Reduction of Toxic Air Contaminants (TACs) and particulate matter emissions from heavy-duty natural gas engines

Increasing urban pollution levels have driven the Federal and the local air control boards to impose stricter emissions regulations on heavy-duty engines earmarked for transit buses. This has made natural gas a promising fuel for reducing the emissions of oxides of nitrogen and predominantly particulate matter from heavy-duty transit buses. Recent research studies performed at WVU and elsewhere have showed that natural gas engines emit an order of magnitude lower PM emissions, on a mass basis, when compared to diesel engines without any exhaust aftertreatment devices. However, on a number basis the emissions from natural gas fueled buses were an order of magnitude higher than their diesel counterparts.;This project was initiated by Southern California Air Quality Management District to design and develop an exhaust aftertreatment device for retrofitting urban transit buses powered by heavy-duty natural gas engines. The exhaust aftertreatment device was developed for a Cummins Westport C8.3G+ natural gas engine. Exhaust samples were collected by operating the vehicle on the Central Business District cycle on a chassis dynamometer. Regulated emissions were continuously measured while non-regulated emissions samples were collected on different media from a full flow dilution tunnel. In addition, PM concentrations and size distributions were also measured. (Abstract shortened by UMI.)

Development of a Reference Dataset to Evaluate PEMS Post-Processing Software

Since the implementation of in-use emissions standards, an outcome of the consent decree between heavy-duty diesel engine manufacturers and the Environmental Protection Agency (EPA), there has been an increased interest in the research and development of portable emissions measurement systems (PEMS) that are capable of analyzing exhaust emissions continuously while a vehicle or equipment powered by an internal combustion engine is performing its intended vocation. Ultimately for an engine to pass in-use emissions requirements, the brake specific emissions of regulated pollutants measured over valid Not-to-Exceed (NTE) events must be less than or equal to 1.25 or 1.5 times the engine emission certification standards, based on the engine model year (MY), plus an additional margin known as in-use measurement allowance. The vehicle has to satisfy the in-use emissions standard for 90% of the NTE events provided the brake specific emissions over the rest of the events are less than two times the certification level to comply with in-use emission regulations.;As in-use emissions measurement and regulation together form a requirement since 2004 for certification of engines, it is imperative to develop procedures of oversight similar to ones that exist for laboratory-based engine certification. Therefore, a reference data set that incorporates all the in-use emissions regulations used to quantify the measured emissions over an NTE event, including the conditions used to validate an NTE event is developed in the direction of providing a means to validate commercial PEMS data analysis software.;A reference data set was designed and used to evaluate the post-processing software of two commercial PEMS devices. A black box testing methodology was implemented to evaluate the performance of the post-processing software. Specifically, the input data set was developed to execute different sections of the program based on logical conditions required to branch into a particular section therefore verifying the truth in executing a logical condition and the interpretation of in-use emissions regulation. Also, the brake specific emissions results to be expected from the given input data set were known a priori to verify the accuracy of the equations used in calculating the final emissions results. The dataset was also used to evaluate PEMS data post-processing software developed at WVU.;The test results indicated that definition of NTE emissions performance was not in agreement for the post-processing software evaluated. Being that compliance is required for manufacturers to sell engines without penalty, it is critical that the metric by which compliance is assessed must be accurate and robust. As such, the reference data set developed will serve in identifying interpretation errors of in-use emissions regulations as well as calculation error and reduce the chances of triggering false positives and negatives that could prove costly to engine manufacturers as well as air quality regulating agencies. This reference data set will also serve in effective implementation of any modification of existing or additional new in-use emissions compliance requirements and verify it across different in-use emissions data post-processing software supplied by PEMS manufacturers and developed in-house. Test results showed that PEMS post-processors outcome were not in agreement with expected total number of 166 NTE events as the in-house, PEMS A and PEMS B returned 216, 288 and 190 NTE events respectively. The reference dataset was instrumental in identifying interpretation error in the in-house data post-processor leading to a revised version of the software that matched the expected results

