Browsing by Subject "Diesel"
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Item Efficacy Of Heated Hydrous Ethanol Injection For Improving Emissions From Dual Fuel Diesel Engines(2017-05) Nord, AlexWith emissions standards becoming ever more stringent, aftermarket dual-fuel solutions are being developed to allow legacy diesel engines to reach higher regulatory emissions tiers. Manufacturers are reluctant to adopt dual-fuel systems due to perceived lack of consumer interest. However, the use of aftermarket dual-fuel systems with partially renewable fuels has sparked interest in limited markets. Previous research has shown slight emissions reduction benefits from fumigation with 120 proof hydrous ethanol in a diesel engine using a commercially available dual-fuel system. However, the findings do not match manufacturer claims of emissions reductions. The work presented here examines the design, development, performance, and emissions from an engine equipped with a novel aftermarket port fuel injection (PFI) dual fuel system with a fuel heating system integrated into the fuel injector rail. Finite element modeling techniques in ANSYS were used to optimize the heat exchanger and analyze its performance. In addition, cross-sections and flow path lines were created in ANSYS to examine thermal profiles and flow turbulence at varying ethanol flow rates. A John Deere 4045HF475 Tier 2 diesel engine was retrofitted with a custom PFI rail designed to inject hydrous ethanol with the ability to preheat the ethanol using circulated hot engine coolant to improve the vaporization and mixing of the secondary fuel and air in the intake port. Port-injected fuel flow was controlled by varying injector pulse width and throttle position was adjusted manually to maintain testing mode parameters. Heated ethanol, unheated ethanol, and diesel only operating modes were run over a modified ISO 8178 eight-point test plan. Fumigant energy fraction (FEF), defined as the amount of energy provided by the fumigant based on the lower heating value (LHV) divided by the total fuel energy, up to 37% was achieved in the experiments. Ethanol fuel rail heat exchanger effectiveness decreased with increasing FEF and log-mean temperature difference (LMTD) increased. These opposite effects were likely due to dimensional design constraints of the heat exchanger limiting the heat transfer. Experiments found that with increasing FEF, engine NO emissions decreased, whereas NO2, CO, THC, and ethanol emissions increased. NO emissions reductions were countered by increasing NO2, resulting in constant NOX emissions. Soot concentrations produced varying trends, but with a tendency to decrease overall at high FEF. Preheating the ethanol with circulated engine coolant yielded few benefits to engine out-emissions. This study showed that the dual-fuel heated PFI rail system provided modest emissions benefits over diesel-only operation. Preheating the liquid ethanol was not as successful as anticipated because ethanol’s high latent heat of vaporization dominated over the sensible heat required to heat the liquid prior to the injectors.Item Evaluation and development of methods for measurement of penetration of filtering facepiece respirators(2015-07) Satish, SwathiElevated concentrations of diesel exhaust have been linked to adverse health effects. Filtering facepiece respirators (FFRs) are widely used as a form of respiratory protection against diesel particulate matter (DPM) in occupational settings. The objective of this study was to evaluate NIOSH-certified R95 and P95 electret respirators challenged with Diesel exhaust and get a better understanding of the factors that influence penetration. Two techniques were employed for the measurement of penetration: (a) particle counting technique using a Scanning Mobility Particle Sizer (SMPS, TSI Inc.) which measures particle size distribution, and (b) Gravimetric analysis using polyfluortetraethylene (PTFE) and polypropylene (PP) filters. Gravimetric measurements using PP filters were variable compared to SMPS measurements and biased high as a result of the adsorption of gas-phase semi-volatile material. Relatively inert PTFE filters adsorbed less semi-volatile material resulting in more accurate measurements. To attempt to correct for these artifacts associated with adsorption of semi-volatile material, primary and secondary filters were used in series upstream and downstream of the FFR. Correcting for adsorption by subtracting the secondary mass from the primary mass improved the result for both PTFE and PP filters but this correction is subject to “equilibrium” conditions that depend on sampling time and the concentration of particles and semi-volatile material. Overall, the results demonstrate that great care must be taken when using filters to determine filtration efficiency of FFRs challenged with diesel exhaust. Pure PTFE or other filters that minimize adsorption of semi-volatile artifacts and two filters should be used in tandem to allow correction for adsorbed artifacts. Analysis of SMPS measurements indicated that the respirators behave differently for Diesel exhaust generated at light and heavy load on engine. At light load, the penetration of the R-95 and P-95 respirators showed a steep increase with time, exceeding the maximum allowed penetration of 5% after about 40 minutes. Whereas at heavy load, the respirators were found to have a relatively unchanging penetration (less than 5%) throughout the 90-minute test duration. This difference was attributed to the presence of a high concentration of organic carbon (OC) in Diesel exhaust which has a tendency to degrade the electric charges on the respirators, thus reducing the filtration enhancement from electrostatic attraction forces. To account for the complex nature of DPM and its varying properties with changes in operating and sampling condition, an oxidation-dilution tunnel was designed to produce Diesel exhaust with a controlled set of properties: elemental carbon (EC) concentration, OC concentration, EC/OC ratio and volume flow rate. This device was used to evaluate R-95 and P-95 respirators for solid Diesel exhaust aerosol. The methodology proved to be effective in controlling the EC concentration and total volume flow rate. Results showed that the R-95 and P-95 respirators were more than 95% efficient for solid Diesel exhaust aerosol. This thesis is divided into two parts. The first focuses on the measurement of penetration of FFRs for Diesel exhaust, the second on the development of a standard DPM generator for testing filtration systems.Item Measurement and Fractionation of Diesel Exhaust Hydrocarbons through Variable Temperature Controlled-Condensation and Flame Ionization Detection(2014-05) Avenido, AaronThe industry standard for measuring hydrocarbons in engine exhaust is the flame ionization detector (FID). FID can measure total hydrocarbon concentrations but is limited in that it is not equally sensitive to all hydrocarbons present in exhaust. Instruments capable of measuring individual gas species such as gas chromatography with mass spectrometry (GC/MS) are expensive and sensitive to sample conditioning. A need exists for a simple and relatively inexpensive method to estimate the distribution of lube oil, partially burned, and unburned hydrocarbons present in the exhaust of internal combustion engines. In this work, a custom-designed variable temperature sample conditioner was developed for use with two fast-response FIDs to determine the condensable fraction of hydrocarbons present in engine exhaust over a range of temperatures. A correction model was developed to compensate for water condensing from the exhaust, nitrogen and carbon dioxide dissolving in the condensing water, and the reduced response factor of a FID in the presence of water. Sample conditioner data processed with the correction model were used to analyze low temperature combustion (LTC) and conventional engine operating modes for diesel fuel and various biodiesel blends. A theoretical model predicting the condensation of unburned biodiesel as a function of temperature was created using Antoine's equation and was used to validate the hypothesis that the middle weight condensing hydrocarbons were largely unburned fuel. The model was also used to estimate a relative response factor of 0.65 for the unburned biodiesel, resulting in a response factor of 0.77 for the total HC in the exhaust using the FID tested.