Search

In order to maximum reduction in hydrocarbon fuels consumption as the largest source of greenhouse gas emissions, the aim of this study is to evaluate a RCCI engine performance fueled with diesel fuel and pure hydrogen as sole low reactive fuel. For this purpose, a single-cylinder heavy-duty diesel engine with bathtub piston bowl profile and compression ratio of 14.88:1 is assessed that operates at its mid-load range from 9.4 to 13.5 bar gross IMEPs. In order to overcome the NOx challenge resulted from using pure hydrogen, the use of suitable amount of EGR and nitrogen addition as air-hydrogen diluents along with the advanced SOI timing were employed. The simulation results show that in a hydrogen-fueled RCCI engine, while reducing the diesel fuel energy share as the only supplier of air-hydrogen mixture ignition energy to about 13%, the HES percentage can be enhanced up to 87%. Although, the SOC will occur with a long delay and the CA50 will take place about 15°CA after the TDC compared to the experimental data, however, the maximum loss of the engine load is less than 6% with the GIE of more than 48% without any exposure to diesel knock. Moreover, not only the EURO VI level of the CO and UHC emissions and the EPA level of Formaldehyde emission can be met, but also, the EURO VI level of NOx emission as the most important challenge of a hydrogen-fueled engine is achievable.

Direct Dual Fuel Stratification (DDFS) strategy is a novel Low Temperature Combustion (LTC) strategy that has comparable thermal efficiency to the Reactivity Controlled Compression Ignition (RCCI) strategy, while it offers more control over the combustion process and the rate of heat release. The DDFS strategy uses two direct injectors for the low- and high-reactivity fuels (gasoline and diesel) to benefit from the RCCI concept. In this study, the injection strategy of the injectors of a gasoline/diesel DDFS engine was optimized from the thermodynamic perspective to maximize exergy efficiency and minimize exergy destruction and an engine noise index. An artificial neural network was developed with 576 samples from a CFD code to predict the DDFS mode behavior, and the non-dominated sorting genetic algorithm (NSGA-II) was used to obtain the Pareto Front and the optimal solutions. Compared to the base case, the exergy efficiency of the optimal cases increased by up to 2%, exergy destruction and Peak Pressure Rise Rate (PPRR) reduced by about 2.3%, and 2 bar/deg, respectively, in the optimal solutions. NOX and soot emissions were reduced by 40% and 35%, respectively, in the best-case scenarios.

A detailed investigation of employing landfill gas together with additives such as hydrogen or propane or both as a primary low reactivity fuel in a reactivity controlled compression ignition combustion of a diesel engine is conducted. A 3401E caterpillar single-cylinder diesel engine with a bathtub piston bowl profile is utilized to execute the study. The engine is operated at various intake pressures of 1.6, 1.9, and 2.2 bar, and runs at a fixed engine speed of 1300 rpm. For verification purposes, the conduct of the present engine running on pure methane as a low reactivity fuel is compared to that of the same engine available in the literature. Next, a numerical simulation is made to assess the performance of the present engine running on landfill gas plus the additives. Based on the obtained results, injecting either hydrogen or propane or a combination of both up to a total amount of 10% by volume to the premixed of landfill gas and air, and advancing diesel fuel injection timing of about 20–30 deg. crank angle, render the landfill gas utilization quite competitive with using methane alone. Applying an enriched landfill gas in a reactivity controlled compression ignition diesel engine, as a power generator, drastically reduces the greenhouse gas emission to the atmosphere. Also, the CO and UHC mole fraction in the exhaust gas can be eliminated by either advancing the start of diesel injection or using hydrogen or propane or both as additives. In addition, utilizing hydrogen or propane or a combination of both with the primary fuel improves the peak pressure to about 16% in comparison with that of landfill gas alone.

Reactivity-controlled compression ignition (RCCI) engines have been introduced as a promising alternative to compression ignition engines, especially in reducing emissions. It is common practice in an RCCI engine to use two fuels with distinctly different reactivity to control the combustion process. Also, abundant biogas fuel could be considered as a potential and suitable alternative to conventional fuels. Biogas can easily be derived from renewable resources and is basically composed of methane (CH4), carbon dioxide (CO2), a small amount of hydrogen (H2), nitrogen (N2), oxygen (O2) and hydrogen sulfide (H2S). In this paper, biogas as an alternative fuel together with diesel oil is used for reactivity-controlled compression ignition in a modified heavy-duty engine. The biogas fuel with low reactivity is fed through the inlet port and diesel oil with high reactivity directly injected into the engine cylinder. Then, a detailed study of biogas composition, engine speed, intake temperature, fuel metering and injection strategies on combustion characteristics such as engine efficiency and emission levels is carried out. It is demonstrated that the amount of CO2 in biogas composition plays a significant role in combustion and emission processes. Typically, at IMEP = 9.4 bar, as the amount of CO2 in biogas composition is changed from 0 to 40%, the maximum in-cylinder temperature and pressure are reduced about 143 K and 4.6 bar, respectively, while NOx emission is reduced drastically by 75%.

