Inlet Charge Research Articles

Experimental and numerical investigation of iron ore pellet firing using coupled CFD-DEM method

Iron ore pellets are the main feedstock in ironmaking processes. While extensive research has addressed numerical modeling of the iron ore pellet induration process, little effort has been made to describe the intricate thermochemical processes occurring within the reactor starting from the pellet and particularly at the intra-particle scale. In this regard, discrete-continuous methods like CFD-DEM can generate more realistic, irregular particle assemblies, which leads to significantly more accurate predictions of voidage variation, wall effects, temperature distribution, and associated mass transfer phenomena. This study presents a numerical model based on computational fluid dynamics (CFD) coupled with the discrete element method (DEM) to simulate the thermal induration process of iron ore pellets. The presented model solving heat, mass, and momentum conservation equations for both continuous and discrete phases, provides detailed information on the thermochemical aspects of the process. Pilot-scale induration experiment was conducted to validate model predictions in terms of thermal history and final conversion fraction. It was found that inlet charge specifications, such as particle and pellet size, significantly impact the productivity of pelletizing plants, highlighting the potential of the presented model to optimize the process and improve plant productivity.

Increasing the wear resistance of the ICE’s valves with the laser cladding method

BACKGROUND: There is plenty of factors leading to failure and expensive repair of piston engines at their operation. One of the widespread factors capable of affecting the engine operation is combustion chamber sealing failure. During the engine operation, gases combusting in a chamber bring pressure on working surfaces of a valve and a valve seat. If these surfaces do not ensure sealing, exhaust gases begin to leak in the exhaust manifold untimely, in some cases in the intake manifold as well. In addition, filling of cylinders with inlet charge worsens. In majority of cases, combustion chamber sealing failure caused by defect formation at working surfaces of the valve — valve seat coupling. In order to avoid combustion chamber sealing failures and other issues of operation of piston engines, it is necessary to minimize working surfaces wearing by means of wear-resistant coating. AIMS: Wear- and corrosion-resistant coating of valve’s working surface to increase service life. METHODS: The factors affecting the reliability of the valve — valve seat coupling were defined by means of literary sources analysis. Laser cladding at the valve’s chamfer was conducted with the laser robotized facility based on ytterbium fiber laser. Quality of the coated surface at the valve’s working chamfer was defined by means of metallographic study and liquid penetrant test. RESULTS: After laser cladding of the PR-08Kh17N8S6G powder material at the valve’s working chamfer, the uniform coated surface with microhardness of 435–485 HV (44–48 HRC) was obtained. CONCLUSIONS: The study results may be used for development and implementation of new kinds of wear-resistant surfaces that make it possible to increase the service life and to repair worn-down surfaces of components.

Thermodynamic analysis on coupling characteristic of Twin-VGT and fuel injection parameters at variable altitudes

ABSTRACT The decrease of inlet charge and mismatch of air and fuel are main reasons for the decrease of engine performance at variable altitudes. Understanding coupling mechanism between two-stage turbocharging and fuel injection system is key to maximize its potential for engine power recovery at variable altitudes. This paper focused on the coupling characteristic of twin variable geometry turbocharging (Twin-VGT) and fuel injection parameters on key parameters of gas path, in-cylinder combustion, and energy flow of the diesel engine at variable altitudes. Firstly, a thermodynamic cycle model of a Twin-VGT diesel engine aiming at variable altitudes was established and validated by experimental data. Furthermore, the coupling mechanism of high-pressure variable geometry turbocharging (HVGT) and low-pressure variable geometry turbocharging (LVGT) vanes on exhaust available energy (EAE), global expansion ratio (GER) and its distribution, global boost ratio (GBR) and its distribution, isentropic efficiency of the Twin-VGT, combustion process, and energy flow of the engine were studied at different altitudes. Enthalpy drop ratio is regulated by HVGT and LVGT and the isentropic efficiency of two-stage turbine reaches to maximum when openings of HVGT and LVGT at 0.35 and 0.75, respectively, at the altitude of 5500 m. Finally, this paper investigated the coupling characteristic of turbocharging and fuel injection parameters on combustion process and engine performance, which provides the theoretical basis for collaborative controlling of the Twin-VGT and fuel injection parameters at variable altitudes. Brake thermal efficiency (BTE) is affected by exhaust temperature which is mainly controlled by HVGT openings and injection advance angle (IAA) at variable altitudes, and BTE reaches to maximum when openings of HVGT at 0.4 and IAA at −5.5°CA under fixed engine load at the altitude of 5500 m.

