Cycle Diesel Engine Research Articles

密閉サイクル・ディーゼル機関技術史，拾い読み

密閉サイクル・ディーゼル機関技術史，拾い読み

A Model to Predict the Influence of Inconsistencies in Thermal Barrier Coating (TBC) Thicknesses in Pistons of IC Engines

LHR (Low heat Rejection) engines comprise of components that are modified with ceramic Thermal Barrier Coatings (TBC) to derive improvements in performance, fuel efficiency, combustion characteristics and life. In addition to engine parameters, the ability of TBCs (250 - 300µm thick) to function favorably depends on materials technology related factors such as surface-connected porosity, coating surface roughness, uniformity and consistency in coating thickness [1]. Right since the nineties, emphasis has been placed on the complexity of piston contours from a coating processing standpoint because the piston bowl geometry although appears simple, is actually quite complex. Robotic plasma gun manipulation programs have been developed to obtain uniform coating properties and thicknesses which are highly classified information.Thicker coatings offer better thermal insulation characteristics but in thickness deficient regions, TBCs may be as thin as ∼30 microns. Applied via the ‘line of sight’ process, in the Atmospheric Plasma Spray System the coating thickness does not get developed adequately if the components comprise of contours with shadow regions. Thus the coating quality of a LHR engine heavily depends upon the shape of the engine components. This affects the barrier effects offered by the TBC and is reflected via generation of unwanted thermal gradients in the combustion chamber and on the external piston walls that adversely influence the engine performance.Extensive diesel engine cycle simulation and finite-element analysis of the coatings have been conducted to understand their effects on (a) diesel engine performance and (b) stress state in the coating and underlying metal substructure. Research work presented here involves the need and developmental efforts made via Computational Fluid Dynamics (CFD) to generate a model via ANSYS - Fluent simulation software that predicts the temperature gradient across TBCs of various ceramics and coating thicknesses. The geometric model was developed using the dimensions obtained using a CMM (Coordinate Measuring Machine) in Solidworks and the mesh was developed in Altair Hypermesh. The generated mesh consists of 221938 elements. Interfaces were created between the piston-bond coat-top coat surfaces. The Ansys-FLUENT CFD code solves the energy equation to find out the temperature drop in the piston for different combustion temperatures. Although most of the cavities presented are not rectangular, incompressible and steady laminar flow was assumed. The Semi-Implicit Method for Pressure-linked Equations (SIMPLE) was used to model the interaction between pressure and velocity. The energy variables were solved using the second order upwind scheme. In addition, the CFD program uses the Standard scheme to find the pressure values at the cell faces. Convergence was determined by checking the scaled residuals and ensuring that they were less than 10-6 for all variables.Two cases with combustion temperatures varying between 700 and 800 K were developed in Ansys FLUENT, wherein the thickness was deficient in the ‘shadow’ region. The model was validated via experimentation involving thermal shock cycle tests in prototype burner rig facility and measuring the temperature drop across the TBC as well.Non uniform coatings, leading to non-uniform drop in temperature across the thickness are most likely to affect the lubrication system of the engine and therefore the performance. Substantial efforts must be directed towards development of consistent and uniformly thick coatings for optimum performance of the LHR engine.

About some peculiarities of calculating the energy flow in the non – equilibrium diesel engine cycle

In the modern methods of calculating the reciprocating engines there is an assumption that the ideal gas is used as actuation fluid in the cycle that makes the current task much easier however brings sufficient untrueness to the achieved results and mispresents the description of the process itself. It was suggested an algorithm of calculating the thermodynamic cycle through releasing the equilibrium component of the energy flow in the non-equilibrium combined cycle at the cost of accepted concept of the process volume speed as a cycle parameter. The developed method allows to separate the most efficient cycle part and after achieving in the remaining part of energy can be used for ship power plant operation by means of effectively set phase of releasing the exhaust gases.

Effect of turbo charging and steam injection methods on the performance of a Miller cycle diesel engine (MCDE)

In this study, application of the steam injection method (SIM), Miller cycle (MC) and turbo charging (TC) techniques into a four stroke, direct-injection diesel engine has been numerically and empirically conducted. NOx emissions have detrimental influences on the environment and living beings. They are formed at the high temperatures, thus the Diesel engines are serious NOx generation sources since they have higher compression ratios and higher combustion temperatures. The international regulations have decreased the emission limits due to environmental reasons. The Miller cycle (MC) application and steam injection method (SIM) have been popular to abate NOx produced from the internal combustion engines (ICEs), in the recent years. However, the MC application can cause a reduction in power output. The most known technique which maximizes the engine power and abates exhaust emissions is TC. Therefore, if these three techniques are combined, the power loss can be tolerated and pollutant emissions can be minimized. While the application of the MC and SIM causes to diminish in the brake power and brake thermal efficiency of the engine up to 6.5% and 10%, the TC increases the brake power and brake thermal efficiency of the engine up to 18% and 12%. The experimental and theoretical results have been compared in terms of the torque, the specific fuel consumption (SFC), the brake power and the brake thermal efficiency. The results acquired from theoretical modeling have been validated with empirical data with less than 7% maximum error. The results showed that developed combination can increase the engine performance and the method can be easily applied to the Diesel engines.

