Combustion Characteristics Of Diesel Research Articles

Effects of water content on evaporation and combustion characteristics of water emulsified diesel spray

Due to its potential of reducing NOx and soot emissions simultaneously while improving thermal efficiency, water emulsified diesel is considered as one of the most promising fuels for compression ignition engines. In this study, spray and combustion characteristics of neat diesel and water emulsified diesel with various water contents (10%, 20% and 30% by mass) were investigated. The influence of micro-explosion on high pressure spray characteristics of water emulsified diesel was optically observed and discussed. Experiments were conducted in a constant volume combustion chamber with a high-speed schlieren system to capture the spray and combustion processes. The results show that water content plays a significant role in affecting spray and combustion characteristics of water emulsified diesel. Under non-evaporating condition, the spray tip penetration increases with the water content but the corresponding spray angle decreases with the water content. Such an effect was found diminishing under evaporating condition. The spray volume of test fuels increases from non-evaporating to evaporating condition, and the relative volume increase of water emulsified diesel is at least 5 times higher than that of neat diesel. Both the ignition delay and flame lift-off length increase with water content. Consequently, the integrated natural flame luminosity decreases with the increase of water content. In addition, indirect evidences have proven that the occurrence of micro-explosion can enhance the breakup and evaporation processes of water emulsified diesel spray, and the use of water emulsified diesel can effectively reduce soot emission.

Experimental investigation on spray, evaporation and combustion characteristics of ethanol-diesel, water-emulsified diesel and neat diesel fuels

This paper explored the spray and combustion characteristics of ethanol-diesel (E10), water-emulsified diesel (W10) and neat diesel (D100), especially micro-explosion of E10 and W10. The experiments were conducted in a constant volume combustion chamber under cold (383 K, 0% O2), evaporating (900 K, 0% O2) and combustion (900 K, 21% O2) conditions. Results showed that the spray expansion capacities of E10 and W10 under cold condition were much weaker than that of D100 due to the larger viscosity of emulsified diesels. Under evaporating condition, the spray volume of E10, W10 and D100 increased by 59%, 34% and 21% respectively comparing with cold spray volume. The higher increasing rates of E10 and W10 were mainly due to the micro-explosion effects of ethanol and water contents. Under combustion condition, the integrated natural flame luminosity (INFL) demonstrated that the ethanol content could accelerate the oxidation of soot, while the water content could prohibit soot generation. Therefore, both ethanol- and water-emulsified diesels could inhibit the soot emission, causing lower final residual soot emission of E10 and W10 than that of D100 by 21% and 39% respectively. Moreover, the flame lift-off length (LOL) and flame spread velocity showed that the effects of micro-explosion in E10 and W10 are different. The micro-explosion in ethanol occurred earlier, which enhanced the reaction rate in upstream flame and reduced the LOL. However, the micro-explosion in W10 occurred later, which enhanced the combustion rate in downstream flame.

Effect of wall surface temperature on ignition and combustion characteristics of diesel fuel spray impingement

This paper investigated the ignition and combustion characteristic of wall-impinged diesel sprays in a constant volume combustion vessel simulated the diesel engine condition. A steel flat wall was installed perpendicular to the fuel injector axis. Wall surface temperatures were set at 45 °C, 90 °C, 150 °C, 280 °C, 380 °C, 460 °C, 510 °C and 570 °C separately, and a single nozzle hole with a diameter of 0.12 mm was adopted. Direct image method was applied to capture the natural luminosity and liquid spray to analyze the ignition and initial combustion process. The results reveal that, with the decrease of the wall temperature, ignition delay time becomes longer and the ignition positions become farther away from the wall. The total flame luminosity reduced and more time has been spent to reach the saturation under low wall temperature. When the wall surface temperature decreased, both flame height and flame width reduced. And they decreased more sharply in the low temperature zone. There obviously exists the temperature gradient near the wall surface for the low temperature surface is in the high ambient temperature condition. The low temperature zone was negative to the ignition and initial combustion of the fuel mixture. For this reason, the initial ignition location transferred to the high temperature zone.

Hot surface ignition and combustion characteristics of sprays in constant volumecombustion chamber using various sensors

In present study, ignition and combustion characteristics of hollow conical diesel fuel sprays are studied experimentally in constant volumecombustion chamber using hot surface ignition technique a...

