Full Load Operating Conditions Research Articles

Simulation of the Performance of an Electrically Turbocharged Engine Over an Urban Driving Cycle

The study aimed to estimate the energy recovery potential of a decoupled electric turbocharger and its boosting ability in a spark-ignition engine using simulation-based work. Passenger vehicle engines operate at low loads and speeds, requiring characterization and estimation of energy available for recovery under normal driving conditions. A 1-D numerical model of the engine and boosting system was developed to predict energy recovery over steady-state full-load operating conditions, part-load conditions, and actual, transient Klang Valley and Kuala Lumpur drive cycle conditions. The electric turbocharged engine consists of two motors and a battery pack, which were modeled and utilized using GT-Power engine simulation software. The study found that the electrical turbocharger system could recover 0.57 kW and 0.50 kW at 2500 rpm and 3000 rpm, respectively. Part-load studies showed that the maximum amount of electrical energy recovered at 6500 rpm was 5.25 kW. Drive cycle analysis revealed that fuel consumption was the same for both engine models due to the similar turbocharger output performance and lower back pressure caused by the recalibrated wastegate controller. This was partially mitigated by the inclusion of two electric motors. Drive cycle analysis revealed that the electric turbocharger can perform better than a conventional turbocharger when optimized.

Effects of diesel-biodiesel fuel blends doped with zinc oxide nanoparticles on performance and combustion attributes of a diesel engine

To improve the fuel properties and enhance the overall characteristics of a diesel engine, the current work assesses the performance and combustion attributes of a diesel engine fueled by different blends of diesel, second generation biodiesel, and zinc oxide (ZnO) nanoparticles. The biodiesel was prepared using the transesterification of waste cooking vegetable oil. Zinc oxide nanoparticles were dispersed in diesel and biodiesel fuel blends at one dosage level of 50 ppm using ultrasonication process to prevent their agglomeration in the base liquid. The experiments were performed at different engine speeds (1700, 2000, 2300, 2600, 2900) RPM and full load operating conditions. The experimental results revealed that the addition of ZnO compensated for the poor combustion characteristic of biodiesel and hence promoted diesel engine performance and combustion attributes. The engine torque improved by 6.74, 4.9 and 3.69% while the BSFC reduced by 5.6, 6.44 and 2.5% for B0ZnO, B20ZnO and B40ZnO fuel blends compared to B0, B20 and B40 respectively at 2300 RPM. In addition, the engine heat release rate, ignition delay period and in-cylinder pressure were promoted. ZnO nanoparticles additives could be an effective approach for improving the combustion and performance characteristics in diesel engine applications.

Thermo-economic analysis of a solid oxide fuel cell-gas turbine hybrid with commercial off-the-shelf gas turbine

The thermodynamic and economic performance of a natural gas-fueled solid oxide fuel cell (SOFC)-gas turbine (GT) hybrid system with a commercial off-the-shelf GT is investigated. Until today, commercial GTs are primarily engineered for the direct use of energy dense fuels, such as natural gas, and the integration of commercial GTs into a SOFC-GT hybrid remains challenging. In this work technically feasible and economically viable GT operating modes are identified to gauge the technology’s competitiveness on the free market. Steady state, full load operating conditions were established for various GT operating modes: I) constant spool speed operation, II) variable spool speed operation and III) partially closed compressor inlet guide vanes. For each GT operating mode, the performance was investigated over a range of SOFC fuel utilization factors, while considering physical constraints inside the SOFC, such as local temperature gradients in flow direction as well as overall cell temperature differences. The results of the thermodynamic evaluation served as inputs for the economic analysis of the SOFC-GT hybrid power plant. The results show that the integration of an off-the-shelf GT not only results in a significant derating of the GT, but also substantially impacts the SOFC operation, the main power producer in this SOFC-GT hybrid. To maximize the SOFC power output it is desirable operate the GT in a region of high air mass flow rates and low pressure ratios, which increases the number of stacks that can be accommodated and reduces the SOFC cooling requirement. The lowest costs of electricity are obtained at constant spool speed operation, while the highest efficiencies are reached at variable spool speed operation. Critical for the integration of off-the-shelf GTs, which historically have been designed for natural gas, is the surge margin. The largest surge margins are obtained by closing the compressor inlet guide vanes. Furthermore, higher SOFC fuel utilization factors are shown to increase the surge margin as the turbine firing temperature is decreased.

