Two-stroke Diesel Engine Research Articles

A Zero-Dimensional Mixing Controlled Combustion Model for Real Time Performance Simulation of Marine Two-Stroke Diesel Engines

The paper presents a performance prediction model of marine low-speed two-stroke diesel engines based on an advanced MCC (mixture controlled combustion) model coupled with a fuel injection model. Considering the time of real calculation, the so-called “concentrated exhausting gas” scavenging model and the working process model are used in the present work, and improved by introducing the ratio of pure combustion product over the total gas mass in the cylinder as an expression of the working medium components. The reaction rate model in the zero-dimensional MCC model is improved by introducing the fraction of combustion product in the fuel spray, and the relationship between the combustion model and scavenging quality is established. Meanwhile, the combustion model was simplified in the diffusion combustion phases and integrated with the fuel injection model in order to respond to the change of injection profile and injection timing. A large-scale low-speed marine diesel engine was used for a simulation. The results of the whole model are consistent with experimental data and the speed of calculation is fast enough for real time simulation of low speed and medium speed diesel engines. The prediction model can be used in the design and calibration of the electronic control system and performance optimization of the marine two-stroke diesel engine.

Matching method of electric turbo compound for two-stroke low-speed marine diesel engine

Two-stroke low-speed diesel engine is widely employed in marine industry thanks to its evident advantages on fuel economy and reliability. Normally, turbocharger together with an auxiliary air blower are employed in the two-stroke engine to ensure the smooth scavenging over whole propeller characteristics, but fuel economy and layout compactness of the engine are scarified due to the employment of the auxiliary device. This paper investigates influences of electric turbo compound, which integrates a conventional turbocharger with electric motor/generator (EMG) and capable of replacing the auxiliary blower, on the performance of a two-stroke low-speed marine engine as well as the matching method of the turbocharging system. Firstly, influences of EMG power and compressor/turbine matching on the engine nominal efficiency are discussed in details. The analytical model together with simulation results show that the efficiency of the turbocharger is the most important factor influencing variation behaviors of engine nominal efficiency. In particular, the peak engine nominal efficiency can be achieved when the operational points of the compressor and turbine are pushed to their peak efficiency islands by either the control of EMG power or compressor/turbine matching. Therefore, a matching guideline of the electric turbo compound is proposed based on the study and then applied on a two-stroke low-speed marine engine. Compared with the conventional turbocharger, a smaller compressor is matched at high loads while a smaller turbine is matched at low loads for the optimal electric turbo compound turbocharger. Specifically, brake specific fuel consumption (BSFC) of the engine is reduced by about 2–3% at three load profiles by the new technology.

A Three-Zone Scavenging Model for Large Two-Stroke Uniflow Marine Engines Using Results from CFD Scavenging Simulations

The introduction of modern aftertreatment systems in marine diesel engines call for accurate prediction of exhaust gas temperature, since it significantly affects the performance of the aftertreatment system. The scavenging process establishes the initial conditions for combustion, directly affecting exhaust gas temperature, fuel economy, and emissions. In this paper, a semi-empirical zero-dimensional three zone scavenging model applicable to two-stroke uniflow scavenged diesel engines is updated using the results of CFD (computational fluid dynamics) simulations. In this 0-D model, the engine cylinders are divided in three zones (thermodynamic control volumes) namely, the pure air zone, mixing zone, and pure exhaust gas zone. The entrainment of air and exhaust gas in the mixing zone is specified by time varying mixing coefficients. The mixing coefficients were updated using results from CFD simulations based on the geometry of a modern 50 cm bore large two-stroke marine diesel engine. This increased the model’s accuracy by taking into account 2-D fluid dynamics phenomena in the cylinder ports and exhaust valve. Thus, the effect of engine load, inlet port swirl angle and partial covering of inlet ports on engine scavenging were investigated. The three-zone model was then updated and the findings of CFD simulations were reflected accordingly in the updated mixing coefficients of the scavenging model.