Fuel injection strategy optimisation and experimental performance and emissions evaluation of diesel displacement by port fuel injected methanol in a retrofitted mid-size genset engine prototype

The reliance of the transport, agriculture, marine, and power generation sectors on heavy-duty diesel engines would continue in the foreseeable future due to their higher efficiency, torque, fuel economy, and durability, despite growing concerns about emissions. This dependence would rise further due to the unavailability of an equally efficient alternative prime mover having a similar or better power density. The adoption of alternative fuels has emerged as a promising solution to tackle emission issues. Methanol has exhibited great potential to reduce pollutants by adopting advanced combustion technologies among various new fuels. Retrofitment of existing engines can be a viable solution for methanol adaptation because engine design modifications are not practical for on-field engines. The present study focused on evaluating the performance and emissions of a commercial Genset CI engine adapted to operate using diesel-methanol dual-fuel combustion (DFC) technology, which required very few hardware modifications to facilitate retrofitment for methanol adaptation. Inlet charge temperature was controlled using hot air from the turbocharger. Port fuel injection was used to induct methanol into the engine manifold, and a premixed charge entered the engine combustion chamber. This charge was ignited by spraying diesel directly into the engine combustion chamber. The engine's performance and emissions were compared with the OEM configuration (diesel fuelling mode) at methanol's low, medium, and high diesel replacement. The fuel injection parameters (injection timing and pressure) of diesel were varied to obtain optimum fuel injection strategies for various engine loads. A sharp increase in thermal efficiency was observed at 30% diesel displacement (on an energy basis) by methanol at a 9 kW generator load. In contrast, a slight penalty in thermal efficiency was observed at 80% diesel displacement (on an energy basis) by methanol. Higher HC and CO emissions were also observed for the engine using higher methanol fractions. The CO2 emission was comparable to or less than the OEM diesel configuration at identical loads. Exhaust smoke was considerably lower for methanol-fuelled operation, indicating a significant reduction in particulates in the engine exhaust. Advancing fuel injection timings and higher fuel injection pressure of diesel proved to be a good strategy for methanol adaptation in genset engines, with an acceptable cylinder noise.

Thermal efficiency analysis of the phase change material (PCM) microcapsules

The aim of the present study is to evaluate the thermal behavior of cylindrical modules in a thermal energy storage unit as a combined sensible and latent heat. A thermal energy storage unit is designed, fabricated, and connected to a cold and hot water supply at constant temperatures to monitor the performance of the storage unit. The thermal energy storage unit contains the cylindrical microcapsules containing paraffin waxes as a phase change material which is located inside an insulating cylinder storage tank. Water is used as a heat transfer fluid to transfer heat from a hot water reservoir to the thermal energy storage unit during the phase change material charging process and also during the discharging process water receives heat from the thermal energy storage unit. Charge tests are carried out at the constant temperature. Moreover, the effect of different inlet flow on storage unit performance is investigated. Data were analyzed using Design Expert software and regression analysis which indicated that the increase of charge inlet temperature and charge inlet flow leads to the increase of heat power, thermal performance of thermal energy storage unit, and output variables. In comparison to the heat storage system without phase change material, microcapsules phase change material can improve the heat power of the heat storage system. Also, based on the optimization process, the maximum thermal performance of 96.4% and the maximum heat power level of 1.7 kW can be achieved in the optimized condition of the charging inlet temperature of 75 °C, charging inlet flow of 1.8−4 m3/s, and discharging inlet temperature of 35 °C.

