High-Temperature CO2 Sensor with Second-Level Response for Diesel Engine Exhaust Gas Detection Applications.

The employment of aftertreatment systems in modern diesel engines has become indispensable to meet the stringent emissions regulations. However, a minimum exhaust gas temperature of approximately 200 °C must be reached to initiate the emissions control operations. Low-load engine operations usually result in relatively low exhaust gas temperature, which lead to reduced or no exhaust emissions conversion. In this context, this study investigated the use of different combustion control strategies to explore the trade-off between exhaust gas temperature, fuel efficiency, and exhaust emissions. The experiments were performed on a single-cylinder heavy-duty diesel engine at a light load of 2.2 bar indicated mean effective pressure. Strategies including the late intake valve closing timing, intake throttling, late injection timing (Tinj), lower injection pressure (Pinj), and internal exhaust gas recirculation and external exhaust gas recirculation were investigated. The results showed that the use of external exhaust gas recirculation and lower Pinj was not effective in increasing exhaust gas temperature. Although the use of late Tinj could result in higher exhaust gas temperature, the delayed combustion phase led to the highest fuel efficiency penalty. Intake throttling and internal exhaust gas recirculation allowed for an increase in exhaust gas temperature at the expense of higher fuel consumption. In comparison, late intake valve closure strategy achieved the best trade-off between exhaust gas temperature and net indicated specific fuel consumption, increasing the exhaust gas temperature by 52 °C and the fuel consumption penalty by 5.3% while reducing nitrogen oxide and soot emissions simultaneously. When the intake valve closing timing was delayed to after −107 crank angle degree after top dead centre, however, the combustion efficiency deteriorated and the HC and CO emissions were significantly increased. This could be overcome by combining internal exhaust gas recirculation with late intake valve closure to increase the in-cylinder combustion temperature for a more complete combustion. The results demonstrated that the ‘late intake valve closure + internal exhaust gas recirculation’ strategy can be the most effective means, increasing the exhaust gas temperature by 62 °C with 4.6% fuel consumption penalty. Meanwhile, maintaining high combustion efficiency as well as low HC and CO emissions of diesel engines.

<div class="section abstract"><div class="htmlview paragraph">This paper presents several methods to improve the exhaust gas temperature of a modern diesel engine. A high exhaust gas temperature is needed to improve the after-treatment system efficiency and particulate filter regeneration in low engine loads. This study is based on experimental measurements of two Stage 5 level off-road diesel engines. The effect of the different heating methods determined over steady state runs and emission and performance are presented with standard emission transient test procedure (NRTC). In the first step of the study, an intake air restriction and an exhaust gas restriction method are compared. The intake restriction produces better fuel economy over the measuring cycle. However, with the exhaust restriction, higher exhaust gas temperature can be achieved in low engine loads. In the second phase of study, the intake air restriction method was implemented in the research engine. In addition, active waste gate controlling, and injection retardation methods were taken in use for heating purposes. The engine performance was determined with normal calibration and with high exhaust temperature calibration. The differences to the exhaust temperature, engine performance and emission were presented in transient emission cycle NRTC.</div></div>

<div class="htmlview paragraph">This paper presents the results of experimental and theoretical investigations on measuring particulate emissions of diesel engines in a dilution tunnel. The results offer a contribution to understanding the influence of several parameters on the particle phase of exhaust gas when diluted and mixed with air. These parameters include the exhaust gas temperature, the dilution ratio of the exhaust gas in the air, the mixture temperature, the flow and mixture conditions, the amount of filter loading and the filter material. In order to determine which physical/chemical processes dominate particle formation in diluted exhaust gas, the results of calculations in terms of condensation and adsorption are compared with the experimental findings. An increase in measured particulate concentrations is generally favoured by short sampling times, fast mixing processes, high exhaust gas temperatures, low mixture temperatures and low dilution ratios. Furthermore, the results show that adsorption of hydrocarbons to soot particles rather than condensation is the major influence on particulate formation.</div>

