A wetted wall cyclone is a device that delivers hydrosol in a single stage from which real-time detection of airborne particles can be readily achieved. This dissertation presents the design, development, and characterization of a family of wetted wall bioaerosol cyclone concentrators that consume very low power and are capable of delivering very small liquid effluent flow rate of highly-concentrated hydrosol. The aerosol-to-aerosol penetration cutpoint for the cyclones is about 1µm. The aerosol-tohydrosol collection efficiency for the 1250 L/min cyclone is above 90% for particle sizes greater than 2 µm at the 1 mL/min liquid effluent flow rate. The aerosol-to-hydrosol collection efficiency for the 100 L/min cyclone is above 85% for particle sizes larger than 2 µm at the 0.1 mL/min liquid effluent flow rate when it is operated at air flow-rate of 100 L/min. The pressure drop across the 1250 L/min and 100 L/min cyclones are approximately 22 inches of water and about 6.4 inches of water, respectively. A study, based on the empirically obtained aerosol-to-aerosol collection efficiency, was conducted to develop a performance modeling correlation that enables prediction of the aerosol performance as a function of the Reynolds number and Stokes number. Since the Reynolds number and Stokes number govern the particle motions in the cyclone, the aerosol performance could be expressed in terms of the Reynolds number and Stokes number. By testing the three cyclones (100, 300, and 1250 L/min cyclones) with several different air flow rates, the aerosol-to-aerosol collection efficiencies for wide range of the Reynolds numbers (3,500 < Re < 30,000) were able to be obtained. Performance modeling correlations for wetted wall cyclones show that the aerosol-toaerosol collection efficiency in the cyclone can be well predicted by the Reynolds number and Stokes number.

Problems associated with the use of compact cylindrical cyclone gas/liquid (CCGL) separators can be attributed to two physical phenomena: gas carry-under and liquid carryover (LCO). Inadequate understanding of the complex multiphase hydrodynamic flow pattern inside the cylindrical separator has inhibited complete confidence in its design and use, hence the need for more research. While many works have been done with a fixed inlet slot to predict the operational efficiency of the cyclone separator, very little is known about how separator performance can be influenced due to changes in fluid properties. During the operations of the CCGL separator the complex flow situations arising from severe foaming within the separator has not been addressed. Also the effects of emulsion formation under three phase flow conditions on the properties of cyclone separators are yet to be studied. An understanding of liquid holdup and hydrodynamic nature of flow in a compact separator under zero net liquid flow (ZNLF) and zero net gas flow (ZNGF) conditions is necessary in many field applications, especially for the prediction of LCO and in the design of the CCGL separators. Also, ZNLF holdup is an important parameter in predicting bottom-hole pressures in pumping oil wells. This research investigated the effects of fluid properties such as density, foam and emulsion formation on ZNLF, zero net gas flow ZNGF, and LCO in compact cyclone separators; this was achieved by replacing water, which is the conventional fluid used as the liquid medium in many previous research efforts with a foamy oil while maintaining air as the gas phase. Variable-inlet-slots that regulate the artificial gravity environment created by the separator were used to check for improved separator performance. Also experiments to check separator response to a range of water-cut in three-phase flow were performed. All experiments were carried out under low constant separator pressures. The ZNLF holdup is observed to decrease as the density of the fluid medium decreases. Varying the inlet slot configurations and recombination points does not have any effect on the ZNLF holdup when changes in density of the liquid phase occur. Comparisons with previous work show that there exists a wide variation in the LCO operational envelope when severe foaming occurs in the CCGL separator. At high watercut (greater than 30%), the separator LCO performance was observed to be normal. However, at water-cut below 30%, LCO was initiated much earlier; this is attributed to severe foaming in the CCGL separator.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 210-215).

Major excursions in the position of the South Pacific Convergence Zone (SPCZ) and/or changes in its intensity are thought to drive tropical cyclone (TC) and precipitation variability across much of the central South Pacific. A lack of conventional sites typically used for multimillennial proxy reconstructions has limited efforts to extend observational rainfall/TC data sets and our ability to fully assess the risks posed to central Pacific islands by future changes in fresh water availability or the frequency of storm landfalls. Here we use the sedimentary record of Apu Bay, offshore the island of Tahaa, French Polynesia, to explore the relationship between SPCZ position/intensity and tropical cyclone overwash, resolved at decadal time scales, since 3200years B.P. Changes in orbital precession and Pacific sea surface temperatures best explain evidence for a coordinated pattern of rainfall variability at Tahaa and across the Pacific over the late Holocene. Our companion record of tropical cyclone activity from Tahaa suggests major storm activity was higher between 2600-1500years B.P., when decadal scale SPCZ variability may also have been stronger. A transition to lower storm frequency and a shift or expansion of the SPCZ toward French Polynesia around 1000years B.P. may have prompted Polynesian migration into the central Pacific.

