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This paper investigates the influences of EGR and Miller cycle on NOx emission of a heavy-duty two-stroke diesel engine. The NOx emission is strictly restricted by the IMO Tier III Emission Regulations, resulting in an insufficient application of the single emission reduction technology to meet the emission requirements. It is asserted that EGR is the most effective manner to reduce NOx emission, but the fuel consumption increases simultaneously. In consideration of emission reduction with fuel economy, EGR and Miller cycle were combined and studied in this paper. Parameters like in-cylinder pressure, in-cylinder temperature, mass in the chamber, emission (NOx and soot) and fuel consumption rate were investigated based on a single-cylinder 3D model. The wet condition that happens in the engine application was considered in the model development process. The model was validated and compared with the experimental data.

In this study, the effect of volatile fractions from engine lubricating oil on diesel particle emissions were studied experimentally. One commercial CF lubricating oil was used and distilled to subtract the different volatile fractions with boiling temperature of 220 °C, 260 °C and 300 °C, respectively. Oils derived from this distillation process were applied as the lubricating oil and following engine experiments were conducted. Diesel primary particles were sampled with a costume designed thermophoretic system. A fast response particulate spectrum equipment was employed to study the size distribution and number concentration of particles in the exhaust. Transmission electron microscopy was used to characterize the size distribution of the primary diesel particles relates to different oil volatile fractions.

Spray-wall impingement is an unavoidable physical process in homogeneous charge compression ignition (HCCI) diesel engines using early injection strategy which is the main source for the hydrogen carbon (HC) and monoxide (CO) emissions. Dimethyl ether (DME) is a potential fuel additive to decrease HC and CO emissions due to its higher oxygen content. However, issues relating to structural design and early injection timing mean spray-wall impingement still occurs when using the diesel-DME blended fuels, which directly affect the fuel-air mixture formation in the near wall region and further influence the emission characteristics. The better understanding for the effects of spray-wall impingement parameters on fuel-air mixture formation in near wall region for diesel-DME blended fuels is helpful for the improvement of HC and CO emissions for HCCI diesel engines.

The aim of this research is to investigate the effects of ashless dispersant of lube oils on diesel exhaust particles. Emphasis is placed on particle size, morphology, nanostructure and graphitization degree. Three kinds of lube oils with different percentages of ashless dispersant were used in a two-cylinder diesel engine. Ashless dispersant (T154), which is widely used in petrochemical industry, were added into baseline oil at different blend percentages (4.0% and 8.0% by weight) to improve lubrication and cleaning performance. A high resolution Transmission Electron Microscope (HRTEM) and a Raman spectroscopy were employed to analyze and compare particle characteristics. According to the experiment results, primary particles diameter ranges from 3 nm to 65 nm, and the diameter distribution conformed to Gaussian distribution. When the ashless dispersant was used, the primary particles diameter decrease obviously at both 1600 rpm and 2200 rpm.

Due to the mechanical forces under static conditions, the engine cylinders cross section will not be a round circle any more once they are installed. The deformation of an engine cylinder causes increasing lubricating oil consumption and abnormal wear, resulting in worse fuel economy and emissions. However, prediction of deformation on a liner has not been made because of the complication of conditions and structure. In this study, a V6-type engine body model was built and meshed with Hypermesh suit software. Then, cylinder deformation under static condition has been simulated and analyzed. First of all, experimental work was done to verify the engine model. Basically, few parameters like pre-tightened force, structure and distribution of bolts have been investigated to figure out how the cylinder bore deformation behaves via finite element analysis. Also, a simple Matlab program was developed to process the data.

In this paper, the influences of metallic content of lubricating oils on diesel particles were investigated. Three lubricating oils with different levels of metallic content were used in a 2.22 Liter, two cylinders, four stroke, and direct injection diesel engine. 4.0 wt. % and 8 wt. % antioxidant and corrosion inhibitor (T202) were added into baseline lubricating oil to improve the performance respectively. Primary particle diameter distributions and particle nanostructure were compared and analyzed by Transmission Electron Microscope. The graphitization degrees of diesel particles from different lubricating oils were analyzed by Raman spectroscopy. Conclusions drawn from the experiments indicate that the metallic content increases the primary particles diameter at 1600 rpm and 2200 rpm. The primary particles diameter ranges from 5 nm to 65 nm and the distribution conformed to Gaussian distribution.