The aim of this study is to enhance hydrogen energy share in a RCCI engine. The engine under consideration is fueled with diesel oil and natural gas enriched with hydrogen or syngas and is set to operate at 9.4 bar gross indicated mean effective pressure (Mid- Load). The syngas used in this study consists of hydrogen and carbon monoxide which are mixed together on a volumetric ratio of 80:20. A fixed amount of diesel oil is injected per cycle into the combustion chamber of the RCCI engine. Based on two different strategies, hydrogen or syngas mixed with exhaust gas recirculation are admitted gradually along with natural gas while ensuring that always the low temperature combustion concept is fulfilled. The RCCI engine operation is simulated through commercial software coupled with chemical kinetics solver. The simulation results show that without any engine diesel knock occurrence, by adding hydrogen to natural gas, the share of hydrogen energy could be increased up to 40.43% while the engine power output is reduced only by about 1%. Also, syngas addition to natural gas causes that the share of hydrogen energy could be increased up to 27.05% while improves the engine power more than 4%. At the same time, by considering two mentioned strategies, the overall hydrocarbon fuel consumption per cycle can be reduced by up to 46.60% and 33.86%, respectively. Moreover, having the gross indicated efficiency of well over 50% and significant reduction in the engine emissions compared to RCCI combustion fueled solely with natural gas and diesel oil are achievable.

Despite the potential benefits of the Homogenous Charge Compression Ignition (HCCI) engines, controlling the combustion phasing and emissions are the main obstacles in its development but, in conventional engines the load demand is simply controlled by accelerator. The aim of present work is developing a HCCI engine controller which controls its main parameter similar to conventional engine: controlling the combustion phasing based on load demand. In the present study, A Multi-Input Multi-Output (MIMO) controller has been designed and validated which is used to control HCCI engine main parameters such as: optimum combustion phasing, engine load and minimum emissions. Similar to conventional IC engine the controller is capable of tracking all desired set-points solely by means of load demand as the only reference trajectory. A physic-based control model together with application of Artificial Neural Networks (ANN) is developed to predict the optimum combustion phasing with minimum emissions based on load demand. The results of proposed model are validated with the experimental data for steady state and transient cases. The optimal CA50 is selected based on minimizing the emissions using a multi-zone kinetic coupled with a genetic algorithm. The developed controller performance has been tested thoroughly to evaluate the tracking and disturbance rejection capabilities. Results show that it is capable of rejecting the disturbances for fix engine loads. The controller is quick to reject the disturbances within 3–5 engine cycles, while deviations within 0.04 bar, 0.5CAD and 0.03 for IMEP, CA50 and emissions respectively.

By using two types of different fuels and changing the ratios of these fuels, Reactivity Controlled Compression Ignition Engine (RCCI) is able to provide a more effective control over combustion phase at different loads and speeds. In a typical RCCI engine which could be considered as a type of homogeneous charge compression ignition (HCCI) engine, a low reactive fuel is injected into the intake port and a high reactive fuel is directly injected into the combustion chamber. In this study, a multi-dimensional model coupled with chemical mechanism is developed to simulate an RCCI engine operation fueled with iso-octane as the low reactive fuel and n-heptane as the high reactive one. Initially, the engine map was derived using different quantities of total above-mentioned fuels at different ratios and then engine inappropriate operating points were detected and improved by changing intake air pressure and injection timing strategies. The improved criteria to extend engine map are ringing intensity limit, NOx formation standard and gross indicated efficiency. It was concluded that high ringing intensity and NOx formation can be reduced by increasing intake air pressure; also badfire and misfire points can get improved by retarding the injection timing.

In this paper, various fuels with different reactivities were implemented as a strategy to optimize the heat release rate which could be a dominant combustion controller in an internal combustion engine. Using a blend of ethanol and gasoline fuels is one of the best approaches to decrease heat release rate, as well as prolonging combustion duration and retarding combustion phasing. Application of ethanol fuel, however, may lead to misfire and unstable combustion in reactivity controlled compression ignition engines. A multi-dimensional model coupled with a detailed chemical kinetic mechanism was applied to investigate the effects of single and double injections within misfire zones in a research engine using iso-octane, n-heptane, and ethanol fuels. A parametric approach is employed to analyze the engine model behavior through varying energy fraction of fuels through both single and double injections strategies. Three performance maps of engine at varying total fuel energy with different ratios of the port to direct fuel injections have been simulated. The first map is related to using net iso-octane and n-heptane fuels; the other two maps are related to the use of 20% and 40% ethanol fuels instead of net iso-octane fuel, respectively. The results highlight that double injection strategy with the injection timing between 27° and 47° before top dead center is capable of improving misfire points also effective on reducing both nitrogen oxide formation and ringing intensity, as well as improving engine gross indicated efficiency.

The aim of this study is to investigate the effects of hydrogen addition on RCCI combustion of an engine running on landfill gas and diesel oil. A single cylinder heavy– duty diesel engine is set in operation at 9.4 bar IMEP. A certain amount of diesel fuel per cycle is fed into the engine and hydrogen is added to landfill gas while keeping fixed fuel energy content. The developed simulation results confirm that hydrogen addition which is the most environmental friendly fuel causes the fuel consumption per any cycle to reduce. Also, the peak pressure is increased while the engine load is reduced up to 4%. Landfill gas which is enriched with hydrogen improves the rate of methane dissociation and reduces the combustion duration at the same time the engine operation would not be exposed to diesel knock. Moreover, hydrogen addition to landfill gas would reduce engine emissions considerably.

