The Effect Mechanisms of Intake Manifold Water Injection on the Emissions of a Natural Gas Engine

NOx is the main emission of lean burn natural gas engine (NGE). Water injection (WI) is an effective method to reduce NOx, which has been widely studied in conventional fuel engine. Currently, there are few researches on the application of WI in NGE. The influences of WI on NGE are not clear. In the paper, the effect mechanisms of WI on the emissions of NGE are studied. Based on the thermodynamic properties of water and the combustion mechanism of natural gas, the emissions generation mechanism of NGE with WI was analyzed. According to the experimental system, the effects of intake manifold water injection (IMWI) on the emissions of a lean burn NGE was carried out. The results show that, with WI, the in-cylinder temperature decreased greatly, which effectively inhibited the formation of thermal NO. Water generated a lot of OH groups, which effectively inhibited the formation of rapid NO. At 1800 rpm and 0.92g/s WI rate, NOx is reduced by 70.4%. OH group could effectively promote CO oxidize to CO2. At 1000 rpm and 0.92g/s WI rate, CO is decreased by 22.2%. However, since the decrease of the total activation energy of combustion reaction, the chain breaking reaction increased, resulting in a significant increase in HC. At 800rpm and 0.92g/s WI rate, HC was increased by 11.6%.

Tagasaste, leucaena and paulownia: three industrial crops for energy and hemicelluloses production

Background Burning fast-growing trees for energy production can be an effective alternative to coal combustion. Thus, lignocellulosic material, which can be used to obtain chemicals with a high added value, is highly abundant, easily renewed and usually inexpensive. In this work, hemicellulose extraction by acid hydrolysis of plant biomass from three different crops (Chamaecytisus proliferus, Leucaena diversifolia and Paulownia trihybrid) was modelled and the resulting solid residues were used for energy production. Results The influence of the nature of the lignocellulosic raw material and the operating conditions used to extract the hemicellulose fraction on the heat capacity and activation energy of the subsequent combustion process was examined. The heat power and the activation energy of the combustion process were found to depend markedly on the hemicellulose content of the raw material. Thus, a low content in hemicelluloses resulted in a lower increased energy yield after acid hydrolysis stage. The process was also influenced by the operating conditions of the acid hydrolysis treatment, which increased the gross calorific value (GCV) of the solid residue by 0.6–9.7% relative to the starting material. In addition, the activation energy of combustion of the acid hydrolysis residues from Chamaecytisus proliferus (Tagasaste) and Paulownia trihybrid (Paulownia) was considerably lower than that for the starting materials, the difference increasing with increasing degree of conversion as well as with increasing temperature and acid concentration in the acid hydrolysis. The activation energy of combustion of the solid residues from acid hydrolysis of tagasaste and paulownia decreased markedly with increasing degree of conversion, and also with increasing temperature and acid concentration in the acid hydrolysis treatment. No similar trend was observed in Leucaena diversifolia (Leucaena) owing to its low content in hemicelluloses. Conclusions Acid hydrolysis of tagasaste, leucaena and paulownia provided a valorizable liquor containing a large amount of hemicelluloses and a solid residue with an increased heat power amenable to efficient valorization by combustion. There are many potential applications of the hemicelluloses-rich and lignin-rich fraction, for example as multi-components of bio-based feedstocks for 3D printing, for energy and other value-added chemicals.

Tagasaste, Leucaena and Paulownia. Three Industrial Crops for Energy and Hemicelluloses Production

