, most regrowth occurred in the heater tank, reducing the relative growth in the pipes. When cold water with ~1 mg/L chloramine was present, cold-water total bacteria regrowth plateaued after about 2 days WRT with cell counts 14 times higher than influent water, but regrowth still occurred in the heater tank. With 1 mg/L chloramine and elevated heater temperature (60 °C), regrowth in the tank was suppressed and cell counts in the pipes increased 82 times above cold-water influent levels at 7.5 days WRT. Legionella spp. and Mycobacterium spp. demonstrated opposite responses to flow rate with chloramine minimization. The highest levels of Legionella spp. (1.7 log higher than influent) were present when flow velocity was >2 feet per second (fps), but the highest levels of Mycobacterium spp. (1.5 log higher than influent) were observed at the lowest flow velocity (0.33 fps). This study highlights the tradeoffs between water conservation and water quality. / Master of Science / Regulations that decrease flow rates of faucets and showers have driven water conservation in buildings, increasing the time water sits in pipes and tanks (i.e., water retention time or WRT) elevating the likelihood of harmful bacterial growth. A novel faucet rig was designed to carry out a comprehensive experiment revealing the combined effects of WRT, flush frequency, flow rate, pipe diameter, water temperature, and disinfectant residual presence on water quality at the tap. In water without disinfectant, growth in cold water pipes increased with WRT, but in hot water the growth of bacteria occurred mostly in the warm water tank at 40 °C, which is a temperature known to leave a system vulnerable to bacterial growth. Cold pipes with a disinfectant residual saw a decrease in bacterial regrowth in comparison to cold pipes without disinfectant. However, if there was a disinfectant residual and an elevated water heater temperature set point in the tank, regrowth occurred when water was in the pipes at room temperature and there were lower disinfectant residuals. Potentially harmful bacteria, like Legionella spp. and Mycobacterium spp., which cause Legionnaires' disease and nontuberculous Mycobacteria (NTM) infections, grew more readily at higher flow rates, whereas others grew less readily, but all harmful bacteria were reduced by lowering WRT to less than ≈ 2 days and maintaining the water at 60 °C with a disinfectant. This study has important implications for regulations requiring minimum disinfectant levels to buildings, faucet flow rates regulations, and design and operation of building plumbing systems.

The dispersion model was used to study mixing levels in a full scale aeration tank. The effect of air flow rate, water flow rate and diffuser type was investigated. The peak time technique proved satisfactory in predicting the theoretical tracer response curve generated using the dispersion model. The dispersion model adequately described the longitudinal mixing that occurred in a full scale aeration tank equipped with fine and coarse bubble air diffusers. Response curves from two tanks-in-series were also obtained. / Thesis / Master of Engineering (ME)

