Hydrogen effects on the diesel engine performance and emissions

In this research, effects of hydrogen addition on a diesel engine were investigated in terms of engine performance and emissions for four cylinders, water cooled diesel engine. Hydrogen was added through the intake port of the diesel engine. Hydrogen effects on the diesel engine were investigated with different amount (0.20, 0.40, 0.60 and 0.80 lpm) at different engine load (20%, 40%, 60%, 80% and 100% load) and the constant speed, 1800 rpm. When hydrogen amount is increased for all engine loads, it is observed an increase in brake specific fuel consumption and brake thermal efficiency due to mixture formation and higher flame speed of hydrogen gas according to the results. For the 0.80 lpm hydrogen addition, exhaust temperature and NOx increased at higher loads. CO, UHC and SOOT emissions significantly decreased for hydrogen gas as additional fuel at all loads. In this study, higher decrease on SOOT emissions (up to 0.80lpm) was obtained. In addition, for 0.80 lpm hydrogen addition, the dramatic increase in NOx emissions was observed.     

Hydrogen electronic injection system for a diesel power generator

This work presents an electronic control system developed for hydrogen injection in a diesel power generator. The full system is basically constituted by a gas fuel injection rail with injection valves, a speed sensor and an electronic control unit. The electronic injection system was installed and tested in a diesel power generator of 44 kW rated power. The tests were carried out with hydrogen injected in the intake manifold and diesel oil directly injected in the combustion chamber. The results show the injection valve opening periods necessary to obtain hydrogen mass flow rates equivalent to 5%, 10%, 15% and 20% of the diesel oil mass replaced. The measured hydrogen mass flow rate injected is presented as a function of load power demand and hydrogen concentration in the fuel.     

CO2 emissions,energy usage,and output in Central America

This study extends the recent work of Ang (2007) [Ang, J.B., 2007. CO₂ emissions, energy consumption, and output in France. Energy Policy 35, 4772–4778] in examining the causal relationship between carbon dioxide emissions, energy consumption, and output within a panel vector error correction model for six Central American countries over the period 1971–2004. In long-run equilibrium energy consumption has a positive and statistically significant impact on emissions while real output exhibits the inverted U-shape pattern associated with the Environmental Kuznets Curve (EKC) hypothesis. The short-run dynamics indicate unidirectional causality from energy consumption and real output, respectively, to emissions along with bidirectional causality between energy consumption and real output. In the long-run there appears to be bidirectional causality between energy consumption and emissions.     

CO2 emissions,electricity consumption and output in ASEAN

This study examines the causal relationship between carbon dioxide emissions, electricity consumption and economic growth within a panel vector error correction model for five ASEAN countries over the period 1980–2006. The long-run estimates indicate that there is a statistically significant positive association between electricity consumption and emissions and a non-linear relationship between emissions and real output, consistent with the environmental Kuznets curve. The long-run estimates, however, do not indicate the direction of causality between the variables. The results from the Granger causality tests suggest that in the long-run there is unidirectional Granger causality running from electricity consumption and emissions to economic growth. The results also point to unidirectional Granger causality running from emissions to electricity consumption in the short-run.     

Hydrogen applications in selective catalytic reduction of NOx emissions from diesel engines

Diesel engines have been considered as a major source in nitrogen oxide (NO_x) formation worldwide. The widespread use of diesel engines in consequence of their low fuel consumption, high durability and efficiency increases NO_x emissions day by day. NO_x emissions from diesel engines cause unavoidable damage on environment and people health. Although so many technologies such as exhaust gas recirculation (EGR), lean burn combustion, electronic controlling fuel injection systems, etc. have been developed to control NO_x emissions from diesel engines, they couldn't meet the desired reduction in NO_x emissions. In any case, Selective Catalytic Reduction (SCR) as one of the most promising aftertreatment-emission control technologies is an effective solution in restriction of NO_x emissions. The use of SCR systems especially in heavy-duty diesel powered vehicles has been increasing nowadays. In these systems, to use of hydrogen (H₂) as a reductant or promoter have been improved the conversion efficiency especially at low exhaust temperatures. Many researchers have been focused on the use of H₂ in SCR systems for controlling NO_x emissions.In this study, the applications of H₂ in SCR of NO_x have been discussed. The studies on use of H₂ in SCR of NO_x emissions were examined and the effects on NO_x conversions were determined. Consequently, it is confirmed that H₂ is a promising and alternative reductant in SCR of NO_x and it has been kept as an attracting subject for many researchers.     