An investigation of the fuel injector dedicated to the aircraft opposed-piston two-stroke diesel engine

The paper presents the research results of the injector construction with the modified injection nozzle. The injector is designed for a prototype opposed-piston aircraft diesel engine. The measurements were based on the Mie scattering technique. The conditions of the experiment corresponded to maximum loads similar to those occurring at the start. The measuring point was selected in line with the analysis of engine operating conditions: combustion chamber pressure at the moment of fuel delivery (6 MPa) and fuel pressure in the injection rail (140 MPa). The analysis focused on the average spray range and distribution, taking into account the differences between holes in the nozzle. As a result of the conducted research, the fuel spray range was defined with the determined parameters of injection. The fuel spray ranges inside the constant volume chamber at specific injection pressures and in the chamber were examined, and the obtained results were used to verify and optimize the combustion process in the designed opposed-piston two-stroke engine.

Design and Optimisation of Marine two-stroke Diesel Engine Piston

ABSTRACT In the cylinder of conventional compression ignition engine, temperature distribution and stress variation set up in the entire piston due to the inherent nature of combustion. This project will investigate causes and effects of high gas pressure and temperature on marine two-stroke diesel engine piston. Investigation has shown that stress-related piston damages play a dominant role mainly due to mechanical and thermal stress or combination of both. The simulation parameters that will be considered in this report are piston material, combustion temperature and combustion pressure. In the present study, conventional marine two-stroke diesel engine piston will be modelled using Autodesk Inventor software. The working condition of the piston will be simulated based on the selected parameters using finite element analysis method to analyze the magnitude of mechanical stresses acting on the piston. The piston will be re-designed using a material superior to the conventional piston material and will be optimized by reducing the stresses acting on the piston. Two materials will be used in the analysis after which the results will be compared and the best will be proposed. The structure and stress analysis (mechanical, thermal and thermal-mechanical stress) of the design will be modelled using the software mentioned earlier.

Nitrogen Oxides Reduction Effect and the Influence Mechanism of Exhaust Valve Lift on a Two-Stroke Marine Diesel Engine

For the two-stroke marine diesel engine, the action of exhaust valve has a significant impact on scavenging and combustion processes and ultimately affects the engine performances and emissions. In order to reduce nitrogen oxides (NOx) emissions of a two-stroke marine diesel engine, different exhaust valve lifts (EVLs) were achieved by computational fluid dynamics simulation method in this study. The NOx reduction effect and influence mechanism of EVL on a two-stroke marine diesel engine were investigated in detail. The results showed that the in-cylinder residual exhaust gas and the internal exhaust gas recirculation (EGR) rate gradually increased with the decreasing EVL. Although the total mass of charge enclosed in the cylinder did not change much, the composition changed gradually and the maximum internal EGR rate reached 13.17% in this study. The maximum compression pressure and combustion pressure both rose first and then decreased with the decreasing EVL. While the start of combustion and the maximum combustion temperature were basically unaffected by EVL, the indicated power of the engine was also not much impacted when the EVL was changed from increasing 10 mm to decreasing 20 mm. The indicated specific fuel consumption first declined slowly and then rose rapidly as the EVL reduction exceeded 20 mm. NOx emissions decreased monotonously with the decreasing EVL. The reduction of NOx formation rate and the amount of NOx formation mass mainly occurred at the middle and late stages of combustion for the downward moving of residual exhaust gas. NOx emissions were reduced by 12.57% without compromising other engine performances at medium-reduced EVL in this study. However, in order to further reduce NOx emissions at low EVLs, other measures may be needed to make the residual exhaust gas more evenly distributed during the initial stage of combustion.

An implicit boundary approach for viscous compressible high Reynolds flows using a hybrid remeshed particle hydrodynamics method

We present an implicit boundary particle method with background mesh adaptation. We use a Brinkman penalisation to represent the boundary of the domain and a remeshed particle method to simulate viscous flow with high Reynolds numbers. A penalty term is added to the Navier-Stokes equations to impose the boundary conditions. The boundary conditions are enforced to a specific precision with no need to modify the numerical method or change the grid, achieving an implicit approach for flow around complex boundaries/geometries simulation. The main idea of the Brinkman penalisation method is to model the solid obstacle as a porous medium. The governing equations for the compressible fluid and penalised Navier-Stokes for the porous medium are solved simultaneously, without need for interface conditions. The accuracy of the method is tested for a number of benchmark problems starting with simple cases such as a periodic laminar flow in a channel (Poiseuille flow), to more complex problems such as the lid-driven cavity with high Reynolds numbers, the reflection and propagation of a compressible shock wave, and finally swirling flow in a model two-stroke diesel engine. The remeshed particle-mesh method coupled with Brinkman penalisation provides a good quality simulation and the results are in agreement with analytical or reference solutions.

