The free piston engine linear generator (FPELG) is a simple engine structure with few components, making it a promising power generation system. However, because the engine works without a ...crankshaft, the handling of the piston motion control (PMC) is the main challenge influencing the stability and performance of FPELGs. In this article, the optimal operating parameters of FPELG for maximising engine performance and reducing exhaust gas emissions were studied. Moreover, the influence of adding hydrogen (H2) to compressed natural gas (CNG) fuel on FPELG performance was investigated. The influence of operating parameters on in-cylinder pressure was also analysed. The single-piston FPELG fuelled by CNG blended with H2 was used to run the experiments. The response surface methodology (RSM), including the central composite design (CCD), was used. Then, adequacy models were developed and verified by ANOVA. Three independent factors on seven responses were utilised for optimisation. Results showed that the optimal operating conditions of lambda, ignition velocity, and injection position were 0.96, 0.53 m/s, and −14.9 mm, respectively. The best-predicted values were as follows: indicated mean effective pressure (IMEP) of 7.6 bar, in-cylinder pressure of 27.87 bar, combustion efficiency of 39.64%, CO of 9531.41 ppm, CO2 of 2.4%, HC of 551.75 ppm, and NOX of 113.737 ppm. Furthermore, results showed that the experimental data could be fitted well with the predicted quadratic model.
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•Three independent factors on seven responses were used for the optimisation.•The adequacy models were developed in RSM and verified by ANOVA.•The operating parameters of FPELG were optimised using RSM.•Maximum performance and minimum emission of FPELG were obtained.•The effect of operating parameters on FPELG performance was investigated.
Biodiesel (methyl esters) has been produced using numerous catalysts to enhance its quality and related productivity. Generally, the raw materials for biodiesel production and its catalysts ...significantly impact the produced biodiesel's quality. In addition, the heterogeneous catalysts are promising as catalysts in the transesterification for biodiesel production and can be used continuously during this production. In particular, these catalysts are essential for green biodiesel production because of their high activity, thermal stability, and reusability. Hence, several homogeneous and heterogeneous (acidic and alkaline) catalysts for biodiesel production, particularly the naturally derived heterogeneous catalysts, are reviewed in this article. Further, the different heterogeneous catalysts for biodiesel production have been studied extensively as replacements for the respective homogeneous catalyst. Specifically, this replacement is aimed at the simultaneous esterification and transesterification of the nonedible and low-cost biomasses under moderate conditions producing biodiesel. Moreover, this study analyzes biodiesel's impact and long-term performance in various applications. Finally, it also reports the advancements in biodiesel production in terms of the catalysts used in it and its processes to aid further developments in biodiesel production.
Due to the finite stock of fossil fuels and its negative impact on the environment, many countries across the world are now leaning toward renewable sources energies like solar energy, wind energy, ...biofuel, hydropower, geothermal and ocean energy to ensure energy for the countries development security. Biodiesel is one kind of biofuel that is renewable, biodegradable and has similar properties of fossil diesel fuel. The aim of this paper is to provide the substantial information on biodiesel to the researchers, engineers and policy makers. To achieve the goal, this paper summarizes the information on biofuel development, feedstocks around the world, oil extraction technic, biodiesel production processes. Furthermore, this paper will also discuss the advantages of biodiesel compared to fossil fuel. Finally, the combustion behavior of biodiesel in an internal combustion engine is discussed and it will help the researchers and policy maker and manufacturer. To determine the future and goal of automotive technology the study found that, feedstock selection for biodiesel production is very important as it associates 75% production cost. Moreover, the test of fuel properties is very important before using in the engine which depends on the type of feedstocks, origin country, and production process. Most of the researchers reported that the use of biodiesel in diesel engine reduces engine power slightly but reduces the harmful emission significantly. Finally, the study concludes that biodiesel has the potential to be used as a diesel fuel substitute in diesel engines to solve the energy and environment crisis.
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•Pure α-Al2O3 with high thermal stability and OSC synthesized via combustion method.•4–10% of Power and 2–6% of BTE reduced by using B5 and B20 compared to B0.•Inclusion α-Al2O3 ...enhanced the power (up to 5% for B5Al) and BTE (up to 3.5% for B20Al).•The HC and CO emissions reduced using blend fuels and dropped 50% and 10% by adding α-Al2O3.•Although biodiesel increased the NOx emissions, it was reduced over 23% with the addition of α-Al2O3.