Analysis of emission models integrated with traffic models for freight transportation study in urban areas

In the present work, two dynamic emission models integrated to traffic simulators were analysed: Panis et al. and EnViver integrated to traffic simulators AIMSUN and VISSIM, respectively. These models were selected due to their capacity to execute emission estimations of particulate matter (PM), a pollutant found in the incomplete combustion in diesel cycle engines and extremely harmful to human health and because of their negative impact was the study object of this paper. Estimated data were confronted with collected data emission in the field through a collecting procedure built by Dias et al. (2015) from a typical urban service vehicle of Fortaleza City - CE, aiming to verify the model that estimated particulate matter data emission closer to the reality of vehicles studied in this research. The selected models can estimate the main rates of particulate matter or originated in urban freight transport. However, the model proposed by Panis et al. was considered more appropriate in the representation of this phenomenon.

Analysis of emission models integrated with traffic models for freight transportation study in urban areas

In the present work, two dynamic emission models integrated to traffic simulators were analysed: Panis et al. and EnViver integrated to traffic simulators AIMSUN and VISSIM, respectively. These models were selected due to their capacity to execute emission estimations of particulate matter (PM), a pollutant found in the incomplete combustion in diesel cycle engines and extremely harmful to human health and because of their negative impact was the study object of this paper. Estimated data were confronted with collected data emission in the field through a collecting procedure built by Dias et al. (2015) from a typical urban service vehicle of Fortaleza City - CE, aiming to verify the model that estimated particulate matter data emission closer to the reality of vehicles studied in this research. The selected models can estimate the main rates of particulate matter or originated in urban freight transport. However, the model proposed by Panis et al. was considered more appropriate in the representation of this phenomenon.

Biodiesel Glycerides from the Soybean Ethylic Route Incomplete Conversion on the Diesel Engines Combustion Process

An evaluation was made to determine the effect of the glycerides presence resulting from the incomplete conversion of soybean biodiesel produced via alkaline catalysis and ethylic route on engine performance, and emissions in formulations containing 10 and 20% (m/m) of biodiesel used as additives in base diesel with low sulfur content and cetane ratings of 45 and 50. By way of comparison, similar formulations were used with soybean biodiesel methyl route with low concentration of glycerides. Tests on a diesel cycle engine with a mechanical fuel injection system indicated that the presence of glycerides decreases the volatility of biodiesel and increase the cetane number of fuels. The higher the cetane number, the higher the particulate matter emissions and the lower the unburned hydrocarbon emissions. Formulations with cetane number 50 showed higher emissions of particulate matter. The presence of glycerides in biodiesel reduces the fuel's vapor pressure, thereby increasing the cetane number and emissions of particulate matter and lower emissions of unburned hydrocarbons. The specific consumption of fuels formulated with biodiesel increases due to its lower enthalpy of combustion and to the presence of glycerides in fuels formulated with soybean biodiesel produced via the ethanol route.

Air and fuel supercharge in the performance of a diesel cycle engine

ABSTRACT: This paper aimed to evaluate the performance of a Diesel cycle engine, changing the configurations for the air and fuel supply system. Variables analyzed were torque, power, specific fuel consumption and thermal efficiency in four different engine configurations (aspirated, aspirated + service, turbocharged + service and turbocharged). For that, there were dynamometer experiments by power take-off of an agricultural tractor. The experimental outline used was entirely randomized, in a bifatorial design with three repetitions. Results indicated that the engine supercharge, compared to its original configuration, provided a significant increase of torque and power. Only the addition of turbo does not caused a significant effect in the engine performance. Application of turbocharger provides an improvement in the burning of the air/fuel mixture, which favors the increase of engine power and; consequently, reduced the specific fuel consumption.