Combustion and Emissions Investigation on Low-Speed Two-Stroke Marine Diesel Engine with Low Sulfur Diesel Fuel

Abstract With the implementation and expansion of international sulfur emission control areas, effectively promoted the marine low sulfur diesel fuel (MLSDF) used in marine diesel engines. In this study, a large low-speed, two-stroke, cross-head, common rail, electronic fuel injection marine diesel engine (B&W 6S35ME-B9) was used for the study. According to diesel engine’s propulsion characteristics, experiments were launched respectively at 25%, 50%, 75%, 100% load working conditions with marine low sulfur diesel fuel to analyze the fuel consumption, combustion characteristics and emissions (NOx, CO2, CO, HC) characteristics. The results showed that: Marine diesel engine usually took fuel injection after top dead center to ensure their safety control NOx emission. From 25% to 75% load working condition, engine’s combustion timing gradually moved forward and the inflection points of pressure curve after top dead center also followed forward. While it is necessary to control pressure and reduce NOx emission by delaying fuel injection timing at 100% load. Engine’s in-cylinder pressure, temperature, and cumulative heat release were increased with load increasing. Engine’s CO2 and HC emissions were significantly reduced from 25% to 75% load, while they were increased slightly at 100% load. Moreover, the fuel consumption rate had a similar variation and the lowest was only 178 g/kW·h at 75% load of the test engine with MLSDF. HC or CO emissions at four tests’ working conditions were below 1.23 g/kW·h and the maximum difference was 0.2 or 0.4 g/kW·h respectively, which meant that combustion efficiency of the test engine with MLSDF is good. Although the proportion of NOx in exhaust gas increased with engine’s load increasing, but NOx emissions were always between 12.5 and 13.0 g/kW·h, which was less than 14.4 g/kW·h. Thus, the test engine had good emissions performance with MLSDF, which could meet current emission requirements of the International Maritime Organization.

The Analysis of Overall Ship Fuel Consumption in Acceleration Manoeuvre Using Hull-Propeller-Engine Interaction Principles and Governor Features

Abstract The problem of reduction of greenhouse gas emissions in shipping is currently addressed by many research works and related industries. There are many existing and visionary technologies and ideas, which are conceptually defined or practically realised. This goal can be achieved in different ways, and reducing fuel consumption is one of the major methods. In these circumstances, the aim of this study is to analyse the possibility of fuel consumption reduction by using an alternative control strategy for low-speed marine diesel engines which would take into account the interactions between hull, propeller and main engine. For this purpose, a mathematical model including ship hull and propulsion system is developed. A case study is conducted for a ship for which the results of both the ship hull and screw propeller model tests are available. A low-speed two-stroke diesel engine is then selected for the considered ship. Two different governors are included in the model and their parameters are changed to investigate the dynamic behaviour of the system when simulating the forward acceleration mode in calm sea conditions. The research is mainly focused on variations of fuel consumption by the ship passing a certain distance to reach the nominal constant speed. It is concluded that, for a given travel distance, it is possible to save considerable amount of fuel at the expense of slight increase of journey time.

Numerical Study on the Effects of Multiple-Injection Coupled with EGR on Combustion and NOx Emissions in a Marine Diesel Engine

In this work, the potential of multi-injection strategies coupled with EGR to improve the trade-off relationship of NOx-BSFC (Brake specific fuel consumption) is carefully studied by multi-dimensional simulation using CONVERGE in a low-speed two-stroke diesel engine. The present study reveals that by introducing high EGR rate, the reduction of NOx emissions, the peak heat release rate and the peak pressure can be observed. But the effective fuel consumption rate is increased. We investigate the effects of various multiple-injection strategies on the engine performance, that is, single pilot-injection, single post-injection, single pilot-injection combined with single post-injection, and double pilot-injections, coupled with 39% EGR. The results show that low BSFC can be effectively achieved by a single pilot-injection strategy of small interval and large quantity. However, with a comprehensive consideration of low NOx emissions and BSFC, a strategy of 25 °CA pilot-main interval and 20% quantity should be chosen to obtain the best performance. The analysis of post-injection reveals that it is beneficial to reducing NOx emissions, but BSFC can be deteriorated. Moreover, it can be concluded that it is possible to achieve low NOx emissions and fuel consumption simultaneously by using the pilot-injection combined with post-injection. It also can be found that NOx emissions are deteriorated remarkably when using double pilot-injections.