Numerical and experimental evaluation on the pooled effect of waste cooking oil biodiesel/diesel blends and exhaust gas recirculation in a twin-cylinder diesel engine

Nowadays, worldwide, many countries are engaged in reducing the vehicular exhaust emissions from diesel engines as diesel engines are the main source of power in various transport applications. Biofuels obtained from various feedstocks serve as a better alternative fuel in CI engines because of its emission reducing capabilities. The major drawback in the usage of biofuels in CI engine is the rise in the formation of nitrogen oxides which would be harmful to human health. WCO biofuel was processed using trans-esterification technique and the contents available were analyzed using gas chromatography mass .spectroscopy (GCMS). Four different blends, namly B100, B60, B40, and B20 were made. The physio-chemical properties of the prepared test fuels were identified using ASTM standards. The investigation on the characterisation of performance, combustion, sound and emission of the test engine was done. Fuel combustion modeling was done using ANSYS Fluent for diesel, WCO biofuel and best suited blend obtained from experimental results. From both the simulated and the experimental results, it was found that B20 blend fuel would be best suited to the test engine with a maximum reduction of 17% in unburned hydrocarbon (HC), 30% in carbonmonooxide (CO), 14.08% in smoke, 7.35% in carbondioxide (CO2) and 16.46% increase in NOx emission respectively. With an intention to reduce NOx emission in the selected B20 blend fuel, EGR at three rates, namely (5%, 10%, and 15%) were utilized. Again, the experiments were conducted with varying EGR rates for B20 blend fuel. A good percentage of reduction in NOx was obtained with increase in EGR rates. But other emissions like CO, HC, smoke, and CO2 emissions were found to increase with rise in EGR rates. Thus, a comparison was made with three rates of EGR emission values with all types of test fuels to optimize the EGR rate leading into the inlet charge. 10% EGR rate gave a maximum reduction of 16.34% in NOx emission without affecting much in the emissions like HC, CO, Smoke, and CO2 along with a small drop in performance.

Experimental investigation and exergy analysis on homogeneous charge compression ignition engine fueled with natural gas and diethyl ether.

In this work, diethyl ether (DEE) and compressed natural gas (CNG) port fuel injection (PFI) was investigated in direct injection (DI) compression ignition engine to determine the performance, combustion, and emission behaviors. In dual fuel mode, DEE and neat diesel were used as fuel energy, whereas in homogeneous charge compression ignition (HCCI) mode, DEE, and CNG were used as fuel energy. The engine behavior was analyzed for different inlet charge temperatures. Exergy analysis has been carried out for analyzing the various availability shares in the engine. The maximum brake thermal efficiency of the engine increased at peak load from 27.31% in neat diesel to 29.12% for dual fuel mode (D + CNG). Hydrocarbon and carbon monoxide emissions were reduced and oxides of nitrogen increased with the inlet charge heating mode. Maximum exergy efficiency was observed as 57.1% in dual fuel operation. The result of this work proves that CNG in dual and HCCI are effective for engine operation.

INCREASING EFFICIENCY OF THE DIESEL ENGINE STARTING

Introduction.The paper is devoted to the investigation of the D-type diesel engines’ start-up of the B-2 type under low temperatures, especially to the influence of the fresh charge temperature on the starting characteristics of the diesel engines. The Russian Federation is located in climatic zones with predominance of low ambient air temperatures and under extreme conditions. However, such situation is not adequately studied in scientific literature.The main problem is in the search for rational values of the temperature of the fresh charge at the beginning of the compression stroke. The increase of such temperature leads to the decrease in the oxygen mass, and to the decrease to an insufficient temperature at the end of the compression stroke and, as a result, it would not provide ignition. Therefore, the aim of the research is to substantiate the rational values of the fresh charge temperature and further practical implementation of these values at modern BTWT facilities.Materials and methods.The author uses standard theoretical and theoretical methods based on widely approved dependences of the piston internal combustion engines’ theory, gas dynamics and thermodynamics, which have been refined taking into account the features of the diesel engine start. Results. As a result, the author determines rational values of the fresh charge temperature, makes the analysis of the pre-launch preparation and facilitating of the D-type diesel engines’ start-up and demonstrates the method of increasing and further stabilizing of the temperature of the inlet charge at modern BTWT facilities.Discussion and conclusion.The research confirms the rational values of the fresh charge temperature, by using of which the diesel has the best starting characteristics. The author also proposes a technical solution for values’ realization by using a vortex induction heater.

