<p dir="ltr"> Diesel engines are widely used in various off-road settings, ranging from railroad locomotives and marine vessels to agricultural, construction, logging, and mining equipment. Diesel engines are favored due to their reliability, durability, high thermal efficiency, and capacity to generate significant power. However, they also emit a range of harmful pollutants, such as oxides of nitrogen (NOx), particulate matter (PM), carbon monoxide (CO), and hydrocarbons (HC). Over the past three decades, original engine manufacturers have faced increasingly stringent emission regulations. In the United States, the proposed Tier 5 emission standards aim to achieve a significant reduction in NOx emissions, targeting a reduction of up to 90%, as well as a reduction in particulate matter emissions of up to 75%. To meet these stringent regulations, original engine manufacturers are investigating new technologies.</p><p dir="ltr"> Cooled exhaust gas recirculation (EGR) is a widely used method to lower NOx emissions. The EGR flow rates are contingent on positive engine delta pressure (exhaust manifold pressure - intake manifold pressure) to drive EGR. Eaton’s Generation 3 Exhaust Gas Recirculation Pump (EGRP) eliminates the need for positive engine delta pressure and enables the application of a high-efficiency turbocharger. A high-efficiency turbocharger reduces the pumping work and thus improves fuel efficiency.</p><p dir="ltr"> Transient tests were conducted on a 13.6 L S750 John Deere Engine with both the stock hardware and the EGRP and high-efficiency turbocharger hardware, to evaluate the benefits of the new technology. The transient tests included the Constant Speed Load Acceptance Test (CSLA), the Nonroad Transient Cycle (NRTC), and the Low Load Application Cycle (LLAC). There was no aftertreatment systems in the test cell setup, so engine-out brake specific oxides of nitrogen (BSNOx) and engine-out brake specific particulate matter (BSPM) were examined. To evaluate the technology, results from the stock hardware setup were compared to the results from the EGRP and high-efficiency turbocharger setup.</p><p dir="ltr"> During the CSLA, the time response to 90% load with the EGRP-equipped engine was <a href="" target="_blank">generally slower</a> than the stock engine, with deviations ranging from 0.1s to 1.6s. This result was attributed to the EGR pump not reducing speed fast enough, resulting in insufficient fresh air to produce torque. In the NRTC, engine torque was compared between both configurations. It was discovered that the EGRP-equipped engine did not reach the desired torque setpoints. There was more EGR flow than expected and not enough fresh air. This pattern was also revealed in the LLAC.</p><h4> To ensure accurate comparisons, measured engine speed and load data from the EGRP configuration were used to establish a Modified NRTC and Modified LLAC. For the Modified NRTC, the brake specific fuel consumption (BSFC) improved by 1.3%, and the engine-out brake specific particulate matter improved by 33.1% with the EGRP and high-efficiency turbocharger. However, the engine-out BSNOx increased by 12.9%. For the Modified LLAC, the BSFC and engine-out BSNOx improved by 2.5% and 11.1%, respectively, with the EGRP setup. However, this improvement came at the expense of engine-out BSPM, which increased by 34.2%. The improvement in BSFC for both cycles could be attributed to the increased open-cycle efficiency seen in steady state data with the EGRP and high-efficiency turbocharger.</h4><p></p>

<p>The ion current measured from the spark plug in a spark ignited combustion engine is used </p><p>as basis for analysis and control of the combustion variability caused by exhaust gas </p><p>recirculation. Methods for extraction of in-cylinder pressure information from the ion </p><p>current are analyzed in terms of reliability and processing efficiency. A model for the </p><p>recognition of combustion variability using this information is selected and tested on both </p><p>simulated and car data.</p>

The objectives in this thesis are to present a model of a variable venturi in an exhaust gas recirculation (EGR) system located in a heavy duty diesel engine. A new legislation called EURO~4 will come into force in 2005 which affects truck development and it will require an On-Board Diagnostic system in the truck. If model based diagnostic systems are to be used, one of the advantages is that the system performance will increase if a model of a variable venturi is used. Three models with different complexity are compared in ten different experiments. The experiments are performed in a steady flow rig at different percentage of EGR gases and venturi areas. The model predicts the mass flow through the venturi. The results show that the first model with fewer simplifications performs better and has fewer errors than the other two models. The simplifications that differ between the models are initial velocity before the venturi and the assumption of incompressible flow. The model that shows the best result is not proposed by known literature in this area of knowledge and technology. This thesis shows that further studies and work on this model, the model with fewer simplifications, can be advantageous.