Experimental comparison between an optical and an all-metal large bore engine

Rising engine efficiency, increasingly stringent exhaust limits, and the use of synthetic and renewable fuels are all factors that demand a deeper knowledge of the combustion process. State-of-the-art investigations employ optical and laser-optical measurement techniques that rely on having optical access to the engine. In this paper, a new endoscopic system that provides full optical access to a high-speed large-bore engine is compared by thermodynamic experimentation to the equivalent all-metal engine. This comparison provides an insight into the altered combustion behavior resulting from modifying the engine to accommodate the optical elements. The successfully realized concept consists of two individually usable access points integrated in an engine with a bore of 170 mm and a stroke of 210 mm. The lateral endoscopic access is designed for full-load operating conditions and provides the best comparability to an all-metal engine. It is compared directly to the all-metal engine in the present investigations. Despite the changes in engine-out emissions from the optical engine, the experimental results display relatively equal combustion behavior in both setups. The lateral endoscopic access is then extended by adding a fisheye endoscope in place of one exhaust valve. This setup is compared to findings obtained with the endoscopic lateral access. The investigations reveal further deviations of the combustion process due to the more extensive modifications needed to fit the fisheye endoscope to the cylinder head. Nevertheless, the results display an overall good level of comparability of the combustion behaviors in these setups and, in turn, of the validity of further fundamental experiments based on the optical engine.

Fatigue Crack Growth Evaluation of IMO Type B Spherical LNG Cargo Tank Considering the Effect of Stress Ratio and Load History

The crack propagation on a spherical IMO Type B LNG tank deployed on a 150K class LNG carrier is studied. IMO Type B tanks require a high level of safety . Therefore, analyses such as strength evaluation, fatigue analysis, fatigue crack propagation analysis, and LNG leak rate should be conducted to ensure safety. Various fatigue crack growth models were proposed for fatigue crack propagation analysis. The Forman model and the Walker model consider the stress ratio. Furthermore, the Huang model, and the Lee and Kim model consider the stress ratio and the effects of overload and underload present in the past load history on crack propagation.To examine the effects of stress ratio and load history for the fatigue crack propagation models, the crack growth of the LNG tank was evaluated by considering the stresses under full load and ballast load operating conditions, and three stress amplitude sequence cases.

Modelling an Electrically Turbocharged Engine and Predicting the Performance Under Steady-State Engine

This paper discusses the evaluation of the energy recovery potential of turboshaft separated (decoupled) electric turbocharger and its boosting capability in a spark-ignition engine through simulation-based work and comparing it to a conventional turbocharged engine in terms of fuel consumption. The main objective of this study is to evaluate the amount of energy that can be recovered over a steady state full-load operating conditions and boosting capabilities from a decoupled electric turbocharger of an SI engine using a 1-D engine simulation software. The electric turbocharged system includes two motors and a battery pack to store the recovered electrical energy. Gt-Power engine simulation software was used to model both engines and utilizes each of the components described earlier. The conventional turbocharged engine is first simulated to obtain its performance characteristics. An electric turbocharger is then modelled by separating the turbine from the compressor. The turbine is connected to the generator and battery, whereas the compressor is connected to the motor. This electrically turbocharged engine was modelled at full load and controlled to produce the same brake power (kW) and brake torque (Nm) properties as the similarly sized conventional turbocharged engine. This step was necessary to investigate the effect an electrical turbocharger without a wastegate has on the engine’s BSFC and determine the energy that can be recovered by the electrical boosting components, and cycle-averaged fuel consumption was evaluated. The evaluation of energy recovered from the electrically turbocharged engine from the analysis can assessed in full-load steady state conditions that can be useful for research in part-load and transient studies involving the decoupled electrical turbocharger. The study revealed that a maximum of 21.6 kW of electrical power can be recovered from the decoupled electrical turbocharger system, whereas 2.6% increase in fuel consumption can be observed at 5000 rpm engine speed.

