Performance Characteristics Of System Research Articles

Performance and Emission Characteristics Using Dual Injection System of Gasoline and Ethanol

This study successfully investigated the engine performance and emission characteristics of a dual injection system that uses both gasoline and ethanol fuels. The study utilized a microcontroller-based control system (PGM-FI) to substitute ethanol fuel injection for gasoline injection. Ethanol fuel was injected at the inlet with three different pressures: 1.0 bar, 1.2 bar, and 1.4 bar, while gasoline injector pressure was fixed at 2 bar. Results showed that substituting ethanol injection with a pressure of 1 bar resulted in a slight decrease in torque and power, but it was the best compared to the other pressures tested. The study found that the use of ethanol injection resulted in improved fuel economy at an ethanol injector pressure of 1 bar with a reduction in SFC of 8.89%. Exhaust emissions were also reduced, with a maximum reduction in CO emissions of 42.54% occurring at a pressure of 1 bar. Similarly, the lowest HC content in exhaust gas was observed at a pressure of 1 bar, which was reduced by 44.48%. However, the results highlighted that ethanol injection pressure could significantly reduce fuel consumption for case A-04 and increase the air-fuel ratio.

Comparative Study of Thermodynamic Performance and System Characteristics of Solid Oxide Fuel Cell System with Three Different Fuels

This work focuses on the fuel characteristic of the Solid Oxide Fuel Cell (SOFC) system. Three types of fuel have been considered and two type of the SOFC system layout have been analyzed with in-house SOFC system simulator (H-Twin). In the case of non-recirculation system, ammonia fed system shows the highest efficiency. In the case of recirculation system, methane fed system show the highest efficiency. The hydrogen-fed system shows the lowest efficiency in both types of systems.

Аналіз робіт з модернізації ЗСЗВ 9К51 «Град» для визначення технічних характеристик перспективного некерованого РС калібру 122 мм

The article dwells on the multiple launch rocket systems with high firepower, firing rate and manoeuvrability, which continue to be one of the basic means of destruction of the land forces in the conditions of the modern armed conflicts. Authors observed the importance of reconstruction and upgrading of multiple launch rocket systems of Grad 9К51, Hurricane 9К57 and Tornado 9К58 types and missiles they use by the enterprises of the domestic military-industrial complex. The article dwells on the main areas of upgrading of the multiple launch rocket system Grad 9K51 performed by NPO Splav and co-operating enterprises in 1997‒1998 for a foreign customer. The key factors that allowed improving the performance of the Grad system in the upgrading process are identified in this article. The main characteristics of the unguided missiles 9M217, 9M218, 9M521, 9M522, designed for the foreign customer, had been investigated. The performance characteristics of the Tornado-G multiple launch rocket system which went into service with the Ministry of Defense of the Russian Federation in 2014, as well as the family of the upgraded unguided missiles 9M538, 9M539, 9M641, are analyzed. The article identifies the main areas of work for further improvement of the performance characteristics of the 122-mm unguided missile, developed by Yuzhnoe Design Office for the multiple launch rocket system 9K51 Grad. This article can be useful for the specialists in development of new and upgrading outdated systems of rocket weapons. Key words: multiple launch rocket system (MLRS), missile, 9K51 Grad, 9M217, 9M218, 9M521, 9M522, Tornado-G, 9M538, 9M539, 9M541.

Vibration characteristics control of hybrid radial gas foil bearing-rotor system: Simulation and experiment

Currently, tiny, high-speed rotating machines frequently employ air foil bearings. Air is employed as the working medium, however, when the rotor speed is high, the rigidity of the air film is insufficient, which restricts the usage of air foil bearings. This study utilizes the external gas supply method of hydrostatic gas bearings to strengthen the air film stiffness of air foil bearings. The original air foil bearings are combined with external gas supply piping to create the hybrid gas foil bearing(HGFB), which may be utilized to increase the air film support stiffness of the bearings through the external gas supply. Additionally, by altering the gas supply pressure, this bearing may be used to actively manage the vibration characteristics of the shaft system, allowing the bearing performance to be adjusted to changing operating conditions. The static and dynamic properties of the HGFB with a 24 mm diameter are solved in this study using Newton's iterative approach and the finite difference method. The bearing-rotor system is modeled using this information. An Analysis is done on the impact of various air supply pressures and throttle hole widths on bearing performance and vibration characteristics of the shaft system. In this article, the vibration parameters of the bearing-rotor system are tested using an open-loop control test. The open-loop control experiment on the vibration response of the bearing-rotor system is performed using HGFBs with orifice sizes of 0 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm. The experimental results confirm the accuracy of the simulation results. Correspondingly, this paper conducted closed-loop control comparison experiments on the vibration properties of the bearing-rotor system using the PID control method and the fuzzy PID control method in succession. It then evaluated the control effect of the two control strategies on the vibration of the bearing-rotor system and managed to improve the conventional PID control method used for gas bearings.