An Approach for Predicting the Specific Fuel Consumption of Dual-Fuel Two-Stroke Marine Engines

Increasing environmental demands, alongside the planned penetration of natural gas as marine fuel, have rendered dual-fuel engines as an attractive prime mover alternative. In this context, knowing the specific fuel consumption is essential to selecting the most efficient engine. The specific fuel consumption can be approached by simulation models with varying levels of complexity that are either implemented by basic programming languages or simulated by dedicated packages. This study aims to develop a simplified model to predict the specific fuel consumption of dual-fuel two-stroke marine engines driving fixed or controllable pitch propellers. The model relies on clear trends approachable by polynomials that were revealed by normalizing specific fuel consumption. This model requires only the value of specific fuel consumption at a nominal maximum continuous rating to predict the engine consumption at any specified rating, including at partial engine load. The outcome of the study shows that the maximum deviations regarding the two simulated engines did not exceed −3.6%. In summary, the proposed model is a fast and effective tool for optimizing the selection of dual-fuel, two-stroke Diesel engines regarding fuel consumption.

Simulation of the Transient Thermal Response of a High Pressure Selective Catalytic Reduction Aftertreatment System for a Tier III Two-Stroke Marine Diesel Engine

The IMO tier III legislation, applicable to vessels with a keel laying date from Jan. 1, 2016, has compelled engine builders to apply new technologies for NOx abatement. One of the most promising technologies for tier III compliance is the selective catalytic reduction (SCR) of nitrogen oxides (NOx). Despite that SCR technology has been applied in powerplants and heavy duty truck engines for years, there are challenges that stem from its applications in large two-stroke marine diesel engines. In this paper, an SCR model applicable to large two-stroke marine diesel engines is introduced. The goal of the model is to predict the thermal response of a marine SCR aftertreatment system when the engine undergoes transient loading. The model has been developed and validated using testbed measured data from a large two-stroke marine diesel engine. The output of the model is the SCR outlet temperature. It is shown that the model can accurately predict the transient inertial response of the SCR during engine acceleration, deceleration, and low load operation.

Design and experimental development of a new electronically controlled cylinder lubrication system for the large two-stroke crosshead diesel engines

Accurate, stable and reliable lubrication for the cylinders is very important to ensure the trouble-free operation of the marine diesel engines. A new electronically controlled cylinder lubrication system has been developed to remedy the defects of the conventional mechanical lubrication system. This new system’s design method, composition and implementation are described. The sensitivity tests are conducted on the test bench and the verification tests are also fulfilled on operating vessels. The main performance data are as follows: oil injection pressure about 3.0 MPa, oil injection timing precision 0.1 ms, oil injection duration 15 °CA or less. The oil injection concentrates onto the piston rings pack to ensure the good lubrication and neutralization, and the oil injection frequency is regulated according to engine load, the sulphur content in fuel, total base number of cylinder oil, cylinder liner running-in condition and so on. This results in the cylinder oil consumption rate falling approximately 25% compared with that of the conventional mechanical lubrication system. As a retrofit on vessels in service, the lubrication system has been fitted more than 120 main engines and has a payback period of less than 2 years.

New concept and design of electronically controlled cylinder lubrication system for large two-stroke marine diesel engines

Lubrication of cylinders between liners and rings is one of the crucial factors that affects the efficient operation of diesel engines. Marine diesel engines usually use inferior heavy fuel oil with high sulphur content, and the acidic substances formed by fuel combustion need alkaline cylinder oil to neutralize. For the operational cost to a marine engine, besides fuel oil, cylinder oil also takes a big share. This article first analyses the advantages and disadvantages of existing cylinder lubrication systems with regard to oil injection control. Second, the control parameters and variables such as the oil injection pressure, timing, oil feed rate and reliability are analysed, and the corresponding control schemes formulated. Third, the control strategies are developed in detail. Finally, verification tests are carried out on an actual engine, with the results showing that the control strategies developed in this article provide a stable, cost-effective, creative and excellent solution for cylinder lubrication with reduced cylinder wear. A thin and uniform oil film distribution is retained on the liner surface, with savings in cylinder oil consumption, lower particulate matter emission levels and improved cylinder liner and piston rings running conditions. The experimental results show that the oil consumption could be reduced by up to 50%.