Identification of 1-D cavitation model parameters by means of computational fluid dynamics

Hydropower is a key energy conversion technology for stabilizing electrical power. When running at full load, a 3-D cavitation vortex rope develops in Francis turbines that acts as an internal source of energy and instability. 1-D models allow this phenomenon to be predicted and the range of safe operating points to be defined. These models involve three parameters: the mass flow gain factor, the wave speed and the second viscosity that must be calibrated. For the first time, the present work aims at identifying these parameters using 3-D URANS cavitating simulations. Two cavitation test cases are considered: a 2-D Venturi and a reduced scale model of a Francis turbine at full load operating conditions. RANS simulations allow the mass flow gain factor to be determined, whereas URANS simulations coupled with an optimization process allow the determination of the wave speed and the second viscosity. The new methodology shows its ability to identify the three parameters.

A Study on the Effect of Ignition Timing on Residual Gas, Effective Release Energy, and Engine Emissions of a V-Twin Engine

The ignition timing of an SI engine is a critical parameter. The influence on residual gas, effective release energy, and emissions characteristics of ignition timing for the V-twin engine is investigated in this research. For this purpose, an experiment system was built with a dynamometer, and a model of the simulation was created. In this research, the ignition timing was varied from 10 to 45 degrees BTDC under full load operating conditions, with engine speeds ranging from 3000 to 10,000 rpm. Based on the output data, ignition timing has a major impact on the proportion of residual gas, efficient release energy, performance of the engine, and the emission characteristics. The smallest proportion of residual gas was 0.07% at 8000 rpm and ignition timing of 10 °CA. At 15 °CA of ignition timing, the highest efficient release energy was 0.817 kJ at 4000 rpm, while at 8000 rpm and 25 °CA of ignition timing, it was 0.8305 kJ. At 6000 rpm, the greatest braking torque of the engine was 21.57 Nm, while the minimal BSFC was 343.821 g/kWh. The nitrogen oxide emission and HC emission increase with the advanced ignition timing, but CO emission decreases.

Measurement and modelling of a linear electromagnetic actuator driven camless valve train for spark ignition IC engines under full load condition

Camless engine valve train for gasoline engines particularly port injection engines offer major improvements over traditional system with fixed valve timing and lift, in terms of efficiency, maximum torque and power, and emissions. Electromagnetic driven valve actuators are very promising in this context, but there are significant control problems. The use of displacement sensor could add extra cost to the camless engine. In this work, a moving coil actuator driven valve train was designed and prototyped and a 1D single-cylinder internal combustion engine model was built to investigate the benefit of without throttle by adopting such camless valve train using Ricardo WAVE under full load operating conditions. A novel low-cost sensor named linear actuator position sensor (LAPS) based on flux linkage change on search coil was constructed in LabVIEW by using current, voltage and proximity sensors to detect the valve lift. The measurement of valve lift and current was reported to prove the feasibility of the camless valve train. The valve lift was used for the single-cylinder engine model and the simulation shows that the peak overall engine efficiency using camless valve train reaches 38.2% and the peak torque increases by 5 Nm compared conventional throttled engine under full load operating conditions. The LAPS model was validated by the experimental valve lift and the high accuracy indicates that the LAPS can be adopted for future development of camless valve train for spark ignition IC engines.

Exergetic, economic, and environmental life cycle assessment analyses of a heavy-duty tractor diesel engine fueled with diesel–biodiesel-bioethanol blends

