Steven Rogak

Using energy exchangers in winter conditions, and hot and humid summer conditions can result in condensation. Condensation might affect the performance of the exchanger, facilitate the growth of micro-organisms and be a precursor to frost formation at lower temperatures. As a result, information about the impacts of condensation on the performance of the energy exchanger and the operating conditions that result in condensation is essential for the design of ventilation systems and the selection of the proper exchanger.In this study, a widely used energy exchanger is experimentally tested under various operating conditions. The presence of condensation is inferred from visual observation, investigation of the sensible and latent effectiveness, and measurements of pressure drop. It is shown that condensation increases the sensible effectiveness of the supply side and decreases the sensible effectiveness of the exhaust side. Additionally, the latent effectiveness of both air streams increases when condensation occurs, although the increase in exhaust side latent effectiveness is more significant. Finally, the accumulation of water in the channels significantly increases the pressure drop in the exhaust side while it does not significantly impact the effectiveness. Additionally, a heat and mass transfer model is developed to investigate condensation in a wide range of operating conditions. The permeability of the composite membrane of the exchanger used in this study, is measured at various temperature and humidities and the effects of membrane orientation and the phase of water (liquid/vapor) on the permeability of the membrane are investigated. An empirical membrane model is then added to the heat and mass transfer model. The heat and mass transfer model is validated against experiments and is then used to determine the operating conditions resulting in condensation and to investigate the effect of variation in the permeability of the membrane on the occurrence of condensation. It is shown that assuming a constant permeability for the membrane can result in errors of up to 25% in the prediction of the rate of condensation. Furthermore, it is shown that condensation in the energy exchanger will be significant only when the indoor air temperature and humidity are high.

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Multirotor drones are an ideal platform for a range of environmental studies, but wind measurement by anemometer payload suffers from the downwash of the propellers. This work presents a machine learning (ML) based disturbance observer, which implicitly estimates the wind based on the drone state without requiring a dedicated anemometer. Experimental data is collected by flying an instrumented quadrotor in proximity to two reference anemometers. Four ML models are developed: a long-short-term-memory (LSTM) neural network, an artificial-neural-network, a gated-recurrent-unit (GRU) neural network, and a Gaussian-process-regression. These models are trained with variations in their inputs, considering the addition of drag estimations by rigid-body equations of motion and control inputs, both of which improve performance. Two key processing methods are developed: Data augmentation by global coordinate frame rotation enforces rotational invariance and grid-based data reduction removes data imbalance. The best performing GRU achieves 0.48 m/s root-mean-square-error on unseen complete flight data, although the LSTM performs similarly. This approaches the experimental limits of performance, as reference anemometers cannot be exactly co-located with multirotors in flight. The difference between both spatially offset anemometers accounts for 73% of the GRU estimation error. These results are useful for emissions measurement, gas source localization and other applications.

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Alternative fuels such as hydrogen (H2), natural gas (NG), and biodiesel can be substitutes for diesel fuel in compression ignition engines. Dual-fuel combustion technology is an effective way to utilize gaseous fuels ignited by pilot liquid fuels in existing diesel engines with minor modifications. The effects of different fuels on engine emission especially under real-world operating conditions are important information for engine manufacturers as well as vehicle operators. For this reason, this study aims to evaluate the in-use emissions for CI engines operating on the alternative fuels.The first study focused on the unburned H2 emission from a heavy-duty truck equipped with a 15 L diesel engine retrofitted to run in dual-fuel mode with port-injected H2. A Portable Emission Measurement System (PEMS) was developed integrating a semi-conductor H2 sensor, which gives the H2 concentration in the exhaust stream. On-road emission tests were implemented on the truck with the PEMS to measure the in-use H2 emission under real-world operating conditions. H2 slip maps were generated using the concentration data. The work presented the methodology to use a low-cost sensor for in-use vehicle's exhaust H2 measurement. In the second study, in-use emission measurements were taken for a diesel/NG dual-fuel marine vessel. The emissions under diesel mode and dual-fuel (NG + pilot fuel) mode were considered with diesel (baseline), Soybean Methyl Ester (SME), and Canola Methyl Ester (CME). It was found that under diesel mode steady states, NOx emissions were increased by 21.6% on average by both biodiesels. Particle number (PN), particularly in the submicron range, were substantially increased by the biodiesels, likely an artefact of nucleation mode or volatile compounds. Under load increase conditions, transient CO and PM concentrations were substantially higher than the steady state results. Both biodiesels resulted in reduced PM emissions compared to diesel. Under dual-fuel mode, when used as thepilot fuel, SME and CME reduced NOx emissions by 14 .7% and 19. 7%, respectively. The results proved that biodiesels are a potential alternative fuel for heavy-duty marine engines, though some questions remain to be answered.

