Diesel Engine Characteristics Research Articles

Influence of Nano Additives on Performance, Combustion, and Emission Characteristics of Diesel Engine using Tamarind Oil Methyl Ester-Diesel Fuel Blends

Hazardous emissions majorly NOx and the poor performance of alternative fuels (biodiesel/its blends) are global concerns, as fossil fuel depletion and rising energy prices encourage researchers to rely on alternative energy sources with the addition of nano additives in the recent decade. The current experimental study investigates the performance, combustion, and emission characteristics of biodiesel-diesel mixtures dispersed with titanium dioxide (TiO2) as a fuel additive on a 1-cylinder diesel engine. TiO2 was dispersed in a Tamarind Oil Methyl Ester (TOME)-diesel blend (B20) in three concentrations of 40, 80, and 120 ppm via ultrasonication in the presence of QPAN80 surfactant to enhance the stability of the prepared fuel sample. A ratio of 1:4 TiO2:QPAN80 was found to produce the highest stability and homogeneity which is evidenced by the characterization of TiO2. The engine tests revealed that the greatest decrement in BSFC, CO, HC, and NOx was observed as 15.2%, 15.2%, 11.10%, and 9.06%, and the maximum BTE, HRR,and CP were improved by 9.76%, 50.32 J/degree, and 50.32 bar for the B20T80 blend correlated with B20 blend. Thus, the inclusion of TiO2 nano additives improved overall engine performance and decreased emissions of CI engines significantly.

Experimental and simulation study of methanol/coal-to-liquid (CTL) reactivity and combustion characteristics of diesel engines in RCCI mode

An experimental and simulation study of the RCCI combustion mode of coal-based fuels (methanol prepared from coke oven gas/coal-to-liquid, Methanol/CTL)) was carried out on a modified dual-fuel compression ignition (CI) engine. The mechanism by which Methanol/CTL, which has a significant difference in reactivity, promotes engine combustion and thermal efficiency is revealed. The results show that with the increasing load (i.e., load recovery ratio (LRR)) supplied by methanol, the reactivity gradient inside the cylinder increased from 28% to 451%, and the area of the ignition region was rapidly enlarged, and the reactivity of the ignition region increased. The HC and CO emissions increase by 1350% and 6866%, while the soot and NOX are reduced by a maximum of 25% and 15%. The reactivity of the ignition region increased by 8% to 26 %. Diffusion combustion forms a strong linear correlation with reactivity, with a maximum reduction of about 30 times in the premixed-to-diffusion combustion ratio. Concentration of the exothermic centre towards the top-dead-centre (TDC) is increased by a maximum of 18%, with an increase in the coefficient of variability (COV) by a maximum of 90%, indicative thermal efficiency (ITE) by a maximum of 22% and brake thermal efficiency (BTE) by a maximum of 17%. The LRR does not exceed 50% while the engine maintains stable operation and 30% while maintaining power and fuel economy.

Evaluation of Hydrogen Addition on Combustion and Emission Characteristics of Dual-Fuel Diesel Engines with Different Compression Ratios

In this paper, a computational fluid dynamics (CFD) model was established and verified on the basis of experimental results, and then the effect of hydrogenation addition on combustion and emission characteristics of a diesel–hydrogen dual-fuel engine fueled with hydrogenation addition (0%, 5%, and 10%) under different hydrogenation energy shares (HESs) and compression ratios (CRs) were investigated using CONVERGE3.0 software. And, this work assumed that the hydrogen and air were premixed uniformly. The correctness of the simulation model was verified by experimental data. The values of HES are in the range of 0%, 5%, 10%, and 15%. And, the values of CR are in the range of 14, 16, 18, and 20. The results of this study showed that the addition of hydrogen to diesel fuel has a significant effect on the combustion characteristics and the emission characteristics of diesel engines. When the HES was 15%, the in-cylinder pressure increased by 10.54%. The in-cylinder temperature increased by 15.11%. When the CR was 20, the in-cylinder pressure and the in-cylinder temperature increased by 66.10% and 13.09%, respectively. In all cases, HC, CO, CO2, and soot emissions decreased as the HES increased. But, NOx emission increased.