BackgroundBurning fast-growing trees for energy production can be an effective alternative to coal combustion. Thus, lignocellulosic material, which can be used to obtain chemicals with a high added value, is highly abundant, easily renewed and usually inexpensive. In this work, hemicellulose extraction by acid hydrolysis of plant biomass from three different crops (Chamaecytisus proliferus, Leucaena diversifolia and Paulownia trihybrid) was modelled and the resulting solid residues were used for energy production.ResultsThe influence of the nature of the lignocellulosic raw material and the operating conditions used to extract the hemicellulose fraction on the heat capacity and activation energy of the subsequent combustion process was examined.The heat power and the activation energy of the combustion process were found to depend markedly on the hemicellulose content of the raw material. Thus, a low content in hemicelluloses resulted in a lower increased combustion efficiency and energy yield after acid hydrolysis stage.The process was also influenced by the operating conditions of the hydrolysis treatment, which increased the superior calorific value (SCV) of the solid residue by 0.6–9.7% relative to the starting material. Also, the activation energy of combustion of the hydrolysis residues from tagasaste and paulownia was considerably lower than that for the starting materials, the difference increasing with increasing degree of conversion as well as with increasing temperature and acid concentration in the acid hydrolysis.The activation energy of combustion of the solid residues from acid hydrolysis of tagasaste and paulownia decreased markedly with increasing degree of conversion, and also with increasing temperature and acid concentration in the hydrolysis treatment. No similar trend was observed in leucaena owing to its low content in hemicelluloses.ConclusionsAcid hydrolysis of tagasaste, leucaena and paulownia provided a valorizable liquor containing a large amount of hemicelluloses and a solid residue with an increased heat power amenable to efficient valorization by combustion. There are many potential applications of the hemicelluloses-rich and lignin-rich fraction, for example as multi-components of bio-based feedstocks for 3D printing, for energy and other value-added chemicals.

Review Paper on Inverted Brayton Cycles

The exhaust gas from an internal combustion engine contains approximately 30% of the thermal energy of combustion. Waste heat recovery (WHR) systems aim to reclaim a proportion of this energy in a bottoming thermodynamic cycle to raise the overall system thermal efficiency. One of promising heat recovery approaches is to employ an inverted Brayton cycle (IBC) immediately downstream of the primary cycle. However, it is a little-studied approach as a potential exhaust-gas heat-recovery system, especially when applied to small automotive power-plants.The experiments of the IBC prototype were conducted in the gas stand. The correlated IBC model can be utilized for the further development of the IBC system. Researchers were reviewed core paper on Inverted Brayton Cycles (IBC) and concluded that there were possibility of heat recovery system in that for changing different mechanical components.

Thermodynamics Properties of 1,1-Carbonyldiimidazole (CDI) and 4-Imidazole Acrylic Acid, Obtained by DSC and Combustion Calorimetry

In this work, thermodynamic properties of 1,1-carbonyldiimidazole (CDI) and 4-imidazole acrylic are reported. The melting temperature, the enthalpy of fusion and the heat capacity of the compounds were determined by differential scanning calorimetry. The standard molar energy of combustion of both compounds were determined by static-bomb combustion calorimetry and the standard molar enthalpy of formation in the crystalline phase, at T = 298.15 K, was derived and evaluated for the two imidazole derivatives studied. The energetic influence of the acrylic group on the imidazole ring in each of the properties obtained is analyzed and compared with the existing results in the literature. Resumen. Se presentan las propiedades termodinámicas del 1,1-carbonildiimidazol (CDI) y el 4-imidazol acrílico. La temperatura de fusión, la entalpía de fusión y la capacidad calorífica de los compuestos se determinaron mediante calorimetría diferencial de barrido. La energía molar estándar de la combustión de ambos compuestos se determinó mediante calorimetría de combustión en bomba estática y la entalpía de formación en fase cristalina, a T= 298.15, fue derivada y evaluada para los dos compuestos derivados del imidazol. La influencia energética del grupo acrílico sobre el anillo de imidazol en cada una de las propiedades obtenidas se analiza y compara con los resultados existentes en la literatura.

Influence of the functional groups −NH2, −OCH3, and −OH on the thermochemistry of indanes

This work is a contribution to the thermochemical characterization of bicyclic hydrocarbons, reporting the study of six indane derivatives: 4-aminoindane, 5-aminoindane, 5-methoxyindane, 1-indanol, 2-indanol, and 5-indanol. The combustion calorimetry technique was used to measure the massic energy of combustion of each compound in the condensed state, which has been used to derive the corresponding standard (p° = 0.1 MPa) molar enthalpy of formation, at 298.15 K. The standard molar enthalpies of sublimation or vaporization of the compounds were determined by high-temperature Calvet microcalorimetry. For each indane derivative, the results obtained for those two properties, allowed to derive the respective value of standard molar enthalpy of formation, in the gaseous phase. Additionally, a theoretical study at the G3(MP2)//B3LYP level has been carried out, and the calculated enthalpies of formation have been compared with the experimental values. The values of the enthalpy of formation, in the gaseous phase, were analysed in terms of correlations between the structural (different substituents in the indane core) and energetics characteristics.

