Selected parameters of the combustion process in a compression-ignition engine at different angles of the beginning of injection of mixtures of rapeseed oil with n-hexane

The modification of the source of fat in pigs feed did not influence the content of protein and total minerals (ash), whereas it significantly influenced the content of fat and moisture. A different source of fat in pigs feed did not influence the content of fat, saturated fatty acids (SFA) and UFA (unsaturated fatty acids) in fat, whereas it significantly influenced the participation of particular fatty acids belonging to monounsaturated (MUFA) and n-3 and n-6 groups.

CFD analysis of combustion characteristics of CI engine run on biodiesel under various compression ratios

Methanol (CH3OH) emerges as a highly promising, economically feasible, environmentally friendly, and renewable energy source amid the rising global energy demand. As contemporary energy utilization techniques advance and the imperative to curtail dependence on depleting fossil fuels intensifies, the focus on methanol-fueled compression ignition (CI) engines, particularly in the automotive sector, becomes dominant. Over the past decade, the exceptional resistance of methanol fuel to engine knocking and its capacity to mitigate harmful emissions have gained substantial attention from researchers. While numerous review articles have been published, few have delved comprehensively into the technical advancements of methanol-fueled CI engines with an increased investigation of their environmental and renewable applications. This research review endeavors to address this gap by offering a comprehensive analysis of methanol, whether in its pure form or as a blended fuel, in technically developed CI engines. The main goal is to review enhanced engine performance, combustion efficiency, and emission characteristics. The review examines the impact of critical parameters, including the incorporation of blended fuels with controlled volume fractions (VF), engine load (EL), engine speed (ES), injection methods, compression ratio (CR), ignition timing (IT), intake fuel temperature, injection timing (I/T), combustion methods, crank angle (CA), and air-to-fuel (A/F) ratio. These parameters are assessed by performance indicators such as brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and thermal efficiency (TE). Additionally, combustion parameters, including combustion duration (CD), ignition delay (ID), heat release rate (HRR) and injection timing, phasing, are studied, along with emissions parameters including nitrogen oxides (NOx), carbon oxides (CO), hydrocarbons (HC), unburned methanol (UBM), formaldehyde (FA), particulate matter (PM) and soot in methanol-fueled CI engines. Finally, the research summary and future direction of methanol-fueled compression ignition (CI) engines have been concluded based on the previous work.

Renewable fuels have advantages in terms of energy recycling, biodegradability, energy security, environmental concerns, foreign exchange savings and socio-economic issues compared to fossil fuels. The high viscosity of vegetable oils leads to problem in pumping and spraying characteristics. The inefficient mixing of vegetable oils with air contributes to incomplete combustion. The best way to use vegetable oils as fuel in compression ignition engines is to convert them into biodiesel. Biodiesel is a methyl or ethyl ester of fatty acids made from vegetable oils (both edible and non-edible) and animal fat. The main resources for biodiesel production can be non-edible oils obtained from plant species, such as Pongamia pinnata (Honge oil), Jatropha curcas (Ratanjyot), Oryza sativa (Rice bran oil) and Calophyllum inophyllum (Nagchampa). Biodiesel can be used in its pure form or can be blended with diesel to form different blends. It can be used in compression ignition (CI) engines with very little or no engine modification as it has properties similar to mineral diesel. This paper presents comprehensive results of investigations carried out by us on the use of Jatropha oil, Jatropha oil methyl ester and blends with diesel or ethanol in a single-cylinder, four stroke, direct-injection, CI engines. Comparative measures of brake thermal efficiency, smoke opacity, HC, CO, NOX, ignition delay, combustion duration and heat release rates with diesel fuel have also been presented and discussed.

<div class="section abstract"><div class="htmlview paragraph">This work has the objective to present the extension of a novel quasi-dimensional model, developed to simulate the combustion process in diesel Compression Ignition (CI) engines, to describe this process when Dimethyl ether (DME) is used as fuel. DME is a promising fuel in heavy-duty CI engines application thanks to its high Cetane Number (CN), volatility, high reactivity, almost smokeless combustion, lower CO2 emission and the possibility to be produced with renewable energy sources. In this paper, a brief description of the thermodynamic model will be presented, with particular attention to the implementation of the Tabulated Kinetic Ignition (TKI) model, and how the various models interact to simulate the combustion process. The model has been validated against experimental data derived from constant-volume DME combustion, in this case the most important parameters analyzed and compared were the Ignition Delay (ID) and Flame Lift Off Length (FLOL). Following this first validation process, the model has been tested against experimental values obtained from a heavy-duty DME-fueled CI engine in different operating conditions, representative of real engine applications. In this second comparison, the focus shifted on Heat Release Rate (HRR) and in-cylinder pressure trends and NO<i><sub>x</sub></i> production during combustion. The results show good agreement between the experimental and computed values in all operating conditions, leading to the possibility of using the presented model to accurately predict the performance of engines with DME as fuel in a fast 1D- or quasi-dimensional simulation tool.</div></div>