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Experiments conducted on a commercial energy exchanger show that an applied pressure differential between the supply and exhaust flows leads to variations in the pressure drop along each flow path, which are caused by the membrane deflection. Membrane deflection in energy exchangers affects their performance. This is because of a change in passage geometry due to the deflection of the membrane. This study examines the relationship between the membrane deflection and the corresponding variation in the pressure and flow distribution. The membrane deflection is a strong function of the applied pre-tension. Thus, one needs to know the value of pre-tension to estimate the membrane deflection. This information might not be available from the manufacturer, or it might not be accurate because of the subsequent manufacturing steps or structural damage. This study describes a novel contact-based method to measure the pre-tension for applications, such as membrane energy exchangers, where optical access to the membrane is limited. The technique is used to measure the tension of membranes pre-tensioned to set values. The RMS deviation between the measured tension and the set pre-tension is 0.55 N/m, which is approximately 3% of the pre-tension used in a typical membrane energy exchanger.Finally, a numerical model is proposed to find the deflection pattern in an ERV. The model is validated against experimental data. The model is consistent with experiments to within 0.15 and 0.08 inches of water RMS error, which corresponds to approximately 15% and 8% of the pressure drop under typical working conditions of the exchanger. For conditions typical of a commercial exchanger core, the membrane deflections can lead to changes in flow in the open channels of about 16%. The influence of unbalanced flow on the pressure drop is also investigated and shown to be fairly minor if the flow rate difference is small. For larger flow differences, the unbalance flow could change the pressure drop up to 20%.

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The world is in critical need of technologies that will make a significant andimmediate impact in our fight against climate change. As global temperaturesrise, building cooling demands could rise by 72% by the year 2100,meaning that the development of energy efficient space cooling technologiesis becoming increasingly important. Radiant cooling panels have shown a lotof potential as an energy efficient method of supplying space cooling. However,they need to operate alongside dehumidification in many environmentsso that air moisture does not condense on their chilled surfaces.This thesis focuses on the development of the membrane assisted radiantcooling panel, a technology used to provide energy-efficient space cooling inhot and humid climates without the need for mechanical dehumidification.A heat balance model is developed that estimates the operational membranetemperature and cooling capacity of a membrane assisted panel. The modelis then calibrated using data collected from a field experiment in Singapore.Additionally, a framework is developed that allows the heat transfer modelto operate within a TRNSYS environment. This allows for the energy simulationof buildings that utilize membrane assisted panels for sensible spacecooling. The framework is then used to predict the potential energy savingsthat could be obtained by implementing this technology in both Singapore and Vancouver.The membrane temperatures predicted by the calibrated heat transfermodel differ from those observed through experimentation by 0.21°C. Themodel is sufficiently accurate for condensation mitigation, however, concernsregarding the coefficients used to model natural convection, along with thedata used for calibration, need to be addressed before the model can beapplied to different panel geometries. While some aspects of the TRNSYSframework need to be further developed, it was found through simulationthat membrane assisted radiant cooling can provide significant energy savingsin both tropical and temperate climates.The framework developed in this study will bring membrane assistedradiant cooling closer to widespread implementation, as modelers will beable to optimize the design of a radiant system before its construction in abuilding.

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Soot is an important contributor to climate change and has negative effects on human health. These impacts depend on the morphological properties which influence the optical properties, mobility and surface area available to adsorb other contaminants. Different combustion sources may produce soot with different morphologies and thus, different environmental and health impacts. Three soot sources were studied: a dual-fuel natural gas marine engine and two laboratory gas flares. The ship studied operated on its normal route during the measurement campaign and was run both in dual-fuel mode, and diesel-only mode to serve as a comparison. Dual-fuel mode produced substantially less soot, ~96% less, than diesel-only mode at all loads except idle. Soot morphology appeared to be independent of operating load but did vary slightly based on fuelling mode. Dual-fuel mode produced on average smaller aggregates than diesel-only mode however, the small dual-fuel mode aggregates tended to have slightly larger primary particles when compared to diesel-only generated aggregates. Overall the differences in morphology are small compared to the reduction in the amount of soot produced. Gas flaring is used in the oil and gas industry to dispose of gas. The laboratory flares studied were designed to simulate conditions which would be found in the upstream oil and gas industry. Raman spectroscopy showed that the heavier fuels had more graphitic nanostructures and transmission electron microscopy (TEM) and mobility size distributions showed that the aggregates tended to be larger. The relationship between the primary particle size and the aggregate size, did not depend on the fuel. During hydraulic fracturing operations, it is likely that the flowback fluids become entrained in the flare fuels resulting in liquids with inorganic salts becoming part of the combustion process. The morphology of the soot did not change due to the salt however, most of the soot particles became internally mixed with the salt. Unlike soot, salt tends to be an effective cloud condensation nucleus (CCN) and the large number of salt particles will likely influence local cloud formation. Furthermore, the salt particles which attach to the soot may turn the soot itself into an effective CCN.