A study on the interaction among hull, engine and propeller during self-propulsion of a ship

Hull-engine-propeller matching is one of the key issues of ship design. It plays an important role in improving the economy and safety of ship navigation. The hull-engine-propeller matching is generally based on the Factory Acceptance Test of engine and the Sea Acceptance Test of ship. These conventional methods cost money and time. To overcome these defects, this paper proposes a simulation method based on the quasi-steady model of engine and CFD for ship hydrodynamics to study the interaction among the hull, engine and propeller, which provides the basis for ship-engine-propeller matching. Taking the PA6 diesel engine and the ONR tumblehome ship as the study objects, the quasi-steady model of engine is constructed by using simulation software and applied to carry out simulation under the operation conditions; the ship resistance test, propeller open-water test and self-propulsion test are simulated by using CFD method. Based on the simulation results, an integrated simulation platform is established for studying the hull-engine-propeller interaction. Further, the external characteristics of diesel engine under the effects of hull-engine-propeller interaction are predicted for the ship sailing straight ahead at different speeds. This paper provides a new method for studying the characteristics of hull-engine-propeller interaction.

Utilization of renewable biodiesel blends with different proportions for the improvements of performance and emission characteristics of a diesel engine

This work investigated and compared the impact on performance and emission characteristics of diesel engine fueled with five different proportions of biodiesel blends. Firstly, the three-dimensional simulation software CONVERGE was used to create a 3D simulation model of in-cylinder combustion for a diesel engine. Secondly, the experimental data of cylinder pressure and NOx emissions at 50% and 100% loads were employed to verify the simulation model. Finally, the combustion processes of blends with proportions of 0%, 5%, 10%, 15%, and 20% biodiesel were simulated and compared by using the model. The study showed that the brake thermal efficiencies (BTEs) of biodiesel blends with 5%, 10%, 15%, and 20% of biodiesel were increased by 1.24%, 1.89%, 3.13%, and 3.82% at 50% load, respectively, compared with pure diesel. In addition, the soot emissions were decreased by 1.20%, 2.64%, 3.88%, and 4.65%, respectively. However, as the proportion of biodiesel in the biodiesel blends increased, the brake specific fuel consumption (BSFC) and NOx emissions increased. At 50% load, the BSFCs of biodiesel blends with 5%, 10%, 15%, and 20% of biodiesel increased by 0.61%, 1.34%, 1.42%, and 2.17%, respectively, compared with pure diesel. Additionally, the brake powers (BPs) were decreased by 0.64%, 1.31%, 1.88%, and 2.62% at 100% load, respectively.

Multi-objective optimization of the combustion chamber geometry for a highland diesel engine fueled with diesel/n-butanol/PODEn by ANN-NSGA III

In China, about one-third of the land area is over 2000 m, and a large number of equipments using diesel engines are operating in these areas. In order to optimizate the performance and emission characteristics of diesel engines, the investigation have been carried out for a highland diesel engine fueled with 80% diesel +10% n-butanol +10% PODE3 at an altitude of 2000 m. Firstly, a source model of the diesel engine was developed in CONVERGE and validated. Secondly, the combustion chamber geometry (CCG) of the diesel engine was expressed using two cubic Bézier curves and the shape of the curves was controlled using five variables (Hdep, C1, C2, LP2a and LP2b) and two fixed values. Then, the soot, NOx and HC emissions were predicted for different CCG shapes using response surface methodology and artificial neural networks (ANN), and a more appropriate prediction method for ANN was determined by comparing the performance of both. Finally, the predictions of the ANN were optimized using Non-dominated sorting genetic algorithm III (NSGA III) to obtain the Pareto fronts and the optimal solutions were selected from the Pareto fronts using VlseKriterijumska Optimizacija I Kombrissino Resenje (VIKOR). Through optimization, the optimal solution reduced soot, NOx and HC emissions by 67.15%, 7.08% and 92.48%, respectively, compared with the original CCG of the CI engine. In addition, the best CCG was analyzed in detail. Overall, ANN-NSGA III is an efficiently optimized method. The optimized CCG can effectively reduce the emission of CI engine.

Effects of waste cooking oil biodiesel addition on combustion, regulated and unregulated emission characteristics of common-rail diesel engine

The use of waste cooking oil biodiesel as diesel fuel is one of the essential measures to achieve global energy transition and sustainable development. This work aims to explore the influence mechanism of waste cooking oil biodiesel/diesel blended fuel on the combustion and emission characteristics of a common-rail diesel engine. The effects of four fuel blending ratios (0%, 10%, 20%, and 30%) on engine combustion and emission characteristics under different operating conditions were investigated experimentally. The study results showed that adding biodiesel from waste cooking oil prolongs the combustion duration and is also beneficial for combustion at medium and high load conditions (50% and 75%). For the low load condition (25%), the emission concentration showed a decreasing trend with the increase of the blending ratio. In particular, the NOx and CH3CHO emissions increased, and the Soot emission was insensitive to the blending ratio. For medium and high load conditions, as the blending ratio increases, the emission concentration decreases. Moreover, the NOx emission increased slightly. Within the scope of the current work, the addition of waste cooking oil biodiesel improves the combustion and emissions characteristics of a common-rail diesel engine for both 50% and 70% load conditions.