Preparation and Characterization of a New High-Performance Plastic Explosive in Comparison with Traditional Types

EPX-2R is a high-performance plastic explosive produced for different applications. EPX-2R is based on RDX (1,3,5-trinitro-1,3,5-triazinane) bonded by the elastic matrix of the softened styrene butadiene binder. A computerizing mixer plastograph was used for the production of EPX-2R. The internal energy of combustion was measured and used to determine the enthalpy of formation. Friction and impact sensitivities were measured. The velocity of detonation was determined experimentally, and the detonation properties were calculated by the EXPLO 5 code. For comparison, traditional plastic explosives, composition C-4, Semtex 10, Formex P1, EPX-1, and Sprängdeg m/46, were studied. It was concluded that the velocity of detonation of EPX-2R was higher than the studied samples except composition C-4, while its sensitivity is the lowest. Interesting inversely proportional relationship between the measured internal energy of combustion and the calculated heat of detonation was observed.

MHD effects in continuous spin detonation

Conversion possibility of the chemical energy of combustion products of a hydrogen–oxygen mixture into electrical energy with the use of continuous spin detonation has been demonstrated for the first time in an MHD system. The specific conductivity of detonation products in the region of rotation of the detonation front was measured to be ~3 · 10–2 Ω–1 m–1. The structure of transverse detonation waves was examined, their velocity was measured (2220 ± 50 m/s), and the flow in their vicinity was studied.

Theoretical and experimental studies of a gas stamping device with a piston pressure multiplier

In many industries, the share of small-scale production plants is significant. In these conditions, compared with traditional methods of pressure treatment, pulse pressure treatment methods, one of the varieties of which is gas stamping, are more efficient. However, the known devices of gas stamping provide mainly stamping of thin-walled parts. To expand the technological capabilities of gas stamping, the authors developed a gas stamping device with a piston pressure multiplier, in which heating and deformation of the stamping workpiece is carried out using the energy of combustion of fuel mixtures in the combustion chamber, in the working cylinder and in the cavity of the matrix. This article is devoted to the study of the workflow of this device. Theoretical analysis of the workflow was carried out, and, as a result, a pattern was determined for the variation of the pressure that performs the stamping process in the working cylinder. In particular, it was found that at the final stage of the stamping process, due to the energy of combustion of the fuel mixture, the pressure in the working cylinder increases 1.5...2 times, which allows a significant increase in the thickness of the parts to be stamped. An experimental gas stamping device with a piston pressure multiplier was developed, and experimental studies were carried out. The studies confirmed the main results of the theoretical analysis: the discrepancy between the theoretical and experimental values of the degree of pressure multiplication in the working cylinder does not exceed 11%.

Combustion Characteristics and Kinetics Study of Pulverized Coal and Semi-Coke

Combustion process of bituminous coal, steam coal, anthracite (AC) and semi-coke were investigated through thermogravimetric analysis method and influence of metamorphic grade as well as heating rate on combustion characteristics were analyzed. Results show that combustion performance could not be represented by single combustion characteristic parameter. Through analysis of comprehensive combustion characteristic indexes, with increase of metamorphic grade combustion performance of coal is lowered, and combustion performance of semi-coke and AC are close to each other. With increase of heating rate, combustion curves move into high temperature region and comprehensive combustion characteristic indexes are increased, which show that the combustion performance is improved. Random pore model (RPM), unreacted shrinking core model (URCM) and volume model were used to calculate kinetic parameters of combustion process. Results show that RPM has the best performance to represent combustion process of the four samples and through calculation by RPM kinetic energy of combustion process for all samples are between 43.08 and 99.43 kJ/mol, and there is compensation effect during combustion process.