This thesis examines potential improvements to current coal mine fire response measures. In the event of a fire scenario, indirect testing and analysis of the exhausting air is needed to characterize changes in the fire. The application of multiple passive source tracers provides improved detail of complex ventilation interactions over an extended period of time. The first work in this thesis details the testing of the passive release rates for three Perfluorocarbon tracer compounds over a 180-day period. The results of this study demonstrate the ability for the permeation plug release vessel design to release Perfluorocarbon tracers at a steady rate. Current response methods for a fire in a coal mine gob consist of injection of inert gas and sealing of the mine openings. Injection of high expansion foam into the gob from the surface has potential to improve extinguishment of the fire and reduce the time needed to bring the mine back to an operational state. The applicability of this method requires computational modeling and field testing. The second part of this thesis determines the Darcy and Forchheimer values for high expansion foam flow in simulated gob material with a lab experiment. The experiment was replicated in the CFD software, OpenFOAM, to validate the methods for calculation of the Darcy and Forchheimer values. The results of this study provide a tested methodology for a future full scale modeling of high expansion foam injection in a coal mine gob. / Master of Science

Ventilation in underground mines is vital to creating a safe working environment. Though there have been numerous improvements in mine ventilation, it is still difficult to ascertain data on the state of the ventilation system following a disaster in which ventilation controls have been potentially damaged. This information is important when making the decision to send rescue personnel into the mine. By utilizing tracer gas techniques, which are powerful techniques for monitoring ventilation systems, especially in remote or inaccessible areas, analysis of the ventilation system immediately following a mine emergency can be more rapidly ascertained. However, the success of this technique is largely dependent on the accuracy of release and sampling methods. Therefore, an analysis of sampling methods is crucial for rapid response and dependable results during emergencies. This research project involves evaluating and comparing four well-accepted sampling techniques currently utilized in the mining industry using sulfur hexafluoride, an industry standard, as the tracer gas. Additionally, Solid Phase Microextraction (SPME) fibers are introduced and evaluated as an alternative sampling means. Current sampling methods include plastic syringes, glass syringes, Tedlar bags, and vacutainers. SPME fibers have been successfully used in a variety of industries from forensics to environmental sampling and are a solvent-less method of sampling analytes. To analyze these sampling methods, samples were taken from a 0.01% standard mixture of SF6 in nitrogen and analyzed using electron capture gas chromatography (GC). The technical and practical issues surrounding each sampling method were also observed and discussed. Furthermore, the use of multiple tracer gases could allow for rapid assessment of the functionality of ventilation controls. This paper describes experimentation related to the determination of a novel mine tracer gas. Multiple tracer gases greatly increase the level of flexibility when conducting ventilation surveys to establish and monitor controls. A second tracer would substantially reduce the time it takes to administer multiple surveys since it is not necessary to wait for the first tracer to flush out of the mine which can take up to a few days. Additionally, it is possible to release different tracers at different points and follow their respective airflow paths, analyzing multiple or complex circuits. This would be impossible to do simultaneously with only one tracer. Three different tracer gases, carbon tetrafluoride, octofluoropropane, and perfluoromethlycyclohexane, were selected and evaluated on various GC columns through utilizing different gas chromatographic protocols. Perfluoromethylcyclohexane was selected as the novel tracer, and a final protocol was established that ensured adequate separation of a mixture of SF6 and perfluoromethylcyclohexane. Since there is limited literature comparing sampling techniques in the mining industry, the findings and conclusions gained from the sampling comparison study provide a benchmark for establishing optimal sampling practices for tracer gas techniques. Additionally, the determination of a novel tracer gas that can be used with and separated from SF6 using the same analytical method increases the practicality and robustness of multiple mine tracer gas techniques. This initial work will contribute to the larger project scope of determining a methodology for the remote characterization of mine ventilation systems through utilizing multiple mine tracer gases and computational fluid dynamics (CFD). This will be completed through several phases including initial laboratory testing of novel tracer gases in a model mine apparatus to develop a methodology for releasing, sampling, and modeling a mine ventilation plan and tracer gas dispersion in CFD and eventually completing field trials to validate and enhance the multiple tracer gas methodology. / Master of Science