Implications of generator siting for CO2 pipeline infrastructure

The location of a new electric power generation system with carbon capture and sequestration (CCS) affects the profitability of the facility and determines the amount of infrastructure required to connect the plant to the larger world. Using a probabilistic analysis, we examine where a profit-maximizing power producer would locate a new generator with carbon capture in relation to a fuel source, electric load, and CO₂ sequestration site. Based on models of costs for transmission lines, CO₂ pipelines, and fuel transportation, we find that it is always preferable to locate a CCS power facility nearest the electric load, reducing the losses and costs of bulk electricity transmission. This result suggests that a power system with significant amounts of CCS requires a very large CO₂ pipeline infrastructure.     

Anthropogenic emissions of CO2 and CH4 in an urban environment

Regular observations of atmospheric mixing-ratios of carbon dioxide and methane in the urban atmosphere, combined with analyses of their carbon-isotope composition (δ¹³C, δ¹⁴C), provide a powerful tool for assessing both the source strength and source partitioning of those gases, as well as their changes with respect to time. Intense surface fluxes of CO₂ and CH₄, associated with anthropogenic activities result in elevated levels of these gases in the local atmosphere as well as in modifications of their carbon-isotope compositions. Regular measurements of concentration and carbon-isotope composition of atmospheric CO₂, carried out in Krakow over the past two decades, were extended to the period 1995–2000 and also to atmospheric mixing-ratios of CH₄ and its carbon-isotope composition. Radiocarbon concentrations (δ¹⁴C) in atmospheric CO₂ recorded at Krakow are systematically lower than the regional background levels. This effect stems from the addition of ¹⁴C-free CO₂ into the local atmosphere, originating from the burning of fossil fuels. The fossil-fuel component in the local budget of atmospheric carbon calculated using a three-component mixing model decreased from ca. 27.5 ppm in 1989 to ca. 10 ppm in 1994. The seasonal fluctuations of this component (winter–summer) are of similar magnitude. A gradually decreasing difference between the ¹⁴CO₂ content in the local atmosphere and the regional background observed after 1991 is attributed to the reduced consumption of ¹⁴C-free fuels, mostly coal, in southern Poland and the Krakow municipal area. The linear regression of δ¹³C values of methane plotted versus reciprocal concentration, performed for the data available for Krakow sampling site, yields the average δ¹³C signature of the local source of methane as being equal to −54.2‰. This value agrees very well with the measured isotope signature of natural gas being used in Krakow (−54.4±0.6‰) and points to leakages in the distribution network of this gas as the main anthropogenic source of CH₄ in the local atmosphere.     

H2 effects on diesel combustion and emissions with an LPL-EGR system

In this study, we examined H₂ effects on the combustion and emissions of a diesel engine with low-pressure loop (LPL) exhaust gas recirculation (EGR). We converted a 2.2-L four-cylinder direct-injection diesel engine satisfying Euro5 for H₂ supply. An LPL-EGR system replaced the high-pressure loop (HPL) EGR system. For all tests, the brake mean effective pressure (BMEP) was kept at 4 bar and the EGR ratio was varied from 9 to 42%. The H₂ energy percentage was varied from 0 to 7.4% independently to evaluate the H₂ effects and EGR effects separately. The heat release rate was calculated from the measured cylinder pressure. We found that substitution of H₂ for diesel fuel made the premixed burn fraction larger, and reduced the nitrous oxide (NOx) and particulate matter (PM) emissions simultaneously. For example, the NOx emissions were reduced by 36% for an EGR of 42% and an H₂ percentage of 7.4%. PM emissions were reduced by 18% for an EGR of 35% and an H₂ percentage of 7.4% compared with diesel fuel only cases.     