Crankcase explosion for two-stroke marine diesel engine by using fault tree analysis method in fuzzy environment

Abstract The purpose of this study is to investigate crankcase explosion in two-stroke marine diesel engine systematically by using fault tree analysis method in fuzzy environment for system reliability and shipping sustainability. Maritime accidents might cause deadly and costly results in both human lives, commodities, environmental and financial aspects. Crankcase explosion is one of the most dangerous causalities that might possibly damage both ship structure and crew members. In this study, we determine all root causes of crankcase explosion, and calculate the probabilities in a stepwise manner by implementing field expert consultations. As a result, we find that the occurrence probability of the crankcase explosion is 1.249428E-007 which is close to real case. Bearing originated hot spots and personnel failures are also found as the most risky events.

Mixed Flow Reactor Experiments and Modeling of Sulfuric Acid Neutralization in Lube Oil for Large Two-Stroke Diesel Engines

Lubrication oil for marine diesel engines contains additives in the form of CaCO3-based reverse micelles, which can neutralize condensing H2SO4, and thereby limit uncontrolled corrosive wear of the piston rings and cylinder liner. In the present work, the neutralization mechanism was studied experimentally and through modeling. Using a mixed flow reactor (MFR), the rate of the acid–base reaction was measured as a function of relevant process parameters. In addition, the competition between CaCO3 reverse micelles and NaOH droplets for a reaction with H2SO4 droplets in a lube oil emulsion was explored in a batch reactor. For the residence times investigated, the results show that CaCO3 conversion is significantly reduced when reaching a critically low Ca/S ratio. Furthermore, a mathematical model for the neutralization of H2SO4 droplets by CaCO3 reverse micelles in lube oil under well-mixed conditions was developed. Both the experimental data and simulations support previous results, suggesting that the limiting step in the neutralization mechanism is adsorption of reverse micelles onto the much larger H2SO4 droplets. Using the video-microscopy experiments of Fu et al. [ Tribol. Lett. 2006, 22 (3), 221], it was possible to estimate kinetic parameters for the adsorption-controlled reaction. The model was used to predict conversion of H2SO4 in a lube oil film at the cylinder liner surface for conditions relevant for a full-scale application. Calculations indicated that H2SO4 may reach the liner surface regardless of how well-wetted the surface is.

ЗАСТОСУВАННЯ МЕТОДУ БЕЗГРАДІЕНТНОЇ ОПТИМІЗАЦІЇ ПРИ СИНХРОНІЗАЦІЇ ДАНИХ МОНІТОРИНГУ РОБОЧОГО ПРОЦЕСУ ДВИГУНІВ ВНУТРІШНЬОГО ЗГОРЯННЯ

The possibility of using the gradientless n-parametric minimization of Powell'64 in the tasks of monitoring the workflow of ship diesel engines is considered. Monitoring the workflow of ship diesel engines includes the problem of cyclical analysis of indicator diagrams in the working cylinders. The problem of data synchronization should be solved - the transfer of pressure charts from the time function to an angle of crankshaft rotation function. It is shown that the hardware detection of the crankshaft rotation phases applying pick-up sensors configured in statics will have errors when the engine is under load. The synchronization task should be solved with the help of an algorithm by analyzing the indicator diagram in real time. Examples of the search for a global minimum of the Rosenbrock test function are given. Applying the Powell'64 method, least square method functionals are minimized in problems of synchronization and modeling of compression-expansion curves in the working cylinder. Cases of data synchronization calculation for low-speed two-stroke and mid-envelope four-stroke marine diesel engines are shown. Taking into account the assumptions made in practice, it was shown that at the point of maximum pressure growth rate on the compression curve, the cylinder volume above the piston can be calculated applying the known geometric dimensions of the cylinder and the P and dP/dφ values obtained from the indicator diagram. The next step is to calculate the first approximation of the position of the top dead center of the piston, and the application of the digital filters is necessary. Finally, the synchronization problem is solved on the basis of the equation dP/dφ = 0, compiled for the section from the start of compression to the start of combustion in the cylinder. The selection of boundary conditions for modeling is shown. The advantage of applying the Powell'64 method is its high efficiency for quadratic functionals. Unlike gradient methods, the Powell'64 method does not require the calculation of derivatives and is universal to minimize complex nonlinear functionals of a general form. The original author's algorithm for data synchronization by analyzing indicator diagrams, which applies the Powell'64 method, is used in the latest versions of the D4.0HT marine diesel engine monitoring systems