An experimental mine simulator was constructed which will be used to conduct tracer gas experiments in the laboratory. The test apparatus simulates a mine in a tabular deposit and is modular and simple and can be easily rearranged to represent a variety of mine geometries. The apparatus is appropriate for the use of tracer gases by being both airtight and open-circuit (exhausting to the atmosphere) and by maintaining turbulent flow throughout the model, ensuring the tracer gas is fully dispersed. The model features ports for injection and sampling of tracer gases, which represent boreholes present in an actual mine. The model is designed, in part, for the practice of tracer gas release and sampling methods in the laboratory. Valves on the apparatus represent ventilation controls, such as stoppings or regulators, or changing resistances in a mine, such an increase in resistance due to a roof fall or a decrease in resistance due to stoppings being destroyed. The relative resistances of airways can be changed by changing the status of the valves to represent different states of the ventilation controls. The mine simulator should serve as a tool for identifying and investigating novel tracer gases, developing a procedure for performing ventilation surveys using multiple tracer gases, and eventually developing a method for remotely inferring ventilation changes using tracer gases. / Master of Science

Master of Science / Department of Mechanical and Nuclear Engineering / Mohammad H. Hosni / Byron W. Jones / Due to the high occupant density and large number of travelers on commercial aircraft, it is crucial to limit the transport of contaminants and pathogens amongst passengers. In order to minimize the exposure of passengers to various contaminants of different sizes and characteristic, all mechanisms influencing airflow movement within an aircraft cabin need to be understood. The use of personal gaspers on commercial aircraft and their relation to airborne contaminants and pathogens transport is one such mechanism that was investigated. Tracer gas testing using carbon dioxide (CO[subscript]2) was conducted in a wide-body, 11-row Boeing 767 aircraft cabin mockup using actual aircraft components for air distribution. Three separate experiments were conducted investigating the effect of gaspers on the transport of contaminants. The first series of experiments focused on the effect of gaspers on longitudinal transport patterns within an aircraft cabin environment by measuring the concentration of tracer gas along the length of the aircraft cabin. The second experiment investigated what fraction of air a passenger inhales originates from a gasper in relation to the overall cabin ventilation. The final set of experiments determined if gaspers could limit close range person-to-person transmission of exhaled contaminants. Three separate sets of conclusions were drawn, one for each series of experiments. The first conclusion is that gaspers disrupt the longitudinal transport of contaminants within the aircraft cabin. The second conclusion is that less than 5% of the air inhaled by a passenger is originating from a gasper even with a gasper directed at the passenger's face. This low percentage is a result of the turbulent airflow within the aircraft cabin causing the gasper jet to quickly mix with the overall cabin ventilation air. The last conclusion is that gaspers can reduce person-to-person transmission of exhaled contaminants as much as nearly 90% in some cases. In other cases the gaspers are found to have negligible or negative impact on the transmission of contaminants. These conclusions are dependent upon where the tracer gas plume emanated from, the sampling location, and the configuration of gaspers around the tracer gas release point.