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The suitability of Sound Decay per Doubling of Distance (??₂), as a universal room acoustics rating parameter was investigated.??₂ was combined with the Speech Transmission Index (???) to rate acoustical room quality. This follows the methodology of ISO 3382-3, allowing evaluation of room quality using speech intelligibility as a foundation quantity.To prescribe rating criteria, all rooms where unamplified speech is present were postulated to be categorizable into one of three room types: Case 1 (intelligibility) rooms where intelligibility is required at all distances, Case 2 (distraction) rooms where distraction is permissible until a defined distance, or Case 3 (privacy) rooms where privacy is expected beyond a defined distance. For rating metrics, Case 1 used listening effort, Case 2 used loss of productivity, and Case 3 used percentage of speech intelligible.An idealized initial tool was developed which calculates ??? at all points along a ??₂ curve. The tool calculated ??? based only on reverberant speech and was therefore applicable only to rooms where direct speech is impeded by obstacles.Assumptions used in the initial tool were checked using experimental data collected in 62 rooms of varying case classifications from 22 buildings. The data were used to evaluate the accuracy of regressions using sound pressure level measurements over a limited range of 1 – 16 m (??2,?,?,1−16?,), the octave band variation in ??2, and the sound pressure level at 1 m from a sound source. The maximum regression error for ??2,?,?,1−16?, was 5.6 dB, and 2.5 dB on average.DL2 trends observed in the experimental data were then implemented in the DL2 tool and the STI calculation model was updated to include direct speech contributions.The updated tool was used to evaluate theoretical rooms for each case using the developed rating schemes. Room reverberation time (RT, ?) and background noise levels (BNL, ??) were modeled using values recommended in standards.Due to the variability of RT and BNL within rooms of similar types, standardized rating schemes based on ??₂ were deemed unfeasible. However, ??₂ and the tool developed provide valuable insight on how to optimize rooms acoustically.

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Soot is one of the important contributors to climate change and has adverse effects on humans’ health and the environment. Some of these impacts can be modeled based on the soot morphological and material properties that influence the optical properties of the soot. Uncertainties around the optical properties can lead to unreliable climate prediction models; therefore, accurate modeling and calculation of soot optical properties can mitigate this issue. A new model is implemented using existing equations to describe the relationship between aggregate size and their primaries: the external mixing hypothesis (EMH). The EMH model is based on the recent studies for non-premixed flames, which quantifies the relationship between primary particle diameter and aggregate mobility diameter based on the mass-mobility exponent and the effective density. Compare to the constant primary particle size assumption and using the Rayleigh-Debye-Gans theory for fractal-like aggregates (RDG-FA) as the optical model, EMH demonstrates an increase in size-dependent and the total mass-specific scattering cross-section (MSC), which is an essential factor in climate modeling. RDG-FA neglects spherule-to-spherule interactions, which reduce its accuracy. In the next step, the multiple-sphere T-matrix method (MSTM) is used as the optical model. A previously published database of MSTM is coupled with the EMH. EMH-MSTM is able to model the variation of mass-specific absorption cross-section (MAC) for different aggregate sizes, which is not resolved by RDG-FA. The MSTM results show that size-dependent and total MAC and MSC levels are increased relative to the RDG-FA predictions, as expected, due to sphere-sphere interactions. Next, an experiment at the University of Alberta used a laboratory buoyant turbulent diffusion flame to produce soot for the model’s validation. Based on the model results, the best agreement can be expected to be for Dm ≈ 2.6, ρ(eff,100) ≈ 600 kg/m^3 and σp|dm ≈ 1.5 for the model and experiment datasets. The uncertainty around the refractive index and other variables such as mass-mobility exponent and the effective density may have caused this inconsistency between model and experiment MSC results. Providing more accurate input information to the model can increase its ability to estimate the optical footprint of the soot aggregates.

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The combustion of natural gas is an interesting alternative to liquid fossil fuels due to its competitive price and lower CO₂ emissions. One technique to burn natural gas inside direct-injection engines is the hot-surface ignition-assist method. The natural gas jet impinges on the hot surface, which acts as an ignition source. As a constant high temperature is required in the hot surface to have quick and consistent ignition events, a numerical prediction of the temperature of an application of the hot surface technique was done, and a method to study the temperature of the hot surface was developed. One proposed application of the hot-surface method consists in a fuel injector equipped with a heater ring. The high temperature of the heater could produce an excessive temperature in the injector, affecting its functioning or the fuel. To study this, heat transfer simulations were performed. A sensitivity analysis revealed a large effect of the coolant temperature in the temperature of the injector, and a large effect of the input power and surface emissivity on the temperature of the heater. With an input power of 100 W, the injector temperature is expected to remain within 200 °C, while the heater reaches a temperature beyond 1300 °C. During the injection of the fuel, the hot surface experiences a rapid cooling event. This can affect the ignition delay, hampering the combustion efficiency. To study this, a pyrometer method with high spatial and temporal resolution was developed. A hot surface was subject to a series of cooling jets. The pyrometer method revealed that the jets with a direct orientation produced a larger temperature drop compared to jets with a side orientation, regardless of their pressure or duration. The thermometer method developed has the potential to be used in different applications where rapid changes in temperature are expected, allowing to calculate the temperature of a surface in transient-state using a digital camera and the radiation intensity at a single wavelength.

