Effective management of air quality in Shanghai, China, requires an understanding of the emissions, chemistry, and local meteorology. The local and regional factors responsible for the spatial and temporal variations in NO2, SO2, and PM10 concentrations observed at 10 air quality monitoring sites in Shanghai from August 1, 2003 to July 31, 2004 were analyzed in intersite, interspecies, and species-meteorology correlations.

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The contamination of groundwater and soils has been a big issue of great interest and importance to human health. When organic compounds from leaking underground storage tanks or accidental spills on the surface infiltrate into the subsurface environment, they migrate downward through the unsaturated zone. These contaminants are dissolved into groundwater and move with groundwater flow. Thus, there is a need for remediation technologies. Air sparging is relatively cost-effective, as well as an efficient and safe technique for recovering organic contaminants in the subsurface. This technique introduces air into the subsurface system to enhance the volatilization and bioremediation of the contaminant in the groundwater system. In this operating system, the movement of air phase can take place either as a continuous air phase or as discrete air bubbles. However, the present research focused on continuous air phase assumption and mass balance equations of individual phases rather than taking into account the movement of air bubbles and colloidal particle capture on discrete air-water interface. Generally colloidal particles are treated as suspended particles in the water, so the hypothesis is that the rising air bubble can collect the particles and transport them up to the water table where the pump extracts the dirty bubbles from the groundwater system to the processing unit on the ground surface. This dissertation developed a pore-scale study to model the migration of discrete air phase in the presence of colloidal particles captured on the air-water interface. The model was based on the pore-scale balance equation for forces acting on a bubble rising in a porous medium in the presence of colloids. A dimensional analysis of the phenomenon was also conducted to provide a more generalized methodology to evaluate the effect of individual forces acting on an air bubble. The results indicate that the proposed model can predict the terminal velocity of a rising bubble without or with colloidal particles and provide the effect of numbers of colloidal particles, properties of colloidal particles, and solid grain size. The results showed that the terminal velocity of a discrete bubble was affected by the attachment of particles on a bubble, and then the volatile organic compound (VOC) removal rate was changed by the various radii of a bubble and the number of colloidal particles on a bubble.

Air foil bearings offer several advantages over oil-lubricated bearings in high speed micro-turbomachinery. With no contact between the rotor and bearings, the air foil bearings have higher service life and consequently lesser standstills between operations. However, the foil bearings have reliability issues that come from dry rubbing during start-up/shutdown and limited heat dissipation capability. Regardless of lubricating media, the hydrodynamic pressure generated provides only load support but no dissipation of parasitic energy generated by viscous drag and the heat conducted from other parts of the machine through the rotor. The present study is a continuation of the work on hybrid air foil bearings (HAFB) developed by Kim and Park, where they present a new concept of air foil bearing combining hydrodynamic air foil bearing with hydrostatic lift. Their experimental studies show that HAFB has superior performance compared to its hydrodynamic counterpart in load capacity and cooling performance. In this article, the bearing stiffness and damping coefficients of HAFB are calculated using a linear perturbation method developed for HAFB. The study focuses on circular HAFB with a single continuous top foil supported by bump foil. The research also includes a parametric study which outlines the dependence of the stiffness and damping coefficients on various design parameters like supply pressure ( P s ), feed parameter ( Г s ), excitation frequency (v), and bearing number (Λ). Furthermore the present research also includes experimental investigation of HAFB with bump foil as compliant structure. In the first phase of the experimental research a high speed test facility was designed and fabricated. The facility has the capability of running up to 90,000 RPM and has an electric motor drive. This article gives detailed description of this test rig and also includes data acquired during the commissioning phase of the test rig. The test rig was then used to measure the load capacity of HAFB.