Tracer gas surveys are a powerful means of assessing air quantity in underground mine ventilation circuits.  The execution of a tracer gas style ventilation survey allows for the direct measurement of air quantity in locations where this information is otherwise unattainable.  Such instances include inaccessible regions of the mine or locations of irregular flow.  However, this method of completing a mine ventilation survey is an underused tool in the industry.  This is largely due to the amount of training required to analyze survey results. As well, the survey is relatively slow because of the time required to perform analysis of results and the time required to allow for the total elution of tracer compounds from the ventilation circuit before subsequent tracer releases can be made.  These limitations can be mitigated with the development of a protocol for a novel tracer gas which can be readily implemented with existing technology.  Enhanced tracer gas techniques will significantly improve the flexibility of ventilation surveys.  The most powerful means to improve tracer gas techniques applied to mine ventilation surveys is to alter existing protocols into a method that can be readily applied where tracer surveys already take place. One effective method of enhancing existing tracer gas survey protocols is to simply add a second tracer gas that can be detected on a gas chromatograph -- electron capture detector (GC-ECD) using the same method as with the existing industry standard tracer, sulfur hexafluoride (SF6).  Novel tracer gases that have been successfully implemented in the past called for complex analysis methods requiring special equipment, or were designed for inactive workings.  Experimentation with perfluoromethylcyclohexane (PMCH) and SF6 allowed for ideal chromatographic results.  PMCH is a favorable selection for a novel tracer to work in tandem with SF6 due to its chemical stability, similar physical properties and detection limits to SF6, and its ability to be applied and integrated into an existing system.  Additionally, PMCH has been successfully utilized in other large-scale tracer gas studies. Introduction of a novel tracer gas will make great strides in improving the versatility of underground tracer gas ventilation surveys, but further improvement to the tracer gas technique can be made in simplifying individual steps.  One such step which would benefit from improvement is in sampling.  Solid phase microextraction (SPME) is a sampling method that is designed for rapid sampling at low concentrations which provides precise results with minimal training.  A SPME extracting phase ideal for trace analysis of mine gases was selected and a GC-ECD protocol was established.  The protocol for fiber selection and method optimization when performing trace analysis with SPME is described in detail in this thesis.  Furthermore, the impact of sampling with SPME under varying turbulent conditions is explored, and the ability of SPME to sample multiple trace analytes simultaneously is observed. / Master of Science

There are many instances where fluid and particles traveling through a narrow passage, such as a crack in a window or door, have large but sometimes unseen effects on our daily lives. For instance, in the cold months of the year a pressure gradient can exists between the inside and outside of a building which causes cold, outdoor air to flow inside through any cracks; significantly decreasing heating efficiency. This inflow of atmospheric air can bring with it dangerous contaminant particles to the inside of a building. Pollution can also occur inside a structure from internal sources of contamination, such as smoke generation from a fire. This thesis represents a two-fold examination of these phenomena. The first part of the thesis showcases a method for local measurement of air leakage flow rate, which can be used to quickly assess leakage rates across a surface, such as a window. The method uses a small local enclosure with constant volume placed about a region on the structure under investigation, which is depressurized and injected with a small concentration of carbon dioxide as a tracer gas. The time variation of the pressure and carbon dioxide concentration inside the enclosure are monitored and used to quantify the leakage flow rate as a function of pressure difference. Because of the small size of the enclosure, advanced data processing techniques are necessary to reduce uncertainty in determination of the rate of change of the carbon dioxide concentration that arises from sensor variability. Results of a laboratory demonstration of the proposed leakage detection and characterization device are reported for the problem of leakage through a circular hole in a plate with prescribed pressure differences. Experimental results from the laboratory tests are found to be in excellent agreement with results of a numerical simulation of leakage flow through a hole, as well as predictions from a number of empirical equations for this problem found in the literature. The second part of the thesis is a numerical study of particle capture in the entrance region of a crack, which is a phenomenon previously not well understood or accounted for in empirical correlations. The computational domain for laminar flow through a crack consists of the crack channel and both inlet and exit reservoirs that are much larger than the channel width. The simulations examined different mechanisms for particle capture within the channel entrance region, including collision on the inlet reservoir wall just outside the crack channel, collision within the crack channel due to cross-stream inertia imparted by the entrance flow, collision induced by Brownian diffusion both on the inlet reservoir wall outside of the channel and within the channel, and gravitational collision within the channel. A detailed study of the variation of the entrance penetration factor with parameters such as the Stokes, Peclet, and Froude numbers was performed, and comparison of the numerical predictions with different theoretical expressions were made when the latter were available. Validity of the assumption of penetration factor independence was also examined for cases where both entrance region inertia and gravitational settling are significant.