The ion current measured from the spark plug in a spark ignited combustion engine is used as basis for analysis and control of the combustion variability caused by exhaust gas recirculation. Methods for extraction of in-cylinder pressure information from the ion current are analyzed in terms of reliability and processing efficiency. A model for the recognition of combustion variability using this information is selected and tested on both simulated and car data.

<p>The objectives in this thesis are to present a model of a variable venturi in an exhaust gas recirculation (EGR) system located in a heavy duty diesel engine. A new legislation called EURO~4 will come into force in 2005 which affects truck development and it will require an On-Board Diagnostic system in the truck. If model based diagnostic systems are to be used, one of the advantages is that the system performance will increase if a model of a variable venturi is used. </p><p>Three models with different complexity are compared in ten different experiments. The experiments are performed in a steady flow rig at different percentage of EGR gases and venturi areas. The model predicts the mass flow through the venturi. The results show that the first model with fewer simplifications performs better and has fewer errors than the other two models. The simplifications that differ between the models are initial velocity before the venturi and the assumption of incompressible flow. </p><p>The model that shows the best result is not proposed by known literature in this area of knowledge and technology. This thesis shows that further studies and work on this model, the model with fewer simplifications, can be advantageous.</p>

the 18th World Congress The International Federation of Automatic Control, Milano (Italy), August 28 - September 2, 2011

The member states of European Union aim to promote the reduction of harmful emissions. Emissions from combustion processes cause effects on human health and pose environmental issues, for example by increasing greenhouse effect. There are two ways to reduce emissions; one is to promote renewable energy sources and the other to utilize more effectively the available fossil fuels until a long-term solution is available. Hence, it is necessary to strive for CO2 mitigation technologies applied to fossil fuels. Low natural gas prices together with high energy efficiency have made gas turbines popular in the energy market. But, gas turbine fired with natural gas come along with emissions of CO2, NOx and CO. However, these disadvantages can be eliminated by using gas turbine with precombustion CO2 capture, separating carbon from the fuel by using fuel reforming process and feeding pure hydrogen as a fuel. Hydrogen fired gas turbines are used in two applications such as a gas turbine with pre-combustion CO2 capture and for renewable power plants where hydrogen is stored in case as a backup plan. Although the CO2 emissions are reduced in a hydrogen fired gas turbine with a pre-combustion CO2 capture, there are still several challenges such as high flame temperatures resulting in production of thermal NOx. This project suggests a method for application of hydrogen fired gas turbine, using exhaust gas recirculation to reduce flame temperature and thus reducing thermal NOx. A NOx emission model for a hydrogen-fired gas turbine was built from literature data and used to select the best operating conditions for the plant. In addition, the economic benefits of switching from natural gas to pure hydrogen are reported. For the techno-economic analysis, investment costs and operating costs were taken from the literature, and an economic model was developed. To provide sensitivity analysis for the techno-economic calculation, three cases were studied. Literature review was carried out on several journal articles and websites to gain understanding on hydrogen and natural gas fired gas turbines. Results showed that, in the current state, pure hydrogen has high delivery cost both in the US and Europe. While it’s easy to access natural gas at low cost, therefore in the current state gas turbine fired with natural gas are more profitable than hydrogen fired gas turbine. But, if targeted hydrogen prices are reached while fuel reforming process technology are developed in the coming future the hydrogen fired gas turbine will compete seriously with natural gas.