Multi-response optimization of energy, exergy, emission, economic characteristics of a variable compression ratio diesel engine fuelled with diesel–bioethanol–Al2O3 nanoparticle blend using Taguchi–Grey approach

Multi-response optimization of energy, exergy, emission, economic characteristics of a variable compression ratio diesel engine fuelled with diesel–bioethanol–Al2O3 nanoparticle blend using Taguchi–Grey approach

Impact of variable exhaust valve timing on diesel engine characteristics fueled with waste cooking oil biofuel blends: A numerical analysis

The quantity of the conventional sources of energy such as petroleum, coal, and the deposits of hydrocarbon are limited in nature. The rapid growth is observed in the industrial and transportation section due to increase in population that has compelled the mankind to look for an alternative to conventional fuels. Biodiesel can be a potential substitute due to its ease of availability, accessibility, lower cost, and nontoxic characteristics. In this study, waste cooking oil (WCO) as the feedstock for biodiesel due to its abundance and low prices is chosen. It has been observed that the high prices of cooking oil have compelled people to reuse it multiple times, which can have negative health consequences such as inflammation, cholesterol issues, diabetes, and cancer. However, if people can obtain WCO at a reasonable cost, they will refrain from reusing it repeatedly. This article presents a numerical method that investigates the effects of variable exhaust valve timing on the performance, emissions, and combustion parameters of WCO and its different blends in a conventional mechanical fuel injection system diesel. The study was conducted using a single-cylinder, water-cooled, in-line diesel engine running at a constant speed. As, it is not possible to determine the values of engine performance, emissions, and combustion parameters for different valve timings experimentally, a numerical method has been adopted. The valve timing range was taken as 46–66° before bottom dead center (BDC) for exhaust valve opening and 6–20° after top dead center (TDC) for exhaust valve closing and the inlet valve opening and closing are constant at 16° b TDC and 33° a BDC, respectively.

Effect of injection parameters on the hydrogen enriched dual-fuel CRDI diesel engine

ABSTRACT To maximize the performance of the diesel engine run with alternative renewable fuels, operational parameters such as injection time (IT) and injection pressure (IP) must be fine-tuned. Meanwhile, hydrogen has come out as a one of the best alternative fuel for dual-fuel mode of operation, since it minimizes the drawback that use of biodiesel alone possesses like low calorific value, high viscosity etc. Based on the above findings, the objective of the current study is set as “to evaluate the impact of varying injection parameters on the engine characteristics of hydrogen-enriched palm fueled CRDI diesel engine.” In this research work, a hydrogen-enriched (7 lpm and 10 lpm) palm biodiesel blend (P20) with diesel fuel was used to examine how changing injection pressure (IP) and injection time (IT) affected CRDI diesel engine performance, combustion, and emission characteristics. Three different IPs (240 bar, 420 bar, and 600 bar) and ITs (23°CA bTDC, 25°CA bTDC, and 27°CA bTDC) are used at a steady speed of 1500 rpm under full load circumstances. The results showed a maximum BTE of 31.09% for P20 + 10 H2 at 25°CA bTDC IT and 600 bar IP. Better fuel atomization is responsible for the improvement in BTE (17.94%) and BSFC (15.15%) with increased IP (600 bar). Advancement in IT (25°CA bTDC) leads to superior performance in terms of HC (32%) and CO (8.33%) emissions reduction for P20 + 10 H2 because more time is available for optimal air-fuel mixing. However, NOX emission increases significantly because of the rise in temperature within the cylinder with hydrogen enrichment. This can be attributed to the high calorific value of hydrogen which is almost three times to that of diesel. A maximum increase in NOX emission of 45.65% is obtained for P20 + 10 H2 w.r.t. diesel. With an increase in IP, ICP and HRR improve by 28.04% and 22.70%, respectively, due to improved fuel atomization, resulting in the greatest amount of fuel being burned during the pre-mixed combustion stage. It can be concluded that the 25°CA bTDC IT and 600 bar IP is the optimum condition when the engine performs at its peak.

