Air-fuel Ratio Research Articles

Toward gasoline vehicles with zero harmful emissions by storing NO at Pd nanoparticle–CeO2 interface during the cold-start period

A significant amount of NO is emitted from advanced gasoline vehicles during preheating three-way catalysts (TWCs) to operating temperature (>150°C). Pd nanoparticles (NPs) loaded on CeO2 are studied as a NO abatement material to mitigate NO emissions during the cold-start period. The air-fuel equivalence ratio is systematically switched from high to low while increasing temperature to promote NO storage below the operating temperature of TWCs and NO reduction at high temperature. Combined experimental and theoretical studies indicate that the Pd-NP–CeO2 interface modified by oxygen vacancies (VOs) plays an important role in converting NO∗ to NO2. NO2 is captured by VOs formed on the CeO2 surface, enabling the use of Pd/CeO2 as a NO storage material. Consequently, NO emission decreases by 67.6% during the cold-start period under practical conditions, which has been unattainable with conventional TWCs, thus bringing us a step closer to zero harmful emissions.

Design of a Hybrid Fault-Tolerant Control System for Air–Fuel Ratio Control of Internal Combustion Engines Using Genetic Algorithm and Higher-Order Sliding Mode Control

Fault-tolerant control systems (FTCS) are used in safety and critical applications to improve reliability and availability for sustained operation in fault situations. These systems may be used in process facilities to reduce significant production losses caused by irregular and unplanned equipment tripping. Internal combustion (IC) engines are widely used in the process sector, and efficient air–fuel ratio (AFR) regulation in the fuel system of these engines is critical for increasing engine efficiency, conserving fuel energy, and protecting the environment. In this paper, a hybrid fault-tolerant control system has been proposed, being a combination of two parts which are known as an active fault-tolerant control system and a passive fault-tolerant control system. The active part has been designed by using the genetic algorithm-based fault detection and isolation unit. This genetic algorithm provides estimated values to an engine control unit in case of a fault in any sensor. The passive system is designed by using the higher-order sliding mode control with an extra fuel actuator in the fuel supply line. The performance of the system was tested experimentally in MATLAB/Simulink environment. Based on the simulation results, the designed system can sustain the AFR despite sensor failures. A new method of managing the AFR of an IC engine has been demonstrated in this study, and it is highly capable, robust, reliable, and highly effective. A comparison with the existing works found in the literature also proves its superior performance. By inserting the fault in each sensor, it was clearly observed that proposed HFTCS was much better than the existing model as it was more fault-tolerant due to its ability to work in both online and offline modes. It also provided an exact value of 14.6 of AFR without any degradation.

Effect of Adding Combustion Air on Emission in a Diesel Dual-Fuel Engine with Crude Palm Oil Biodiesel Compressed Natural Gas Fuels

A diesel dual-fuel engine uses two fuels designed to reduce the consumption of fossil fuels. Generally, the specific fuel consumption of diesel dual-fuel engines has increased. However, in combination with alternative fuels, namely compressed natural gas injected through air intake, the use of diesel fuel can be reduced. However, using two fuels in a diesel dual-fuel engine increases the equivalent ratio; therefore, the air and fuel mixture becomes richer because the air entering the cylinder during the intake stroke is partially replaced by compressed natural gas. This results in incomplete combustion and increases exhaust emissions, particularly hydrocarbon (HC) and carbon monoxide (CO) emissions. This study aims to improve the combustion process in dual-fuel diesel engines by improving the air-fuel ratio; thus, it can approach the stoichiometric mixture by adding combustion air forcibly to produce complete combustion to reduce CO and HC emissions. An experimental approach using a single-cylinder diesel engine modified into a diesel dual-fuel engine powered by crude palm oil biodiesel and compressed natural gas was adopted. The combustion air was forcibly added to the cylinder using an electric supercharger at different air mass flow rates ranging from 0.007074 to 0.007836 kg/s and different engine loads (1000 to 4000 watts). The results indicated that adding more air to the cylinder could produce complete combustion, reducing the emission levels produced by a diesel dual-fuel engine. An air mass flow rate of 0.007836 kg/s can reduce CO, HC, and particulate matter emissions by averages of 60.55%, 49.63%, and 86.87%, respectively, from the standard diesel dual-fuel engine. Increasing in the amount of oxygen concentration improves the quality of the air-fuel ratio, which results in improved combustion and thereby reducing emissions.