The aim of this study is to implement the multi-input–multi-output optimization of reactivity-controlled compression-ignition combustion in a heavy-duty diesel engine running on natural gas and diesel fuel. A single-cylinder heavy-duty diesel engine with a modified bathtub piston bowl profile is set on operation at 9.4 bar indicated mean effective pressure and running at a fixed engine speed of 1300 r/min. A certain amount of diesel fuel mass per cycle is fed into the engine at a fixed equivalence ratio without any exhaust gas recirculation. The optimization targets include reduction in engine emissions as much as possible, avoiding diesel knock occurrence, and achieving low temperature combustion concept with the least or no engine power losses. To implement the optimization, the effects of three control factors on the engine performance are assessed by the design of experiment concept—fractional factorial method. These selected control factors are intake temperature and intake pressure (both at intake valve closing) and the diesel fuel start of injection timing. Some randomized treatment combinations of chosen levels from the three selected control factors are employed to simulate reactivity-controlled compression-ignition combustion. Based on the engine’s responses derived from the simulation, reactivity-controlled compression-ignition combustion’s mathematical model is identified directly using an artificial neural network. Next, an optimization process is conducted using two different optimization algorithms, namely, genetic algorithm and particle swarm optimization algorithm. For assessing and validating the obtained optimal results, the obtained data are used to simulate reactivity-controlled compression-ignition combustion as the engine input factors. The results show that the proposed artificial neural network design is effectively capable of identifying reactivity-controlled compression-ignition combustion’s mathematical model. Also, by optimizing reactivity-controlled compression-ignition combustion through different optimization algorithms, the optimal range of the engine operation at 9.4 bar indicated mean effective pressure is well estimated and extended.

Introduction Non-alcoholic fatty liver disease (NAFLD) is one of the main causes of chronic liver disease worldwide. Flavonoids, a group of natural compounds, have garnered a great deal of attention in the management of NAFLD because of their profitable effects on glucose and lipid metabolism, inflammation, and oxidative stress which are the pivotal pathophysiological pathways in NAFLD. Naringenin is a citrus-derived flavonoid with a broad spectrum of potential biological effects including anti-inflammatory and antioxidant properties, which may exert protective effects against NAFLD. The present clinical trial aims to examine the efficacy of naringenin supplementation on plasma adiponectin and neurogulin-4 (NRG-4) concentrations, metabolic parameters, and liver function indices in overweight/obese patients with NAFLD. Methods and analysis This is a double-blind, randomized, placebo-controlled clinical study that will investigate the impacts of naringenin supplementation in overweight/obese patients with NAFLD. Liver ultrasonography will be applied to diagnose NAFLD. Forty-four eligible overweight/obese subjects with NAFLD will be selected and randomly assigned to receive naringenin capsules or identical placebo (each capsule contains 100 mg of naringenin or cellulose), twice daily for 4 weeks. Participants will be asked to remain on their usual diet and physical activity. Safety of naringenin supplementation was confirmed by the study pharmacist. The primary outcome of this study is changes in adiponectin circulating levels. The secondary outcomes include changes in NRG-4 levels, liver function indices, metabolic parameters, body weight, body mass index (BMI), waist circumference (WC), blood pressure, and hematological parameters. Statistical analysis will be conducted using the SPSS software (version 25), and P value less than 0.05 will be regarded as statistically significant. Discussion We hypothesize that naringenin administration may be useful for treating NAFLD by modulating energy balance, glucose and lipid metabolism, oxidative stress, and inflammation through different mechanisms. The current trial will exhibit the effects of naringenin, whether negative or positive, on NAFLD status. Ethical aspects The current trial received approval from the Medical Ethics Committee of Tehran University of Medical Sciences, Tehran, Iran (IR.TUMS.MEDICNE.REC.1399.439). Trial registration Iranian Registry of Clinical Trials IRCT201311250155336N12. Registered on 6 June 2020

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the hepatic component of metabolic syndrome. Despite the beneficial health effects of cardamom on dyslipidemia, hepatomegaly, and fasting hyperglycemia, no previous human study has been conducted on the efficacy of cardamom in NAFLD. The aim of this study was to assess the effects of green cardamom (GC) on serum Sirtuin-1 (Sirt1), inflammatory factors, and liver enzymes in overweight or obese NAFLD patients. METHODS: The recruitment of subjects was conducted at the polyclinic of the central hospital of National Iranian Oil Company (NIOC), Tehran. Eighty-seven patients who participated were divided randomly into two groups according to the ultrasonography and eligibility criteria as cardamom (n = 43) or placebo (n = 44). The intervention involves taking two 500 mg capsules three times per day with meals for 3 months. General characteristics, dietary intake and physical activity status, weight and height were determined. In addition, serum Sirt1, tumor necrosis factor-alpha (TNF-α), high sensitive c-reactive protein (hs-CRP), interleukin-6 (IL-6), alanine transaminase (ALT), and aspartate transaminase (AST) were measured. The degree of fatty liver was determined at beginning and end of the study. RESULTS: In comparison with placebo, GC significantly increased Sirt1 and decreased hs-CRP, TNF-α, IL-6, ALT, and the degree of fatty liver (P 0.05). CONCLUSION: GC supplementation could improve some biomarkers related to fatty liver including inflammation, ALT, and Sirt1 in overweight/obese NAFLD patients. Further trials on cardamom’s potential are suggested. TRIAL REGISTRATION: Iranian Registry of Clinical Trials, IRCT2015121317254N4. Registered 27/12/2015.