Investigation of the effects of the steam injection method (SIM) on the performance and emission formation of a turbocharged and Miller cycle diesel engine (MCDE)

The steam injection method (SIM) has been widespread to abate NOx of internal combustion engines (ICEs). Another NOx reduction method known in the literature is the Miller cycle (MC) application. However, this method causes a reduction in the power output. The most known technique which improves the engine power and decreases emissions is the turbo charging (TC). Hence, these three methods can be combined to make up for the power loss and to decrease pollutant emissions at higher rates. In this study, the combination of the SIM, TC and MC methods (SIM-TC-MC) has been carried out for a direct injection (DI), naturally aspirated diesel engine. The results have been compared with standard condition (STD) in terms of the engine performance and CO, CO2, NO, HC. Optimal condition has been determined as 10 CA retardation, 20% steam ratio of the fuel mass and 1.1 TC pressure (C62-S20-T1.1) in terms of the minimum NO formation. At this condition, NO, HC, CO and CO2 reduced by 48%, 35%, 64% and 8%; the increase rates in the brake power and brake thermal efficiency are 17% and 11, respectively. The results indicated that SIM-TC-MC may be implemented into a diesel engine to control NO and to obtain higher engine performance.

Wear of ceramic tools when machining Inconel 751 using argon and oxygen as lubri-cooling atmospheres

The aim of this work is to study the tool life and wear (types and mechanisms) experienced by ceramic tools (SiAlON, whisker and mixed ceramic) when turning the nickel-based superalloy Inconel 751 using argon and oxygen atmospheres. This material is largely used as inlet and outlet gas valves in Otto and Diesel cycle engines. Design of experiment (DOE) planning techniques were used with the following input variables: tool materials [SiAlON (Si3N4+Al2O3), Whisker (Al2O3+SiCw) and Mixed (Al2O3+TiC)], cutting speed, tool geometry and lubri-cooling atmosphere (dry cutting as a benchmark, followed by argon- and oxygen-enriched atmospheres). These atmospheres support sustainable manufacturing, in contrast to common practices in which cutting fluids are considered a polluting component. In each machining test, a new tool edge was used through the end of the tool life, with interruptions conducted for wear measurements. At the end of the tests, the tools were analysed by optical and scanning electron microscopy. The results indicated that the cutting speed, tool geometry and lubri-cooling atmosphere influence the types of wear and the tool life. Notch wear (VBN), average flank wear (VBB) and nose wear (VBC) prevailed and depended on the cutting conditions and tool material. Overall, the SiAlON tools exhibited the best tool life performance, followed by the mixed and whisker ceramics. The lowest tool life was observed for whiskers in dry conditions. Notch wear was accelerated by an oxygen-rich atmosphere, particularly at low cutting speeds. Attrition and chipping were the dominant wear mechanisms.

English

Given the need for new alternatives to finite source of energy from fossil fuels, testing of alternative fuels has become quite important. Studies have been carried out using sets of tractor with equipment to evaluate the operational performance together with supplying diesel and biodiesel. Biodiesel is a feasible alternative as it waives adjustments in diesel cycle engines, unlike other clean fuels such as natural gas or biogas, for example. This study aimed at to assess the operational performance and smoke density of a tractor running on diesel and biodiesel, through the parameters of fuel type and engine speed. The assessed engine speeds were 1800, 1900, 2000, 2100, 2200, 2400 and 2600 rpm and the fuel types were diesel B S1800, diesel B S500, soyabean biodiesel and murumuru biodiesel. The results showed that there was an increase in the specific consumption for all fuel types with increasing engine speed, and 1900 and 2000 rpm, mainly for the use of biodiesel speed range that least interferes with the performance. The smoke density was reduced when using soyabean and murumuru biodiesels. Key words: Biofuel, specific consumption, smoke density, operational performance, engine speeds.

English

Renewable energy benefits and disadvantages have been subject of major discussions and studies. Thus, this study aimed at assessing the smoke opacity from a farming tractor running two types of diesel, B S1800 (B0) and B S10 (B0), and ethyl biodiesel from babassu oil at two rates (B50 and B100), at six day periods (2, 6, 10 am, 2, 6 and 10 pm). The study was conducted at the Department of Agricultural Engineering of the Faculty of Agricultural and Veterinary Sciences, UNESP, in Jaboticabal - SP, Brazil. The results showed a reduced smoke opacity during daytimes of lower ambient temperature and higher air relative humidity. In addition, smoke opacity was reduced as higher rates of babassu biodiesel were added to B S1800 diesel and B S10; thus, consisting of an efficient procedure of reducing smoke opacity in farming tractor engines. Key words: Biofuel, emissions, pollutants, renewable energy, diesel engine cycle, Orbinya martiana.