Diesel Combustion Characteristics of Coconut Oil Isopentyl Ester

Diesel Combustion Characteristics of Coconut Oil Isopentyl Ester

Diesel Combustion Characteristics of Coconut Oil Biodiesel with Alcohol

Diesel Combustion Characteristics of Coconut Oil Biodiesel with Alcohol

Effect of injection pressure on performance, emission, and combustion characteristics of diesel-acetylene-fuelled single cylinder stationary CI engine.

In this paper, the effect of injection pressure on the performance, emission, and combustion characteristics of a diesel-acetylene fuelled single cylinder, four-stroke, direct injection (DI) diesel engine with a rated power of 3.5kW at a rated speed of 1500rpm was studied. Experiments were performed in dual-fuel mode at four different injection pressures of 180, 190, 200, and 210bar with a flow rate of 120 LPH of acetylene and results were compared with that of baseline diesel operation. Experimental results showed that highest brake thermal efficiency of 27.57% was achieved at injection pressure of 200bar for diesel-acetylene dual-fuel mode which was much higher than 23.32% obtained for baseline diesel. Carbon monoxide, hydrocarbon, and smoke emissions were also measured and found to be lower, while the NO x emissions were higher at 200bar in dual fuel mode as compared to those in other injection pressures in dual fuel mode and also for baseline diesel mode. Peak cylinder pressure, net heat release rate, and rate of pressure rise were also calculated and were higher at 200bar injection pressure in dual fuel mode.

Combustion and flame spreading characteristics of diesel fuel with forced air flows

Research on combustion and flame spreading behaviors in a system with forced air flow is crucial for actual fire protection design and scientific meanings. Flame spread tests over sub-flash diesel fuel are conducted by using a self-developed cross flow system, in both opposed and concurrent configurations. Some key parameters to characterize the flame spread performance, namely, flame tilt, flame spread rate, temperature distribution and scale characteristic of subsurface flow are achieved and analyzed. The variations of flame tilt angle in opposed and concurrent flame spreads follow well with Thomas’s classical model, and the tangent value of the flame tilt angle is correlated with the wind Froude number with the power value of 0.8. The flame spread rate decreases monotonically with an increase in the opposed air flow velocity. By contrast, the flame spread rate decreases initially and increases afterwards as the concurrent air flow velocity increases, with the critical air velocity of 1.725 m/s. Furthermore, the step temperature rise remains stable in the range of 27 °C to 30 °C for opposed air flows, but it is not pronounced for concurrent air flows. The subsurface flow length increases with opposed air flow velocity, while it becomes irregular under concurrent air flows. The primary contribution of heat transfer to flame spread is liquid-phase thermal convection for opposed or low-speed concurrent air flow conditions, whereas it is flame radiation and gas conduction for high-speed concurrent air flow conditions. The finding of current study is favorable for the fire hazard assessment of spilling hydrocarbon fuel in air flow environments.

The Effects of Camelina Ethyl Ester on the Performance of Diesel Engine and Combustion Characteristics

Energy is a primary factor which is necessary for the basic needs of human life. Striking progress has been made in internal combustion engines since they were invented in which petroleum gasoline and diesel are generally used as an energy source and they have an important position in industry and in our daily lives. However, searches for new energy sources have been started due to the fact that petroleum-based fuels will run out and they damage the environment. This study is intended to determine the effects of cameline ethyl ester, which is obtained from raw camelina oil by using ethanol, on engine performance mixing it with diesel fuel proportionately. Diesel, 80% diesel and 20% cameline ethyl ester volumetrically and 100% cameline ethyl ester fuels were used as fuel. In the experiments, a four-cylinder, 1900cc, turbocharger supplier diesel engine with Common - Rail fuel injection system was used. The experiments were repeated 3 times and the averages of the results were taken. When the results were investigated, it was seen that maximum torque value was measured in diesel fuel as 167,68 Nm at 2000 rpm, maximum power value was measured in diesel fuel as 40,88 kW at 3000 rpm and minimum specific fuel consumption was measured in diesel fuel as 219,52 g/kWh at 2500 rpm. Power and torque values of B20 and B100 fuels were a little lower than in diesel fuel and their specific fuel consumption was higher than the others.