Experimental Investigations on Manifold Injection of Diesel and Biodiesel in a HCCI Engine with Inlet Charge Heating

In the present study, engine tests were conducted on a modified single cylinder four stroke compression ignition (CI) engine operated in homogeneous charge compression ignition (HCCI) mode with injection of diesel and biodiesels through intake manifold. The intake air temperature varied from 50 to 80 °C for diesel and 55 to 85 °C for biodiesel using air pre heater. The coolant temperature varied from 40 to 60 °C for both the diesel and biodiesel operation. For the comparison purpose, CI engine fuelled with diesel was operated at the injection timing of 23°BTDC and an injector pressure of 205 bar. It is seen that HCCI mode of engine operation with diesel and biodiesel resulted into 35-45% lower brake thermal efficiency (BTE) with significant reduction in nitrogen oxide (NOx) emission by 98% and smoke emissions by 65-75%. On the other hand, HCCI engine operation with diesel and biodiesels showed increased hydrocarbon (HC) emissions by 20-25 times and carbon monoxide (CO) emissions by 30-40%. However, peak pressure (PP) and heat release rate (HRR) decreased by 20-25% when compared to CI mode of engine operation.

TOPSIS-based parametric optimization of compression ignition engine performance and emission behavior with bael oil blends for different EGR and charge inlet temperature.

The demand for higher fuel energy and lesser exhaust emissions of diesel engines can be achieved by fuel being used and engine operating parameters. In the present work, effects of engine speed (RPM), injection timing (IT), injection pressure (IP), and compression ratio (CR) on performance and emission characteristics of a compression ignition (CI) engine were investigated. The ternary test fuel of 65% diesel + 25% bael oil + 10% diethyl ether (DEE) was used in this work and test was conducted at different charge inlet temperature (CIT) and exhaust gas recirculation (EGR). All the experiments are conducted at the tradeoff engine load that is 75% engine load. When operating the diesel engine with 320K CIT, brake thermal efficiency (BTE) is improved to 28.6%, and carbon monoxide (CO) and hydrocarbon (HC) emissions have been reduced to 0.025% and 12.5ppm at 18 CR. The oxide of nitrogen (NOx) has been reduced to 240ppm at 1500rpm for 30% EGR mode. Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method is frequently used in multi-factor selection and gray correlation analysis method is used to study uncertain of the systems.

Effect of exhaust gas recirculation and charge inlet temperature on performance, combustion, and emission characteristics of diesel engine with bael oil blends

The threat of fossil fuel depletion and augmented environmental pollution caused by diesel fleets can be curbed by adopting suitable fuel and engine modifications. In the present work, effects of engine speed (r/min), injection timing, injection pressure and compression ratio on performance and emission characteristics of a compression ignition engine were investigated. The ternary test fuel of 65% diesel + 25% bael oil + 10% diethyl ether has been used, where the tests have been conducted at different charge inlet temperature and exhaust gas recirculation. All the experiments were conducted at the trade-off engine load that is 75% engine load. When the diesel engine operating with 320 K charge inlet temperature, brake thermal efficiency has been improved to 28.6%. Meanwhile reduced emission levels of carbon monoxide (0.025%) and hydrocarbon (12.3 ppm) were observed during the engine operation with 320 K charge inlet temperature and compression ratio of 18:1. The oxides of nitrogen have been reduced to 226 ppm at 16:1 compression ratio with 30% exhaust gas recirculation mode.