Turbocharging is a key technology for reducing emissions in modern automotive internal combustion engines. The application of turbochargers has been regarded as the next step in the downsizing I.C. Engines. The technology has demonstrated its ability to increase the power of small engines by over 30%. This technology had a few drawbacks such as selection of appropriate air-fuel ratio which could either provide better transient response at low load condition or provide increased power at full load condition. In the quest to obtain the benefits of the both conditions, Variable Geometry Turbochargers (VGTs) were introduced. They account for a significant share of the market in mechanical turbocharging for diesel engines. The most common and efficient type of flow control device in use in VGT is the pivoting vane array located at the inlet of the turbocharger. The technology has been effectively applied over the past 20 years in diesel engines due to their relatively lower exhaust gas temperature (compared to gasoline engines) which has allowed inexpensive materials to be used. This isn’t the case for gasoline engines due to their high exhaust gas temperatures. In light of this technical challenge, the current paper discusses the attempts at application of VGTs in gasoline engines and evaluates further material options which can be considered as appropriate candidates for use in the movable nozzle section of a VGT. Exhaust gases temperatures of up to 1050°C with the working pressures reaching in excess of 2 bar is the working environment of a typical VGT. A CFD analysis of appropriately selected materials is presented in this paper and was applied to a generic pivoting vane mechanism, producing results for the stresses and deformations experienced by the selected materials. This paper also includes cost and manufacturability discussion of requirements which will eventually dictate the choice of any given material for mass production. The material is chosen with the help of an in-depth selection processes such as the Paul and Beitz method which includes weighing factors and performance indices. Performance indices can be considered as groups of material properties which represent few important aspect of the performance of the component.

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition Natural Gas engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Most of the heavy duty NG engines are diesel engines which are converted for SI operation. These engine’s components are in common with the diesel-engine which put limits on higher exhaust gas temperature. The engines have lower maximum load level than the corresponding diesel engines. This is mainly due to the lower density of NG, lower compression ratio and limits on knocking and also high exhaust gas temperature. They also have lower efficiency due to mainly the lower compression ratio and the throttling losses. However performing some modifications on the engines such as redesigning the engine’s piston in a way to achieve higher compression ratio and more turbulence, modifying EGR system and optimizing the turbocharging system will result in improving the overall efficiency and the maximum load limit of the engine. This paper presents the detailed information about the engine modifications which result in improving the overall efficiency and extending the maximum load of the engine. Control-related problems associated with the higher loads are also identified and appropriate solutions are suggested.

Dual-fuel diesel engine is an engine with the use of two fuels in the combustion process to get labor on the engine. The types of fuels used include methane gas and marine gas oil fuels. Methane is produced from vapor cargo tank liquified natural gas. The purpose of this study was to determine what causes high exhaust gas temperatures on the performance of the dual-fuel diesel engine using the fault tree analysis data analysis method. From the analysis of the research data, several problems were formulated, namely, the factors that could cause high exhaust gas temperatures in the dual fuel diesel engine were the lack of combustion air supply in the engine combustion chamber, incompatible combustion composition between oil and gas fuel, and the engine room that is extremely hot. The impact caused is damage to the machining components and decreased performance of the dual-fuel diesel engine. To overcome the decrease in work on the dual fuel diesel engine is to carry out maintenance and repair on every component of the engine that has problems and damage in accordance with standard procedures.

Experimental investigation on thermal OS/ORC (Oil Storage/Organic Rankine Cycle) system for waste heat recovery from diesel engine

Biodiesel is an alternative fuel for diesel engine. Considering the differences between diesel and biodiesel fuels, the engine condition should be modified based on the fuel or fuel blends to achieve optimum performance. This study presented a performance analysis of a direct-injected (DI) diesel engine with a dynamometer fueled with diesel-tomato seed biodiesel (TSOB) blends employing ANOVA and universal nonlinear model based on ANN. The experiments were carried out under conditions of some independent variables including different engine loads (0, 50, 100%) and speed (1800, 2150, and 2500 rpm) for four diesel-biodiesel combinations (B0, B5, B10, and B20). In this research, the effect of these factors on dependent variables including power, torque, SFC, FC, and Exhaust Gas Temperature (EGT) are investigated. Duncan′s multi-domain test at a significance level of R < 0.01 shows that the highest and lowest of the torque and power are produced from B5 and B20, respectively. These results show that the lowest EGT of 613 K is related to B20 and the highest EGT is related to B5 and B10. The regression models showed that the torque decreases with increasing the engine speed and biodiesel percentage. These results also show that the highest and the lowest SFC is related to B0 and B20, respectively. The ANN model shows high capability of predicting the engine performance parameters and emissions, without running costly and time-consuming experiments with the histogram error of 0.004 and R = 0.96. It also proved that ANN is a non-linear model of choice to deal with these data, instead of multivariate linear regression employed for preliminary analysis.