Foil bearings are widely used for oil-free micro turbomachinery. One of the critical technical issues related to reliability of the foil bearings is a coating wear on the top foil and rotor during start/stops. Bearing cooling is also mandatory for certain applications because the foil bearings can generate significant amount of heat depending on operating conditions. Usually axial flow is used through the space between the top foil and bearing sleeve. In this thesis, a hybrid air foil bearing with external pressurization is introduced. The hybrid operation eliminates the coating wear during start-up/shut down, and also reduces drag torque during starts. Furthermore, this hybrid foil bearing does not need cooling system. An experimental test with a loaded bearing under hydrostatic mode demonstrates the high potential of hybrid air foil bearings. The load capacity of the hybrid foil bearing was measured at 20,000 rpm, and compared with that of hydrodynamic foil bearing. The hybrid foil bearing has much higher load capacity than the hydrodynamic foil bearing. The starting torque was also measured and compared with hydrodynamic bearing. A simple analytical model to calculate top foil deflection under hydrostatic pressurization has been developed. Predictions via orbit simulations indicate the hybrid air foil bearings can have a much higher critical speed and onset speed of instability than the hydrodynamic counter part. Major benefits of the hybrid foil bearings also include very low starting torque, reduced wear of the top foil and rotor, and very effective cooling capability by the pressurized air itself. This new concept of hybrid air foil bearings are expected to be widely applied to the oil free turbomachinery industry, especially for heavily loaded and/or high temperature applications.

Near-road air quality studies have indicated the presence of high levels of pollutants. In this study, a three dimensional Eulerian model is developed which can be used to study the air quality near freeways. A vehicle-induced turbulence parameterization is included in the model to estimate better the turbulent diffusion of pollutants. The near-road air quality model is used to study two different cases. In the first case, the model is validated using the data from General Motor's SF6 dispersion experiment, conducted at Michigan in 1976. Sensitivity of the model to meteorology and traffic-related parameters are studied in detail. In the second case, the spatial distribution of ozone, carbon monoxide, NOx and 1,3-Butadiene near a simulated 8-lane freeway was studied. Model simulation for the first case yielded better results than US EPA's CALINE models which were previously used for regulatory purposes. Model performance when analyzed at different wind directions shows an overall good performance. The results also show that the model performs well at surface but slightly over predicts pollutant concentration at higher elevations. The simulation results for second case at different directions of wind and at different boundary conditions for model species, places emphasis on the importance of the inclusion of the chemical mechanism in the study of near-road air quality.

Based on field measurement data, the air-conditioning system consumes more than 40% of the building total energy use, followed by 30% of lighting, and 30% of miscellaneous pumping systems.. Among them, 60% power was consumed by chiller plants, while the chilled water pumping and air side equipment each accounts for another 20%. It is no doubt, that the energy efficiency improvement of chillers is one of the most important items in building energy conservation. It is common practice to design an air-conditioning system based on peak cooling load, namely, peak cooling demand on August 17, 3 p.m. Therefore, the chillers were mostly over-sized, while most of the time the chiller plant is operating under partial load conditions (PLF), which consumes more energy resulting in higher kw/RT and lower COP. It is the goal of this project to develop intelligent operation strategies of chiller plants under various seasonal conditions and to validate the effectiveness by full-scale experiment. At first, a typical central air-conditioning system will be selected and operated under various PLF conditions with the supply and return chilled water and flow rates recorded for energy calculations. By applying the simulation procedure developed by the ASHRAE using regression technique, the performance curve of a specific chiller under various PLF can be obtained with the kw/RT value identified. By simulating the multiple chiller cooperating combinations, an optimal operation strategy can be developed with the best economic benefits. Through the execution of this project, such an operation strategy, developed and validated under local weather conditions warrants good potential for engineering applications