The potential benefits of Homogenous Charge Compression Ignition (HCCI) engines are higher thermal efficiency, lower Nitrogen Oxides (NOx) and Particulate Matter (PM) emissions in contrast with conventional engines. This mode of combustion faces its own set of challenges, such as lack of a direct means to control timing initiation of combustion together with higher unburned hydrocarbon and Carbon Monoxide emissions. In the present study, a multi-zone thermo-kinetic model developed to investigate the HCCI engine performance and to predict its emissions. In addition, to determine the optimal HCCI combustion phasing, a grey-box control model used to predict major variables. In order to optimize conditions for higher thermal efficiency and lower emissions, the thermo-kinetic model coupled with a Genetic Algorithm. The octane number and equivalence ratio are two qualitative parameters, which determine the optimal conditions. The grey-box model consists of a combination of physical models and Artificial Neural Networks (ANN) models. The steady state and transient validations show that the grey-box model is capable of predicting HCCI engine outputs including combustion phasing, load, THC, CO emissions. By means of coupling the GA and thermos-kinetic model, the optimal engine operating conditions can be derived without the use of test results. The validation results show that the grey-box model is able to predict CA50, IMEP, CO and THC with the average errors of 1.2 CAD, 0.4 bar, 10 PPM, 0.8%, and 394 PPM, respectively.

In this paper, a detailed multi-dimensional simulation based on fuel chemical reactions has been presented to investigate the effects of the most important parameters on performance and emission of a reactivity controlled compression ignition (RCCI) engine. The different characteristics of combustion phasing such as start of combustion, combustion duration, and 10%–90% of mass fraction burned (MFB) for iso-octane/n-heptane fuels have been studied. The effects of each important parameter such as amount of fuel delivered by varying fuels ratio, engine load and speed, injection timing, equivalence ratio, exhaust gas recirculation (EGR) application, boost pressure, injection pressure as well as combination of these different parameters and improved fuel octane number at higher compression ratios were evaluated to discover the most effective parameter on performance and emission of an RCCI engine. Distribution and coefficient of variation (COV) of equivalence ratio were examined in base cases to evaluate the influence of high reactivity fuel on distribution points. In addition, to acquiring a comprehensive perception, the results highlighted that by concurrently applying different parameters with diverse effects, new corridors to significantly abate nitrogen oxides (NO x ) pollutant can be achievable depending on the specific situations. Generally, the parameters that prolong the combustion duration demonstrated positive effects on combustion process leading to cleaner combustion with lower engine-out NO x .

The aim of this study is to investigate in details the effects of a number of combustion parameters to optimize the reactivity controlled compression ignition operation running on natural gas and diesel fuel. In the present work, a single-cylinder heavy-duty diesel engine with a specially modified bathtub piston bowl profile for reactivity controlled compression ignition operation is studied and simulated through commercial software. A broad load range from 5.6 to 13.5 bar indicated mean effective pressure at a constant engine speed of 1300 r/min, fixed amount of diesel fuel mass, and with no exhaust gas recirculation is considered. The results from the developed model confirm that the model can accurately simulate the reactivity controlled compression ignition combustion. Also, by focusing on the time of formation of certain important radicals in combustion, the start of combustion and the time of natural gas dissociation are accurately predicted. Furthermore, the influence of some parameters such as different diesel fuel injection strategies, intake temperature, and intake pressure on the reactivity controlled compression ignition combustion is evaluated and the limitation of the engine operation at low temperature combustion is investigated.

Background Despite the reported health effects of cardamom on dyslipidemia, hepatomegaly, and fasting hyperglycemia, no human research has studied its potency in non-alcoholic fatty liver disease (NAFLD) as the hepatic part of metabolic syndrome. Our aim was determining the effects of green cardamom (GC) on serum glucose indices, lipids, and irisin level among overweight or obese NAFLD patients. Methods The place of participant recruitment was the polyclinic of the National Iranian Oil Company (NIOC) central hospital in Tehran. Based on the ultrasonography and eligibility criteria, 87 participants were randomly divided into two groups as cardamom (n = 43) or placebo (n = 44). The supplementation was two 500 mg capsules 3 times/day with meals for 3 months. Serum irisin, fasting blood sugar (FBS), insulin (FBI), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) were measured. Quantitative insulin sensitivity check index (QUICKI) and homeostasis model assessment-insulin resistance (HOMA-IR) were also calculated. Results In comparison with placebo, GC significantly increased irisin, HDL-c, and QUICKI and decreased FBI, TG, LDL-c, HOMA-IR, and the grade of fatty liver (P 0.05). Conclusion GC supplement improved the grade of fatty liver, serum glucose indices, lipids, and irisin level among overweight or obese NAFLD patients. The changes in these biomarkers may yield beneficial effects on NAFLD. Further trials on the efficacy of GC for clinical practice are suggested. Trial registration Iranian Registry of Clinical Trials, IRCT2015121317254N4. Registered 27/12/2015, Electronic supplementary material The online version of this article (10.1186/s12906-019-2465-0) contains supplementary material, which is available to authorized users.