Miller cycle has been shown as a promising engine strategy to reduce in-cylinder nitrogen oxide (NOx) formation during the combustion process and facilitate its removal in the aftertreatment systems by increasing the exhaust gas temperature. However, the level of NOx reduction and the increase in exhaust gas temperature achieved by Miller cycle alone is limited. Therefore, research was carried out to investigate the combined use of Miller cycle with other advanced combustion control strategies in order to minimise the NOx emissions and the total cost of ownership. In this article, the effects of Miller cycle, exhaust gas recirculation, and post-injection were studied and analysed on the performance and exhaust emissions of a single cylinder heavy-duty diesel engine. A cost–benefit analysis was carried out using the corrected total fluid efficiency, which includes the estimated urea solution consumption in the NOx aftertreatment system as well as the fuel consumption. The experiments were performed at a low load of 6 bar net indicated mean effective pressure. The results showed that the application of a Miller cycle–only strategy with a retarded intake valve closing at −95 crank angle degree after top dead centre decreased NOx emissions by 21% to 6.0 g/kW h and increased exhaust gas temperature by 30% to 633 K when compared to the baseline engine operation. This was attributed to a reduction in compressed gas temperature by the lower effective compression ratio and the in-cylinder mass trapped due to the retarded intake valve closing. These improvements, however, were accompanied by a fuel-efficiency penalty of 1%. A further reduction in the level of NOx from 6.0 to 3.0 g/kW h was achieved through the addition of exhaust gas recirculation, but soot emissions were more than doubled to 0.022 g/kW h. The introduction of a post-injection was found to counteract this effect, resulting in simultaneous low NOx and soot emissions of 2.5 and 0.012 g/kW h, respectively. When taking into account the urea consumption, the combined use of Miller cycle, exhaust gas recirculation, and post-injection combustion control strategies were found to have relatively higher corrected total fluid efficiency than the baseline case. Thus, the combined ‘Miller cycle + exhaust gas recirculation + post-injection’ strategy was the most effective means of achieving simultaneous low exhaust emissions, high exhaust gas temperature, and increased corrected total fluid efficiency.

To improve the performance of a variable geometry turbocharged SI engine by porous material application

<div class="section abstract"><div class="htmlview paragraph">This study’s objective is to examine the combustion and performance of mosambi waste peel biodiesel (MWPB) combined with butylated hydroxytoluene (BHT) nanoparticles as a substitute fuel for diesel engines. It also aims to assess the impact of this blend on engine combustion, such as in-cylinder pressure, heat release rate (HRR), ignition delay (ID), combustion duration (CD) and mass fraction burnt (MFB) and performance indicators, including brake thermal efficiency (BTE), brake-specific energy consumption (BSEC), engine torque, exhaust gas temperature (EGT), indicated mean effective pressure (IMEP), air-fuel ratio (A/F ratio) and volumetric efficiency, while also considering the feasibility of employing waste materials in fuel generation. The experimental configuration utilized a research diesel engine functioning under standard conditions, emphasizing the maintenance of uniform injection pressure to ensure optimal fuel atomization and combustion. The test fuels are diesel, MWPB, MWPB+10 μm BHT 10 ppm and MWPB+20 μm BHT 10 ppm mixtures were utilized, and essential performance metrics were assessed. The results showed that incorporating BHT nanoparticles enhances the combustion properties of the MWPB mixes. The in-cylinder pressure increased in MWPB, and HRR increased in MWPB+20 μm BHT 10 ppm blend compared to diesel, but the diesel fuel has a higher ID, CD and MFB than other test fuels. Also, findings indicate an increase in BTE and a reduction in BSEC relative to pure diesel fuel. Furthermore, diesel fuel has higher engine torque, IMEP, A/F ratio and volumetric efficiency than other test fuels, but MWPB has higher EGT than diesel. The research suggests that biodiesel derived from mosambi peel, combined with BHT nanoparticles, is a feasible alternative to traditional diesel fuel, providing improved combustion efficiency and decreased energy usage. This study underscores the potential of agricultural waste for biodiesel generation. It enlightens the significant role of additives such as BHT in enhancing fuel performance and sustainability in diesel engines.</div></div>

Purpose The study aims to determine the the optimal value of output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of operation experimentally. The output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of operation experimentally. The performance parameters like brake thermal efficiency (BTE) and brake specific energy consumption (BSEC), whereas CO emission, HC emission, CO2 emission, NOx emission, exhaust gas temperature (EGT) and opacity are the emission parameters measured during the test. Tests are conducted for 2, 6 and 10 kg of load, 16.5 and 17.5 of CR. Design/methodology/approach In this investigation, the first engine was fueled with 100% diesel and 100% Calophyllum inophyllum oil in single-fuel mode. Then Calophyllum inophyllum oil with producer gas was fed to the engine. Calophyllum inophyllum oil offers lower BTE, CO and HC emissions, opacity and higher EGT, BSEC, CO2 emission and NOx emissions compared to diesel fuel in both fuel modes of operation observed. The performance optimization using the Taguchi approach is carried out to determine the optimal input parameters for maximum performance and minimum emissions for the test engine. The optimized value of the input parameters is then fed into the prediction techniques, such as the artificial neural network (ANN). Findings From multiple response optimization, the minimum emissions of 0.58% of CO, 42% of HC, 191 ppm NOx and maximum BTE of 21.56% for 16.5 CR, 10 kg load and dual fuel mode of operation are determined. Based on generated errors, the ANN is also ranked for precision. The proposed ANN model provides better prediction with minimum experimental data sets. The values of the R2 correlation coefficient are 1, 0.95552, 0.94367 and 0.97789 for training, validation, testing and all, respectively. The said biodiesel may be used as a substitute for conventional diesel fuel. Originality/value The blend of Calophyllum inophyllum oil-producer gas is used to run the diesel engine. Performance and emission analysis has been carried out, compared, optimized and validated.