Effect of Low Heat Rejection on Performance and Emission Characteristics of a 4-Stroke Diesel Engine

Effect of Low Heat Rejection on Performance and Emission Characteristics of a 4-Stroke Diesel Engine

Effect of green synthesized zinc oxide nanoadditives and rice bran oil biodiesel blend on performance and combustion characteristics of a variable compression ratio diesel engine: an experimental study

AbstractThe aim of this research was to investigate experimentally the performance and combustion characteristics of a four‐stroke, single‐cylinder, water‐cooled variable compression ratio diesel engine using rice bran oil biodiesel blends with zinc oxide nanoparticles. Rice bran oil biodiesel was prepared using a transesterification reaction with a 6:1 methanol‐oil molar ratio and 1% w/w potassium hydroxide as catalyst. Zinc oxide nanoparticles were synthesized using a green method incorporating Psidium guajava leaf extract as a capping agent to reduce precursor use and to reduce the toxicity of the nanomaterial. The synthesized zinc oxide nanoparticles were characterized by using X‐ray diffraction and Fourier‐transform infrared spectroscopy to confirm the formation of highly crystalline pure zinc oxide nanoparticles with a hexagonal wurtzite crystal structure with an average diameter of 20.963 nm. Rice bran‐oil biodiesel‐diesel blend was prepared by volumetrically mixing 20% biodiesel and 80% mineral diesel and was considered as a base fuel for comparison. Zinc oxide nanoparticles were diffused in the base fuel at dosage levels of 25, 50, and 75 ppm, with the aid of ultrasonication. Measurement of the major physicochemical properties of test fuels showed an increase in the cetane number and calorific value and a reduction in viscosity with an increase in the zinc oxide concentration. The overall properties of all the test fuels were found to be similar in comparison with commercial diesel. An experimental engine test was carried out under different loading conditions with a constant speed of 1500 RPM and two different compression ratios – that is, 17.5:1 and 15:1. Among all the test fuels at both compression ratios, engine performance and combustion properties improved with an increase in the zinc oxide concentration. Test fuel with 75 ppm of zinc oxide additive at 17.5 compression ratio resulted in an overall improvement at full load: brake thermal efficiency increased by 2.45%, brake specific fuel consumption reduced by 5.45%, cylinder peak pressure increased by 3.27% and net heat release increased by 10.32% in comparison with base fuel.

Experimental Investigation of Diesel Engine Characteristics under Various Loads

Internal combustion engines (ICEs) are widely used in the road, sea, air and railway vehicles and stationary such as generators, pumps elevators or agricultural and construction machinery. The features expected from the ICEs differ according to the usage areas. For example; a vehicle engine should operate at a certain lower and upper engine speeds according to the engine load in constant gas condition and the features of the engine should be known in this range. On the other hand, a power plant engine must work at a constant speed under various loads for the electricity produced to be at a desired frequency. Diesel engines are widely used as stationary engines due to the higher fuel economy, especially in places where high power is required.Therefore, it is important to be known of the characteristics of the stationary engine under various operating conditions. In the presented study, it is aimed to determine experimentally the characteristics of a diesel engine under variable loads and at constant speed. In the experimental study, the characteristics of the engine such as air excess coefficient, torque, brake power, various efficiencies and fuel consumption were determined under variable loads by using a single–cylinder, four–stroke and water–cooled direct injection experimental diesel engine. Experimental results show that the variation of engine load affected considerably the investigated engine characteristics.

The Method of Process of Formation of the Tactical and Technical Requirements for Armored Armament and Technology at the Organization of Production