Review of Recent Advances in Transcritical CO2 Heat Pump and Refrigeration Cycles and Their Development in the Vehicle Field

Refrigerant substitution is an urgent need in the context of reducing carbon emissions and slowing global warming. CO2 is now being proposed as a promising solution based on its excellent properties and system performance, especially in low-temperature environments. This paper presents an overview of recent advances in system configuration and operation characteristics to improve the performance of transcritical CO2 heat pump and refrigeration systems. The paper first introduces the basic research background, system cycle, and thermodynamic characteristics. Secondly, CO2 cycle improvements with single modifications and modification combinations are reviewed. Then, some important operation characteristics and control methods are discussed. Additionally, the paper provides a detailed description of the development of transcritical CO2 heat pump and refrigeration systems in the vehicle field. At the end of this review, conclusions and opportunities for future work in this field are presented.

Energy Storage Systems for Photovoltaic and Wind Systems: A Review

The study provides a study on energy storage technologies for photovoltaic and wind systems in response to the growing demand for low-carbon transportation. Energy storage systems (ESSs) have become an emerging area of renewed interest as a critical factor in renewable energy systems. The technology choice depends essentially on system requirements, cost, and performance characteristics. Common types of ESSs for renewable energy sources include electrochemical energy storage (batteries, fuel cells for hydrogen storage, and flow batteries), mechanical energy storage (including pumped hydroelectric energy storage (PHES), gravity energy storage (GES), compressed air energy storage (CAES), and flywheel energy storage), electrical energy storage (such as supercapacitor energy storage (SES), superconducting magnetic energy storage (SMES), and thermal energy storage (TES)), and hybrid or multi-storage systems that combine two or more technologies, such as integrating batteries with pumped hydroelectric storage or using supercapacitors and thermal energy storage. These different categories of ESS enable the storage and release of excess energy from renewable sources to ensure a reliable and stable supply of renewable energy. The optimal storage technology for a specific application in photovoltaic and wind systems will depend on the specific requirements of the system. It is important to carefully evaluate these needs and consider factors, such as power and energy requirements, efficiency, cost, scalability, and durability when selecting an ESS technology.

Computational fluid dynamics (CFD) analysis of air-cooled solar photovoltaic (PV/T) panels

The operating temperature of the PV penal has a significant impact on its conversion efficiency. High operating temperature reduce output power under the same solar radiation conditions. This study presents a CFD analysis of a solar PV/T system with a bottom active air cooling system to optimise the PV/T system operational characteristics. The study model was developed using fluent (ANSYS) software, along with bottom air duct with an inlet/outlet manifold for uniform airflow to the back side of the PV/T system. The performance of operating parameters of PV/T system was studied for various mass flow rates of air such as 0.04, 0.06, 0.08, and 0.1 kg/sec with irradiance intensity of 800 W/m2. The maximum temperature of the operational parameters such as the Solar PV/T system top surface, cell, bottom surface, and air inlet/outlet of the PV/T system were determined to be 48.8, 48.4, 47.3, and 24.5 °C at a flow rate of air of 0.01 kg/s and 800 W/m2 intensity of solar radiation.

Dynamic Wireless Power Transfer Characterization Environment

Dynamic Wireless Power Transfer is one of the emerging technologies for electric vehicle charging applications. This paper presents an electromagnetic Finite Element-State Space based characterization environment to predict the performance characteristics of DWPT systems. This environment is applied to characterize several configurations of a prototype DWPT system utilizing multi-ground transmitter coils and a vehicle receiver coil. The proposed environment would be useful as a characterization tool in a design process and could be used as a system identifier in a design optimization environment for this class of devices.