Analysis the optimum inlet air temperature for controlling homogeneous charge compression ignition (HCCI) engine

Homogeneous charge compression ignition engine is promising replacement for conventional CI diesel engine with lower oxides of nitrogen (NOx) and smoke emissions and improves the thermal efficiency with consume less amount of fuel. In general, HCCI engine operates with lean air/fuel charge for all operating condition, and it makes the HCCI combustion more complex and difficult to control the start of ignition point. The inlet air temperature is the primary parameter for controlling the HCCI combustion. In this study, the HCCI engine was operated at different inlet air temperatures as 90°C, 100°C, 110°C, 120°C, 130°C, 140°C and 150°C respectively. From this study, it was observed that the level of NOx emission increased with increasing the inlet air temperature and smoke emission was reduced with increasing the inlet charge temperature. The inlet air temperature about 120°C showed maximum reduction of smoke emission about 15HSU at 60% load. Similarly, CO and HC were reduced with increasing the inlet air temperature. The specific fuel consumption of HCCI mode engine decreased with increasing the inlet air temperature and the power output of the engine increased with increasing the suction air temperature.

Numerical investigation of stratified air/fuel preparation in a GDI engine

A numerical study has been performed to study atomization and preparation of air/fuel mixture under Gasoline Direct Injection (GDI) conditions. Performance of a single-hole injector was initially investigated and effects of ambient pressure, temperature and temperature of the injected fuel on liquid and vapour penetration lengths were analysed. Subsequently, air/fuel mixture preparation for a multi-hole injector in a simplified GDI engine was investigated. To simulate part load engine conditions, fuel spray and mixing was studied during the compression stroke of the engine. Effect of charge stratification, wall wettability and droplet statics on engine operating conditions like start of injection, injection pulse width, charge inlet temperature, engine RPM and overall equivalence ratio was studied. The droplet phase was tracked using Lagrangian framework and the continuous phase was simulated within the Eulerian framework. Turbulence modelling was performed using the standard k−ε model and ideal gas law was assumed while performing vapour-liquid equilibrium calculations.

Effect of inlet charge temperature on a diesel-fuelled homogeneous charge compression ignition engine

In this work, experimental investigations were carried out on a diesel-fuelled homogeneous charge compression ignition (HCCI) engine with different inlet charge temperatures such as 80°C, 90°C, 100°C, 110°C and 120°C. Initially, the HCCI engine was operated under normal room temperature from no load to full load. Secondly, the HCCI engine was operated with different inlet charge temperatures and the effect of charge temperature on the HCCI engine output was analysed. In general, the HCCI engine has ultra-low NOx and smoke emissions. From this study, it was observed that the level of NOx emission increased with increasing inlet charge temperature within a certain limit and then reduced. However, smoke emission was reduced with increasing inlet charge temperature. The charge temperature of 100°C shows the maximum reduction of smoke emission is about 23 HSU. Similarly the exhaust emissions of CO and HC were reduced than the other charge temperatures. The specific fuel consumptions were increased with increasing charge temperature.

Modelling of oxide of nitrogen formation in a lean burn premixed charge stirred chemical reactor based engines

Lean burn premixed charge stirred chemical reactor based combustion engines have developed to simultaneously reduce oxides of nitrogen (NOx) and soot from engine. Estimation of the in-cylinder nitric oxide (NO) in these engines is needed to understand its effects on the combustion phasing of these engines in modifying the ignition and combustion kinetic via NO-promoted production of OH radical, HO2 + NO ↔ OH + NO2. In the present work, modelling work on NO formation in the premixed charge stirred chemical reactor combustion based engine is presented. Firstly, the current understanding about the kinetics of accelerating and inhibiting effect of NO and its formation is presented. Secondly, factors (reaction rates and heat transfer coefficient) affecting in-cylinder NO formation were investigated and quantified. Thirdly, the relationship between the in-cylinder NO formation with in-cylinder heat transfer, combustion duration, charge inlet temperature and pressure were established. Finally, the impacts of parameters currently used for controlling in-cylinder combustion characteristics was investigated and presented for NO formation inside engine cylinders.