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Hydrogen substitution can reduce the diesel consumption and CO₂ output of diesel engines. This thesis investigates its effect on the real-world, on-road emissions of CO₂, NOx and particulate matter (PM) from a heavy-duty diesel truck. Testing was conducted on a Class 8 truck fitted with a 13 L common-rail direct-injection (CDI) engine and a supplemental intake manifold-injection hydrogen fuel system. The peak hydrogen energy substitution rate was 40%, while the observed average was 24%. The truck operated with Gross Combined Vehicle Weights (GCVWs) between 20,000 kg and 60,000 kg. A Portable Emissions Measurement System (PEMS) was built and was used to sample engine-out, pre-aftertreatment exhaust gases. Torque was measured on the driveshaft with a wireless transducer, CO₂ was measured via non-dispersive infrared sensor, NOx was measured with an electrochemical sensor, and PM was measured via light scattering and gravimetric methods. Data was logged at 10 Hz by a data acquisition system (DAQ) that was also connected to the truck’s J1939 communication networks. From this data, detailed emission maps were generated which showed the varied emissions across the engine’s speed/load operating range. For accurate comparison on-road testing was conducted in both hydrogen/diesel and plain diesel fueling modes, totaling over 2500 kilometers logged. Overall CO₂ emissions decreased by 25±1%, which was approximately equal to the hydrogen displacement. Engine-out NOx emissions increased by 10±1% and engine-out PM emissions increased by 2±3%. For PM measurement, high correlation (R2 = 0.9) was found between integration of the instantaneous light scattering and the total gravimetric measurement methods. Overall thermal efficiency was virtually unchanged between the two fueling modes, with small decrease noted at low loads and small increase at high loads. Increased exhaust gas temperature (EGT) was measured while operating in hydrogen/diesel mode and increased in-cylinder temperature is suspected as the cause of the increased NOx emissions. Preliminary analysis of the post-aftertreatment NOx showed a decrease of 36±2% in hydrogen/diesel mode versus the diesel baseline, suggesting that the increased engine-out NOx does not increase tailpipe emissions. Furthermore, the consumption of diesel exhaust fluid (DEF) only increased by 3±3% in hydrogen/diesel mode, suggesting a higher conversion efficiency.

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Modeling sound transmission is a challenging task. An existing beam-tracing model for empty, parallelepiped rooms with specularly-reflecting surfaces is extended to predict room-to-room sound transmission between a source and receiver rooms separated by a common wall. This wall is modeled as one locally-reacting homogenous partition with frequency-independent transmission loss. Besides, sound transmission is modeled in Ray-Tracing (CATT-TM) and FEM (COMSOL). A reference configuration consists of two identical reverberation rooms is chosen following the recommendations of the literature and most of the prescriptions of the reverberation room standard, ASTM 3423. The capability of various room-to-room predictions models, in particular, the phase and energy-based beam tracing models (PBTM, EBTM) in reproducing the results of the diffuse-field theory is investigated. Both EBTM and CATT-TM are found to be reasonably accurate in reproducing the diffuse sound field for a reverberation room (i.e. for diffuse sound fields). However, the predicted levels deviate considerably from the diffuse-field theory with changes in the acoustical characteristics of the room (room aspect ratio, the magnitude of the surface absorption and surface absorption distribution (i.e. for non-diffuse sound fields). EBTM has been validated in both source and receiver rooms through existing results from ODEON in the literature and by comparing the prediction results with the new CATT-TM for the reference configuration. PBTM has been compared with finite element method (COMSOL) results in the low-frequency region. Both phase-based models match well in source room with a reasonable discrepancy. However, the PBTM has not reproduced the sound field predicted by COMSOL in the receiver room. Moreover, Waterhouse effect is studied by both PBTM and EBTM model in the reverberation rooms which is ignored in the classical diffuse-field concept. However, its significant effect is exhibited near the reflecting boundaries inside the reverberation room only in the PBTM predictions. Hence, based on recommendations of the ASTM standards during measuring sound transmission between rooms, sources and receivers should be placed sufficiently far away from the reflecting surfaces, edges and corners of the rooms to avoid the errors due to the Waterhouse effect.