Spray impacting on a lube oil film with a finite thickness is a common phenomenon in IC engines and plays a critical role in the fuel-air mixture process and combustion. With the use of early injection strategy to achieve HCCI combustion mode in diesel engines, this phenomenon becomes more and more prominent. In addition, oxygenated fuels such as methanol and ethanol are regarded as alternative fuel and additives to improve the overall performance of HCCI engine. Therefore, a better understanding about the role of lube oil film thickness in methanol-diesel and ethanol-diesel blended fuels spray/wall impingement is helpful for accumulating experimental data to establish a more accurate spray/wall impingement model and optimize the combustion in HCCI engines. In this paper, the effect of lube oil film thickness on the characteristics of spray/wall impingement of different fuels are investigated in a constant volume bomb test system.

In this paper, the influence of sulfur and ash fraction of lubricating oil on particle emissions was investigated via experimental works. Especially, we focus on the characterizations like size distribution, morphology and element composition in diesel particles. All of the research was done on a two-cylinder diesel engine under different load conditions. Five kinds of lubricating oils with different levels of sulfur and ash fraction were used in this study, among which a kind of 5W-30 (ACEA, C1) oil was used as baseline oil. Diesel primary particles were collected by thermophoretic system, and analyzed by transmission electron microscopy and energy dispersive X-ray spectrum technique, respectively. Conclusions drawn from the experiments indicate that the sulfur and ash change the primary particle emissions directly.

Impingement of spray against the cylinder wall or piston bowl is an unavoidable physical process in homogeneous charge compression ignition (HCCI) and premixed charge compression ignition (PCCI) engines using early injection strategy. It directly affects fuel-air mixture formation, combustion and exhaust emission. In addition, the alcohol fuels such as methanol, ethanol and n-butanol are regarded as hopeful alternative fuels as well as fuel additive for HCCI and PCCI diesel engines to improve the emission level. The better understanding for the effect of alcohol-diesel blending fuel on the spray-wall impingement process is helpful for the improvement of HCCI and PCCI diesel engines. In this paper, the effects of three different alcohol-diesel blending fuels (methanol, ethanol and n-butanol) on the spray-wall impingement process were studied. Numerical investigation was performed in AVL FIRE code.

Impingement of injected fuel spray against the cylinder liner (wall wetting) is one of the main obstacles that must be overcome in order for early injection Homogeneous Charge Compression Ignition (EI HCCI) combustion. In the strategies to reduce or prevent wall wetting explored in the past, limiting the spray cone angle was proved to be a useful approach. This paper is presented to study the effect of the spray cone angle on the mixture formation, particularly the region near the cylinder wall (wall wetting region), and CO/Soot emissions of an EI HCCI diesel engine. Three-dimensional modeling was performed in AVL FIRE code. The calculation grid was divided into three regions which were defined as the combustion chamber region, the wall wetting region, and the central regions. The history of the CO/soot mass of each region and the equivalent ratio/temperature (φ-T map) of wall wetting region were analyzed.

In the present paper, a three-dimensional numerical analysis model based on elastic deformation was applied to analyze the compression top piston ring-liner friction of heavy duty diesel engine, considering the rheological lubrication, the newton fluid model was applied to the numerical analysis. The result illuminates that the turning point of friction transforms from rigid hydrodynamic lubrication to elastohydrodynamic lubrication is around 4°∼8°CRA BTDC (crank angle before top dead center) on the compression stroke in this calculation model. In comparison, the surface elastic deformation was started near 10°CRA BTDC on the compression stroke which is significantly clearer than the lubricant elastic deformation. A friction tester was applied to verify the calculation results. The experiment proved that the model based on elastic deformation is closer to the actual situation and the calculation result at a lower temperature is more precise than that of higher temperature.