Exhaust Aftertreatment and Low Pressure Loop EGR Applied to an Off-Highway Engine

Spray cooling for high temperature of exhaust gas using a nozzle array in a confined space: Analytical and empirical predictions on cooling capacity

To meet stringent vehicular exhaust emission norms worldwide, several exhaust pre-treatment and post treatment techniques have been employed in modern engines. Also concern of environmental pollution and energy crisis all over the world have caused the research attention on reduction of diesel engine exhaust emissions and saving of energy simultaneously. This investigation mainly focuses on reducing exhaust emission and energy saving by investigating diesel combustion with neat diesel fuel and a new attachment of pressurized inlet air with Exhaust Gas Recirculation (EGR) system. Experiment was conducted in a four stroke direct injection water cooled constant speed diesel engine with pressurize inlet air attachment and EGR system, which is typically used in agricultural farm machinery. EGR was applied to the experimental engine separately and also with varying pressure of inlet air. In this study, compressor was used to pressurize the inlet air. The experiments were carried out to experimentally evaluate the performance and emissions for combine effect different EGR rates and varying inlet air pressure of the engine. Emissions of hydrocarbon (HC), NOx, carbon monoxide (CO), carbon dioxide (CO2) and temperature of the exhaust gas were measured. Performance parameters such as Brake thermal efficiency, brake specific fuel consumption (BSFC) were calculated. It was found that combined effect of pressurize inlet air attachment and EGR system provided better result on engine performance than individual EGR effect. Reductions in NOx and exhaust gas temperature were observed but emissions of HC, CO and CO2 were found to have increased with combine usage of EGR and inlet air pressure. Thus the modified engine provides more NOx reduction and better fuel economy without reducing useful characteristics (brake power, brake thermal efficiency etc) of the engine. Keyword: Diesel engine, Emission, Exhaust gas recirculation, Inlet air pressure, NOx. I. Introduction Better fuel economy and higher power with lower maintenance cost has increased the popularity of diesel engine vehicles. Diesel engines have inherently high thermal efficiencies, resulting from their high compression ratio and fuel lean operation. The high compression ratio produces the high temperatures required to achieve auto-ignition, and the resulting high expansion ratio makes the engine discharge less thermal energy in the exhaust. The extra oxygen in the cylinders is necessary to facilitate complete combustion and to compensate for non-homogeneity in the fuel distribution. However, high flame temperatures predominate because locally stoichiometric air-fuel ratios prevail in such heterogeneous combustion processes (11). Consequently, Diesel engine combustion generates large amounts of NOx because of the high flame temperature in the presence of abundant oxygen and nitrogen (6, 7). NOx comprise of nitric oxide (NO) and nitrogen dioxide (NO2) and both are considered to be deleterious to humans as well as environmental health. NO2 is considered to be more toxic than NO. It affects human health directly and is precursor to ozone formation, which is mainly responsible for smog formation. The ratio of NO2 and NO in diesel engine exhaust is quite small, but NO gets quickly oxidized in the environment, forming NO2. Since diesel engine mainly emits NO hence attention has been given to reduce the NO formation (3). Diesel engines are used for bulk movement of goods, powering stationary/mobile equipment, and to generate electricity more economically than any other device in this size range. In most of the global car markets, record diesel car sales have been observed in recent years (1). The exhorting anticipation of additional improvements in diesel fuel and diesel vehicle sales in future have forced diesel engine manufacturers to upgrade the technology in terms of power, fuel economy and emissions. Diesel emissions are categorized as carcinogenic (2). Also the stringent emission legislations are compelling engine manufacturers to develop technologies to combat exhaust emissions. To meet these emission regulations with competitive fuel economy, exhaust gas after-treatment and optimized combustion are necessary. In fact, partial recirculation of exhaust gas, which is not a new technique and also well-established technology for NOx reduciton, has recently become essential, in combination with other techniques, for attaining lower emission levels (18).