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Energy Recovery Ventilators (ERVs) save energy by recovering sensible and latent heat from exhaust ventilation streams. They consist of compact channels in a cross- or counter-flow arrangement separated by moisture-permeable membranes. This work employs computational fluid dynamics with experimental validation to study angled rib mixing features to enhance heat and mass transport in membrane-based ERVs. The model simulates air-to-air heat and mass exchange between two rectangular ducts in a counter-flow arrangement. Local results from these simulations are used in a mathematical model to predict the effectiveness of a cross-flow ERV. The flow is steady and laminar. The channels are modeled with and without ribs for various channel aspect ratios and flow rates. Periodic inlet/outlet conditions are assumed for all cases to highlight the effect of the ribs. Ribs are either on the membrane surface or the opposite wall, however ribs on the membrane surface are the focus of this work due to their superior performance. Results show that the ribs increase the channel Sherwood and Nusselt numbers by a larger fraction than the corresponding increase in friction factor. The improvement is larger for sensible recovery than latent recovery because the membrane’s mass-transfer resistance is higher than its thermal resistance. For a typical commercial grade, counter-flow ERV, total effectiveness can be improved by over 10% for an equal pressure drop by adding ribs and slightly increasing the channel height. Mass-transfer and pressure drop results from the simulations were validated experimentally for channels with and without ribs using a commercially available membrane (dPoint Technologies). Ribs were either formed into the membrane surface or made as extensions of the channel wall. The experimental and simulation results agree with one another within the experimental uncertainty of the test apparatus and variability of the membrane permeability.Typically, ERV performance targets (recovery effectiveness, pressure drop) are met by varying the channel dimensions or number of channels. The work presented here indicates that angled ribs could be used instead, which would not require altering the ERV footprint or using extra materials.

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Direct injection of natural gas in compression-ignition engines offers benefits such as emissions reduction, fuel diversity, and energy security. However, in order to meet the upcoming stringent emissions regulations, further improvements in the performance of the High-Pressure Direct-Injection of Natural Gas (HPDI-NG) is needed. For this reason, different natural gas injection strategies and nozzle designs are numerically studied.The in-cylinder phenomena during the closed portion of the cycle is simulated using a Large-Eddy Simulation (LES) turbulence model and the Trajectory-Generated Low Dimensional Manifold (TGLDM) for chemistry coupling. Soot is modeled with a two-equation Hiroyasu model. To partially investigate the effect of LES variability, simulations with successive mesh refinements and infinitesimally varied inputs are carried out. Anticipated emission trends were observed for parametric sweeps with substantial variation of soot about the trend-line. This motivated the analysis of in-cylinder mixture, jet penetration and other more robust metrics.A novel paired-nozzle geometry was designed to increase the fuel-air mixing at the base of the jet, thus reducing soot. In reality, the paired jets increased exhaust PM. The CFD analysis revealed that the gas jet penetration was reduced compared to the baseline single-hole jet, while more air was entrained into the core of the jet. However, the effect of mixing due to impaired penetration dominates and results in more rich mixture and therefore more soot.CFD predicted the PM reduction benefits of “Late Post-Injection” (LPI) due to two major reasons: 1- the reduction in formed PM from the 1st pulse due to shortened pulse width, 2- negligible PM formation from the 2nd pulse for enough pulse separation. A second injection strategy, “Slightly Premixed Combustion” (SPC) also reduced PM in experiments. The CFD package had not been developed for such combustion regime, wherein the diesel-gas kinetic interactions should be resolved; hence perfect matching between the experimental and numerical combustion for SPC was not attained. Nevertheless, by optimizing the injection timing to resemble the phasing of experimental Heat Release Rate (HRR) curve, to the “best extent possible”, more premixing, higher rate of penetration, and less rich-mixture mass was observed.

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Heavy-duty engines must meet strict emission standards and retain high fuel efficiency. This thesis examines a new type of fuel injector nozzle for a pilot-ignited direct-injection natural gas engine. The nozzle uses paired jets that increase mixing with air during combustion, which aims to reduce the amount of particulate matter (PM) formed. Tests were performed for different speeds and loads and over engine parameter sweeps (including timing, EGR, EQR, and diesel pilot mass) to compare the effects on the emissions to a single-hole nozzle. Low-PM strategies and morphology of the soot were compared as well.Contrary to expectations, the tests showed large increases in CO and PM from all the paired nozzles at all modes compared to the single-holed injector. Changing speed and load did not affect the relative emissions so further tests were only done with the paired nozzle that had the least emissions.The engine parameter sweeps at mid speed, high load (B75) showed similar emission patterns for the paired-hole nozzle and the single-hole nozzle. This suggests that the reasons for the high emissions lie in the characteristics of the jets, which are not changed much under normal HPDI operation.Injecting the natural gas before the pilot injection reduced PM. Late post-injection of some of the gas reduced PM by 50% without increasing other emissions for both injector types. Apparently, these strategies could work for other HPDI injectors.Compared to the reference injector, the paired-hole nozzle produced larger soot aggregates and larger numbers of particles but soot primary particle size showed different trends at different conditions. Soot fractal dimensions were the same and consistent with conventional diesel soot.CFD simulations showed that fuel packets moved through a richer high PM and CO forming zone during combustion for the paired nozzle. This high sooting zone had to be avoided either by further mixing or less mixing to avoid the high emissions produced.The results presented here were developed on a single-cylinder engine. While trends are expected to be similar to those from an equivalent multi-cylinder engine, emission levels and fuel consumption are not directly comparable to production multi-cylinder engines.