Alumina has been recently studied as a fuel additive in diesel–biodiesel blends to enhance combustion characteristics in the engine chamber and reduce emissions. However, concerns have been raised about the potential formation of high NOx emissions. Alumina exists in different phases, each with distinct properties. In this research, the pure alpha phase of alumina was synthesized using the solution combustion method and mixed into diesel–biodiesel blends (B0, B5, and B20). Performance parameters (power, BSFC, BTE, and EGT) and emissions (CO2, CO, HC, and NOx) of a single-cylinder diesel engine were then examined. The prepared alumina exhibited alpha phase with high thermal stability over 500 °C and proper oxygen storage capacity (1741.8 μmol g−1) which provide it as a suitable catalyst to mix with fuel. The addition of α-Al2O3 to the fuel slightly increased the density, calorific value, and cetane number, while decreasing the viscosity and flash point. These changes in fuel properties influenced the engine performance, resulting in a 4.9 % (B5Al fuel) increase in power and a 3.5 % (B20Al fuel) increase in BTE while B5 and B20 fuels showed less power and BTE compared to diesel fuel at all engine loads. Furthermore, a 3.2 % and 16.2 % reduction in BSFC and EGT was respectively observed using B20Al due to the decrease in viscosity and flash point of fuels by adding α-Al2O3. The inclusion of α-Al2O3 also impacted emissions, resulting in reductions of 16–50 % in CO, 3–12 % in HC, and 1–23 % in NOx emissions. The results demonstrate the potential of α-Al2O3 as a catalyst for fuel combustion, owing to its high OSC and its ability to regulate engine temperature and promote complete combustion reactions.
In recent years, the approaches paid much attention to are adding nanoparticles in biodiesel-based fuels to overcome the disadvantages of biodiesel like high molecular mass, high viscosity, and ...pouring point, and low calorific value significantly affecting the spray, atomization, and combustion characteristics. Among the aforementioned nanoparticles, Cerium oxide (CeO2) nanoparticles show their advantages such as flexible capacity in valence transformation, large oxygen storage, and good thermal properties, CeO2 nanoparticles are thus believed to have a great potential to become an additive for the diesel engine. Indeed, in this review paper, the preparing methods and physicochemical properties of biodiesel-based fuels containing CeO2 nanoparticles were fully introduced. Furthermore, the effects of CeO2 on the atomization and micro-explosion of as-used fuels were also discussed in detail. More importantly, the combustion behavior, performance, and emission characteristics of diesel engines fuelled with biodiesel containing CeO2 nanoparticles were thoroughly analyzed. In general, the addition of CeO2 nanoparticles into biodiesel has demonstrated positive effects on reducing toxic emissions (soot, smoke opacity, NOx, CO, HC), enhancing thermal efficiency and brake power, and improving fuel consumption. However, the impacts of CeO2 nanoparticles on PM emission, human health, and the environment need to be further investigated in future researches.
•Preparing methods for CeO2-added fuels and their properties were introduced.•Effects of CeO2 nanoparticles on spray and fuel properties were mentioned.•Performance of engine fuelled with CeO2-added biodiesel was thoroughly analyzed.•Combustion and emission characteristics of diesel engine were discussed in detail.
In this research study, fuel blends of pine oil and waste cooking oil biodiesel (P/WCO) were examined for combustion analysis, engine performance, and emission characteristics tests. Improved ...combustion and engine performance were achieved using a toroidal re-entrant combustion chamber (TCC) and hydrogen supply as a dual fuel. The combustion behavior of fuel blends and hydrogen fuel was examined by varying the engine load at a constant speed. The results revealed that significant reduction in the specific fuel consumption for rich pine oil. Thus, a slightly lesser energy share from the fuel blends and a higher energy share from the hydrogen fuel was required for the engine to maintain the same brake power. Lower viscosity, higher flash point, and presence of oxygen in the pine oil enhance the combustion rate and brake thermal efficiency. Furthermore, hydrogen induction in the engine improves the flame velocity. A lesser crevice volume in the TCC can trap the unburnt fuel which can further increase the combustion efficiency. Thus, rich pine oil with the support of hydrogen induction in TCC causes advanced ignition, improved combustion, and more heat release during the combustion. The investigation results revealed that hydrogen induction increases the heat release rate and peak pressure by 7.4% and 2.67%, respectively. Similarly, the maximum of 24.55% increase in BTE and 18.22% reduction in BSFC was observed due to a constant 10 lpm hydrogen induction. Furthermore, hydrogen fuel significantly reduces the emissions such as CO, HC, CO2, and smoke. However, more NOx was generated due to more heat release rate during combustion. Thus, pine oil and waste cooking oil biodiesel blends with the support of hydrogen induction in TCC improve the engine performance and mitigate the toxic pollutants and can be a suitable alternative to diesel fuel.