Cogeneration system has become a valuable alternative approach for cascade waste heat recovery (WHR). In this paper, a novel electricity-cooling cogeneration system (ECCS) based on organic Rankine cycle-absorption refrigeration cycle (ORC-ARC) combined system is proposed to recover the waste heat of marine engine. ORC was adopted in the higher temperature cycle, in which alternatives D4, MDM and MM were selected as the working fluids. An ARC was adopted in the lower temperature cycle to recover the heat of the working fluid at the regenerator outlet in ORC. It aims to satisfy refrigeration requirement aboard ship, in which a binary solution of ammonia-water is used as the working pairs. Electricity output, cooling capacity, total exergy output, primary energy ratio (PER) and exergy efficiency are chosen as the objective functions.

A novel combined power and cooling cycle based on the Organic Rankine Cycle (ORC) and the Compression Refrigeration Cycle (CRC) is proposed. The cycle can be driven by the exhaust heat from a diesel engine. In this combined cycle, ORC will translate the exhaust heat into power, and drive the compressor of CRC. The prime advantage of the combined cycle is that both the ORC and CRC are trans-critical cycles, and using CO₂ as working fluid. Natural, cheap, environmentally friendly, nontoxic and good heat transfer properties are some advantages of CO₂ as working fluid. In this paper, besides the basic combined cycle (ORC-CRC), another three novel cycles: ORC-CRC with an expander (ORC-CRCE), ORC with an internal heat exchanger as heat accumulator combined with CRC (ORCI-CRC), ORCI-CRCE, are analyzed and compared.

We studied the influence of extreme pressure (EP) antiwear additive on the emission and distribution of particulate matters (PMs), since EP antiwear additive is necessary to improve the property of lubricating oil with the downsizing development of engines. We used a four-cylinder, turbocharged, and inter-cooled system with SAE15W-40 lubricant diesel engine. Pure diesel and fuel blends with varying weight percentages (0.5%, 1.0%, and 1.5%) of EP antiwear additive were used. Engine speed increased by increments of 400 from 1,200 rpm to 2,800 rpm under medium load and full load. The DMS500 was used to acquire particle data, and the Wave Book was employed to record oil and cylinder pressure. Conclusions drawn from the experiments suggest that EP antiwear additive has significant effects on PM emissions and distributions. Increments and decrements were observed on the number of accumulation mode particles and nucleation mode particles with BDAW-0.5.

A bottoming waste-heat-recovery (WHR) model based on the Organic Rankine Cycle (ORC) is proposed to recover waste heat from exhaust gas and jacket water of a typical diesel engine (DE). The ORC model is detailed built based upon real structural and functional parameters of each component, and is able to precisely reflect the working process of the experimental ORC system constructed in lab. The DE is firstly tested to reveal its energy balance and the features of waste heat. The bottoming ORC is then simulated based on experimental data from the DE bench test using R245fa and R601a as working fluid. Thermodynamic evaluations are done on key parameters like waste heat recovered, expansion power, pump power loss and system efficiency. Results indicate that maximum expansion power and efficiency of the ORC are up to 18.8kW and 9.6%. Influences of engine condition, fluid mass flow and evaporating pressure on system performance are analyzed and meaningful regularities are revealed.

The combined thermo-generator and organic rankine cycle (TEG-ORC) used in exhaust heat recovery of internal combustion engine (ICE) is analyzed theoretically. Only about one third of the total energy released from fuel combustion is converted into useful work in engines, while the remaining energy goes into ambient environment, among which exhaust gas possesses high-grade thermal energy. Most of previous studies on energy recovery from engines have focused on exhaust heat recovery by ORC. However, if the heat is exchanged directly with high-temperature exhaust gas, organic working fluid would resolve with its lower decomposition temperature, and this is extremely harmful to ORC system. To avoid this phenomenon and utilize waste heat, preliminary thermoelectric modules are used to lower exhaust temperature and to generate electricity simultaneously.