Numerical investigation of multiphase reactive processes using flamelet generated manifold approach and extended coherent flame combustion model

One of the possibilities to reduce diesel fuel consumption and at the same time reduce the emission of diesel engines, is the use of alternative gaseous fuels, so far most commonly used to power spark ignition engines. The presented work concerns experimental research of a dual-fuel compression-ignition (CI) engine in which diesel fuel was co-combusted with CNG (compressed natural gas). The energy share of CNG gas was varied from 0% to 95%. The study showed that increasing the share of CNG co-combusted with diesel in the CI engine increases the ignition delay of the combustible mixture and shortens the overall duration of combustion. For CNG gas shares from 0% to 45%, due to the intensification of the combustion process, it causes an increase in the maximum pressure in the cylinder, an increase in the rate of heat release and an increase in pressure rise rate. The most stable operation, similar to a conventional engine, was characterized by a diesel co-combustion engine with 30% and 45% shares of CNG gas. Increasing the CNG share from 0% to 90% increases the nitric oxide emissions of a dual-fuel engine. Compared to diesel fuel supply, co-combustion of this fuel with 30% and 45% CNG energy shares contributes to the reduction of hydrocarbon (HC) emissions, which increases after exceeding these values. Increasing the share of CNG gas co-combusted with diesel fuel, compared to the combustion of diesel fuel, reduces carbon dioxide emissions, and almost completely reduces carbon monoxide in the exhaust gas of a dual-fuel engine.

본 연구는 주요 구성지방산이 Oleic acid인 유채유, 동백유, 올리브유와 Palmitic acid가 주요 구성 지방산인 팜유를 기준으로 중량비로 혼합하여 지방산 조성 및 물성변화를 관찰 하였다. 지방산 조성의 변화를 전체적으로 살펴보면 50:50(w/w)비율에서는 Oleic acid은 유채유와 대두유의 혼합 시 42.8%로 가장 낮았고 동백유와 유채유의 혼합비율에서 72.1%로 가장 높았다. 75:25(w/w)유채유와 대두유 혼합비율에서 가장 낮았고 동백유와 올리브유의 혼합비에서 가장 높았다. 팜유를 기준으로 식물성 유지를 혼합하였을 시에는 다른 유지와 혼합 후 총 포화지방산은 감소하였다. 혼합 후 지방산 조절을 통한 산화안정성 및 저온에서의 유동성 개선이 기대 된다. 혼합 후 동백유 > 올리브유 > 유채유 순으로 산가 안전화 경향을 보였으며 이는 Oleic acid 함량에 따라 기인한 것으로 보인다. 또한 혼합을 통한 산화안정성을 개선시킬 수 있을 것으로 판단되며, 색도는 비율 및 유지에 따른 유의적인 변화를 보이지는 않았으나 바이오디젤 생산 정제공정에 있어서 혼합비율 조절에 따른 정제비용 절감이 기대 된다. 본 연구를 통하여 유지간 혼합에 의한 특성변화를 확인하고, 혼합유의 원료 다양성 확보 및 품질개선을 위한 정보를 얻어 향후 연구수행의 기초자료로 활용이 가능할 것으로 생각된다. As there have been lately many worldwide resource challenges such as potential exhaustion of fossil fuels, sudden rise of oil price and ever-rising grain pricing due to global food crisis, there have been more interests focused on recycling vegetable oils and fats into clean natural fuel and producing new resources based on waste cooking oil as a part of reusing waste resources. An Experiment was performed by using ratio of 50:50, 75:25 (w/w) mixture of based rapeseed oil, camellia oil, and olive oil. 50:50, 25:75 (w/w) mixture of based palm oil. The result was that the oleic acid (<TEX>$C_{18:1}$</TEX>) got the lowest percentage of 42.8%, when we combined the mixture of rapeseed oil and soybean oil. While the highest percentage of 72.1% was when the mixture of camellia oil and rapeseed oil were combined at 50:50 ratio. In 75:25 (w/w) case, mixture of rapeseed oil and soybean oil got the lowest. The highest ratio was the mixture of camellia oil and olive oil. Based on the component of palm oil, the total saturated fatty acid was decreased. It is expected that stabilizing oxidation through controlling of fatty acid after mixture and that liquidity at a low temperature. The acid value indicated that stabilizing oxidation got a range of highest to lowest. Camellia oil ranked as the highest, followed by olive oil, and the oil seeds as the lowest in rank. Controlling iodine value through mixture and improvement of stabilizing oxidation will provide a good quality. The quality of color has no significant change about mixture in ratio and maintenance. The reduction of the cost of refining process is expected by controling of mixture ratio at biodiesel production in the future.