The experience of conducting a Special military operation confirms the need to improve the characteristics of domestic weapons and military equipment in order to effectively counter Western weapons. Effective counteraction can be provided by improving the basic properties of the combat effectiveness of weapons and military equipment. Taking into account the high level of effectiveness of the intelligence means used by the enemy, which make it possible to quickly determine the location of weapons and military equipment complexes used by the Armed Forces of the Russian Federation, as well as the use of high-precision weapons with satellite guidance systems on the target, a special role is played by such a property of combat effectiveness as mobility. Military tracked vehicles, which are the main means of ensuring the mobility of troops, are represented by a large variety, which is associated with their functional purpose. Regardless of the functional purpose, the main evaluation indicator of military tracked vehicles is their combat effectiveness, one of the most important properties of which is mobility. The improvement of the main mobility indicators should begin with a revision of the tactical and technical requirements for weapons and military equipment complexes, after which it is necessary to search for ways to achieve the newly formed tactical and technical requirements. At this stage, methods of assessing the impact of the use of a particular technical solution on the characteristics of weapons and military equipment in general are of particular importance. For a comparative assessment of tracked vehicles of various designs, as well as to assess the impact of the use of new technical solutions on the main indicators of mobility characteristics, a methodology is needed to assess the impact of diesel engine characteristics on the mobility indicators of a military tracked vehicle. The article presents a methodology for assessing the influence of diesel engine characteristics on the mobility indicators of military tracked vehicles, which allows calculating the average speed of a military tracked vehicle depending on the obtained characteristics of a diesel engine based on the probabilistic operating modes of the engine. The developed technique is implemented in a software package for electronic computers.

A review of combustion properties, performance, and emission characteristics of diesel engine fueled with Al2O3 nanoparticle-containing biodiesel

A review of combustion properties, performance, and emission characteristics of diesel engine fueled with Al2O3 nanoparticle-containing biodiesel

Effects of multi-walled carbon nanotubes on the combustion, performance, and emission characteristics of a single-cylinder diesel engine fueled with palm-oil biodiesel-diesel blend

Multi-walled carbon nanotubes (MWCNTs) could be an effective fuel additive for 20 vol% palm-oil biodiesel in fossil diesel (B20) owing to its superior thermal conductivity. The effects of MWCNTs on the combustion, performance, and emission characteristics of B20 are investigated at various concentrations by a single-cylinder diesel engine under different engine speeds. The results show that B20 fuels with MWCNTs addition reduced the ignition-delay (ID), advanced the combustion phasing, and shortened the combustion duration by up to 17.6% (−2.6° CA), 12.9% (−1.8° CA), and 18.5% (−4.3° CA), respectively. The addition of MWCNTs in B20 also improved the brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) by up to 15.7% (−47.4 g/kW·h) and 16.3% (+4.6%), respectively. Compared with B20 fuel without MWCNTs, CO and UHCs emissions reduced by up to 34.7% (−8.2 g/kg-fuel) and 16.0% (−3.8 g/kg-fuel), respectively but NOx emissions increased by up to 43.5% (+7.6 g/kg-fuel). Overall, the results suggest that B20 with MWCNTs addition can enhance the combustion, performance, and emission characteristics of a light-duty diesel engine.

Influence of varying concentrations of TiO2 nanoparticles and engine speed on the performance and emissions of diesel engine operated on waste cooking oil biodiesel blends using response surface methodology

For a few decades now fast depleting fossil fuels has been a major challenge. Fast expanding population and increased rate of urbanization has increased energy demand. This makes the current scenario worse. Fossil fuels' emissions are another challenge. Apart from fossil fuel emissions, the untreated disposal of waste cooking oil presents another environment’s sustainability challenge. The treatment of waste cooking oil as fuel presents a tangible solution to challenge. In this research article, impact of the engine speed and the concentration of titanium dioxide (TiO2) nanoparticles (NPs) in diesel-biodiesel blended fuels on the engine’s performance. The emission characteristics of a single-cylinder four-stroke diesel engine has also been examined. TiO2 NPs were produced by a sol-gel methodology. The diesel-biodiesel combination was fortified with TiO2 NPs at 40, 80 and 120 ppm. These mixtures were used to power the diesel engine, which was then run at 1150, 1400, 1650, 1900 and 2150 RPM. Interaction between engine speeds and nanoparticle concentrations and investigation of their combined effect on engine performance and emissions was done using response surface methodology. The minimum BSFC of 0.33994 kg/kWh and maximum BTE of 25.90% were found for B30 + 120 ppm biodiesel blend at 2150 rpm as compared to all other tested fuels. The emissions including CO and HC emissions were recorded as 25.61486 kg/kWh and 0.05289kg/kWh respectively at 2150 rpm for B30 + 120 ppm biodiesel blend while NOx on the contrary side exhibits a slight escalation with increasing engine speed and nanoparticles concentration. The findings of the experiments demonstrated that adding TiO2 nanoparticles to diesel–biodiesel blends is an effective way to enhance the performance of diesel engines while simultaneously reducing the emissions. It was also discovered that the mathematical model that was built can efficiently estimate the performance of the engine and the emission levels.