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Stringent regulations have been enacted to reduce particulate matter (PM) emissions from heavy-duty compression-ignition (CI) engines. New regulations (Euro VI) restrict PM mass and particle number concentration. To help meet these regulations, a greater understanding of the physical and chemical characteristics of the PM is desired. This thesis is concerned with the mobility, morphology (by electron microscopy), mass (filter sampling), light scattering and semivolatile content of the particles.Natural gas has become an increasingly attractive transportation fuel for both environmental and economic reasons. One technology to utilize gaseous fuels in heavy-duty engines is Westport Innovations Inc.’s High Pressure Direct Injection (HPDI™) system. This is a system where the natural gas is directly injected late in the compression stroke and ignition of the natural gas is provided by a diesel pilot.PM emissions were characterized from a heavy-duty Cummins ISX engine converted to single cylinder operation and operating under HPDI™ fueling. Tests were performed to observe the effects of speed and load combinations, the effects of operating parameter variations (Injection timing, equivalence ratio, gas supply pressure, EGR % and diesel injection mass) and the effects of fuel premixing on the PM emissions.Engine load was more important than speed for qualitatively grouping the PM emission characteristics (mass, number, semi-volatile fraction). The exception is at low engine speeds where low mass and number concentrations were observed, along with nearly constant particle sizes, across different loads.The effects of the input parameter variations were analyzed with response surface methods. The PM emissions were more sensitive to changes in the input parameters than the gaseous emissions. Equivalence ratio, engine power and injection pressure were the most important parameters for PM mass emissions. Overall, the PM emissions varied monotonically with the input parameters and no local PM emission minima were observed.Partially premixing some of the natural gas before ignition can reduce PM emissions by over 80% at some conditions at the expense of cycle-to-cycle variability and pressure rise rates. Some optimized equivalence ratios and EGR percentages were developed to improve the stability of combustion.

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A mathematical model which estimates spatial infection risk as a function of pulmonary rate and deposition region has been developed based on the does-response model. It is specifically designed for enclosed space with consideration of pathogen bio-properties, such as viability and infectivity.Firstly, eleven cases of Tuberculosis (TB) outbreaks in aircraft are studied to develop the optimal parameters set. It is then used to perform model validation and investigation of sample inpatient room spatial infection risk. Secondly, infection risk for eleven TB outbreaks are compared with modeling and Wells-Riley estimations. As a result, modeling results are within the calculated range of Wells-Riley prediction. To determine the importance of viability and ventilation rate regarding HVAC system design for health facilities, infection risks are calculated at different viability and ventilation rates. Based on the observation, ventilation rate or particle concentration in the space dominate the infection risk distribution, except when viability decays extreme rapidly. Thirdly, the spatial infection risk is investigated for TB in a typical 60 m³ inpatient room with displacement and well-mixed ventilation systems. Two room settings, a nurse standing close to the patient’s bed versus a visitor standing far away from the bed, and two coughing directions, horizontal versus vertical, are studied. The results show that for coughing horizontally, when the nurse stands beside the patient's bed, his/her breathing zone is the highest risk zone for displacement ventilation. Under displacement ventilation, the infection risk is lower when visitor stands away from the bed compared to stand close to the bed if the visitor is the only person present in the room besides the patient. The infection risk of the breathing zones in the two cases with horizontal coughing are both higher than 25%. However, when a patient coughs vertically, the displacement ventilation significantly reduces the infection risk. With 24 hours exposure, the infection risk for the nurse and the visitor are both less than 5%.

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Billions of people worldwide use biomass fires or cookstoves on a daily basis, with significant resultantcontributions to emissions of global carbonaceous aerosols. The use of biomass as a fuel has an impact on localecosystems, contributes to CO2 levels in the atmosphere, and black carbon (BC) and organic carbon (OC) affect theearth’s radiative balance. Widespread initiatives, including carbon funding programs, propose to replace traditional“three-stone” open fires with “improved” cookstoves designed to reduce fuel usage. While numerous studiesinvestigate cookstove efficiency and publish emissions factors for gaseous pollutants and overall particulate matter(PM), there is a lack of focus on the size and nature of ultrafine particulate (UFP) emissions. This paper comparesultrafine emissions during steady combustion from a traditional three-stone fire and two improved stoves: a Rocketstove (“Chulika”) and a Gasifier stove (“Oorja”).An AVL emissions bench measured gaseous products. PM instrumentation included a TSI SMPS, TSI APS, TSIDustTrak DRX, Magee Scientific Aethalometer, and 47mm PTFE and quartz filters; a thermophoretic samplingdevice was employed to gather material for PM imaging using transmission electron microscopy (TEM).The improved cookstoves demonstrated high combustion efficiency compared to the three-stone fire and are likelyto reduce biomass consumption. Additionally, emitted PM mass was reduced by a significant amount. PMemissions from improved stoves had a higher proportion of BC compared with total PM, though there was relativelylittle variation in overall BC levels. The reduction in highly scattering OC that would accompany a large-scale shifttowards usage of improved stoves could affect the earth’s radiative balance, but this merits investigation withconsideration to other particle characteristics. Primary particles emitted from the improved stoves were smaller thanthose from the three-stone fire and appeared slightly less likely to coagulate into chain agglomerates. The observedshift towards greater quantities of smaller nanometer-sized particles could pose health concerns and is a point forfurther consideration by health scientists and reinforces the need for adequate ventilation for all cookstoves,independent of type.