Effects of injection pressure on ignition and combustion characteristics of diesel in a premixed methanol/air mixture atmosphere in a constant volume combustion chamber

The experiments on the ignition and combustion characteristics of diesel in air atmosphere (AA) and premixed methanol/air mixture atmosphere (MAA) were conducted in a constant volume combustion chamber (CVCC) equipped with a high pressure common-rail injection system. The ignition and combustion processes were recorded by a high-speed camera and a combustion pressure acquisition system. Results show that with the increase of injection pressure from 40 to 160MPa, the flame lift-off length (FLoL) becomes longer; and the ignition delay is shortened from 2.80ms to 2.03ms (AA) and 2.90ms to 2.27ms (MAA) respectively; and correspondingly the combustion duration is shortened from 5.17ms to 2.47ms (AA) and 4.83ms to 2.13ms (MAA). Compared those in AA, the ignition delay is prolonged by 0.14ms on average, while the combustion duration is shortened by 0.27ms in MAA. At high injection pressure, the moments that the maximum combustion pressure occurs and the apparent heat release rates (AHRR) starts to rise are advanced; while in MAA both of them are delayed; and the peak value of AHRR increases. With the increase of injection pressure, both spatially integrated natural luminosity (SINL) and time integrated natural luminosity (TINL) reduce significantly, but the reduction trends of TINL weaken. Due to the addition of methanol, the FLoL of diesel becomes longer, and the SINL and TINL in MAA are both lower than those in AA.

Comparative study of combustion and emissions of kerosene (RP-3), kerosene-pentanol blends and diesel in a compression ignition engine

Aviation Piston Engines for small general aviation aircrafts are currently facing a transition from being powered by AVGAS (aviation gasoline) to being powered by heavy fuels (diesel or kerosene). The present study compared the combustion and emission characteristics of diesel, aviation kerosene rocket propellant 3 (RP-3) and RP-3-pentanol blends in a single cylinder compression ignition (CI) engine. Heat release rate, indicated thermal efficiency, ignition delay, combustion duration, and coefficient of variation (COV) of indicated mean effective pressure were experimentally determined to reflect the engine combustion performance. The results demonstrated the feasibility of RP-3 and its mild pentanol blend (20% by volume) in modern CI engines whilst further optimisation of the injection strategy is needed if a higher ratio of pentanol (40% by volume) is used. The discrepancy in terms of combustion and emissions between diesel, RP-3 and its pentanol blends are appreciable, especially for ignition delay, combustion duration and soot emissions. Compared with diesel, RP-3 improved the indicated thermal efficiency by 1.4–12.4%, but pentanol addition decreased that by 1–6.5%. RP-3 and its pentanol blends reduced the soot emissions by nearly an order of magnitude at high engine loads compared with diesel without evident impact on nitrogen oxide (NOx) emissions. Meanwhile, Carbon monoxide (CO) and total hydrocarbon (THC) emissions of RP-3 and its pentanol blends experienced a significant increase at low loads, but CO showed a slight decrease at high loads.

Improving combustion characteristics of diesel and biodiesel droplets by graphite oxide addition for diesel engine applications

Summary Graphite oxide (GO) is an important member of the graphene family of carbon nanomaterials with remarkable physical, chemical, and thermal properties. We conducted an experimental investigation on the combustion characteristics of diesel and biodiesel droplets dosed with 0.1% GO. The fuels were tested by a single droplet combustion experiment in which the temporal variation in the burning behavior of a suspended droplet was captured using a high-speed camera. Numerical analysis of the combustion data suggests that the addition of GO in both fuels resulted in shortened ignition delay (by up to 38.2%), increased burn-rate constant (by up to 29.4%), lowered peak temperature (by up to 7.8%), and shortened burning period (by up to 11.6%). To illustrate, the burn-rate constant increased from 0.68 to 0.88 mm2/second, and the burning period reduced from 2.7 to 2.2 seconds when GO was dosed in diesel. By contrast, the ignition delay and peak temperature both decreased from 1.6 to 1.4 seconds and 659 to 611 K, respectively, when GO was added in biodiesel. Our results suggest that the fuel additive–induced benefits could effectively reduce emissions and improve fuel consumption for diesel engine applications.

Investigation of biodiesel obtained from tomato seed as a potential fuel alternative in a CI engine

ABSTRACTWith growing energy needs, depletion of fossil fuel resources and the alarming increase in atmospheric pollutants, the entire world is slowly switching to alternatives. There are many benefits of using biodiesel obtained from vegetables like tomato which are available locally, such as its higher cetane number, lower sulphur and lower ash content to improve the engine characteristics. From this point of view, an experiment was conducted to study the performance, emission and combustion characteristics of diesel fuel blended with tomato seed oil methyl ester tomato seed methyl ester (TSME) and n-butanol at various loads. Here, TSME was blended in percentages of 5, 10 and 15% with diesel fuel, with the concentration of n-butanol kept constant at 10%. The trends for BTE, EGT and NOx were similar and increased with blends. At 25% load, the HC emissions were 26 ppm for ND and decreased by 11.53, 23.07 and 34.61%, respectively, for D85B10T5, D80B10T10 and D75B10T15. The CO and smoke emissions were also found to decrease with blend percentages and load. The peak pressure and HRR were found to be higher with ND than the blends. The work thus reveals that blending tomato seed oil with an n-butanol–diesel mixture gave more desirable engine characteristics.