CO2 emissions from geothermal power plants and natural geothermal activity in Iceland

The ratio of CO₂ emissions from power plants to natural emissions is a measure of the environmental impact associated with geothermal power production. Emissions from Icelandic geothermal power plants amounted to 1.6 × 10⁸ kg year⁻¹ in 2002. Two independent estimates of natural CO₂ emissions range between 1 × 10⁸ and 2 × 10⁹ kg year⁻¹. Thus, power plant emissions are significant compared to estimated total emissions (i.e., not less than 8–16%). However, direct CO₂ flux measurements from four of the approximately 40 geothermal/volcanic systems in the country amounted to 3 × 10⁸ kg year⁻¹, indicating that these estimates of the total natural flux may be too low.     

CO2 emissions,energy consumption and economic growth in China: A panel data analysis

This paper examines the causal relationships between carbon dioxide emissions, energy consumption and real economic output using panel cointegration and panel vector error correction modeling techniques based on the panel data for 28 provinces in China over the period 1995–2007. Our empirical results show that CO₂ emissions, energy consumption and economic growth have appeared to be cointegrated. Moreover, there exists bidirectional causality between CO₂ emissions and energy consumption, and also between energy consumption and economic growth. It has also been found that energy consumption and economic growth are the long-run causes for CO₂ emissions and CO₂ emissions and economic growth are the long-run causes for energy consumption. The results indicate that China's CO₂ emissions will not decrease in a long period of time and reducing CO₂ emissions may handicap China's economic growth to some degree. Some policy implications of the empirical results have finally been proposed.     

Influence of European passenger cars weight to exhaust CO2 emissions

The increase of atmospheric CO₂ concentration influences climate changes. The road transport sector is one of the main anthropogenic sources of CO₂ emissions in the European Union (EU). One of the main parameters influencing CO₂ emissions from passenger cars (PCs) is their weight, which increases during last years. For the same driving distance, heavier vehicles need more work than lighter ones, because they have to move an extra weight, and thus more fuel is consumed and thus increased CO₂ emissions. The weight control of new PCs could be an efficient way to control their CO₂ emissions. After an analysis of the EU new PCs market, their segment distribution and their weight, some estimations for 2020 are presented. Based on this analysis, 13 base scenarios using several ways for the control of the weight of future European new PCs are used to estimate their CO₂ emissions and the benefit of each scenario. The results show that a significant benefit on CO₂ emissions could be achieved if the weight of each PC does not exceed an upper limit, especially if this limit is quite low. The benefit obtained by limitations of weight is higher than the benefit obtained from the expected decreased future fuel consumption. Similar results are obtained when the weight of new PCs does not exceed an upper limit within each segment, or when the weight of each new PC decreases.     

Study of diesel engine performance and emissions during a Transient Cycle applying an engine mapping-based methodology

An engine mapping-based methodology was developed in order to be able to make a first approximation of the engine performance and emissions during a speed/torque vs. time Transient Cycle. The procedure is based on a previous steady-state experimental investigation of the engine for the formulation of polynomial expressions of all interesting engine properties with respect to engine speed and torque. Correction coefficients are then applied to account for transient discrepancies based on individual transient experiments. The developed algorithm was applied for the case of a heavy-duty diesel engine running on the European Transient Cycle. A comparative analysis was performed for each section of the Cycle, which revealed that the first part (urban driving) is responsible for the biggest amount of emissions (in g) owing to the most frequent and abrupt load changes involved. The obvious advantage of the proposed methodology is the fact that the effect of internal or external (after-treatment) measures can be easily incorporated in the code and quantified in terms of emissions improvement.     