Scandinavian countries have always been the first in investigation and development of new ventilation systems. In the last years, engineers from Finland and Sweden are studying a new ventilation system known “Confluent jet ventilation system” which is trying to improve displacement and mixing results. The aim of this thesis master is to study the behaviour of three different ventilation systems, mixing ventilation, displacement ventilation and confluent jet ventilation, in an office room by mean of three analysis, temperature gradient analysis, tracer gas analysis and thermal comfort analysis, and to compare them to know if the new one, confluent jet, increases the performance of mixing or displacement ventilation system. In case of confluent jet ventilation system, there were two different cases: one with the supply air device at 2.2m high, and the other with it at 1.7m high to compare which one was the correct position and gets the best results. For each studied system 3 different cases were analyzed, having the same parameters each one of them for the three ventilation systems.The measurements were taken in an office room located in the laboratory of the University of Gävle, Högskolan I Gävle, in collaboration with the Finnish company specialized in ventilation systems, Stravent. For temperature gradient analysis, ten sensors took temperatures from the low level, 0.1m high, to the top level of the room, 2.4m, during all the time that the other measurements were being taken. For tracer gas analysis, a data logger took measurements of the contaminant concentration, N2O, from when the contaminant was thrown into the room until it disappeared following a Decay curve. Lastly, in thermal comfort analysis 4 transducers took measurements each 12 minutes of air temperature, operative temperature, air velocity and air humidity are measured in 6 different points inside the office room and at 3 different heights, 0.1m, 1.1m and 1.7m. After analyzing the results of temperature gradient, tracer gas and thermal comfort the best results were obtained by confluent jet system with the supply air device at 2.2m in case of temperature gradient, since the difference of temperatures between the low and the top level were the minimum and contaminants and indoor air were not in a homogeneous mixing. In case of tracer gas, the results about air change efficiency were not the expected because they showed a well-mixed situation for every system and it should not have been like that. It was caused for the influence of a cooling system situated in the ceiling of the room and the temperature difference between inside and outside the room that affected more than expected. Finally, in thermal comfort analysis, the best results were obtained by confluent jet ventilation, therefore in case of the supply air device at 2.2m and in case of it at 1.7m. To sum up, taking account the results achieved, the confluent jet ventilation got the best results and showed that it is a new ventilation system that must be taken in consideration in the following buildings. Between supply air device at 2.2m and 1.7m the results were very similar, but a bit better in case of the highest height.

abstract: The modeling and simulation of airflow dynamics in buildings has many applications including indoor air quality and ventilation analysis, contaminant dispersion prediction, and the calculation of personal occupant exposure. Multi-zone airflow model software programs provide such capabilities in a manner that is practical for whole building analysis. This research addresses the need for calibration methodologies to improve the prediction accuracy of multi-zone software programs. Of particular interest is accurate modeling of airflow dynamics in response to extraordinary events, i.e. chemical and biological attacks. This research developed and explored a candidate calibration methodology which utilizes tracer gas (e.g., CO2) data. A key concept behind this research was that calibration of airflow models is a highly over-parameterized problem and that some form of model reduction is imperative. Model reduction was achieved by proposing the concept of macro-zones, i.e. groups of rooms that can be combined into one zone for the purposes of predicting or studying dynamic airflow behavior under different types of stimuli. The proposed calibration methodology consists of five steps: (i) develop a "somewhat" realistic or partially calibrated multi-zone model of a building so that the subsequent steps yield meaningful results, (ii) perform an airflow-based sensitivity analysis to determine influential system drivers, (iii) perform a tracer gas-based sensitivity analysis to identify macro-zones for model reduction, (iv) release CO2 in the building and measure tracer gas concentrations in at least one room within each macro-zone (some replication in other rooms is highly desirable) and use these measurements to further calibrate aggregate flow parameters of macro-zone flow elements so as to improve the model fit, and (v) evaluate model adequacy of the updated model based on some metric. The proposed methodology was first evaluated with a synthetic building and subsequently refined using actual measured airflows and CO2 concentrations for a real building. The airflow dynamics of the buildings analyzed were found to be dominated by the HVAC system. In such buildings, rectifying differences between measured and predicted tracer gas behavior should focus on factors impacting room air change rates first and flow parameter assumptions between zones second. / Dissertation/Thesis / M.S. Built Environment 2011