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Time-Resolved Laser-Induced Incandescence (TR-LII) uses a high-energy laser pulse to detect airborne soot particles. When a laser pulse encounters a light-absorbing particle, the energy will be absorbed, resulting in an increase in temperature. If the temperature is high enough, incandescence can be used to quantity of the soot mass (EC). TR-LII tracks the incandescent light as the particle cools, providing information on the particle structure. It is a common in LII research to assume that the soot aggregate particles contain only Elemental Carbon (EC) and if these soot aggregate particles are internally mixed with Organic Carbon (OC), the intense energy from the laser beam evaporates the OC instantly. Unfortunately, these assumptions are inaccurate because the existence of OC will alter the structure and heat transfer properties of the aggregate. The existence of OC also has an effect on the energy absorption by the soot particulates. An experiment was conducted using India ink particles as a soot surrogate and Oleyl Alcohol as a model OC coating. The experiment’s objective is to study the effect of coating (OC) on the LII detection. The coating increased the peak temperature, but the apparent primary particle diameter decreased when more coating was introduced, whereas the main output variable (volume fraction) showed a mixed response. Up until a thickness of 40 nm, the apparent volume fraction value was declining, but for a thicker coating condition, the value was increasing. Another experiment was conducted to study the effect of the coating on the particulate distribution downstream of the laser heating in the LII detecting chamber. The soot fragmentation phenomenon was found to occur in the LII system and the existence of coating has an effect on the soot fragmentation phenomenon. Compared to uncoated particle, which produces small fragments (
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Generation IV CANDU Supercritical Water Reactor (SCWR) is being developed to use a light water coolant at high temperature and pressure beyond the critical point of water (374⁰C and 22.1 MPa). The dramatic decrease in the solubility of magnetite in supercritical water suggests that the precipitation of magnetite particles will occur in the reactor core which can deposit on the fuel cladding or be transported to the steam turbine. A once-through flow system was modified to develop experimental techniques for studying the deposition and transport of magnetite particles in supercritical water onto stainless steel 316L. Experiments were run with temperatures ranging from 200°C to 400°C and a pressure of 23.7 MPa. A hydrothermal method for synthesizing magnetite particles was adapted for producing simulated corrosion products in which a typical run had an iron concentration of 0.005 mol/L and lasted for 40 minutes. An online monitoring technique using thermal resistance to infer deposit loadings showed deposition and removal cycles of the corrosion product on the tube wall. Scanning electron microscope images of particles on the tube inner wall and those collected by the high temperature, high pressure filters revealed magnetite particles which were several hundred nanometers to several microns in diameter depending on the precursor and condition of the system. Ultrasound and acid wash cleaning methods were used to remove deposits from the test section for determining deposit thickness and adhesive strength. The strength of deposit adhesion was observed to increase along the tube, particularly under supercritical conditions suggesting precipitation of dissolved species may enhance the strength of the deposit. By comparing the results, a comprehensive approach was developed to study magnetite fouling in supercritical water conditions. Finally, comparison between a simulation model based on mass transport equations and experimental deposition suggests that mass transport alone can overestimate the deposition thickness when surface attachment and removal are significant as they were for many experiments in this study. The simulation predicted as an upper limit scenario that fouling in a CANDU SCWR could increase the fuel cladding temperature at certain locations by up to 23.9⁰C after one year of operation.