Effect of H2 addition on combustion and exhaust emissions in a heavy-duty diesel engine with EGR

The effect of the addition of hydrogen (H₂) on the combustion process and nitric oxide (NO) formation in a H₂-diesel dual fuel engine was numerically investigated. The model developed using AVL FIRE as a platform was validated against the cylinder pressure and heat release rate measured with the addition of up to 6% (vol.) H₂ into the intake mixture of a heavy-duty diesel engine with exhaust gas recirculation (EGR). The validated model was applied to further explore the effect of the addition of 6%–18% (vol.) H₂ on the combustion process and formation of NO in H₂-diesel dual fuel engines. When the engine was at N = 1200 rpm and 70% load, the simulation results showed that the addition of H₂ prolonged ignition delay, enhanced premixed combustion, and promoted diffusion combustion of the diesel fuel. The maximum peak cylinder pressure was observed with addition of 12% (vol.) H₂. In comparison, the maximum peak heat release rate was observed with the addition of 16% (vol.) H₂. The addition of H₂ was a crucial factor dominating the increased NO emissions. Meanwhile, the addition of H₂ reduced soot emissions substantially, which may be due to the reduced diesel fuel burned each cycle. Furthermore, proper combination of adding H₂ with EGR can improve combustion performance and reduce NO emissions.     

CO2 emissions,energy consumption and economic growth in BRIC countries

This paper examines dynamic causal relationships between pollutant emissions, energy consumption and output for a panel of BRIC countries over the period 1971–2005, except for Russia (1990–2005). In long-run equilibrium energy consumption has a positive and statistically significant impact on emissions, while real output exhibits the inverted U-shape pattern associated with the Environmental Kuznets Curve (EKC) hypothesis with the threshold income of 5.393 (in logarithms). In the short term, changes in emissions are driven mostly by the error correction term and short term energy consumption shocks, as opposed to short term output shocks for each country. Short-term deviations from the long term equilibrium take from 0.770 years (Russia) to 5.848 years (Brazil) to correct. The panel causality results indicate there are energy consumption–emissions bidirectional strong causality and energy consumption–output bidirectional long-run causality, along with unidirectional both strong and short-run causalities from emissions and energy consumption, respectively, to output. Overall, in order to reduce emissions and not to adversely affect economic growth, increasing both energy supply investment and energy efficiency, and stepping up energy conservation policies to reduce unnecessary wastage of energy can be initiated for energy-dependent BRIC countries.     

An experimental investigation of the combustion process of a heavy-duty diesel engine enriched with H2

This paper investigated the effect of hydrogen (H₂) addition on the combustion process of a heavy-duty diesel engine. The addition of a small amount of H₂ was shown to have a mild effect on the cylinder pressure and combustion process. When operated at high load, the addition of a relatively large amount of H₂ substantially increased the peak cylinder pressure and the peak heat release rate. Compared to the two-stage combustion process of diesel engines, a featured three-stage combustion process of the H₂–diesel dual fuel engine was observed. The extremely high peak heat release rate represented a combination of diesel diffusion combustion and the premixed combustion of H₂ consumed by multiple turbulent flames, which substantially enhanced the combustion process of H₂–diesel dual fuel engine. However, the addition of a relatively large amount of H₂ at low load did not change the two-stage heat release process pattern. The premixed combustion was dramatically inhibited while the diffusion combustion was slightly enhanced and elongated. The substantially reduced peak cylinder pressure at low load was due to the deteriorated premixed combustion.     

CO2 emissions change from the sales authorization of diesel passenger cars: Korean case study

The climatic change is a matter of grave concern to the whole world. As a countermeasure against the climatic change convention, the Korean government has authorized the sale of diesel passenger cars since 2005. In this paper, we analyze the effects of the sales authorization of diesel passenger cars in its role as a countermeasure. Their share, carbon emissions, and pollutant emissions of each type of passenger car are analyzed using system dynamics. The result is that the carbon emissions are decreased by 5.4% but the pollutant emissions are increased by 5%. If the pollutant emissions are controlled, the sales authorization of diesel passenger cars would be a good countermeasure against the climatic change convention.     