This study aimed to analyze a heavy-duty tractor diesel engine operating on diesel-biodies-bioethanol blends using exergetic, economic, and environmental life cycle assessment analyses. Diesel was mixed with biodiesel and bioethanol with volumetric ratios of 5–15% and 2–6%, respectively. Nine diesel–biodiesel-bioethanol blends and one baseline fuel were tested at different PTO shaft speeds ranging from 800 to 1000 rpm under full load operating conditions. Various exergetic, economic, and environmental indicators were computed to facilitate decision-making on fuel composition and PTO shaft speed. In general, increasing biodiesel concentration in the fuel blend could improve the exergetic, economic, and environmental indicators of the system. However, there was no clear pattern of the effects of bioethanol on the investigated indicators. Interestingly, most of the prepared fuel blends were exergetically, economically, and environmentally superior to diesel. The lowest weighted environmental impact (52.1 mPts/GJ) and PTO shaft power generation cost (0.18 USD/kWh) were found for the fuel blend containing 10 vol% biodiesel and 4 vol% bioethanol at the PTO shaft speed of 1000 rpm. This fuel blend also showed the highest resource utilization efficiency (29.3%) and environmental sustainability (26.1%) at the PTO shaft speed of 1000 rpm. The weighted environmental impact and PTO shaft power generation cost of the selected fuel blend were 44.3% and 46.2% lower than those of diesel, respectively. The resource utilization efficiency and environmental sustainability of the selected fuel blend were 97.3% and 99.8% higher than those of diesel, respectively. Overall, substituting a portion of diesel with biodiesel and bioethanol was proved to be an attractive strategy from the exergetic, economic, and environmental perspectives. The results obtained can be valuable in practical applications to enhance the sustainability and viability of power production in agricultural activities. The applied exergetic, economic, and environmental methodologies appear to be reliable and comprehensive tools for assessing the whole-life sustainability and viability of mineral-biofuel blends.

A New Optical Access for Medium Speed Large Bore Marine Engines under Full-Load Operating Conditions

A New Optical Access for Medium Speed Large Bore Marine Engines under Full-Load Operating Conditions

Stator Flux Producing Current-Based Promoted Rotor Angle Estimator of Doubly-Fed Induction Generator for Encoderless Operations

In the context of position or speed sensorless control scheme, an improved rotor position estimation process for doubly-fed induction generator (DFIG) is presented in this paper. Model reference adaptive system (MRAS) is considered for the computation of rotor position. The stator flux producing current is taken as main working variable for the estimator. The estimator has various desirable features such as free from integrator-differentiator based computation, no information needed about initial rotor position (catch on fly operation), capability to work at very low slip condition (near synchronous speed operation), non-involvement of flux calculation, negligibly sensitive to mismatch in machine parameters. The major advantage of the proposed scheme is that it is insensitive to magnetizing inductance and rotor resistance of the electrical machine. Also, the novelty of the estimator lies in the fact that the suggested estimator works stably and accurately from very light load to full load operating conditions. The robust operation of proposed estimator is verified through real-time experimental set up.

Effect of natural gas composition and gas interchangeability on performance and emission characteristics in an air–fuel controlled natural gas engine

In this study, the effect of low-calorie gas on the output performance and efficiency of engines and the emission characteristics was investigated using an 11 L 6-cylinder supercharged engine for city buses. In order to examine the effect of changes in the physical properties of low calorific gas on combustion, the results with simulated low calorific natural gas by the addition of nitrogen were compared to those with reference natural gas fuel. Pure methane (CH4) is also used to investigate the effect of gas composition change on the performance and emission characteristics. The basic performance factors, including torque and thermal efficiency, were compared by varying the engine speed under full-load operating conditions. The trends of exhaust gas emissions were observed and analyzed with respect to the fuel composition.Another purpose of this study is to determine whether the higher heating value (HHV), Wobbe index (WI), and maximum combustion potential (MCP) index are appropriate factors for determining the performance and exhaust condition of the air–fuel controlled engine for the composition of the gas used in this study. It was found that the combustion rate is the most important physical property of the gas, while the MCP does not match the laminar flame speed of low calorific gas fuel and pure CH4. The modified MCP value is presented and is a suitable gas interchangeability index of the engine that controls the air–fuel ratio because it properly reflects the effect of the inert gas in the fuel gas.

Combustion investigation of waste cooking oil (WCO) with varying compression ratio in a single cylinder CI engine