A new integrated nozzle-flapper valve equipped with a piezoelectric actuator and an isothermal chamber has been developed and studied in detail. The designed single stage valve controls the pressure and flow rate simply, effectively, and separately. This idea can easily be used in the pilot stage of a two-stage valve as well. Application of isothermal condition in the valve load chamber eliminates the dynamic malfunction that may persist from temperature variation within the valve load chamber; consequently, the governing equations for the prediction of pressure dynamics in the chamber are much more accurate and simpler. The valve has been equipped with a stacked type piezoelectric actuator which has a unique behaviour. Furthermore, stiffness, in the selected actuator, is enhanced against the thrust of the discharging flow from the nozzle, thus decreasing the complexity of dynamic equations of the valve. A detail mathematical model and simulation was developed to study the dynamic performance analysis of the proposed valve. An experimental test rig was built to validate the results of simulations. The unique features and performance of the proposed valve were studied thoroughly. The valve's governing equations are nonlinear in nature, and some variables of the equations are a source of some uncertainties; sliding mode approach was used to control the steady and unsteady pressure and output flow rate of the valve. Namen predstavljene raziskave je uvedba novega ventila s šobo in odbojno ploščico (NF), za katerega so značilni spremenjen razpored delovnih elementov za izboljšanje dinamike, poenostavitev enačb ter odprava nekaterih omejitev tradicionalnih NF-ventilov. Za izpolnitev teh ciljev je bil novi ventil s šobo in odbojno ploščico zasnovan in opremljen s piezoelektričnim aktuatorjem in izotermno polnilno komoro. Dinamika polnilne komore, ki je glavni podsestav ventila, ima v celotni dinamiki ventila pomembno vlogo. Neobstoj točnega modela za spreminjanje stanja zraka v komori otežuje krmiljenje ventila. Zagotovitev izotermnih pogojev v komori ventila odpravlja dinamične napake zaradi temperaturnih sprememb v komori, vodilne enačbe za napovedovanje tlaka v komori pa so zato veliko točnejše in preprostejše. Izotermno stanje v komori ventila torej poenostavi njegovo krmiljenje, saj je le z enim samim tlačnim tipalom v komori ventila mogoče krmiliti tlak in pretok.

This paper introduces a new nozzle-flapper valve with isothermal chamber using piezoelectric actuator. It controls the pressure and flow rate simply, effectively and separately. The proposed valve uses isothermal chamber presenting practical isothermal condition due to its large heat transfer interfaces filled by metal wool. The valve uses stacked type piezoelectric actuator with unique advantages. By using this valve, a simple method has been fulfilled to control flow rate or pressure of ideal gases in a pneumatic actuators. Experimental results demonstrated applications of the proposed valve to control either pressure or flow rate in pneumatic circuits. This valve can be also used in the pilot stage valve to actuate the main stage of a much bigger pneumatic valve. Designated structure contains only one pressure sensor installed on the isothermal control chamber, capable of controlling both pressure and flow rate. The desired output mass flow rate of the valve is controlled by the pressure changes during positioning of piezoelectric actuator at proper position. The proposed valve can control steady and unsteady oscillatory flow rate and pressure effectively, using nonlinear control method such as feedback linearization approach. Its effectiveness is demonstrated and validated through simulation and experiments.

This research investigates the performance of a propulsion system and the emissions parameters of a merchant ship by using the consequences derived via a modular ship simulation model that is executed in MATLAB/Simulink. In the model, numerous components of the drive system such as engine, shafting framework, propeller, and vessel are shown by separated blocks whereas proper interfaces and connections are utilised to swap the desired factors between the blocks. Therefore, the created model can be used to explore the steady state and transient behaviour of the ship propulsion system and investigate the engine/propeller/shafting framework and vessel connections. Using this model the performance parameters of a ship in normal speed and slow steaming were calculated and investigated. In addition, the ship's powertrain system was investigated using distributed-lumped parameter model. The shear stress analysis of the propeller shaft was performed using a distributed-lumped model and compared in two normal speed and slow steaming modes. Due to the model's modular structure, its components can be modified and extended to be used in future new technologies and fuel evaluation as a part of the ship designing process.

The aim of this study is to apply the artificial neural network to identify the mathematical model of the combustion of a reactivity-controlled compression ignition (RCCI) engine fueled with natural gas and diesel oil. In this study, a single-cylinder heavy-duty diesel engine is set on operation at 9.4 bar gross indicated mean effective pressure. To implement the identification process, the effects of three control factors, namely the intake temperature, the intake pressure (both at the intake valve closing time), and the single-stage diesel fuel injection timing on the engine performance are assessed. Based on the design of experiments–fractional factorial concept, the randomized treatment combinations of chosen levels from the three selected control factors are employed to simulate the RCCI combustion. According to the engine’s responses derived from the RCCI combustion’s simulation, an artificial neural network is trained directly to identify the mathematical model of the RCCI combustion. The results show that the fractional factorial method is capable to produce an appropriate database for the artificial neural network’s training. Moreover, this method can predict more efficient scenarios in which the engine operation under the RCCI combustion has a desirable behavior. Also, artificial neural network as a powerful tool is effectively capable to predict the range of the excessive combustion noise occurrence, misfire occurrence, and the desirable engine load.