Dynamic operating characteristics of a compressed CO2 energy storage system

For the first time, the study investigated the dynamic performances of a compressed CO2 energy storage (CCES) system based on a dynamic model, which was validated using experimental data. The dynamic round-trip efficiency (RTE) of a scaled-up CCES system in two typical operation modes was studied, including Mode 1: the basic operation mode, where the inlet pressure of the compressor or the expander is not controlled, and Mode 2: the controlled operation mode, where the capacity for compression or expansion is regulated to remain constant. Dynamic RTE varies in the range 16.7%-56.7% in various operation modes. A new key performance indicator, utilization of tank (UOT), was defined to reflect how much working gas is used in a charging or a discharging process. In general, high charging and high discharging capacities lead to low UOTs and low RTEs. Moreover, the comparison between the dynamic model and its equivalent steady-state model showed a significant difference in system performances. The RTE of the steady-state model reaches 68.5%, which is much higher than the corresponding dynamic RTE of 55.3%.

Experimental and economic analysis of optimization potential for annual operating characteristics of air source transcritical CO2 heat pump system

In this study, an experimental system of air source transcritical CO2 heat pump system was established for investigating annual operating characteristics. A new operating strategy was proposed based on experimental results, and the economic analysis was studied based on different operating strategies. The results showed that the ambient temperatures had the slight effect on the system performance for summer and transition seasons conditions, which had the greater influence on that for winter conditions. When the ambient temperatures are lower, there were the obvious variations of the system heating capacity. The coefficient of performance decreases with the rise of water outlet temperatures. The annual operating expenses significantly reduced from 659.71 Chinese yuan to 514.72 Chinese yuan, which accounted for approximately 78% of the before-optimization cost. The optimized cycle was verified to be preferable, and the presented discussion could provide a promising solution for optimizing transcritical CO2 system.

Numerical analysis of pumped two-phase loop: Characterization of steady-state performance

With growing heat dissipation from advanced electronics, two-phase cooling promises effective and unmatched cooling. A pumped two-phase loop (P2PL) can acquire high power and heat flux from the electronics (heat source) and transport and dissipate it to a heat sink with small total thermal resistance at negligible pumping power consumption because of highly effective phase change (boiling and condensation) heat transfer. Owing to many advantages, in recent years, extensive research efforts have been dedicated to understanding fundamental mechanisms of heat and mass transfer in phase change heat exchangers (evaporators or condensers) at a component level. However, there is little work done for an entire two-phase cooling system as a closed loop which is essential to study the system performance characteristics and the contributions/interactions of each component to the system performance. A comprehensive thermal–hydraulic flow network model was developed to study the system performance characteristics. The pressure variation of the P2PL was calculated by considering the compressibility of the vapor volume in the P2PL to account for the effect of the amount of vapor in the system. The numerical results on the thermal and hydraulic performance characteristics of the P2PL for various operating and design parameters – evaporator heat load, mass flow rate, heat sink temperature, and microchannel dimensions – are discussed. It was found that the numerical results match well with the measured steady-state temperature and pressure profiles of the P2PL. The study also highlights the trade-off between the total system thermal resistance reduction and the increased pressure drop (pumping power) with an increase in mass flow rate. It was also found that the microchannels with smaller hydraulic diameters had significant heat transfer enhancement in the evaporator but poor system performance.

Influence Analysis and Performance Optimization of a Pneumatic Actuator Exhaust Utilization System

Due to the loss of exhaust energy, the compressed air energy utilization efficiency in pneumatics system is low. To realize the recovery and utilization of cylinder compressed air, a new type of compressed air utilization system is proposed, and the composition and working principle of the system are introduced. According to the working process of the system, the mathematical model of the system is established by using equations such as energy equation and gas state equation. The model is simulated by MATLAB/Simulink tools, and the correctness of the mathematical model is verified by experiments. The mathematical models are converted into dimensionless models, and the main parameters affecting the system's operating characteristics are obtained through model simulation analysis. The influencing parameters are optimized by using the analytic hierarchy process and the grey correlation analysis method, and the exhaust utilization efficiency of the system is 34.7 % under the optimal parameter combination. To further utilize the compressed air expansion, the opening and closing time of the solenoid valve was controlled to study the energy-saving effect of the system. The study found that when the initial pressure of the compressed air supply tank was set to 0.5 MPa, 0.6 MPa, and 0.7 MPa, the maximum energy saving efficiency was 23.25 %, 24.99 %, and 26.12 %, respectively. When the volume of the compressed air supply tank is set to 0.8 L, 1 L, and 1.2 L, the maximum energy-saving efficiency is 30.01 %, 24.99 %, and 21.51 %, respectively. This paper provides a new technical scheme for compressed air recovery and reuse, as well as a theoretical basis for the control of subsequent compressed air utilization systems.