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-30Bitstream added on 2014-06-13T18:10:03Z : No. of bitstreams: 1 coelho_wr_dr_ilha_prot.pdf: 3240058 bytes, checksum: f2c138a1a2cb98ce4eb9f9618ea59484 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Cavitação em bombas centrífugas é a formação de bolhas de vapor do fluido bombeado na região de sucção do equipamento. As bolhas de vapor formadas em algum local do escoamento, em geral na região de sucção da bomba, entrarão posteriormente em colapso. Este fenômeno é importante cientificamente, tecnicamente e economicamente. Cientificamente é interessante, pois envolve o escoamento de um fluido em estado líquido, simultaneamente ocorre a formação de bolhas de vapor, que também escoam juntamente ao fluido líquido. O processo de vaporização e condensação de um fluido é complexo, pois envolve mudança de fase, um fenômeno térmico não linear. Tecnicamente, é importante porque quando o escoamento se dá com cavitação os parâmetros hidrodinâmicos do escoamento bem como da bomba, em geral, são fortemente alterados na direção termodinâmica de maior produção de irreversibilidades. Economicamente, é custoso porque a cavitação, em geral, leva a perda de eficiência termodinâmica dos processos e em conseqüência haverá maior custo na produção de um dado bem, diminuindo a eficiência econômica e a competitividade da empresa. O escoamento com cavitação na sucção de bombas apresenta três aspectos danosos principais: cavitação pulsante com baixa vazão; cavitação não pulsante com baixa altura útil; e erosão cavitacional. A cavitação pulsante é caracterizada por grande formação de bolhas de forma transitória com baixa freqüência e grande amplitude, gerando forças vibratórias importantes no sistema de bombeamento. A cavitação pulsante também causa colapso do fluxo de massa do fluido bombeado com valores que vão do fluxo normal da instalação até valores quase nulos, transitoriamente. Na cavitação pulsante a erosão cavitacional e a queda na altura útil são pequenas... / Cavitation in centrifugal pumps is the development of vapor bubbles from the pumped liquid into equipment suction region. Vapor bubbles developed somewhere in the flow, generally in the pump suction, will afterwards along the flow to collapse. This phenomenon is scientifically, technically and economically important. Scientifically, it is interesting because involves the flow of a fluid on liquid state, and simultaneously happens vapor bubbles development that also flow together the liquid fluid. Fluid vaporization and condensation processes are complex because involves phase change, a non-linear thermal phenomenon. Technically, it is important because when the flow happens with cavitation the flow and pump hydrodynamic parameters, generally, are strongly modified toward bigger thermodynamic irreversibility production. Economically, it is expensive because cavitation, generally, leads to thermodynamic process efficiency loss, and consequently it will have bigger costs for production of a given good, then decreasing economic efficiency and company competitiveness. Flow with cavitation in the pump suction presents three main devastating aspects: surging cavitation with low flow rate; steady cavitation with low total head; and cavitational erosion. Surging cavitation is characterized by unsteady, low frequency and high amplitude, intense bubbles development, producing strong vibration forces into the pumping system. Surging cavitation also causes the collapse of pumped fluid mass flow rate with values that goes from the normal flow to values that almost reach the zero flow, unsteadily. In surging cavitation, the cavitational erosion and the breakdown in total head are small. In steady cavitation the mass flow rate, and even the flow rate... (Complete abstract click electronic access below)

The hydrograph at the watershed outlet was simulated using the time-area curve concept implemented in a geographic information system (GIS). The goal of this study was to determine if hydrograph prediction accuracy would be improved by accounting for spatial and temporal variation of excess rainfall. Three models with different methods of estimating excess rainfall were developed: the Distributed Curve Number (DCN) model uses a CN for each cell, generating spatially distributed excess rainfall using the Soil Conservation Services curve number method (SCS, 1972); the Uniform Curve Number (UCN) model uses a single "average" CN for the whole watershed, thus generating a uniform excess rainfall; the Phi index model which uses the Phi-index method to generate uniform excess rainfall. With the aid of a GIS, the cumulative flow time to the watershed outlet is estimated for each cell in the watershed and the isochrones of equal travel time are developed. The time-area curve is developed in the form of an S curve. The spatially distributed 1-hr unit hydrograph is derived from the S curve as the difference between the S curve and its value lagged by 1-hr. The models used in this study describe the physical processes and flow mechanisms. They also reflect effects of watershed characteristics (slope, landuse, soil drainage potential) and excess rainfall intensity on the resulting hydrograph at the watershed outlet. Surface flow is divided into channel flow and overland flow based on the upstream drainage area. Flow is routed to the watershed outlet through a channel network derived from the watershed Digital Elevation Model (DEM). The models developed were tested against observed rainfall-runoff data from the 1153-ha Virginia Piedmont watershed (Owl Run). A total of 30 storms were simulated, with statistical comparison of peak flow rate, time to peak flow rate, and the hydrograph shape. The hydrograph shape was compared both visually and statistically. Results indicated that the two models which account for temporal variation in excess rainfall (DCN and UCN) predicted the output hydrograph much more accurately than the Phi model which lacks the ability to capture the temporal variation of excess rainfall. For this watershed, results showed that the spatial variability in excess rainfall which was accounted for by the DCN model did not improve the prediction accuracy over the UCN model which lacks that ability. However, a sensitivity analysis for the effect of the spatial distribution of the excess rainfall indicated that can be a significant effect of spatial distribution on the predicted hydrograph. / Master of Science