Determination of combustion and emission characteristics of liquid Fischer-Tropsch diesel fuel synthesized from coal in a diesel engine

Fischer–Tropsch (FT) synthesis is a production method that processes a liquid diesel fuel from heavy carbon-containing organic compounds such as coal and biomass. FT synthesis is an essential process in demonstrating the usability of coal-to-liquid fuel in internal combustion engines. This study investigates the effects of using FT diesel fuel synthesized from coal on the combustion characteristics of a single-cylinder common-rail direct-injection diesel engine. The engine tests were conducted at 50% of the wide-open throttle position and fixed engine control parameters (cycle duration, fuel amount, start of injection timing, etc.). As a result of the study, it was observed that the combustion with the use of FT diesel fuel started (almost 1.5 °CA) and completed earlier according to the petroleum-based diesel (D100). The cyclic variations were more stable with FT diesel fuel. With the use of FT diesel fuel, the indicated mean effective pressure was 3% lower, peak cylinder gas pressure was slightly lower, and the combustion noise was 2–3 dB quieter compared to D100. The heat release was higher during the premixed combustion phase at the cycle durations of 67 ms and 55 ms, while it occurred very small at the cycle duration of 86 ms. Significant reductions in CO2 and NOx emissions, which are complete oxidation products, were obtained with FT diesel fuel compared to D100. The fuel properties, combustion characteristics and emission results showed that no further measures should be taken to use FT diesel in compression ignition engines. FT diesel fuel can be safely used as an alternative fuel.

ТЕХНОЛОГИЯ ПРИГОТОВЛЕНИЯ И ПОДАЧИ КОМПЛЕКСНОГО ТОПЛИВА ДЛЯ УЛУЧШЕНИЯ ЭКСПЛУАТАЦИОННО-ТЕХНИЧЕСКИХ ХАРАКТЕРИСТИК ДИЗЕЛЬНЫХ ДВИГАТЕЛЕЙ АВТОТРАКТОРНОЙ ТЕХНИКИ

The technology of preparation and supply of complex fuel is proposed to improve the operational and technical characteristics of diesel engines of automotive equipment, as well as technical means for its implementation. The analysis of the work of the ATT samples showed that its operation occurs with low speeds in the field and heavy loads on the internal combustion engine (ICE), while its thermal tension increases and the combustion process worsens in the combustion chamber, leading to the formation of carbon deposits. To solve this problem, a method and technical means are proposed for cleaning engine parts from the formed carbon deposits without parsing it during daily operation in order to improve the operational and technical characteristics of equipment, on which the readiness of samples of the machine and tractor fleet will directly depend. The developed method is based on direct mixing of fuel with water, dispersion of the resulting mixture and feeding into the combustion chamber of the internal combustion engine when the fuel temperature exceeds a given value, and depending on the temperature, as well as the number of revolutions of the internal combustion engine and from different levels of the mixing tank. The versatility of the developed devices for the implementation of the proposed method is that they can be used not only in stationary conditions, but also on board the equipment during its operation. The implementation of the developed method and technical devices will ensure effective removal of carbon deposits due to the interaction of red-hot carbon particles with water droplets (steam), which will lead to an increase in the resource of diesel internal combustion engines, restoration of operational and technical characteristics of especially worn-out diesel internal combustion engines and ultimately increase the readiness of individual samples of ATT and, in general, the technical readiness of the machine and tractor fleet.

Environmental adaptability method for improving the cold start performance of the diesel engine based on pilot injection strategy

The deterioration of cold start performance at high altitudes is one of the main problems that restrict the altitude adaptability of diesel engines. In this study, by adapting the pilot injection strategy to improve cold start performance at different altitudes, the effect of the pilot injection ratio and pilot injection timing on the combustion, performance, and emission characteristics of diesel engines are investigated, and suggestions are proposed for optimizing fuel injection according to the altitude. The experimental results indicated that at high altitudes, the cold start performance was worse and more difficult to reach idle speed, NOx emissions increased due to the longer ignition delay. Compared to the single-injection strategy, the pilot injection strategy can effectively improve the combustion environment in the cylinder and thereby improve the cold start performance. As the altitude increase, decreasing the pilot injection mass can shorten the cold start time. The appropriate advance of pilot injection timing could improve mixture formation, which is conducive to improving the cold start performance and emissions at different altitudes. It can be concluded that advancing the pilot injection timing and increasing the pilot mass is a better injection strategy to improve cold start performance at plain. As the altitude increase, the pilot injection mass should decrease.