VPSA process characterization for ISO quality green hydrogen generation using two practical multi-component biomass gasification feeds

The current work reports on the performance characterization of a VPSA system developed in-house for ISO-quality green hydrogen generation using commercially available zeolite 13X from two practical multi-specie feed streams generated from near-ambient oxy-steam and air gasification of casuarina wood chips. The breakthrough dynamics in a packed column, and the effect of extrinsic and intrinsic decision variables on the separation performance under a cyclic steady state are analyzed. Adsorption pressure and feed flow rate are noted as the most significant influencing factors. The assessment indicates the prevalence of bed thermal gradients and establishes N2 as a limiting gas impurity and CO2 desorption as a rate-determining step. Additionally, Pareto curves signifying the process capability to produce hydrogen of different grades are generated. The average recovery range achieved using syngas feed for obtaining purity >98 mol% (ISO grade A and above) at the lab-scale is noted to be 40.7–74.4%, which is analogous to published literature for fossil streams. Adopting the optimal parameters from the prototype studies and a precise gas contaminant analysis, the technology is practically demonstrated at the pilot scale (feed: 100 Nm3/h) for the continuous generation of fuel cell compliant hydrogen (fuel index ≥ 99.97) and a successful operation at an average recovery of 68.4 ± 3.5% is realized.

Electromechanical dynamic analysis for powertrain of off-grid switched-reluctance wind turbine hydrogen production system

Research on hydrogen production from wind power is important for improving wind energy utilization and hydrogen production efficiency; however, research on switched-reluctance hydrogen production from wind power has been relatively limited, and its system operation characteristics are unclear. Therefore, it is necessary to conduct research on the electromechanical coupling characteristics of switched-reluctance wind turbine hydrogen production systems (WTHPSs). An electromechanical dynamic model was established for the powertrain of an off-grid switched-reluctance WTHPS, including wind turbine, gear transmission system, switched-reluctance generator (SRG), and hydrogen production devices (HPDs). The model considers the detailed characteristics of the gear system, the nonlinear physical details of the HPD, and the electromagnetic characteristics of the generator. An improved control strategy was also developed for the SRG to reduce torque fluctuation. The steady- and transient-state electromechanical characteristics were simulated and analyzed, and the influences of the SRG control strategy and HPD switching on the system dynamic characteristics and hydrogen production rate were investigated. First, with respect to the improved SRG control strategy, the results show that SRG torque fluctuation can be reduced. The influence of the SRG electromagnetic torque on the transmission system gradually decreases from the high-speed stage to the low-speed stage. However, for a sudden decrease in wind speed, the SRG with the improved control strategy tracks the reference speed more slowly. Second, with respect to the hydrogen production rate, almost no difference can be observed between the two SRG control strategies. Single and multiple HPDs have a slight effect on the dynamic characteristics of the system when the HPDs can consume all the generated power. The production rate of HPDs in a parallel connection is higher than that with a single device at the same power, and the difference increases with an increase in power.

Multi-attribute decision-making tools for selection of PCMs as latent heat thermal energy storage integrated with solar-driven LiBr-H2O vapor absorption system

The selection of PCM is quite decisive for the efficient and effective design of latent heat thermal energy storage to be coupled with a solar-powered single-effect LiBr-H2O vapour absorption system. Aligned to the operating characteristics of a solar-powered LiBr-H2O vapour absorption system, PCM must have a melting temperature between 80 and 100°C and high latent heat of fusion. A total of 14 PCMs are first scrutinised in the present research work based on melting temperatures ranging from 80 to 100°C. Further, their ranking is done and verified with the MADM examination. Thermophysical properties (latent heat, density, thermal conductivity, specific heat) and cost have been considered the criteria for selecting PCM. AHP is used to calculate the relative weights among the criteria identified. After that, the ranking is done with the help of TOPSIS. MODM is used to optimise these PCMs by drawing variations between the objective functions of thermal energy storage density and thermal diffusivity. Xylitol, Acetamide, (NH4)Al(SO4)·6H2O have been ranked as the top three due to TOPSIS and MODM examination. This research output supports selecting the appropriate PCM when designing latent thermal energy storage systems to integrate an application.