Identified as an important issue for marginal fields, the removal of sand from hydrocarbon fluids has been investigated. A review of existing sand separation equipment has recognized a need for a new separator which will satisfy the design and performance requirements necessary for protecting offshore processing equipment. This thesis details the work and analysis undertaken which has contributed towards the design and development of a new offshore gas/solid separator. A critique of different separation techniques has identified axial flow cyclone (AFC) separators as a suitable separator design for offshore desanding applications. After reviewing existing models which simulate the performance of AFC separators a simple classification table has been developed. Using the conclusions of this review as a starting platform, a methodology for developing a new computational fluid dynamics (CFD) performance model for the new separator was proposed. Experimental work undertaken at the CALtec laboratories and the BG plc (formerly British Gas Research and Technology) Low Thornley test facilities are presented. The results obtained have been used to analysis the performance of difference separator internal designs. In addition, the results have been used to evaluate the robustness of existing AFC performance models and validate the new CFD model. For the investigated operational duties, the new CFD model has been shown to consistently under-predict the collection efficiency, whereas the other AFC models over-predict. From a design point of view, a model which under-predicts the overall collection efficiency will result in the over-design of the separator for a particular operating duty. Therefore, the use of such a model will ensure the design of a separator which will offer greater than expected levels of protection of downstream equipment from erosion wear.

No description available.

Thesis (M.S.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 81-84).

This dissertation examines the causes of variations in tropical cyclone precipitation (TCP) and the relationship between TCP and river discharge in Texas. The dissertation has three major objectives: 1) investigate the spatial and temporal variations of TCP in Texas from 1950 to 2009, 2) construct seasonal statistical forecast models for TCP and identify the primary factors controlling TCP in Texas, and 3) examine how TCP contributes to the extreme precipitation and river discharge in watersheds surrounding the city of Houston. An automated extraction method is developed to identify TCP from 60 years of precipitation data from Cooperative Observing Network gauges. Texas receives an average of 123.5 mm of TCP/year, which is ~13% of the state’s mean annual precipitation. September is the month with the most TCP, and it receives an average of 18.5 mm. Long-term trends (>50 years) in TCP are evident at some locations, but there are no statistically significant long-term trends in aggregated annual TCP metrics. Despite the lack of long-term trends, TCP metrics show some spectral power at periodicities of ~2-3 years, ~5-8 years, and >10 years. Areas within 400 km of the coast have higher risk of extreme daily TCP (>100 mm), but inland Texas can also occasionally experience extreme TCP. In some areas in southeastern Texas the probability of receiving >100 mm of daily TCP in any given year is ~0.30 (i.e., daily TCP exceeds 100 mm, on average, 1 out every 3 years). The best seasonal forecast models of TCP can explain >20% variance based on three or fewer predictors. ENSO is the most important control of TCP in Texas. La Niña, the major driver in all TCP models, reduces the vertical wind shear in the Caribbean and tropical Atlantic and therefore generates more precipitating storms in Texas. Maximum Potential Velocity (MPV) in the Gulf of Mexico and vorticity in the Atlantic Hurricane Development Region (MDR) are also important predictors of TCP and they can increase the R2 by ~0.2. The negative relationship between MPV and vorticity with the TCP are due to the fact that TCs with weaker wind speed and slower translation speed tend to contribute much more to both extreme and total TCP. Sea level pressure in the Gulf of Mexico, SST in the Caribbean and North Atlantic Oscillation are also identified as useful predictors in some of the models. TCP is associated with many of the annual maximum discharge events in watersheds near Houston. Urbanization can significantly increase river discharge generated by TCP. Both the annual maximum discharge and 90 percentile discharge have increased significantly in many watersheds in Houston. Although no long-term trend can be observed in the TCP and TCP-related extreme discharge, there may be an increased risk of floods from TCP because of the statistically significant increases in annual maximum discharge that have been observed. There are also increased uncertainties in flood risk because extreme precipitation, including TCP, is projected to become more variable in the future.

Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 153-164). / Electronic reproduction. / Also available by subscription via World Wide Web / xviii, 164 leaves, bound ill. (some col.) 29 cm

Thesis (Ph. D - Atmospheric Sciences) - University of Arizona. / Includes bibliographical references (leaves 139-146).