Selective Exhaust Gas Recirculation (S-EGR) consists of selectively transferring CO2 from the exhaust gas stream of a gas-fired power plant into the air stream entering the gas turbine compressor. Unlike in “non-selective” Exhaust Gas Recirculation (EGR) technology, recirculation of, principally, nitrogen does not occur, and the gas turbine still operates with a large excess of air. Two configurations are proposed: one with the CO2 transfer system operating in parallel to the post-combustion carbon capture (PCC) unit; the other with the CO2 transfer system operating downstream of, and in series to, the PCC unit. S-EGR allows for higher CO2 concentrations in the flue gas of approximately 13-14 vol%, compared to 6.6 vol% with EGR at 35% recirculation ratio. The oxygen levels in the combustor are approximately 19 vol%, well above the minimum limit of 16 vol% with 35% EGR reported in literature. At these operating conditions, process model simulations show that the current class of gas turbine engines can operate without a significant deviation in the compressor and the turbine performance from the design conditions. Compressor inlet temperature and CO2 concentration in the working fluid are critical parameters in the assessment of the effect on the gas turbine net power output and efficiency. A higher turbine exhaust temperature allows the generation of additional steam which results in a marginal increase in the combined cycle net power output of 5% and 2% in the investigated configurations with S-EGR in parallel and S-EGR in series, respectively. With aqueous monoethanolamine scrubbing technology, S-EGR leads to operation and cost benefits. S-EGR in parallel operating at 70% recirculation, 97% selective CO2 transfer efficiency and 96% PCC efficiency results in a reduction of 46% in packing volume and 5% in specific reboiler duty, compared to air-based combustion CCGT with PCC, and of 10% in packing volume and 2% in specific reboiler duty, compared to 35% EGR. S-EGR in series operating at 95% selective CO2 transfer efficiency and 32% PCC efficiency results in a reduction of 64% in packing volume and 7% in specific reboiler duty, compared to air-based, and of 40% in packing volume and 4% in specific reboiler duty, compared to 35% EGR. An analysis of key performance indicators for selective CO2 transfer proposes physical adsorption in rotary wheel systems as an alternative to selective CO2 membrane systems. A conceptual design assessment with two commercially available adsorbent materials, activated carbon and Zeolite X13, shows that it is possible to regenerate the adsorbent with air at near ambient temperature and pressure. Yet, a significant step change in adsorbent materials is necessary to design rotary adsorption systems with dimensions comparable to the largest rotary gas/gas heat exchanger used in coal-fired power plants, i.e. approximately 24 m diameter and 2 m height. An optimisation study provides guidelines on the equilibrium parameters for the development of materials. Finally, a technical feasibility study of configuration options with rotary gas/gas heat exchangers shows that cooling water demand around the post-combustion CO2 capture system can be drastically reduced using dry cooling systems where gas/gas heat exchangers use ambient air as the cooling fluid. Hybrid cooling configurations reduce cooling and process water demand in the direct contact cooler of a wet cooling system by 67% and 35% respectively, and dry cooling configurations eliminate the use of process and cooling water and achieve adequate gas temperature entering the absorber.

This master‘s thesis deals with design adjustment of spark ignition combustion engine, which might offer larger share of recirculated exhaust gases in cylinder for reaching a large number of benefits that exhaust gas recirculation can offer. The introductory theoretical part describes exhaust gas recirculation and its influence on spark ignition combustion engine. In the following part the methods of mixture layering and types of intake ports are described. Further design of spiral intake port is made based on calculations. Capability of mixture layering is valuated by numerical simulation. Flow properties of intake ports are compared to production version by an experiment on flow station.

Coal ash deposits were collected in a 160 kWth, down-fired oxy-coal reactor under staged and unstaged conditions for four different coals (PRB, Gatling, Illinois #6, and Mahoning). Concentration measurements of carbon, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, titanium, chromium, manganese, iron, nickel, strontium, and barium were gathered from each deposit sample using scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Backscattered electron micrographs for each deposit sample were analyzed to gather morphological data. Particle size and shape were studied for each deposit collected. The average particle sizes of the particles in upstream deposits were much larger than the average particle sizes of the downstream deposits. The downstream deposits consisted primarily of spherical particles while the upstream deposits consisted of round, irregular polygonal, and porous particles. Deposit particles are believed to have deposited at all stages of burnout; those depositing early during pyrolysis may have continued to react after deposition. Element maps for the aforementioned elements were collected with SEM-EDS and analyzed to quantify both average composition and composition of individual particles. These values were compared to ASTM ash analyses performed for each coal and ash collected from the flue gas stream with a cyclonic particle separator. It was found that sulfur concentrations of deposits do not correlate with corresponding sulfur concentrations of the coal. Comparison of similar experiments performed with air-combustion show that oxy-combustion deposits contain about twice as much sulfur as air-combustion deposits when burning the same coal. Deposition propensity of each coal was also examined, and the PRB and Gatling coals were found to have a moderately high deposition propensity whereas the deposition propensity of the Mahoning and Illinois #6 coals was fairly low.