A Comparative Study of Design of Active Fault-Tolerant Control System for Air–Fuel Ratio Control of Internal Combustion Engine Using Particle Swarm Optimization, Genetic Algorithm, and Nonlinear Regression-Based Observer Model

In this article, three distinct strategies for designing an Active Fault-Tolerant Control System (AFTCS) for Air-Fuel Ratio (AFR) control of an Internal Combustion (IC) engine in a process plant to avoid engine shutdown, are presented. The proposed AFTCS employs a Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and a Nonlinear Regression (NLR)-based observer model in the Fault Detection and Isolation (FDI) unit for analytical redundancy. A comparison between these three proposed techniques is carried out to determine the least expensive and most accurate approach. The results show that the nonlinear regression produces highly accurate results by consuming very low computational power, and its response time is also very low as compared to GA and PSO. The results obtained show that NLR requires 99.6% and 93.1% less computational time for throttle and MAP estimation, respectively, by reducing the estimation error to as low as 0.01. The simulation of the proposed system is carried out in the MATLAB/Simulink environment. The results prove the superior fault tolerance performance for sensor faults of the AFR control system, especially for the Manifold Absolute Pressure (MAP) sensor in terms of less oscillatory response as compared to that reported in existing literature.

Influence of Heat Transfer of Combustion Chamber Wall on the Performance of Gasoline Engine Based on Polishing Technology under Different Compression Ratio and Air-Fuel Ratio

Influence of Heat Transfer of Combustion Chamber Wall on the Performance of Gasoline Engine Based on Polishing Technology under Different Compression Ratio and Air-Fuel Ratio

Evaluation of the Possibility to Use Coalbed Methane to Produce Methanol Both by Direct Partial Oxidation and From Synthesis Gas

The possibility of using coalbed methane to produce methanol is assessed. Methanol can be obtained from methane both by direct partial oxidation and from synthesis gas formed through the oxidative conversion of methane. Thermodynamic analysis of coalbed methane conversion was carried out to determine the conditions for obtaining synthesis gas with the ratio [H2]/[CO] = 2, which is optimal for methanol production. The system consisting of methane, nitrogen, and oxygen, with different contents of oxygen and water vapor, was considered. The fuel-air equivalence ratio varied in the range from 2 to 4. The optimal conditions for obtaining synthesis gas for the production of methanol is the use of a mixture with an equivalence ratio of at least 4. It has also been shown that the addition of water vapor leads to an increase in the [H2]/[CO] ratio. Direct gas-phase oxidation of methane to methanol opens up the possibility of complex use of coal mining waste, including not only coalbed methane but also a large amount of coal waste accumulated during coal mining and beneficiation.

Nucleation-accumulation mode trade-off in non-volatile particle emissions from a small non-road small diesel engine.