Kinetics of the reaction between a brompropionate and silver ions. A heterogeneous reaction taking place on the surface of silver bromide

A detailed study of the kinetics of the reaction between a brompropionate and silver ions has been made in very dilute solutions at 27°C. The hydrolysis of the brompropionate ion in pure aqueous solutions is an extremely slow reaction. In very dilute solutions (below about 0·001 N) the reaction is an extremely slow one even when silver nitrate solution is added. The velocity of reaction becomes rapid only when some silver bromide is formed in suspension and an analysis of the data obtained in the investigation proves beyond all doubt that the reaction is almost entirely heterogeneous, taking place on the surface of silver bromide particles. In dilute solutions in which silver bromide exists in fine and stable suspension, it has been found that the velocity of reaction is strictly proportional to the amount of silver bromide in suspension. It is inferred from the order of the reaction that both silver and brompropionate ions are sparsely adsorbed on the surface of the silver bromide particles. In different experiments, when the initial concentration of one of the reactants is kept constant and that of the other increased, the amount of silver bromide in the different reaction mixtures at the beginning and end of the reaction being nearly the same, it has been found that the velocity constant gradually falls. This variation seems to indicate that as the ratio of the concentrations of the reactants increases under otherwise identical experimental conditions the relative orientation of the two kinds of ions in the adsorbed layer becomes less and less favorable for reaction

Studies on the biology of the commoner gadoides in the Manx area, with special reference to their food and feeding habits

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Electrodeposition of antimony

This article does not have an abstract

Waste Heat Recovery in Heavy‐Duty Diesel Engines: a Thermodynamic Analysis of Waste Heat Availability as Requirement for Implementation of Energy Recovery Systems Based Upon the Organic Rankine Cycle

In the past decade automotive industries have focused on the development of new technologies to improve the overall engine efficiency and lower emissions in order to satisfy the always more stringent emission standards introduced all around the world. Technical progress has primarily focused on two aspects; the optimization of the air-fuel mixture in the combustion chamber as well as the combustion process itself, leading to simultaneous improvements in both, efficiency (lowering fuel consumption for same power output) and emissions levels which ultimately result from the optimized combustion process. Although engine technology has made significant progress, even modern Diesel combustion engines do not exceed a maximum efficiency of approximately 40%. Hence, around 60% of the available energy carried by the fuel and entering the combustion chamber is dissipated as heat to the environment. The next steps in engine optimization will see the integration of waste heat recovery systems (WHRS) to increase the overall energy efficiency of the propulsion system by means of recovering parts of the waste heat generated during normal engine operation. The presented was aimed at analyzing the availability as well as the quality of heat to be used in WHRS for the case of heavy-duty Diesel (HDD) engines employed in Class-8 tractors, which are suitable candidates for optimization via WHRS implementation as their engines spend most of their time operating at quasi steady state conditions, such as highway cruise. Three different primary energy sources have been considered: exhaust gas recirculation (EGR) cooling system, engine cooling system and exhaust gas stream. Experimental data has been gathered at West Virginia University’s Engine and Emissions Research Laboratory (EERL) facility in order to quantify individual heat flows in a model year (MY) 2004 Mack® MP7-355E HDD engine operated over the 13 modes of the European Stationary Cycle (ESC). Analysis based on second law efficiency underlined that not the whole amount of waste heat can be successfully used for recovery purposes and that heat sources which offer a large amount of waste energy reveal to be inappropriate for recovery purposes in case of low operating temperature. Time integral analysis revealed that engine modes which appear to offer high recovery potential in terms of waste power may not be suitable engine operating conditions when the analysis is performed in terms of waste energy, depending on the particular engine cycle. Finally a simple thermodynamic model of a micro power unit running on an Organic Rankine Cycle (ORC) has been used to assess the theoretical improvement in engine efficiency during steady state operations based on a second law efficiency analysis approach.</jats:p