APPLICATION OF THE OPTIMIZATION METHOD IN THE OBJECTIVES OF THE ANALYSIS OF THE WORKING PROCESS OF SHIP DIESELS

The article touches upon the possibility of using the method of gradientless n-parametric minimization of Powell'64 in tasks of monitoring the working process of marine diesel engines. There is given an example of finding a global minimum of the Rosenbrock test function. Using the Powell'64 method, the Least-squares functionals in the synchronization and modelling tasks of compression-expansion curves in the working cylinder are minimized. The calculation results of data synchronization for low-speed two-stroke and medium-speed four-stroke marine diesel engines are shown. The synchronization problem can be solved in terms of equation P' = 0 derived for the sector from compression starting to combustion starting in the cylinder. The selection of the boundary conditions for simulation is shown. The advantage of Powell’64 method is its high efficiency for quadratic functionals. As opposed to gradient methods, the Powell'64 method does not require calculating derivatives and is universal for minimizing complex nonlinear general functionals. The original author's algorithm of data synchronization by analyzing the indicator diagrams using the Powell'64 method has been applied in the latest versions of monitoring systems of D4.0H marine diesel engine.

Evaluating the scavenging process by the scavenging curve of an opposed-piston, two-stroke (OP2S) diesel engine

Due to its inherent advantages of superior manufacturability, power density, and thermal efficiency, the opposed-piston, two-stroke (OP2S) diesel engine has great potential in alleviating energy consumption and improving fuel economy. The scavenging process is the key factor affecting the performance of OP2S diesel engines; however, because there are many evaluation parameters for the scavenging process, there are also many difficulties in matching and optimizing the scavenging system. To bridge this knowledge gap, this study established a three-dimensional model of an OP2S diesel engine to optimize the port height by the scavenging curve. The model was verified and validated through a steady flow experiment. The scavenging performance indicators, including distribution of residual gas, scavenging efficiency, trapping efficiency, and delivery ratio, were investigated under different port heights. The scavenging model method and the scavenging curve method were employed to evaluate the scavenging process. The results show that, when analyzing the factors that affect scavenging performance, the scavenging curve can be used to evaluate not only the optimization potential of the scavenging system but also the development of the scavenging process. After optimizing the port height by the scavenging curve, the actual scavenging curve appeared in the zone enveloped by the scavenging curve of the maximum port (34 mm/34 mm) and the scavenging curve of the minimum port (12 mm/14 mm). In this greater zone, there is a preferred zone where the port height to stroke ratio is from 0.11 to 0.15, which is the optimal value. This study reveals the influence of different port heights on scavenging performance and provides design insights for evaluating and optimizing the scavenging process of an OP2S diesel engine.

Optimization of Combustion and Emission Characteristics of a two-Stroke Marine Diesel Engine Based on Online Ultrasonic and Magnetization of Marine Heavy Fuel Oil

ABSTRACTThis study adopts 25 kHz ultrasonic wave and 0.4T magnetization field in online optimization of Marine Heavy Fuel Oil (MHFO). It aims at studying the feasibility of optimizing the combustion and emission performance of two-stroke marine diesel engine with one kind of MHFO with ultrasonic wave and magnetization field. The results show that engine’s fuel consumption could reach 222 g/kW· h under 25% of engine rated power, while this consumption reduces to 188 g/kW· h under 90% of engine rated power. It can be seen that the rate of fuel consumption decreased by about 15% between 25% and 90% of engine rated power. The improved combustion performance under high operating load conditions produced low carbon monoxide (CO) and carbon dioxide (CO2) emissions. The rise of in-cylinder temperature promoted the formation of nitrogen oxides (NOx), in which nitrogen oxide (NO) accounted for about 99.5% of the NOx composition. Through the optimization of online MHFO with ultrasonic waves and magnetization field device under 25% of engine rated power, the engine’s fuel consumption rate decreased by about 1.5%. This shows that CO and CO2 emissions have been effectively reduced. However, the NOx emissions increased slightly. The CO, CO2 and NOx emissions decreased when the engine’s power increased form 50% to 75%, In this operating range, its fuel saving decreased from 0.4% to 0.08%. At 90% of engine rated power the volume concentration of CO emissions and fuel consumption rate increased. However, its CO2 emissions decreased, while the NOx emissions remained unchanged.