Small (< 8kW) non-road engines are a significant source of pollutants such as particle number (PN) emissions. Many small non-road engines do not have diesel particulate filters (DPFs). They are so designed that air-fuel ratio (AFR) can be adjusted to control visible diesel smoke and particulate matter (PM) resulting from larger accumulation mode particles. However, the effect of AFR variation on smaller nucleation mode nanoparticle emissions is not well understood. Several studies on larger engines have reported a trade-off between smaller and larger particles. In this study, AFR was independently varied over the entire engine map of a naturally aspirated (NA) non-road small diesel engine using forced induction (FI) of externally compressed air. AFR's ranged from 57 to 239 compared to the design range of 23-92 for the engine, including unusually high AFR's at full-load operation, not previously reported for conventional combustion. As expected, larger accumulation mode particles were lowered (up to 15 times) for FI operation. However, the smaller nucleation mode nanoparticles increased up to 15 times. Accumulation mode particles stopped decreasing above an AFR threshold while nucleation particles continuously increased. In-cylinder combustion analysis showed a slightly smaller ignition delay and higher burn rate for FI cases relative to NA operation. Much higher peak cylinder pressures were accompanied by much lower combustion and exhaust gas temperatures (EGT), due to higher in-cylinder mass during FI operation. Peak nucleation mode emissions were shown to be negatively correlated to EGT for all the data, collapsing on a single curve. This is consistent with some other studies reporting increased nucleation mode emissions (and higher accumulation mode particles) with decreased load, lower speed, lower EGR, advanced combustion phasing, and higher injection pressure, all of which reduce EGT. The nucleation-accumulation trade-off has been explained by the 'adsorption hypothesis' by some investigators. In the current work, an alternative/supplemental argument has been made for the possibility that lower cylinder temperatures during the late-burning phase (correlated to lower EGT) phase hampers oxidation of nucleation mode particles and increases nucleation mode emissions.

Effect of primary hole parameters on combustor performance within a slinger combustor

This study experimentally investigated the effect of the primary hole on combustor performance in a full annular slinger combustor and verified it by numerical simulation. Six primary hole structure parameters, including different numbers (0, 2, 4, 6) and positions (L/L0, 2/3L/L0, 1/3L/L0), were studied to discuss the trending of total pressure loss, ignition limits, combustion efficiency, and outlet temperature profiles, where the experiment conditions included Mach number, inlet temperature, and fuel–air ratio (FAR). Results show that when the primary hole number decreases, the total pressure loss increases, and combustion efficiency increases to a certain FAR and then drops. Successful ignition FAR and outlet temperature profiles change complicatedly, in which the trend is not consistent with the primary hole number. When L/L0 decreases, ignition limits increase, combustion efficiency drops, and outlet temperature distribution fluctuates along the circumferential direction. Numerical simulation was applied to analyse the universal impact mechanism, which proved that the primary hole parameters impact not only the airflow distribution and jet velocity but also the flow field features. A high FAR or good recirculation zone does not always lead to good performances; the compromise between aerodynamics parameters and structure characteristics determines the combustor performance.

Investigation of the chemical effect of pilot injection on main combustion in a gasoline controlled auto-ignition engine by in-cylinder measurements and numerical simulation of H2O2, HO2, and OH radicals

Compared to conventional combustion in gasoline engines, Gasoline Controlled Auto-Ignition (GCAI) has the potential to significantly reduce both fuel consumption and nitrogen oxides (NOX) raw emissions. However, GCAI combustion still has a limited operating range due to limitations in combustion stability at low loads and high rates of cylinder pressure rise at high engine loads. Previous research identified hydrogen peroxide (H2O2) decomposition as an effective means to control GCAI, which is formed among other species with pilot fuel injection during the negative valve overlap (NVO) phase. Since the chemical effect of H2O2 on the main combustion has not been experimentally confirmed so far, the aim of the experimental study described in this paper is to detect H2O2 during early compression using optical methods. This is approached by conducting Photofragmentation Laser-Induced Fluorescence (PFLIF) of H2O2 by a pump laser and simultaneous hydroxyl radical Laser-Induced Fluorescence (OH-LIF) detection in the combustion chamber of a dedicated GCAI single-cylinder research engine at low loads after NVO with pilot injection (PI). Thereto, the pilot injection strategy as well as the global air/fuel ratio (AFR) are varied. Interestingly, no H2O2, hydroxyl (OH) or hydroperoxyl (HO2) constituents were detected under the operating conditions studied, despite relatively high pilot injection fuel masses and a highly accurate H2O2 detection limit of about 1 ppm. Numerical three-dimensional computational fluid dynamics (3D-CFD) combustion simulations using a semi-detailed reaction kinetic mechanism predicted 5–8 times higher H2O2 concentrations than the detection limit, yielding an uncertainty estimate of the numerical methods. Furthermore, the 3D-CFD simulations showed a significant mixture stratification which is a possible reason for the lack of H2O2 detection under these operating conditions.