Biodiesel is a popular alternative fuel of mineral diesel which is normally produced by using straight vegetable oils (SVO). Since the conversion of edible oils into biodiesel may affect its supply/availability as a food item, it is desirable to use non-edible oils for biodiesel production for a long time. Waste cooking oil (WCO) is one such non-edible oil, however superior in quality for biodiesel production through transesterification. The current study is mainly focused on the utilization of WCO as an alternative for mineral diesel in a typical agricultural compression ignition four stroke water-cooled engine. Effect of higher compression ratio (CR20) on various combustion and performance parameters such as in-cylinder pressure (P-θ), heat release rate (HRR), peak pressure (Pmax), maximum pressure rise rate (dP/dθ)max, combustion duration, combustion phasing etc. were investigated for WCO biodiesel and compared with mineral diesel. These experiments were performed for five different loading conditions (No load to full load) at 1500 rpm. Increase in compression ratio (CR) from 18 to 20 resulted in lower ignition delay for higher engine load condition which reduced by 6 CAD. Full load engine operation resulted in 32% brake thermal efficiency (BTE) for WCO biodiesel which was 18% higher than diesel. Peak in-cylinder pressures (Pmax) were observed similar for diesel and WCO biodiesel for same operating conditions except full load condition where it showed lower Pmax value. WCO biodiesel turned out to be more efficient with 6% lower BSFC for the full load operating conditions (CR20).

Rubber seed (Hevea brasiliensis) oil biodiesel emission profiles and engine performance characteristics using a TD202 diesel test engine

In this study, biodiesel produced from seeds obtained from a Nigerian bioengineered rubber tree (Hevea brasiliensis, NIG800 series) was investigated for engine performance analysis and emission study. All tests were conducted for diesel, biodiesel, and blends over the entire speed range (1500–3500 rpm, at increments of 500 rpm) under full load operating conditions. The results showed that the brake specific fuel consumption is higher for biodiesel and blends compared to diesel due to the lower heating value of the biodiesel, but B20 and diesel results were the same (0.20 kg/kWh) at 2750 rpm. Exhaust gas temperature is significantly higher for biodiesel because the higher oxygen content (10–12%) and higher cetane number assisted complete combustion. Engine power, brake thermal efficiency, and engine torque were higher with diesel fuel compared to biodiesel and blends because of the higher energy content of diesel fuel. There is a significant reduction in carbon monoxide, unburned total hydrocarbons, and smoke opacity with biodiesel, but nitric oxide and carbon dioxide increased slightly. The B20 blend at 2500 rpm shows the best performance, and biodiesel sourced from rubber seeds is environmentally friendly and can be used in modern diesel engines without technical modifications.

A Numerical Analysis of the Air-Cooling System of a Spark Ignition Aeronautical Engine

It is well known that spark ignition internal combustion engines for aeronautical applications operate within a specific temperature range to avoid structural damages, detonations and loss of efficiency of the combustion process. An accurate assessment of the cooling system performance is a crucial aspect in order to guarantee broad operating conditions of the engine. In this framework, the use of a Conjugate Heat Transfer method is a proper choice, since it allows to estimate both the heat fluxes between the engine walls and the cooling air and the temperature distribution along the outer wall surfaces of the engine, and to perform parametric analyses by varying the engine operating conditions. In this work, the air-cooling system of a 4-cylinder spark ignition engine, designed by CMD Engine Company for aeronautical applications, is analysed in order to evaluate the amount of the air mass flow rate to guarantee the heat transfer under full load operating conditions. A preliminary validation of the model is performed by comparing the results with available experimental data. A parametric study is also performed to assess the influence of the controlling parameters on the cooling system efficiency. This study is carried out by varying the inlet air mass flow rate from 1.0 kg/s to 1.5 kg/s and the temperature of the inner wall surfaces of the engine combustion chambers from 390 K to 430 K.

Hydro-structural stability investigation of a 100 MW Francis turbine based on experimental tests and numerical simulations

This work focuses on a 100 MW Francis turbine prototype, part of one of the four horizontal ternary groups of Grimsel 2 PSPP, in Switzerland. Due to the massive integration of new renewable energy, the number of daily starts/stops of the machines has increased. Consequently, cracks on the runner blades of the Francis turbines have been noticed, without a clear explanation regarding the phenomenon responsible for their onset.To identify the main stress-full operating condition causing these cracks, the full turbine hill chart has been covered during the in situ measurement campaign including start-up, speed no-load, deep part load, best efficiency, full load and shut-down operating conditions. Then hydro-structural stability diagnosis diagrams of the prototype have been established for the whole operating range of the turbine. In addition, CFD numerical simulations for different operating conditions, along with FEM structural and modal analysis of the runner, have been carried out.The onboard measurements evidenced the highest mechanical stresses on the runner blades at speed no-load operating condition. This conclusion is supported by CFD and FEM analysis, which put in evidence the possible excitation of one of the runner’s eigen frequency by the fluctuations of the pressure field.