•Combustion effects of pine oil and waste cooking oil biodiesel blends were examined.•The influence of hydrogen addition in dual fuel mode is highlighted.•Impact of the toroidal re-entrant combustion chamber concerning BTE, BSFC, and emissions was discussed.•The energy share between biodiesel and hydrogen is discussed.
This study investigated the engine performance and emission characteristics of biodiesel blends with combined Graphene oxide nanoplatelets (GNPs) and 10% v/v dimethyl carbonate (DMC) as fuel ...additives as well as analysed the tribological characteristics of those blends. 10% by volume DMC was mixed with 30% palm oil biodiesel blends with diesel. Three different concentrations (40, 80 and 120 ppm) of GNPs were added to these blends via the ultrasonication process to prepare the nanofuels. Sodium dodecyl sulphate (SDS) surfactant was added to improve the stability of these blends. GNPs were characterised using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR), while the viscosity of nanofuels was investigated by rheometer. UV-spectrometry was used to determine the stability of these nanoplatelets. A ratio of 1:4 GNP: SDS was found to produce maximum stability in biodiesel. Performance and emissions characteristics of these nanofuels have been investigated in a four-stroke compression ignition engine. The maximum reduction in BSFC of 5.05% and the maximum BTE of 22.80% was for B30GNP40DMC10 compared to all other tested blends. A reduction in HC (25%) and CO (4.41%) were observed for B30DMC10, while a reduction in NOx of 3.65% was observed for B30GNP40DMC10. The diesel-biodiesel fuel blends with the addition of GNP exhibited a promising reduction in the average coefficient of friction 15.05%, 8.68% and 3.61% for 120, 80 and 40 ppm concentrations compared to B30. Thus, combined GNP and DMC showed excellent potential for utilisation in diesel engine operation.
•Influence of Graphene oxide nanoplatelets (GNPs) and dimethyl carbonate (DMC) were studied.•Surfactant sodium dodecyl sulphate (SDS) was used to stabilise the blend.•The best ratio of GNP to SDS was 1:4 for maximum stability in biodiesel.•Maximum reduction in BSFC and maximum BTE was observed for B30GNP40DMC10.•B30GNP120DMC10 fuel blend showed a maximum reduction of 15.05% in COF.
The present review investigates modification of diesel fuel formulation and development of a new model to enhance engine performance, improve fuel properties and reduce exhaust emissions. Emissions ...arising from the fuel can be controlled by blending an oxygenated fuel (renewable fuel) with the diesel fuel. The blending oxygenated fuels namely Methanol, Ethanol, and n-Butanol are examined in addition to their effects. This review paper studies the implication of different torques and various engine speeds. In some conditions, it can even cause an increase in the content of carbon monoxides (CO), carbon dioxide (CO2) and nitrogen oxides. This review showed that the engine speed has a negative effect on all of the air pollutants, so that increasing of the engine speed leads to reduction of the air pollutants. However, the engine load gives rise to most exhaust emissions. Adding the oxygenate fuels increases brake specific fuel consumption (BSFC), while brake thermal efficiency (BTE) decreases. In some researches, a nano-metal additive has been used in the fuel for improving the engine performance. In case of using the nano-metal additives to the diesel fuel (a nano-metal with small thermal conductivity coefficient), the engine performance is seen increased.
Engine performance parameters, including fuel conversion efficiency (FCE), power, torque and specific fuel consumption (SFC), can be affected by variables such as ignition timing (IGT), injection ...timing (IT) and hydrogen volume fraction (H2%). In this paper an engine fueled with different H2/CNG blend rations from 0 to 50% volume under ignition and injection timing at different speeds were investigated. For model validation, the engine operating conditions were simulated using the AVL fire software and compared with experimental results. The statistical comparison showed that there was no significant difference between them. Also, a support vector machine (SVM) was used to study the engine's behavior according to the variables studied. The SVM model predicted the FCE, power, torque, SFC and CO with error of less than 4%. The Genetic Algorithm (GA) was used to find optimal IGT, IT and H2% values to achieve optimum engine performance. Therefore, the results showed that the optimum engine operating conditions depend on the engine speed. Also, the results showed that independent variables (IT, IGT and H2%) maximize the engine performance and minimize SFC and CO emission. So that the optimum use of hydrogen in this research at different engine speeds was between 20% and 30%.
•Effect of hydrogen fuel in direct injection engine was studied.•Use of HCNG fuel can improve engine performance and exhaust emissions.•The SVM model could predict the engine performance and CO with error of less than 4%.•Ignition timing, injection timing and hydrogen volume fraction at different engine speeds.