Combustion, emissions, and performance of natural gas–ammonia dual-fuel spark-ignited engine at full-load condition

In the present study, the full load performance and emission characteristics of natural gas-ammonia dual fuel engine were investigated using the experimental methodologies with three approaches. An 11–l, 6-cylinder turbocharged natural gas engine was used in the experiments and combustion parameters, such as the energy fraction of ammonia, the air-fuel ratio, and the ignition timing, were varied to assess the effect of the introduction of ammonia as a fuel. The experiments are conducted at 1100 rpm and 1000 Nm of brake toque, which is representing the maximum torque. The effect of volumetric fuel flow rate is examined in the consideration of using a certain fuel supply system. A constant flow rate of the intake air condition was evaluated under a maximum brake torque operation condition. Lastly, the thermal efficiency and exhaust gas emissions were observed with varying the air-fuel ratio at 15% of ammonia energy fraction. The experimental results showed that using the existing fuel supply system could not secure the required brake torque and the insufficient time for the complete combustion of natural gas-ammonia mixture resulted in the increase in instability and unburned fuel of combustion. Fuel NOx was dominant of NOx emissions with the introduction of ammonia.

Bioenergy potential of millet chaff via thermogravimetric analysis and combustion process simulation using Aspen Plus

Millet chaff constitutes one of the most abundant agro-residues in the sub-Saharan Africa and its utilisation as a feedstock in developing sustainable bioenergy solutions is very sketchy. This study presents the first comprehensive physicochemical and combustion characteristics of millet chaff via thermogravimetric analysis and process simulation using Aspen Plus. The millet chaff sample was collected and assessed as received for proximate and ultimate analyses. The results showed the biomass has 71.25 wt%, 15.35 wt%, 13.40 wt% and 13.15 MJ/kg for volatile matter, fixed-carbon, ash content and higher heating value respectively. The material consists of low nitrogen and sulphur content with potassium, aluminium, magnesium, calcium, iron and sodium as the inorganic components. Kinetic study using distributed activation energy model (DAEM) revealed an average frequency factor and activation energy of 1.41 × 1018(s−1) and 149.39 kJ/mol. Ignition and burnout temperature in the range of 232-244°C and 430-489°C were recorded. The average combustion thermodynamic parameters; ΔH, ΔG and ΔS were found to be 144.75 kJ/mol, 167.12 kJ/mol and -40.08 J/mol. The combustion process analysis coupled with steam turbine cycle via process simulation revealed an excellent combustion efficiency at air-fuel ratio of 5.14. (stoichiometric air). The power generation and electric efficiency of 0.7kWh/kg and 21.07% respectively were recorded at 24% excess air with minimal environmental impacts. This suggests that millet chaff is a good biomass feedstock suitable for clean bioenergy production.

Numerical Investigation on the Performance of a 4-Stroke Engine with Different Passive Pre-Chamber Geometries Using a Detailed Chemistry Solver

Pre-chamber turbulent jet ignition represents one of the most promising techniques to improve spark ignition engines efficiency and reduce pollutant emissions. This technique consists of igniting the air-fuel mixture in the main combustion chamber by means of several hot turbulent flame jets exiting a pre-chamber. In the present study, the combustion process of a 4-stroke, gasoline SI, PFI engine equipped with a passive pre-chamber has been investigated through three-dimensional CFD (Computational Fluid Dynamics) analysis. A detailed chemistry solver with a reduced reaction mechanism was employed to investigate ignition and flame propagation phenomena. Firstly, the combustion model was validated against experimental data for the baseline engine configuration (i.e., without pre-chamber). Eventually, the validated numerical model allowed for predictive simulations of the pre-chamber-equipped engine. By varying the shape of the pre-chamber body and the size of pre-chamber orifices, different pre-chamber configurations were studied. The influence of the geometrical features on the duration of the combustion process and the pressure trends inside both the pre-chamber and main chamber was assessed and discussed. Since the use of a pre-chamber can extend the air-fuel mixture ignition limits, an additional sensitivity on the air-fuel ratio was carried out, in order to investigate engine performance at lean conditions.