Modification of four-stroke engine for operation in two-stroke cycle for automotive application

The main disadvantages of two-stroke engines such a big fuel consumption and big emission of hydrocarbons or carbon monoxide can be reduced by new proposal of design of two stroke engine based on four stroke engines. The paper describes the operation of high supercharged spark ignition overhead poppet valve two-stroke engine, which enables to achieve higher total efficiency and exhaust gas emission comparable to four-stroke engines. The work of such engines is possible by proper choice of valve timings, geometrical parameters of inlet and outlet ducts and charge pressure. The engine has to be equipped with direct fuel injection system enabling lower emission of pollutants. The work is based on theoretical considerations and engine parameters are determined on the simulation process by use GT-Power program and CFD program for different engine configurations. The initial results included in the paper show influence of valve timing on engine work parameters and predicted exhaust gas emission. The simulation results show that the nitrogen oxides are considerably reduced in comparison to four-stroke engines because of higher internal exhaust gas recirculation. The innovation of this proposal is applying of variable valve timing with turbocharging system in the two-stroke engine and obtaining a significant downsizing effect. The conclusions shows the possibilities of applying two-stroke poppet valve engine as a power unit for transportation means with higher total efficiency than traditional engines with possible change of engine operation in two modes: two- and four stroke cycles. The main disadvantages of two-stroke engines such a big fuel consumption and big emission of hydrocarbons or carbon monoxide can be reduced by new proposal of design of two stroke engine based on four stroke engines. The paper describes the operation of high supercharged spark ignition overhead poppet valve two-stroke engine, which enables to achieve higher total efficiency and exhaust gas emission comparable to four-stroke engines. The work of such engines is possible by proper choice of valve timings, geometrical parameters of inlet and outlet ducts and charge pressure. The engine has to be equipped with direct fuel injection system enabling lower emission of pollutants. The work is based on theoretical considerations and engine parameters are determined on the simulation process by use GT-Power program and CFD program for different engine configurations. The initial results included in the paper show influence of valve timing on engine work parameters and predicted exhaust gas emission. The simulation results show that the nitrogen oxides are considerably reduced in comparison to four-stroke engines because of higher internal exhaust gas recirculation. The innovation of this proposal is applying of variable valve timing with turbocharging system in the two-stroke engine and obtaining a significant downsizing effect. The conclusions shows the possibilities of applying two-stroke poppet valve engine as a power unit for transportation means with higher total efficiency than traditional engines with possible change of engine operation in two modes: two- and four stroke cycles.

Analysis of exergy loss of gasoline surrogate combustion process based on detailed chemical kinetics

Abstract Chemical reaction is the most important source of combustion irreversibility in premixed conditions, but details of the exergy loss mechanisms have not been explored yet. In this study numerical analysis based on non-equilibrium thermodynamics combined with detailed chemical kinetics is conducted to explore the exergy loss mechanism of gasoline engine like combustion process which is simplified as constant volume combustion. The fuel is represented by the common accepted gasoline surrogates which consist of four components: iso-octane (57%), n-heptane (16%), toluene (23%), and 2-pentene (4%). We find that overall exergy loss is mainly composed of three peaks along combustion generated from chemical reactions in three stages, the conversion from large fuel molecules into small molecules (as Stage 1), the H2O2 loop-related reactions (as Stage 2), and the violent oxidation reactions of CO, H, and O (as Stage 3). The effects of individual combustion boundaries, including temperature, pressure, equivalence ratio, oxygen concentration, on combustion exergy loss have been widely investigated. The combined effects of combustion boundaries on the total loss of gasoline surrogates are also investigated. We find that in a gasoline engine with a compression ratio of 10, the total loss can be reduced from 31.3% to 24.3% using lean combustion. The total loss can be further reduced to 22.4% by introducing exhaust gas recirculation and boosting the inlet charge. If the compression ratio is increased to 17, the total loss can be decreased to 20.4%, and finally to 16.8%, if the compression ratio is further increased to 100.