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Spark-ignited engines are known to produce PM composed of solid, volatile or semi-volatile particles including spheres of carbon soot formed into agglomerates, other forms of carbonaceous particles, metal particles and charred droplets of engine oil. In this thesis, detailed observation has revealed that SI PM is partly composed of fully-formed carbon nanotubes and fullerenes in addition to known particle types previously presented in the literature. The purpose of this work is to ascertain the shape and size of particulate matter being emitted by SI engines. In this thesis, PM thermophoretic sampling and transmission electron microscopy were used to collect and analyze engine soot samples, respectively. Furthermore, the operation of the thermophoretic sampling device used in engine PM sample collection was characterized to identify the sampling efficiency based on particle deposition and sampling biases based on differences in particle thermoconductivity for various forms of carbon such as turbostratic soot, crystalline carbon nanotubes and calcium. In general, the efficiency of the TPS method was roughly estimated to be 30-80% efficient based on experimental results.In this thesis, carbon nanotubes and fullerenes have been identified as being emitted from in-use, spark-ignited natural gas and gasoline burning auto-rickshaw engines tested in New Delhi, India. Emission of fullerenes and CNTs was on the order of 10% +/- 7% of the non-volatile particulate matter. Agglomerates, dense spherical particles believed to be charred engine oil, and unidentified or compound particles were also cataloged. Confirmation that nanotubes are being produced by SI engines was achieved using PM samples collected from the Ricardo Hydra laboratory test engine at the University of British Columbia, Clean Energy Research Centre. Under more controlled conditions than can be achieved sampling in-use vehicles, SI engine PM is found to be a complex collection of dense, dark (possibly charred oil) spheres, small primary particle agglomerates, small particle deposits, volatile droplets, carbon nanotubes and fullerenes and large ‘other’ particles. High resolution TEM confirmed tube-shaped particles to be fully formed multi-walled carbon nanotubes.

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High-pressure direct-injection of natural gas for use in compression-ignition engines has been found to reduce emissions without sacrificing performance relative to pure diesel operation. In the present work, prototype ‘co-injectors’ which inject a diesel and natural gas mixture from a single injector were tested in a heavy-duty, 6-cylinder Cummins ISX engine with 5 cylinders disabled. One prototype (‘B’) was tested under low-speed, low-load conditions, to determine the effects of fuel flows and in-cylinder conditions on the combustion characteristics of co-injection. Co-injector B, and a second prototype (Co-injector CS: A variation of Co-injector B which mixes the fuels differently) were tested at three engine modes using two injections per cycle to determine the effect of the duration of the first injection on emissions and combustion characteristics. The performance of the co-injectors was compared to Westport Innovation’s High Pressure Direct Injection (HPDI) J36 injector to determine if co-injection can produce comparable emissions.Single injection tests carried out with Co-injector B at 800 RPM over a range of diesel flows, gas flows, injection pressures, and cylinder temperatures & pressures were used to generate response surfaces for knock intensity, ignition delay, and combustion efficiency. It was found that diesel flow and the cylinder pressure at the time of injection had the largest effect of knock intensity and ignition delay, and that the knock/ignition delay relationship in co-injection is inverse. The double injection tests showed that the difference in diesel distributions within the gas plenums of CS and B results in more diesel being injected during the first injection in CS compared to B, which supports previous results. It was found that short first pulses resulted in the lowest emissions for both co-injectors, and that with low first gas pulse widths the performance of the co-injectors is comparable to that of Westport’s HPDI-J36 injector.

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Natural gas has a high auto-ignition temperature, therefore natural gas engines use anignition source to promote combustion. The high-pressure direction-injection (HPDI)systems available use small diesel injections prior to the main gas injection. A new seriesof HPDI injectors have been developed that inject diesel and gas simultaneously throughthe same holes. In order to understand and control injection and combustion behavior inan engine, it is essential to understand how injection mass is related to the diesel/gas ratioand injection command parameters.Three prototype injectors are examined. “Prototype B” most closely resembles a standardJ36 HPDI injector, but has a modified diesel needle that injects diesel internally into acommon diesel/gas reservoir. Prototypes “CS & CSX” have the diesel needle eliminatedand replaced with a flow restrictor. The pressure difference between the diesel and thegas controls the quantity of diesel injected. A single pulse width (GPW) for the gasneedle controls the fuel quantities.An injection visualization chamber (IVC) was developed for flow measurements andoptical characterization of injections into a chamber at pressures up to 80 bar. Diesel andnatural gas are replaced by VISCOR® and nitrogen to study non-reacting flows. A novelfeature of the IVC is a retracting shroud that allows the injector to reach steady-state priorto imaging.For low commanded injection duration (GPW less than 0.60 ms), the relation betweenGPW and injected mass is non-linear, for all injectors tested. For gas pulse widths greaterthan 0.65 ms the Co-injectors exhibit approximately linear behavior with higher dieselfuelling quantities lowering gas flow quantities. All Co-injectors are compared tobaseline gas flow quantities of a standard J36 to show design difference effects on flowquantities. The sensitivity of gas flow to diesel in injection quantities, as well as thedischarge coefficient are computed and theoretically modeled for each prototype. Resultssuggest differing diesel/gas distributions, dependent on method of diesel introduction andactuator response.Imaging indicates the mechanical delay of the injectors is independent of chamberbackpressure but dependent on fuel supply pressure. However, gas injection quantitiesare increased by higher chamber backpressure. Changes in the gas/liquid ratio arereflected in different jet image characteristics. These results are compared to theory usingan AMESim model developed for an existing production injector.

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