PENGOLAHAN MINYAK JELANTAH SEBAGAI PENGGANTI BAHAN BAKAR MINYAK PADA KOMPOR MINYAK BERTEKANAN

Used cooking oil (Jelantah's oil) is a frying rest oil which can't be used again to fry because it contains compounds that are quite dangerous for human health, which can be destructive for humans healthy. Beside to reduce an ambient contamination, used cooking oil can be recycled as an alternative fuel, in this case as to replace kerosene. The purpose of this study was to determine the effect of the primary Air Fuel Ratio on the combustion process in pressurized stove oil and knowing whether or not the direct combustion process of used cooking oil as an alternative fuel. The filth on used cooking oil must be removed to avoid a streaming gagging on koil. Analyzing used cooking oil water rate. Fuel tank loaded with used cooking oil. Fill the compressor with an air to pressurize the fuel tank. Used cooking oil streamed inside the tank by manages flow rate then stream air with regulatory crane so up to scale which particular on flowmeter gases. Ruled air flow rate with scales regulatory crane flowmeter until up to stable state on appreciative given. Measuring temperature on burn tool with positioning different one (Spuyer, burner, burner's tip, kindled tip). The larger the primary Air Fuel Ratio, the better the mixing so that the total conversion of triglycerides into CO2 and CO products is greater. Used cooking oil may be directly used as an alternative fuel into an oil stove, especially pressured oil stove.

Optical investigation and thermodynamic analysis of premixed ammonia dual-fuel combustion initiated by dodecane pilot fuel

In view of reducing greenhouse gas emissions the transition from fossils fuels to sustainable energy carriers is a prerequisite to keep global warming within tolerable limits. Since IC engines will continue to play a role in global energy strategies during a transitional phase, especially for large engine applications difficult to electrify, the use of ammonia as substitute fuel may be an approach for decarbonization. However, its utilization needs research since ignition concepts and combustion properties still pose considerable challenges in view of reliable and efficient operation. A new "optical engine" test facility ("Flex-OeCoS") has been successfully adapted enabling dodecane pilot fuel ignited premixed ammonia dual-fuel combustion investigations. It features IC engine relevant operation conditions such as pressures, temperatures, and flow (turbulence) conditions as well as adjustable mixture charge composition and pilot fuel injection settings. In parallel, thermodynamic heat release analysis in terms of ignition and combustion characteristics was performed. Simultaneously applied high-speed Schlieren/OH* chemiluminescence measurements supported the examination of the combustion process. Initially premixed ammonia dual fuel combustion has been compared to a representative methane combustion process in terms of different gas properties (lower heating value, air-fuel ratio) which illustrates its lower reactivity affecting heat release and flame propagation. Moreover, ignition delay, combustion transition, and turbulent flame propagation as well as heat release characteristics have been investigated for premixed ammonia dual-fuel combustion within variation of air-fuel equivalence ratio, start of pilot fuel injection, and pressure/temperature operation conditions. The results illustrate strong dependency on air-fuel equivalence ratio (energy content) and temperature conditions in terms of ignition delay, dual-fuel combustion transition, and corresponding heat release. The optical investigations confirm the thermodynamic analysis and promote assessment of pilot fuel evaporation, ignition, combustion transition, and flame propagation. Conclusions give extended insight into the thermo-chemical processes of ammonia pilot fuel ignited dual-fuel combustion. The acquired data may also support further development of numerical CRFD methods.