The Heavy Duty Diesel or compression ignition (CI) engine plays an important economical role in societies all over the world. Although it is a fuel efficient internal combustion engine design, CI engine emissions are an important contributor to global pollution. To further reduce engine emissions and improve fuel efficiency, modification of the fuel composition is an interesting option. First of all, a (partial or gradual) change over to synthetic fuels can reduce the dependency on fossil fuel, which enables reduction of CO2 emission if renewable feedstock is used. Secondly, modification of the fuel composition potentially can benefit the CI engine's emission tradeoff between particulate matter (PM) and nitric oxides (NOx). The aim of the present work is to give further insight into fuel composition impact on CI engine combustion and resulting emissions. It is shown that fuel composition changes are a powerful instrument to change the PM - NOx tradeoff on existing CI engine designs. Modern CI engines inject liquid fuel into the combustion chamber of the engine. This happens typically at high hydraulic pressure (up to 250 MPa), using a fuel injector with typically 6 to 9 injector holes during a very short time (&lt;3 ms), very close to the end of the compression stroke of the engine. To create fundamental understanding of the CI engine combustion characteristics, the fuel spray vaporization and combustion phenomenology needs to be studied in detail. To do so, an optically accessible constant volume cell EHPC (Eindhoven High Pressure Cell) is used in this work. To facilitate the investigations, the EHPC was further developed to create engine like conditions using the pre-combustion method. This method uses a premixed combustion and by adjusting the mixture composition of the premixed gases, the residual gas mixture composition and properties can be tuned. This means that at the moment of fuel injection, during the cool down period after the pre-combustion event, non-reacting or reacting sprays can be studied. This method allows coverage of ambient conditions in this work up to a gas density of 32 kg/m3 for a temperature range of 750 to 1200 K and oxygen concentrations between 0 and 21 volume percent. To characterize the fuel spray using the EHPC, optical diagnostics and image analysis methods have been developed. Schlieren is used to investigate non-reacting spray penetration and angle dispersion. The liquid core behavior of vaporizing sprays is measured using MIE scattering. To validate the results, regular automotive CI engine fuel is used (EN590). Comparing the non-reacting EN590 fuel spray results with literature data, shows that in general the spray behavior as function of ambient conditions is in line with the trends reported. Detailed analysis reveals that, for the data captured in this work, the often used power law to describe spray penetration is not accurate enough. The spray dispersion angle at one condition is out of the expected range and more experimental data is required to get more understanding and better statistics. This outlier also slightly affects the validation of the liquid length measured using laser MIE scattering at this specific condition. When the measured data is compared with a predicted liquid length using a mixing-limited vaporization model, the liquid length is shorter than expected. The general trend in the results is however still present. For reacting fuel spray characterization the ignition delay is measured using a pressure measurement and laser line of sight extinction is use to qualify the soot presence during quasi-steady state combustion. The results achieved with both methods are in line with results from literature. It can be concluded that the EHPC, the optical diagnostics used and image analysis methods are successfully implemented and validated using EN590 fuel. With this setup and tools at hand, two additional fuels were characterized: SMDS, which is a synthetic gas to liquid fuel, and SMDS blended with 29.3 mass percent Tripropylene G lycol Monomethyl Ether (TPG ME), called fuel S-TP-9. The latter results in an oxygenated fuel with 9.4 9 mass percent oxygen. B oth fuels show differences compared to EN590, especially for reacting fuel sprays. The higher Cetane Number of both fuels results in an, expected, reduced ignition delay. B oth fuels produce less soot during quasi-steady state combustion. O xygenated fuel S-TP-9 clearly shows an even lower soot production compared to SMDS. At reduced ambient temperatures and oxygen concentration soot production for all tested fuels is reduced, but the additional soot production reduction for S-TP-9 is less significant compared to the results at an ambient oxygen concentration of 21 volume percent. Additional to the fuel spray combustion investigations using the EHPC, a broader range of fuels was tested on Heavy Duty CI engine test rig to quantify the effects of fuel composition. The results show that oxygenated fuels up to 15 mass percent oxygen can reduce engine-out PM emission up to one order of magnitude at reduced in-cylinder temperatures and oxygen concentration. The other effects of fuel composition are limited to a minor impact on injection duration, apparent heat release and NOx emission. The results of engine and EHPC combined suggest that the beneficial influence of additional oxygen in the fuel on PM emissions, becomes even more effective after end of combustion, during the late expansion phase of the engine. How this process evolves up to the moment the PM emissions are measured in the exhaust system of the engine, should be part of further investigation.