Master of Science / Department of Mechanical and Nuclear Engineering / Mohammad H. Hosni / Byron W. Jones / The 2015 Airline Traffic Data released by the Bureau of Transportation Statistics (BTS 2016), shows that the commercial flights serving the United States carried an all-time high of 895.5 million passengers in 2015, which represents an approximate 5 % increase in number of passengers from 2014. There is a potential for disease and/or contaminants spreading throughout the airliner cabin raising health risks for passengers and crewmembers onboard flight. In order to limit health risks caused by spread of disease and/or contaminants, it is necessary to understand the various factors affecting the airliner cabin environment. Ventilation effectiveness is one such factor investigated in this study. In addition, experiments were conducted using tracer gas to study the dispersion of tracer gas inside an airliner cabin. Experimental investigations were carried out inside a wide body, eleven-row Boeing 767 mockup cabin and a narrow body, five-row Boeing 737 mockup cabin. The Boeing 767 mockup cabin was constructed with actual aircraft components for air distribution to represent a real aircraft cabin, while the Boeing 737 mockup cabin is a fuselage section from an actual Boeing 737 aircraft. Thermal manikins occupied each seat of both the cabins to simulate thermal load from an average seated person. Four sets of experiments were conducted to evaluate the ventilation effectiveness and dispersion of tracer gas inside the aircraft cabin mockups. The first set of experiments investigated the ventilation effectiveness in a Boeing 767 mockup cabin. The second set of experiments determined the ventilation effectiveness at various heights and locations in a Boeing 737 mockup cabin. The third set of experiments focused on the study of dispersion of tracer gas inside a Boeing 737 mockup cabin with ventilation air. The last set of experiments aimed to study the dispersion of tracer gas inside a Boeing 737 mockup cabin with no ventilation air. The ventilation effectiveness studies were performed by using Carbon Dioxide (CO₂) as a tracer gas and applying the tracer gas decay method. The conclusion for the first set of experiments was that air is efficiently and uniformly supplied to all seat locations inside the Boeing 767 mockup cabin with no clear patterns with respect to seat locations, i.e. window versus center versus aisle observed. From the second set of experiments, it was concluded that the ventilation effectiveness is uniform throughout the Boeing 737 mockup cabin irrespective of seat locations and elevations from cabin floor. In order to determine the spread of disease and/or contaminants, a mixture of CO₂ and Helium (He) was used as a tracer gas. Tracer gas was released from particular locations inside the cabin to simulate gaseous contaminants released by a passenger and sampled at various locations throughout the cabin. The third set of experiments revealed that transport of tracer gas inside an aircraft cabin depends on the source location as well as on the relative distance of the sampling point from the source. Dispersion of tracer gas in the longitudinal direction was also observed inside the cabin. From the fourth set of experiments, it was concluded that even in the absence of ventilation air, considerable dispersion of tracer gas occurred in both the longitudinal and lateral directions.

Proposed diploma work provides capture efficiency measurements of generated pollution captured by reinforced slot exhaust system in modification with work bench using tracer gas method. There are shown results of capture efficiency for traditional exhausting (no radial air added) and reinforced exhausting (using radial air supply effect) in this work. This study also conatins the comparison and discusion of obtained measurement results with measurement errors and uncertainties.