Genetic algorithm based active fault-tolerant control system for air fuel ratio control of internal combustion engines

Internal Combustion (IC) engines are commonly used in the process industry, and proper Air-Fuel Ratio (AFR) regulation in their fuel system is essential for improved engine performance, fuel efficiency, and environmental protection. Since faults in the sensors of the AFR system cause the engine to shut down, fault tolerance is essentially required for them. In this paper, an advanced Active Fault-Tolerant Control System (AFTCS) for AFR control of an IC engine is proposed to prevent the engine shutdown. For analytical redundancy, the proposed AFTCS uses the Genetic Algorithm (GA) based observer model in the Fault Detection and Isolation (FDI) unit to generate estimated value for the faulty sensors using the values of other healthy sensors. The proposed framework was simulated in the MATLAB/Simulink environment to verify its effectiveness. In comparison to previous literature works, the results show that the AFR control system has superior fault tolerance output for sensor faults, especially for the MAP sensor, in terms of less oscillatory response. Finally, a comparison of the proposed GA-based AFTCS was carried out with the existing literature works and its superior performance was elaborated.

Environmental control of the technical condition of electromagnetic nozzles of internal combustion engines

Harmful motor vehicle emissions are often the primary source of urban air pollution worldwide. Incorrectly serviced high-mileage motor vehicles emit significantly more harmful substances into the atmosphere than established by accepted standards. This paper presents an algorithm for the process of diagnostics and analysis of the technical condition of the fuel supply system elements for internal combustion engines (ICE) by means of selective sampling of exhaust gases. A gas analyzer system allows for the simultaneous monitoring of the 4 components of exhaust gases: CO, CH, O2 and CO2, assessment of the air-fuel ratio and internal combustion engine crankshaft rotation speed. Studies were carried out on an engine and a series of malfunctions were created artificially, by means of installing faulty elements and additional elements simulating different degrees of wear on the ICE systems. The study resulted in the development of a method and a hardware and software system. These allow for the test regimes to be established, in order to determine the failure of ICE systems which affect the composition of the exhaust gas.

Computational assessment of effects of throat diameter on combustion and turbulence characteristics in a pre-chamber engine

Towards fundamental investigation of key physical aspects of pre-chamber combustion, the current work utilizes computational fluid dynamics to comprehend the effect of the throat diameter in an engine operated with methane. Previous studies showed that this parameter is dominant in pressure build-up and flow pattern inside the pre-chamber, suggesting that a detailed characterization is necessary. This pre-chamber type is composed of an upper conical part that lodges the spark plug and fuel injector, followed by a straight and tubular region called throat, which tip accommodates the nozzles responsible for the charge exchange between pre and main chambers. Two types of pre-chamber having distinct throat diameters are investigated, while utilizing consistent experimental data for validation of the model. The combustion process is modeled with the G-Equation model; the laminar flame speed was tabulated from a methane oxidation mechanism reduced from the GRI 3.0; the turbulent flame speed was computed using Peters' relation. The simulations were run for a full cycle, starting at exhaust valve opening. A homogeneous charge of methane is considered at the intake port, maintaining a global λ = 1.8, while 3% of total energy fuel is added through the pre-chamber. The results show that the throat changes the flow field inside the pre-chamber, impacts the air-fuel ratio, stratification, turbulence, jet dynamics, and ultimately the pre and main chambers combustion processes and heat fluxes. The combustion regime according to the Borghi-Peters diagram were found to lay in the thin reaction zone and in the flamelet regime.

Effects of intake charge temperature and relative air-fuel ratio on the deterministic characteristics of cyclic combustion dynamics of a HCCI engine