Influence of operating parameters on performance and emissions for a compression-ignition engine fueled by hydrogen/diesel mixtures

Hydrocarbon exhaust emissions are mainly recognized as a consequent of carbon-based fuel combustion in compression ignition (CI) engines. Alternative fuels can be coupled with hydrocarbon fuels to control the pollutant emissions and improve the engine performance. In this study, different parameters that influence the engine performance and emissions are illustrated with more details. This numerical work was carried out on a dual-fuel CI engine to study its performance and emission characteristics at different hydrogen energy ratios. The simulation model was run with diesel as injected fuel and hydrogen, along with air, as inducted fuel. Three-dimensional CFD software for numerical simulations was implemented to simulate the direct-injection CI engine. A reduced-reaction mechanism for n-heptane was considered in this work instead of diesel. The Hiroyasu-Nagel model was presented to examine the rate of soot formation inside the cylinder. This work investigates the effect of hydrogen variation on output efficiency, ignition delay, and emissions. More hydrogen present inside the engine cylinder led to lower soot emissions, higher thermal efficiency, and higher NO_x emissions. Ignition timing delayed as the hydrogen rate increased, due to a delay in OH radical formation. Strategies such as an exhaust gas recirculation (EGR) method and diesel injection timing were considered as well, due to their potential effects on the engine outputs. The relationship among the engine outputs and the operation conditions were also considered.     

Economic growth, CO2 emissions, and fossil fuels consumption in Iran

Environmental issues have attracted renewed interest and more attention during recent years due to climatic problems associated with the increased levels of pollution and the deterioration of the environmental quality as a result of increased human activity. This paper investigates the causal relationships between economic growth, carbon emission, and fossil fuels consumption, using the relatively new time series technique known as the Toda-Yamamoto method for Iran during the period 1967–2007. Total fossil fuels, petroleum products, and natural gas consumption are used as three proxies for energy consumption. Empirical results suggest a unidirectional Granger causality running from GDP and two proxies of energy consumption (petroleum products and natural gas consumption) to carbon emissions, and no Granger causality running from total fossil fuels consumption to carbon emissions in the long run. The results also show that carbon emissions, petroleum products, and total fossil fuels consumption do not lead to economic growth, though gas consumption does.     

Effects of H2 on the number concentration of particulate matter in diesel engines using a low-pressure loop exhaust-gas recirculation system

We investigated the effects of H₂ on the number concentration of particulate matter (PM) emissions from a diesel engine fitted with a low-pressure loop exhaust gas recirculation system. We used a 2.2-L four-cylinder direct-injection diesel engine satisfying EURO V regulations, and converted this engine to include an H₂ feed. The air/fuel (A/F) ratio was varied in the range of 21.9–45.5 and the brake mean effective pressure was varied in the range of 2–6 bars to control the O₂ concentration and in-cylinder temperature, both of which are significant for PM emissions. The number concentration of the emitted PM was measured using a scanning mobility particle sizer. We found that the emitted PM decreased by the addition of H₂ which caused the unburned gas temperature increased. Furthermore, the degree of reduction was larger as the A/F ratio, load, and H₂ energy fraction increased. However, with A/F ratios of less than 21.9, the addition of H₂ increased the number concentration of emitted PM which was attributed to the small O₂ concentration at these A/F ratios.     

Hydrogen permeation through a Pd-based membrane and RWGS conversion in H2/CO2, H2/N2/CO2 and H2/H2O/CO2 mixtures

This study investigated the effect of gases such as CO₂, N₂, H₂O on hydrogen permeation through a Pd-based membrane −0.012 m² – in a bench-scale reactor. Different mixtures were chosen of H₂/CO₂, H₂/N₂/CO₂ and H₂/H₂O/CO₂ at temperatures of 593–723 K and a hydrogen partial pressure of 150 kPa. Operating conditions were determined to minimize H₂ loss due to the reverse water gas shift (RWGS) reaction. It was found that the feed flow rate had an important effect on hydrogen recovery (HR). Furthermore, an identification of the inhibition factors to permeability was determined. Additionally, under the selected conditions, the maximum hydrogen permeation was determined in pure H₂ and the H₂/CO₂ mixtures. The best operating conditions to separate hydrogen from the mixtures were identified.