Objectives Different studies have been conducted on the role of curcumin in health since having multiple properties, including antioxidant and anti-inflammatory effects. Due to the lack of studies regarding curcumin effects on obese patients with non-alcoholic fatty liver disease (NAFLD), our protocol was designed to assess nanocurcumin impacts on blood sugar, lipids, inflammatory indices, insulin resistance and liver function, especially by nesfatin. Setting This trial will be conducted in the Oil Company central hospital of Tehran, Iran with a primary level of care. Participants 84 obese patients with NAFLD diagnosed using ultrasonography will be employed according to the eligibility criteria‎. Interventions The patients will be randomly divided into two equal groups (nanocurcumin and placebo, two 40 mg capsules per day with meals for 3 months, follow-up monthly). Also, lifestyle changes (low-calorie diet and physical activity) will be advised. Measures of the primary and secondary outcomes A general questionnaire, 24 hours food recall (at the beginning, middle and end) and short-form International Physical Activity Questionnaire will be completed. Blood pressure, anthropometrics, serum sugar indices (fasting blood sugar and insulin, insulin resistance and sensitivity and glycosylated haemoglobin), lipids (triglyceride, total cholesterol and low-density and high-density lipoprotein-cholesterol, inflammatory profiles (interleukin-6, high-sensitivity C-reactive protein, and tumour necrosis factor-alpha), liver function (alanine and aspartate transaminase) and nesfatin will be measured at the beginning and end of the study. Conclusion This trial would be the first experiment to determine nanocurcumin efficacy on certain blood factors among obese patients with NAFLD. Nevertheless, studying the potential consequences of curcumin in various diseases, especially NAFLD, is required for clinical use. Trial registration number IRCT2016071915536N3; pre-results.

Model-based control of Homogenous Charge Compression Ignition (HCCI) engine exhaust temperature is a viable solution to optimize efficiency of both engine and the exhaust aftertreatment system. Low exhaust temperature in HCCI engines can limit the abatement of hydrocarbon (HC) and carbon monoxide (CO) emissions in an exhaust aftertreatment system. A physical–empirical model is described for control of exhaust temperature in HCCI engines. This model captures cycle-to-cycle dynamics affecting exhaust temperature and is based on thermodynamic relations and semi-empirical correlations. It incorporates intake and exhaust gas flow dynamics, residual gas mixing, and fuel burn rate and is validated with experimental data from a single cylinder engine at over 300 steady state and transient conditions. The validation results indicate a good agreement between predicted and measured exhaust gas temperature.

The possibility of application of the advanced hypertrochoid curve in the inner surface of the stator of fixed displacement hydraulic vane pump, theoretically was studied in the last our work. By considering the properties of this curve, sealing action between pressure and suction sides of the pump can be improved. One of the important characteristics of a new profile must be improving of the inertial reaction of the vanes in each position where these vanes have a radial movement because it causes a smooth sliding motion of the vanes, and hence, a higher performance of the pump while attaining a longer life of it. Then at this paper, the effect of the inertial force of the vanes on the performance of the pump with this curve will be studied. The regular motion of the vanes on the inner surface of the stator with smooth profile suppresses the lateral reactional force applied to the vanes and results to diminish local wear of the vanes tip and noise.

The design of control system can be divided into two steps. The plant has to be converting into mathematical model form, so that its behavior can be analyzed. Then an appropriate controller has to be design in order to get the desired response of the controlled system. In this paper, the linear model of a Permanent magnet torque motor (PMTM) is considered and three controllers, digital PID controller with two forms of positional and velocity, a deadbeat controller and pole placement controller method are designed and due to a comparing between their, the best controller for this kind of plants will be chosen.

Performance of a fixed displacement hydraulic balance vane pump, theoretically and practically was studied by application of the hypertrochoid curve in the inner surface of its stator. In addition to improving a sealing action between pressure and suction sides of the pump, one of the important characteristics of the hypertrochoid profile is improving of the inertial reaction of the vanes in each position where these vanes have a radial movement. Then it causes a smooth sliding motion of the vanes, and hence, a higher performance of the pump while attaining a longer life of it because of decreasing vane- tip and inner surface of stator wear and decreasing of vibration, noise and high stresses.

In the latest our works, Performance of a fixed displacement- hydraulic balance vane pump, theoretically and practically was studied by application of the basic hypertrochoid curve in the inner surface of its stator. Also the effect of the inertia force of the vanes on the performance of the pump with this curve was studied. This study presents a theoretical analysis of the internal pressure distribution in the pump, and of the resulting forces and torques applied to its components. This analysis is essential to the study of the pump dynamics and control, the pump design, and selection of the pump bearings. These forces are shown to be a function of the line pressure, the shaft rotational speed, the fluid bulk modulus, the fluid viscosity, and the design geometry. These forces are composed of two components: a continuous component due to the exposure of chambers to the line port, and an intermittent component due to a hydraulic lock phenomenon.