Homogenous charge compression ignition (HCCI) combustion can significantly reduce automotive pollution and increase the thermal efficiency of the engine. However, combustion phasing control is a major challenge in HCCI engines due to severe cyclic combustion variations. This study investigates the cyclic combustion dynamics of the HCCI engine using nonlinear dynamic methods such as return maps, recurrence plots (RPs), and recurrence quantitative analysis (RQA). Combustion stability and cyclic variations of HCCI combustion parameters were investigated on a modified four-stroke diesel engine. The experiments were conducted by varying relative air-fuel ratios ([Formula: see text]) and intake air temperatures ([Formula: see text]) at two engine speeds. In-cylinder pressure data of 2000 consecutive engine combustion cycles is logged for each test condition. In this study, deterministic characteristics of combustion phasing (CA50) and crank angle position of maximum cylinder pressure ([Formula: see text]) are investigated and compared by employing nonlinear dynamical methods. Return maps revealed that [Formula: see text] is having distinct and more frequently observed deterministic characteristics in comparison to CA50. Patterns in RPs showed a more persistent and sudden change in the combustion dynamics at higher engine speeds. Recurrence plot-based analysis found the existence of deterministic features in the combustion dynamics irrespective of the operating conditions. It was found using RQA parameters that the deterministic nature becomes stronger with a decrease in [Formula: see text] and any deviation in intermediate values of [Formula: see text]. Additionally, RQA measures advocate that CA50 has more deterministic characteristics at higher engine speed while [Formula: see text] at lower engine speed. Strong coupling and synchronization between [Formula: see text] and CA50 is indicated by cross-recurrence plots and CPR index when engine operated with a comparatively richer mixture.

Study on the Simplification Calculation Model of Marine Diesel Engine Exhaust Flow Based on Air-Fuel Ratio

Because of the large discharge of marine diesel engines, direct measurement is difficult and complicated. In order to obtain accurate data of marine diesel engine exhaust flow, the carbon balance method is generally used for calculation, but the carbon balance method has iterative operation, adopts wet concentration calculation, and does not consider sulfur oxide components, thus resulting in errors in the calculation results. In this paper, according to the calculation model of air-fuel ratio proposed by S H Chan, the law of conservation of C, H, and O atoms is observed, sulfur oxides in the exhaust are considered, and a new exhaust flow calculation model based on air-fuel ratio is obtained. This calculation model is the first to directly use dry gas concentration in the calculation model of air-fuel ratio. Then, the simplified calculation model is obtained by ignoring CO and simplifying coefficient A ∗ , the difference between the carbon balance method, ignoring CO, and the simplified model is compared, and then the exhaust flow value and exhaust density are calculated by the test data. The simplified calculation model can also calculate the mass flow rate of carbon dioxide, unburned hydrocarbon, and carbon monoxide. Finally, a software program is developed for the simplified calculation model, which is convenient for quick calculation and quick acquisition of exhaust flow data, thus laying a solid foundation for the application of the simplified calculation model in real ships.

Effect of Air Fuel Ratio to Quality of Municipal Solid Waste Using Downdraft Gasification

Gasifikasi menggunakan limbah padat kota (MSW) berdampak pada peningkatan kualitas lingkungan dan peningkatan pasokan listrik untuk daerah-daerah yang sulit dijangkau, khususnya di Indonesia. Namun proses gasifikasi membutuhkan proses pengujian kualitas terlebih dahulu agar dapat menghasilkan produk syngas dan kelistrikan yang maksimal. Maka dalam penelitian ini dilakukan proses pengujian pengaruh variasi Air Fuel Ratio (AFR) terhadap kualitas proses gasifikasi (Cold Gas Efficiency (CGE), Carbon Conversion Efficiency (CCE), dan specific fuel consumption (sfc) atau konversi konsumsi spesifik). Penelitian dilakukan dengan melakukan proses gasifikasi dengan tipe downdraft pada nilai AFR 0,5; 0,51; 0,53; 0,54; 0,55. Hasil penelitian ini menunjukkan adanya peningkatan nilai syngas seiring dengan peningkatan nilai AFR. Sedangkan nilai CGE meningkat seiring dengan meningkatnya AFR proses gasifikasi MSW. Peningkatan terjadi dari 9 menjadi 13%, meskipun hasil ini masih sangat rendah. Di sisi lain, CCE juga mengalami peningkatan dengan meningkatnya AFR gasifikasi MSW. Peningkatan nilai terlihat dari 33-43%. Hasil ini juga masih tergolong kecil, artinya efisiensi konversi karbon pada proses ini sangat rendah. Pada akhirnya, dapat dilihat bahwa nilai scf menurun dengan meningkatnya AFR. Penurunan yang didapat adalah dari 5,3 menjadi 2.