DESEMPENHO DE UM TRATOR AGRÍCOLA SOB DIFERENTES CARGAS E VAZÕES DE AR ADMITIDAS PELO MOTOR

O objetivo desse trabalho foi avaliar o desempenho energético, o rendimento na barra de tração e a eficiência de combustão em um motor de ciclo Diesel de um trator agrícola utilizando diferentes cargas na barra de tração e vazões de entrada de ar no sistema de alimentação. Assim, montou-se um experimento em delineamento inteiramente casualizado no esquema fatorial 5 x 4, constituído por diferentes cargas na barra de tração do trator (2,7; 7,4; 11,9; 15,5 e 20,5 kN) e diferentes vazões de ar admitida pelo motor (0,077; 0,085; 0,099 e 0,109 m3 s-1), com três repetições. A vazão de ar admitida pelo motor nas menores proporções, 0,077 e 0,085 m³ s-1, proporcionou aumento no consumo de combustível. O maior rendimento na barra de tração e o menor consumo específico de combustível ocorreram quando o trator tracionou a maior carga, 20,5 kN. A eficiência de combustão reduz com o aumento da vazão de ar admita para o motor.

Effect of replacing nitrogen with helium on a closed cycle diesel engine performance

One of most important problems of closed cycle diesel engine is deterioration of cylinder pressure and consequently the engine power. Therefore this research aimed to establish a multi zone model using Computational Fluid Dynamic (CFD) code; ANSYS Fluent 14.0 to enhance the closed cycle diesel engine performance. The present work investigates the effect of replacing nitrogen gas with helium gas in different concentration under different engine load and equivalence ratios. The numerical model results were validated with comparing them with those obtained from the previous experimental results. The engine which was used for the simulation analysis and the previous experimental work was a single cylinder with a displacement volume of 825cm3, compression ratio of 17 and run at constant speed of 1500RPM. The numerical results showed that replacing nitrogen with helium resulted in increasing the in-cylinder pressure. The results showed also that a percentage of 0.5–10% of helium on mass basis is sufficient in the recovery needed to overcome the drop in-cylinder pressure and hence power due to the existence of CO2 in the recycled gas up to 25%. When the CO2 % reaches 25%, it is required to use at least 10% of He as replacement gas to achieve the required recovery.

An innovative Organic Rankine Cycle system for integrated cooling and heat recovery

Converting a portion of the waste heat into usable power by implementing Rankine and Organic Rankine Cycles (ORC) on long-haul trucks is seen as a potential way to improve the overall system efficiency. To identify techno-economical heat sources across the drive cycle of a Heavy Duty Diesel Engine (HDDE), an energy and exergy analysis was performed on all the available heat streams. As a result, to recover the combined exhaust gases and coolant heat, a reference cascade system was analysed. Owing to the nature of this application, a size vs. performance optimisation was performed for the cascade system utilising water and R245fa fluid combination. Despite a 1.8% Brake Thermal Efficiency (BTE) improvement, the key consideration in the research and development efforts for ORC systems was identified as the investigation of technical paths that may improve the practicality of such a heat-to-power conversion concept. For this, simple holistic solutions were considered vital to meet the impending CO2 regulations. To provide a potential solution, an innovative dual-pressure ORC system is therefore proposed to partially address the shortcomings of the cascade system. This innovative system is a function of new working fluids (i.e. water blends), its associated cycle operating mode and a novel architecture (i.e. direct engine block heat recovery). A screening and evaluation methodology applied to water–organic blends is presented. Simulations conducted in Aspen HYSYS V8 showed that, compared to the reference cascade system, the proposed dual-pressure system has the potential to deliver an average of 20% improvement in the system power, a 50% reduction in the total heat exchanger footprint, and a reduced system complexity. These advantages bode well for an integrated and relatively compact engine cooling and exhaust heat recovery solution for future automotive HDDEs. Implementation of the proposed system at mid-speed high-load engine operating condition increased the overall BTE from 41.4% to a maximum of 43.6%.

Modeling and simulation of the thermodynamic cycle of the Diesel Engine using Neural Networks

Abstract: In this paper, a unique single zone combustion model is proposed to predict Diesel engine’s performance, pressure, and temperature based on the conservation of mass and energy. In order to simulate all phases of combustion, the proposed model takes in consideration the dynamics of the intake and exhaust gas through the valves, the ignition delay, the instantaneous change in gas properties, the properties of the burned fuel, and the heat losses by the walls. Validation of this model has been realized by experimental data. Important issue has been recognized that the physical model takes too much time in calculation. For this purpose, a Feed-Forward Neural Network (FFNN) model is developed and validated experimentally to predict the pressure and temperature in the cylinder in nominal and faulty operations. Finally, the influence of some possible faults that may be produced on the diesel engine cycle during the operation has been analyzed.