Due to projectedincrea ses in air traffic, there are several research efforts underway to evaluate ways to safely increase the capacity of the National Airspace System (NAS), improve operational efficiency, andre duce aircraft noise. At NASA Langley Research Center (LaRC) in Hampton, Virginia, two parallel research efforts have focusedon terminal area research: one is Airborne Precision Spacing (APS), and the other is the Quiet Aircraft Technologies (QAT) project. The APS objective is to increase terminal-area capacity without adversely affecting safety, whereas the QAT project objective is to develop noise- and fuel-efficient approach trajectories. The APS project developed a cockpit tool, called Airborne Merging and Spacing for Terminal Arrivals (AMSTAR), that issues speedco mmands to aircraft to maintain desired spacing between aircraft pairs. The APS studies showed an ability to increase runway capacity; however, capacity increases may negatively impact noise andemissio n levels in airport areas. The QAT project created efficient Continuous Descent Approaches (CDAs), which showedred uctions in aircraft ground noise and fuel consumption. Previous research has shown that CDA trajectories have adverse effects on runway capacity because aircraft must be spacedf urther apart at long distances from the runway to prevent separation losses at the runway threshold. To date, the APS and CDA concepts have been evaluated independently at LaRC.In this study, three different approaches to combining APS and CDA operations were evaluatedto determine the feasibility and benefits of combining these concepts. These methods combined AMSTAR with 3◦-flight-path-angle-CDA approach routes, 3◦-CDA routes with spoilers, and2 ◦-CDA routes without spoilers. Adding the use of spoilers allowedf aster responses to large speedr eductions issued by AMSTAR. This improvement was contrastedwith the effects of a shallower flight-path angle for greater deceleration capabilities. This research indicated that AMSTAR improved the performance of CDA operations, although full capacity improvements were not achieved. Whereas the 2◦-CDA routes were expectedto show the best results, the 3◦-CDA case with spoilers showed the least variability in thresholdspacing errors. All of the CDA routes were more noise, fuel, and time efficient than traditional step-descent routes that are commonly usedto day.

Six types of aerosol samplers were evaluated experimentally in a test chamber with polydisperse fly ash. The Andersen sampler overestimates the mass of small particles due to particle bounce between stages and therefore provides a conservative estimate of respirable particulate mass and thoracic particulate mass. The TSP sampler provides an unbiased estimate of total particulate mass. TSP/CCM provides no information below ESD 2 µm and therefore underestimates respirable particulate mass. The PM10 sampler provides a reasonable estimate of the thoracic particulate fraction. The RespiCon sampler provides an unbiased estimate of respirable, thoracic, and inhalable fractions. DustTrak and SidePak monitors provide relative particle concentrations instead of absolute concentrations because it could not be calibrated for absolute particle concentrations with varying particle shape, composition, and density. Six sampler technologies were used to evaluate airborne dust concentrations released from oilfield pipe rattling operations. The task sampled was the removal of scale deposited on the inner wall of the pipe before it was removed from service in a producing well. The measured mass concentrations of the aerosol samplers show that a Gaussian plume model is applicable to the data of pipe rattling operations for finding an attainment area. It is estimated that workers who remain within 1 m of the machine centerline and directly downwind have an 8-hour TWA exposure opportunity of (13.3 ± 9.7) mg/m3 for the Mud Lake pipe scale and (11.4 ± 9.7) mg/m3 for the Lake Sand pipe scale at 95 % confidence. At distances more than 4 m downwind from the machine centerline, dust concentrations are below the TWA-TLV of 10 mg/m3 for the worker in both scales. At positions crosswind or upwind from the machine centerline there is no measurable exposure. Available data suggest that the attainment area for the public starts at about 9 m downwind from the machine centerline in both scales, as 24 hour average concentrations at these distances are smaller than the 0.15 mg/m3, the NAAQS for unrestricted public access. The PSD of the suspended plume is dominated by particles smaller than ESD 50 µm.

This thesis develops a peers-to-peers intelligent air conditioner (A/C) controller which integrates the power line carrier technology and the infrared remote control. The intelligent air conditioner controller is used for the remote temperature setting and load control of air conditioner without requesting extra communication line and modification of the control circuit in the A/C unit. With the A/C controller developed the demand response in residential and commercial areas can be achieved effectively by reducing the peak power demand of A/C units. In order to investigate the PLC signal transmission over the low voltage distribution lines, the mathematical model of low voltage distribution system under high carrier signal frequency is derived. The computer simulation is executed to analyze the transmission characteristics of power line carrier signal. The proposed controller can receive the command issued by the demand response control center over the distribution lines with carrier frequency to execute the remote temperature setting of A/C units. Based on the field measurement of energy by air conditioner, it is found that significantly power demand reduction of air conditioner has been resulted by applying the proposed controller for remote temperature setting of air conditioner.