Homogeneous Charge Compression Ignition (HCCI) engine is a promising idea to reduce fuel consumption and engine emissions. Natural Gas (NG), usually referred as clean fuel, is an appropriate choice for HCCI engines due to its suitable capability of making homogenous mixture with air. However, varying composition of Natural Gas strongly affects the auto-ignition characteristics of in-cylinder mixture and the performance of the HCCI engine. This paper has focused on the influence of Natural Gas composition on engine operation in HCCI mode. Six different compositions of Natural Gas (including pure methane) have been considered to study the engine performance via a thermo-kinetic zero-dimensional model. The simulation code covers the detailed chemical kinetics of Natural Gas combustion, which includes Zeldovich extended mechanism to evaluate NOx emission. Validations have been made using experimental data from other works to ensure the accuracy needed for comparison study. The equivalence ratio and the compression ratio are held constant but the engine speed and mixture initial temperature are changed for comparison study. Results show that the peak value of pressure/temperature of in-cylinder mixture is dependent of fuel Wobbe number. Furthermore, engine gross indicated power is linearly related to fuel Wobbe number. Gross indicated work, gross mean effective pressure, and NOx are the other parameters utilized to compare the performance of engine using different fuel compositions.

Turbo lag and low starting torque is the challenges of turbochargers. These challenges can be met with the implementation of an additional boosting device which can significantly boost the starting torque of the engine. the goal of this study is to show how the steady-state performance of a turbocharged SI engine can be improved by supercharging turbocharged engine. A one dimensional model for a turbocharged V type, four cylinder CNG engine has been developed and studied in detail using GT-POWER software. For validation purposes the model results are compared with experimental data available where acceptable results with good accuracy has been observed.

A two dimensional, two-phase non-isothermal electrochemical-transport using a fully coupled numerical model is developed to investigate heat transfer and water phase change effects on temperature distribution in a PEM fuel cell. The multiphase mixture is used formulation for the two phase transport process and developed model is treated as a single domain. This process leads to a single set of conservation equations consisting of continuity, momentum, species, potential and energy for all regions of cell. The results indicate that heat release due to condensation of water vapor affects the temperature distribution. When the relative humidity of the cathode is low, phase change would have a small effect on the maximum temperature that appears at the cell inlet, but it has higher effect on temperature variation further down stream towards the exit of cathode channel and its GDL. Under full-humidity conditions, the cell temperature at all regions of cell increases due to the phase change that starts to appear at the inlet, but the maximum effect of phase change occurs further up stream in cathode channel and its GDL. Also, vapor-phase diffusion which provides a new mechanism for heat removal from the cell, affects the cell temperature distribution.

A two-dimensional, non-isothermal, electrochemical-transport using a fully coupled numerical model is developed for a proton exchange membrane fuel cell to investigate simultaneous water, heat transport phenomena and their effects on cell performance. The multiphase mixture formulation for the two-phase transport process is used, and developed model is treated as a single domain. This process is leading to a single set of conservation equations consisting of continuity, momentum, species, potential and energy for all regions of cell. The result indicates that flooding of porous cathode reduces the rate of oxygen transport to the cathode catalyst layer and causes an increase in cathode polarization. Also, flooding could effect current density distribution, where a slight abrupt change occurs in the slope of the local current density curve. The amount and location of condensation in the GDL cathode is directly related to the cell temperature, where the temperature difference predicted by this model is about 3.7 °C at 0.6 V. The maximum temperature occurs near the inlet and at interface between membrane/catalyst layers at cathode side where major heat generation takes place. The results are validated with experimental data available that are in good agreement.

The purpose of this study is to investigate the effect of injection parameters on a heavy duty diesel engine performance and emission characteristics. In order to analyze the injection and spray characteristics of diesel fuel with employing high-pressure common-rail injection system, the injection characteristics such as injection delay, injection duration, and injection rate and number of nozzle holes were investigated by using a quasi-dimensional model. In the present work, the variety of injection rate is performed at various injection parameters where as performance and emission of the engine will be simulated subsequently. Finally the best injection system for a high efficiency and low NO x emission heavy duty diesel engine was investigated.

A two-phase non-isothermal model is developed to explore the interaction between heat and water transport phenomena in a PEM fuel cell. The numerical model is a two-dimensional simulation of the two-phase flow using multiphase mixture formulation in a single-domain approach. For this purpose, a comparison between non-isothermal and isothermal fuel cell models for inlet oxidant streams at different humidity levels is made. Numerical results reveal that the temperature distribution would affect the water transport through liquid saturation amount generated and its location, where at the voltage of 0.55 V, the maximum temperature difference is 3.7 °C. At low relative humidity of cathode, the average liquid saturation is higher and the liquid free space is smaller for the isothermal compared with the non-isothermal model. When the inlet cathode is fully humidified, the phase change will appear at the full face of cathode GDL layer, whereas the maximum liquid saturation is higher for the isothermal model. Also, heat release due to condensation of water vapor and vapor-phase diffusion which provide a mechanism for heat removal from the cell, affect the temperature distribution. Instead in the two-phase zone, water transport via vapor-phase diffusion due to the temperature gradient. The results are in good agreement with the previous theoretical works done, and validated by the available experimental data.