Wave dynamics analysis at the intake of a turbocharged engine: concept proposal of a new active inlet charge air duct for low-speed tuning and high-speed permeability

The unsteady-state gas dynamics at the intake of a turbocharged engine were analysed. The objective is to tune the intake line to low operating speeds where the exhaust gases lack the enthalpy needed to operate the turbocharger at rated speeds and to provide the boost pressure needed. The proposed methodology compensates for the lack of boost pressure by benefiting from the existing wave action at the intake. Zero-dimensional acoustic modelling is first used to investigate the geometrical parameters which have the most influnce on low-end acoustic tuning. Impedance bench and electrically driven engine tests complete the study and compare different intake configurations and two geometries of charge air coolers: an air-to-air charge air cooler and a water-cooled charge air cooler. Optimal intake configurations were found for low-end torque considerations as well as high-speed operation where a reduction in the pressure losses is most important. The findings were validated and established on an engine test bench with torque gain at different rotational speeds of the engine. The study led to the proposal of an active charge air duct which enables a solution to be found for the low-end torque where acoustic tuning is favoured and for high-speed operation where the boost pressure is readily available. The acoustic response of this part was compared with the reference solution, and conclusions and possible topics for future work were obtained from the analysis.

The potential of catalysed exhaust gas recirculation to improve high-load operation in spark ignition engines

Within the literature, there are a number of studies investigating the benefits of exhaust gas recirculation, and as a result it has become established as a promising technology for combustion control to allow engine downsizing technology to be advanced. Aside from the dilution effect of exhaust gas recirculation, some of the components, such as NO, CO, and hydrocarbons, can have significant chemical effects. The literature shows that the component within exhaust gas recirculation which has the largest chemical effect on combustion is NO, which can promote or inhibit the onset of autoignition causing reactions within the end gas at high load. The reduction in NOx gases in catalysed exhaust gas recirculation can increase the knock limit at high load, with some authors reporting up to a 5∘ crank angle improvement in combustion phasing. There is conflicting evidence on whether this translates to an improvement in fuel consumption, with one study finding a decrease of up to 2% comparing to another finding an increase of 1.5%-3.5%. Crude calculations on the emissions of a 2.0-L direct injection spark ignition engine operating at high load show that in an extreme case the reduction in the calorific value of the inlet charge due to catalysis of the recirculated gases can be up to 4.5%. Despite the potential benefits, the literature on catalysed exhaust gas recirculation is fairly limited and the evidence seems so far inconclusive as to whether this technology may have the potential to further enhance the benefits of exhaust gas recirculation. This article uses current literature to ascertain the potential benefits of catalysed exhaust gas recirculation, compare to pre-catalyst exhaust gas recirculation, and investigates its individual components in more detail to explain how chemical interactions can either promote or inhibit ignition depending on their concentration and temperature.

Energy and exergy analyses of homogeneous charge compressin ignition (HCCI) engine

In the present investigation, a single-cylinder, four-stroke cycle, TD43 engine has been used to evaluate the first and second laws of thermodynamics terms. To this aim, the first law analysis is done by using a thermo-kinetic model. The results show a good agreement with the experimental data. Also for the second law analysis, a developed in house computational code is applied. Behaviors of the results have a good accordance with the literature. The result show that an increase in the inlet charge temperature causes the maximum pressure, indicated work availability and entropy generation per cycle be reduced and the in-cylinder temperature, heat loss availability and total availability be increased. Also the results show that an increase in the engine speed causes the total availability be increased and the heat loss availability be decreased. When the engine speed increases, reduction in the duration of cycle evolution causes the reduction of heat transfer.