Concentration Profiles of Regulated and Unregulated Pollutants Emitted from the Combustion of Soybean Biodiesel and Diesel/Biodiesel Blend Originating of a Diesel Cycle Engine

This study evaluated the concentration profiles of regulated and unregulated pollutants emitted from a stationary diesel engine cycle, operating at the speed of 1800 rpm and 0% load, using biofuels and binary blends. The experimental test considered fuel burning time on three different periods and storage times. The operation of the engine when it is still cold, for example at 15 minutes, showed negative effect on particulate matter (PM), benzene and ethylbenzene emissions in pure soybean biodiesel (B100) compared to the blend of diesel with 5% biodiesel (B5). Regarding to the concentration of mono aromatics, aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAH), this study showed similar results to those reported in the literature, where B5 fuel emits more pollutants than pure biodiesel. However, comparing some pollutants individually, benzene and ethylbenzene emissions were higher for B100 and pure soybean biodiesel with butil-hydroxyanisol additive (B100 Adt). The B5 showed the highest concentration profile for the PAH sum in the gaseous and particulate phases in longer engine operation periods.

The Influence of LPG Fuelling on Diesel Engine Cycle Variability

Liquid Petroleum Gas physic-chemical properties lead to specific aspects of the in-cylinder combustion and mechanical running of diesel engines. Comparative to the classic diesel engine, the cycle variability coefficients (COV) are presented at dual fuelling for maximum pressure, maximum pressure rise rate, maximum pressure angle, indicated mean effective pressure, heat release rate and cycle angle points of mass fraction burned. The calculated values of these parameters are bigger comparative to the normal values of diesel engines, but don’t exceed the maximum admitted values that provide engine reliability. From COV values analysis, the maximum admitted LPG cycle dose is also established.

Avaliação das emissões de escapamento veicular em condições específicas do motor: partida e marcha-lenta

<p>O crescimento exponencial do quantitativo de veículos automotores no Brasil, sobretudo nos grandes centros urbanos, contribui com a emissão de elevadas taxas de poluentes atmosféricos comprometendo a qualidade do ar e, consequentemente, a saúde da população. Este trabalho possui como objetivo principal avaliar as emissões de poluentes atmosféricos oriundas de veículos automotores equipados com motor ciclo Otto (gasolina e álcool) e/ou ciclo Diesel em condições específicas do motor, nomeadamente, partida (a frio ou a quente) e marcha-lenta. Os resultados ratificam a importância de se considerar o adicional das emissões de poluentes da partida a frio, uma vez que os veículos a álcool e a gasolina atingiram elevadas concentrações de emissão de CO e HC e, no caso do diesel, o NOx. Em geral, o procedimento utilizado neste estudo para análise dos gases de escapamento de forma instantânea, mostrou-se eficiente na demonstração do adicional da partida a frio em relação às condições estabilizadas de operação do motor. Durante a partida a frio, observam-se os maiores níveis de emissões de HC e CO para o veículo movido a E100, o que se deve principalmente às características físico-químicas do etanol, como o alto calor latente de vaporização. Em termos gerais, a metodologia simples e acessível utilizada nesta pesquisa pode ser útil em diagnósticos de emissões veiculares, como também no monitoramento e manutenção veicular regular/preventiva de fontes móveis de emissão de poluentes, além de corroborar para o estudo do adicional de emissões nas condições avaliadas (i.e. inventários de emissões atmosféricas).</p>

The influences of the engine design and operating parameters on the performance of a turbocharged and steam injected diesel engine running with the Miller cycle

This study reports the influences of the engine design and operating parameters on the performance of a turbocharged, steam injected and Miller cycle diesel engine by using a simulation model based on the finite-time thermodynamics. The model is validated with experimental data and the effects of various engine design and operating parameters such as cycle temperature ratio, cycle pressure ratio, friction coefficient, engine speed, mean piston speed, stroke length, inlet temperature, inlet pressure, equivalence ratio, compression ratio, steam ratio, retarding angle and bore-stroke length ratio on the effective power and effective efficiency are investigated. Furthermore, the energy losses originating from incomplete combustion, friction, heat transfer and exhaust output are demonstrated by using figures. The results show that the engine performance increases with increasing some parameters such as cycle temperature ratio, cycle pressure ratio, inlet pressure; with decreasing some parameters such as friction coefficient, inlet temperature, steam ratio, retarding angle of intake valve closing. However, the engine performance could increase or decrease with respect to different conditions for some parameters such as engine speed, mean piston speed, stroke length, equivalence ratio and compression ratio.