HCCI is considered a very promising solution to reduce engine pollutant emissions, however so far only experimental prototypes have been inspired by this concept. HCCI combustion of both DME and n -heptane fuels display a distinct two-stage ignition reaction with the first stage taking place at fairly low temperatures and the second stage taking place at high temperatures. The second stage is responsible for the main stage of the heat release process. In this study, a single-zone, zero-dimensional, thermo-kinetic combustion model has been developed. MATLAB software is used to predict engine performance characteristics of HCCI engines using two types of diesel fuel: Dimethyl ether and n -heptane. The effects of intake temperature and pressure, fuel loading and addition of EGR gases on auto-ignition characteristics, optimum combustion phasing, and performance of the HCCI engines are considered in this study.

Homogenous Charge Compression Ignition (HCCI) combustion is a promising concept to reduce engine emmisions and fuel consumption. In this paper, a thermo-kinetic single zone model is developed to study the operation characteristics of a natural gas HCCI engine. The model consists detail chemical kinetics of natural gas oxidation including 325 reactions with 53 chemical species, and is validated with experimental results of reference works. Then, the influence of parameters such as manifold temperature/pressure, and equivalance ratio on incylinder temperature/pressure trends, start of combustion and heat release rate is studied. These results are explained in detail to describe the engine performance thoroughly.

In this study a two-phases, single-domain and non-isothermal model of a Proton Exchange Membrane (PEM) fuel cell has been studied to investigate thermal management effects on fuel cell performance. A set of governing equations, conservation of mass, momentum, species, energy and charge for gas diffusion layers, catalyst layers and the membrane regions are considered. These equations are solved numerically in a single domain, using finite-volume-based computational fluid dynamics technique. Also the effects of four critical parameters that are thermal conductivity of gas diffusion layer, relative humidity, operating temperature and current density on the PEM fuel cell performance is investigated. In low operating temperatures the resistance within the membrane increases and this could cause rapid decrease in potential. High operating temperature would also reduce transport losses and it would lead to increase in electrochemical reaction rate. This could virtually result in decreasing the cell potential due to an increasing water vapor partial pressure and the membrane water dehydration. Another significant result is that the temperature distribution in GDL is almost linear but within membrane is highly non-linear. However at low current density the temperature across all regions of the cell dose not change significantly. The cell potential increases with relative humidity and improved hydration which reduces ohmic losses. Also the temperature within the cell is much higher with reduced GDL thermal conductivities. The numerical model which is developed is validated with published experimental data and the results are in good agreement.

The ever increasing cost of hydrocarbon fuels and more stringent emission standards may resolve challenges in producing hydrogen and using it as an alternative fuel in industries. Internal combustion engines are well-established technology and hydrogen fuel in such engines is considered as an attractive choice in exploiting clean, efficient and renewable hydrogen energy. This work presents an improved thermo-kinetics model for simulation of hydrogen combustion in SI engines. The turbulent propagating flame is modeled using turbulent burning velocity model. During combustion the charge is divided into three zones containing unburned charge, flame and burned gas. The adiabatic flame is assumed to be in thermodynamic equilibrium while the detailed chemical kinetics scheme is considered for burned and unburned zones. The results were first validated against published experiments. Good agreements were obtained between simulation and experiment for varying equivalence ratio, ignition timing and compression ratio. Detailed analysis of engine NOX emission was performed afterward. The lean-burn and EGR strategies' potentials were examined by the current model. The effects of different amounts of cooled dry EGR and hot wet EGR on the NOX emission, engine power output and indicated thermal efficiency were investigated and compared theoretically.

The growth of natural circulation and thermal stratification inside LOX, LN2 storage tanks due to heat transfer from surroundings is investigated using a non-equilibrium, two-domain, mathematical model. The two-dimensional model is considered for the liquid domain in two cases and a lumped, thermodynamic model is utilized for vapor domain. The vapor is assumed to behave like an ideal gas. The developed mathematical model for liquid domain consists of conservation of mass, momentum, energy equations with Boussinesq approximation. The coupling of two domains is carried out using energy balance at the interface. An implicit, finite-volume technique with a uniform mesh for liquid domain is used to predict the velocity and temperature fields.

Control and detection of misfire are an essential part of on-board diagnosis (OBD) of modern spark ignition (SI) engines. This study proposes a novel model-based technique for misfire detection for a multicylinder SI engine. The new technique uses a dynamic engine model to determine mean output power, which is then used to calculate a new parameter for misfire detection. The new parameter directly relates to combustion period and is sensitive to engine speed fluctuations caused by misfire. The new technique requires only measured engine speed data and is computationally viable for use in a typical engine control unit (ECU). The new technique is evaluated experimentally on a four-cylinder 1.6-l SI engine. Three types of misfire are studied including single, continuous, and multiple-event. The steady-state and transient experiments were done for a wide range of engine speeds and engine loads, using a vehicle chassis dynamometer and on-road vehicle testing. The validation results show that the new technique is able to detect all three types of misfire with up to 94% accuracy during steady-state conditions. The new technique is augmented with a compensation factor to improve the accuracy of the technique for transient operations. The resulting technique is shown to be capable of detecting misfire during both transient and steady-state engine conditions.