Experimental investigation of the effect of orifices inclination angle in multihole diesel injector nozzles. Part 1 – Hydraulic performance

Nozzle hydraulic performance has a significant impact on diesel spray development and combustion characteristics. Thus, it is important to understand the links between the nozzle geometry, the internal flow features and the spray formation. In this paper, a detailed analysis of the impact of the nozzle orifices inclination angle on its hydraulic performance is performed. For this purpose, three different nozzles with included angles of 90, 140 and 155 degrees are evaluated. Instantaneous injection rate and momentum flux are measured on a set of injector operating conditions (mainly injection pressure and discharge pressure). The results show that higher inclination angles lead to smaller mass flow and momentum flux at steady-state conditions, due to the higher losses at the orifice inlet. These losses are translated in lower both area and velocity coefficients. Nevertheless, the impact of this parameter is limited thanks to the counter-acting effect of the hydrogrinding process, which produces larger rounding radii at the orifice inlet as the included angle increases. Based on the experimental results, correlations of the discharge coefficient as a function of the Reynolds number are obtained and evaluated.

Prediction of diesel engine performance, emissions and cylinder pressure obtained using bioethanol-biodiesel-diesel fuel blends through an artificial neural network

The changes in the performance, emission and combustion characteristics of bioethanol-safflower biodiesel and diesel fuel blends used in a common rail diesel engine were investigated in this experimental study. E20B20D60 (20% bioethanol, 20% biodiesel, 60% diesel fuel by volume), E30B20D50, E50B20D30 and diesel fuel (D) were used as fuel. Engine power, torque, brake specific fuel consumption, NOx and cylinder inner pressure values were measured during the experiment. With the help of the obtained experimental data, an artificial neural network was created in MATLAB 2013a software by using back-propagation algorithm. Using the experimental data, predictions were made in the created artificial neural network. As a result of the study, the correlation coefficient was found as 0.98. In conclusion, it was seen that artificial neural networks approach could be used for predicting performance and emission values in internal combustion engines.

A comparative study of B10 biodiesel blends and its performance and combustion characteristics

ABSTRACTThe current work is to investigate the diesel engine performance and combustion characteristics fuelled with Banalities aegyptiaca (BA) biodiesel and compare those with the performance and combustion characteristics of palm biodiesel, sesame biodiesel,rapeseed biodiesel, soybean biodiesel and diesel fuel. In this study, only 10% of each biodiesel (BA10, PALM10, SESAME10, RAPESEED10 and SOYBEAN10) was tested in a diesel engine. The physical properties of all the fuel samples are mentioned and compared with ASTM standards. The test rig consists of a single cylinder, auxiliary water-cooled and computer-based variable compression ratio diesel engine, which was used to evaluate their performance at a measured torque. All biodiesel fuel samples reduce brake power and brake thermal efficiency and increase brake-specific fuel consumption rate than diesel fuel. Combustion characteristics results indicated that the blended fuel samples performed with a significant reduction in terms of cylinder pressure and heat release rate compared with diesel fuel apart from diesel pressure. Among the biodiesel-blended fuel samples, BA10 showed better performance in terms of brake power, brake-specific fuel consumption and brake thermal efficiency and cylinder pressure and heat release rate in terms of combustion characteristics compared with D100.

Effect of compression ratio on performance, emission and combustion characteristics of diesel–acetylene-fuelled single-cylinder stationary CI engine

The present investigation aims to depict the effect of compression ratio on performance, emission and combustion characteristics of diesel–acetylene-fuelled stationary compression ignition engine. The optimum values for compression ratio, injection timing and injection pressure for diesel were experimentally found, and baseline data were established as 20, 23° before top dead centre and 210 bar, respectively. In order to investigate the effect of acetylene fuelling, acetylene gas was inducted at four different flow rates of 60, 120, 180 and 240 litres per hour at compression ratio 20. It was observed that the flow rate of 120 litres per hour gave the best performance with highest brake thermal efficiency of 25.09%. In order to find the optimum compression ratio for acetylene fuelling at 120 litres per hour, experimentation was done at different compression ratios of 18, 19, 20, 21 and 22. Experimental results showed that highest brake thermal efficiency of 25.72% was achieved at compression ratio 21 for diesel–acetylene fuelling which was much higher than 23.32% for pure diesel. Carbon monoxide, hydrocarbon and smoke emissions were also measured and found to be lower, while the NOx emissions were higher at optimized values in dual-fuel mode as compared to those for pure diesel. Peak cylinder pressure and net heat release rate were also calculated and found to be higher in dual-fuel mode compared to diesel mode.