Experimental-numerical analysis of added resistance to container ships under presence of wind-wave loads.

Experimental and numerical analyses performed on a scaled-down model of a 1900TEU container-ship are reported herein. Wind-tunnel and towing-tank experiments along with computational-fluid-dynamic simulations were performed to obtain (1) wind-load coefficients for superstructure of container ship at different wind angles under full-load operating conditions; (2) wave resistance of the model sans the superstructure under different wave conditions; and (3) combined wind–wave resistance of the model in the head waves coupled with a fluctuating wind. Wind-tunnel experiments were first performed to determine wind-load coefficients concerning of the superstructure at different wind angles. Subsequently, the obtained wind-load coefficients from the wind tunnel test were compared against numerical and empirically obtained results to validate the applicability of the applied numerical methods. Next, the wave-induced resistance to ship motion was investigated via a series of towing-tank experiments and numerical simulations to analyze the resistance and motion of ship under wavy conditions. Finally, characteristics of the added resistance to ship motion under conditions of combined wind–wave load were analyzed, and the coupling between ship motion and combined wind–wave load was used to investigate the changes in added resistance under different load scenarios. The results reveal that combined wind–wave load causes the resistance to ship motion to exceed the algebraic sum of the corresponding resistances under standalone wind- and wave-load conditions. The additional resistance was observed to be a combined manifestation of resistances induced by ship motion and wave-parameter alterations.

Experimental Study on Thermal Balance of Regulated Two-Stage Turbocharged Diesel Engine at Variable Altitudes

It is significant to study thermal balance of diesel engine under different variable geometry turbocharger (VGT) vane openings at variable altitudes, which is helpful to assess the heat distribution, control the heat load and improve the heat efficiency of the diesel engine. A thermal balance test system was built to study the influence of the VGT vane opening angles on a regulated two-stage turbocharged (RTST) diesel engine’s thermal balance performance. The experiment was conducted under full load operating conditions at different altitudes (0 m, 3500 m and 5500 m). Results indicated that the heat load of engine increased and the thermal efficiency decreased with the increase of altitudes under all operating conditions. As the VGT vane openings increased, the exhaust and maximum combustion temperature increased, while the maximum cylinder combustion pressure decreased. In particular, the maximum combustion temperature was more than 2000 K when the VGT vane openings were greater than 70% at the altitude of 5500 m, and the maximum combustion pressure exceeded 17 MPa when the opening of VGT vane was 70% at 0 m. The thermal efficiency of the engine decreased with the increase of VGT vane openings at the altitudes of 0 m and 5500 m, but the thermal efficiency increased and then decreased at the altitude of 3500 m. It was finally obtained that the best openings of VGT vane was 80%, 60% and 50% under the engine speed of 2100 r/min at 0 m, 3500 m and 5500 m, respectively.

Investigation of the effects of diesel-fusel oil fuel blends on combustion, engine performance and exhaust emissions in a single cylinder compression ignition engine

Increasing harmful effects of global warming, consumption of energy and depletion of fossil-based fuels have directed the researches on alternative fuels such as ethanol, methanol, natural gas for compression ignition engines. Among these fuels, alcohols are preferred due to their advantages such as oxygen content, renewable fuel and availability by biomass sources. Fusel oil is obtained as a by-product in ethanol production and it has no usage area and no value for the economy of the country. In this study, pure diesel and fusel oil were mixed in certain proportions. The effects of test fuels on combustion, engine performance and exhaust emissions were examined comprehensively at different engine loads and speeds. In the calculation of heat release rate single-zone combustion model and the first thermodynamics were used. At full load operating conditions similar pressure traces were obtained with F5 and F10 compared to diesel. Specific fuel consumptions were calculated as 201.3, 240.1 and 261.9 g/kWh at 2200 rpm with the usage of diesel, F5 and F10 fuels respectively. In addition, it was determined that as the ratio of fusel oil in the blend increased, CO emissions increased according to the pure diesel operation and smoke and NOx emissions decreased.