Energy scarcity and pollution problems have prompted researchers to search for renewable and clean energy sources for compression ignition (CI) engines. Two C8 biofuels, i.e., n-octanol and di-n-butylether (DnBE), are both promising to be the diesel fuel candidates because of their good ignition ability. However, their physical and chemical properties are different from each other. Thus, the combustion process of a CI engine could be optimized by manipulating the blending ratio of n-octanol and DnBE. In this work, to investigate the effects of n-octanol and DnBE blends on the combustion characteristics and emissions formation in a CI engine, the numerical investigation was carried out by the coupled KIVA4-CHEMKIN code. A multi-component reaction mechanism was implemented in the code to mimic the combustion of the fuels. Different DnBE/n-octanol blends were designed by varying the DnBE from 10% to 90% with an interval of 10% on an energy basis. Then the CI engine fueled with pure n-octanol, pure DnBE, and their blends was simulated at the engine speeds of 1500 rpm and 2280 rpm, respectively. Results suggest that blending more DnBE in octanol can shorten the ignition delay, increase peak pressure, mitigate pressure rise rate, and prolong the combustion duration. The emitted CO of the n-octanol fueled CI engine is high at both speeds. Blending DnBE in n-octanol can reduce CO emissions but inevitably leads to a rise in NO. More importantly, soot-free combustion can be achieved by fueling either n-octanol or DnBE. Finally, the optimal DnBE blending ratio is selected at 50%, of which IMEP can be improved by 6.12% and 6.9%, and CO can be reduced by 69.91% and 65.98% with acceptable increases in NO at 1500 and 2280 rpm, respectively. This implies that the optimization of CI engines can be achieved by adjusting the blending ratio of n-octanol and DnBE.

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

&lt;div class="htmlview paragraph"&gt;Homogeneous charge compression ignition (HCCI), has the potential to improve the fuel economy and to reduce NOx emission significantly. Spark plug in SI engine and fuel injector in diesel engine can be used directly to control the start of combustion and the combustion period. However, the combustion of HCCI engine is controlled by the chemical kinetic mainly due to the temperature histories in the cylinder. Therefore the combustion process of HCCI engine cannot be directly controlled. Ion sensors such as a spark plug or a gasket are useful to detect the combustion information in production engines. In this study, the ion current was measured in an HCCI engine with the heated charge mixture of fuel and air without EGR when the charge temperature, equivalence ratio and fuel were varied. Simultaneously in-cylinder pressure was measured and the rate of heat release was calculated. The relationship between the rate of heat release and the ion current is mainly discussed. In order to investigate the relationship between the rate of heat release and the ion current, the several parameters were defined. The present study indicates that there is a strong correlation between the peak location of differential ion-current and the second peak location of R.O.H.R.. In the case of &lt;i&gt;Tc&lt;/i&gt;=373 and 353K, in spite of decrease of rate of heat release, there is a good correlation between the value of second peak in the rate of heat release, (&lt;i&gt;dQ&lt;/i&gt;/&lt;i&gt;d&lt;/i&gt;θ)&lt;i&gt;&lt;sub&gt;H&lt;/sub&gt;&lt;/i&gt; and the differential value of ion current at θ&lt;i&gt;&lt;sub&gt;G&lt;/sub&gt;&lt;/i&gt;, (&lt;i&gt;dI&lt;/i&gt;/&lt;i&gt;d&lt;/i&gt;θ)&lt;i&gt;&lt;sub&gt;H&lt;/sub&gt;&lt;/i&gt;.&lt;/div&gt;

Combustion characteristics of diesel HCCI engine: An experimental investigation using external mixture formation technique

Hermetia illucens larvae oil (HILO) is among biofuel feedstock from insects that has high potential to reduce dependency on petroleum resources. The present paper is motivated by the need to critically examine the effect of HILO mixed with diesel fuel (DF) on combustion, engine performance, and emission characteristics of a single cylinder direct injection (DI) compression ignition (CI) engine. The experiment was performed at a constant speed of 1500 rpm under various engine loads. The results revealed that the in-cylinder pressure, heat release rate (HRR), and the ignition delay (ID) were reduced by an average of 3.32%, 12.89%, and 4.36%, respectively. The brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT) increased considerably at all engine loads. The brake thermal efficiency (BTE) was discovered to be lower by 11.47% compared to DF. The finding also shows that carbon monoxide (CO), carbon dioxide (CO2), and unburned hydrocarbon (UHC) emissions increased with the addition of HILO. The nitrogen oxides (NOx) emission reduced by 19.80% compared to DF at all the engine loads. Overall, this study concluded the potential of HILO in CI engine as a promising renewable and environmentally friendly resource for the better earth.

Performance and emission characteristics of a DI compression ignition engine operated on Honge, Jatropha and sesame oil methyl esters