Numerical Study of the Performance and Emission of a Diesel-Syngas Dual Fuel Engine

Based on the theory of direct relation graph (DRG) and the sensitivity analysis, a reduced mechanism for the diesel-syngas dual fuel was constructed. Three small thresholds were applied in the process of the detailed mechanism simplification by DRG, and a skeletal mechanism with 185 elements and the 832 elementary reactions was obtained. According to the framework of the skeletal mechanism, the time-consuming approach of sensitivity analysis was employed for further simplification, and the skeletal mechanism was further reduced to the size of 158 elements and 705 reactions. The Chemkin software with the detailed mechanism was utilized to calculate the effect of syngas addition on the combustion characteristics of diesel combustion. The findings showed that the addition of syngas could reduce the ignition delay time and increase the laminar flame speed. Based on the reduced mechanism and engine parameters, a 3D model of the engine was constructed with the Forte code. The 3D model was adopted to study the effect of syngas addition on the performance and exhaust emissions of the engine and the relevant data of the experiment was used in the calibration of the 3D model.

Experimental and modelling investigations of the diesel surrogate fuels in direct injection compression ignition combustion

Experimental investigations on the combustion and emission characteristics of diesel and three potential diesel surrogate fuels have been performed, including the 85% (vol.) n-heptane blended with 15% toluene (T15), 81% n-heptane blended with 14% toluene and 5% c-hexane (T15+CH5), and 80% (vol.) n-heptane blended with 20% toluene (T20). The experimental results showed that due to the lower reactivity of the three diesel surrogate fuels, the combustion phases were more retarded and the indicated thermal efficiencies were lower compared to diesel. For the diesel surrogate fuels with higher volatility, the soot emissions were lower than those of diesel due to more premixed combustion. Moreover, a reduced n-dodecane-toluene reference fuel-c-hexane-polycyclic aromatic hydrocarbon (PAH) mechanism composed of 167 species and 671 reactions was formulated and was extensively validated against the experimental results. To clarify the experimental results, the reduced mechanism was then used for the three-dimensional (3-D) modelling investigations. The modelling results showed that the reduced mechanism can reasonably capture the combustion characteristics of T15+CH5 in the direct injection compression ignition combustion. The NOx and soot emissions were both reasonably predicted. From the modelling investigations, it was inferred that the physical effects on the soot emission were larger than the chemical effects of the different fuel carbon-chain structures. According to the 0-D modelling investigations, the soot tendency of the four pure diesel surrogate constituents can be sequenced as toluene>c-hexane>n-dodecane>n-heptane. Given that toluene is the dominant factor affecting the soot formation than the other three components, the soot tendency of the four diesel surrogate fuels can be sequenced as T20>T15+CH5 (n-dodecane)>T15+CH5 (n-heptane)≈T15.

Computational Investigation on Soot Mechanism of Diesel and Diesel/n-Butanol Blend in Constant Volume Chamber with Various Ambient Temperatures

Computational investigation was carried out in an optical constant volume chamber to explore the combined effects of initial ambient temperatures (800, 900, and 1000 K) and n-butanol additive (20% volume fraction of n-butanol) on diesel combustion and soot characteristics. An improved phenomenological soot model integrated with a reduced n-heptane/n-butanol/polycyclic aromatic hydrocarbon (PAH) mechanism was developed and implemented into the KIVA-3V R2 code to study the soot formation and oxidation mechanism. The predicted chamber pressure and heat release rate as well as soot mass trace and distribution showed good agreements with the experimental data. Results indicated that the ignition delay was retarded and total soot mass was reduced with the decrease of initial ambient temperature and with the n-butanol additive. The heat release rate of pure diesel demonstrated a transition from diffusion-dominated combustion at 1000 K to premix-dominated combustion at 800 K. Diesel/n-butanol blend showed no obvi...