Recursive bit assignment with neural reference adaptive step (RNA) MPPT algorithm for photovoltaic system

Recent research has focused on photovoltaic (PV) systems due to their important properties. The efficiency of the PV system can be enhanced by many Maximum Power Point Tracking (MPPT) algorithms proposals. MPPT algorithms are used to achieve maximum PV output power by optimizing the duty cycle of the DC–DC buck/boost converter. This paper introduces an RNA algorithm as an efficient MPPT algorithm for the photovoltaic system. This proposed RNA algorithm consists of two main segments. The first segment is an artificial neural network for generating reference power. The second segment is a proposed Recursive Bit Assignment (RBA) network to allow variable step size of the boost converter duty cycle. The instant PV power adopts the RBA network to produce the variable duty cycle increment value. Additionally, the neural network is implemented in such a way to obtain the best performance. Many simulation results using MATLAB to test the system performance are presented. The performance characteristics of the photovoltaic system with variable irradiance and variable temperature are simulated. From results, the proposed RNA algorithm achieves fast tracking time, high energy efficiency, true maximum power point and acceptable ripple. Additionally, comparisons between the RNA algorithm and other related algorithms such as Perturb and Observe, the Neural Network and the Adaptive Neural Inference System Algorithms are executed. The proposed RNA algorithm achieves the best performance in all case studies such as; irradiance profile variation, severe temperature and irradiance diversions, and partial shading conditions. Besides, the experimental circuit of the PV system is also presented.

Экспериментальное исследование накопления углеродных отложений в кислородно-метановом модельном газовом тракте

The paper considers mechanisms of the carbon deposits formation on the metal surface at contact with the gas phase containing products of incomplete combustion of the oxygen-methane generator gas. The first mechanism is the socalled mechanism of metal dust formation, which products remain on the wall surface and form the carbon deposits, the second is the mechanism of carbon deposits formation associated with the carbon particles in the gas flow, which are being deposited on the wall. An experimental system was developed with the working section being a model path of the oxygen-methane generator gas of the reducing composition; and accumulation of the carbon deposits was experimentally studied. When selecting performance characteristics of the experimental system, features of the liquid rocket engine gas path were taken into account; therefor, the experimental system was having characteristics closer to the expected characteristics of the full-scale gas path. Intensities of the deposit formation on samples of metallic material and reference quartz were compared. It was established that the main mechanism for the carbon deposits formation was precipitation of soot contained in the generator gas flow onto the wall of the gas path. The number of deposits was determined by weight. The range of the fuel components ratio was identified, where formation of the deposits was minimal

Influence of Air Staging on the Operation Characteristics of the CFB System

Influence of Air Staging on the Operation Characteristics of the CFB System

Performance comparison and characterization of multi-pressure vapor compression systems at optimized conditions for simultaneous cooling and heating application

We performed numerical thermodynamic analyses of 3 multi-pressure vapor compression system configurations (cascaded, with flash tank, and with ejector) to evaluate their coefficient of performance improvements in combined cooling and heating applications. Six refrigerants were evaluated, and 25 temperature pairs of −15 °C to 25 °C cooling and 45 °C to 85 °C heating were specified. Critical parameters of the 3 configurations were varied for performance optimization. The compressor outlet temperature was constrained to prevent lubricant breakdown in actual implementation. Maximum performance improvements of 34.41 %, 39.20 %, and 46.34 % for the cascade, with flash tank, and with ejector systems, respectively, were attained. Moreover, the total number of temperature pairs exceeding the temperature limit was reduced from 19/25 to 17/25, 1/25, and 9/25 for the cascade, with flash tank, and with ejector systems, respectively. The best refrigerants to use were found to be Ammonia or R245fa as the low-pressure loop refrigerant with R245fa as the high-pressure loop refrigerant for cascade systems, Ammonia or R245fa for systems with flash tank, and R245fa for systems with ejector. This work demonstrated and quantified the ability of multi pressure configurations to increase the performance of vapor compression systems in simultaneous cooling and heating applications.

Real-Time Compensation for SLD Light-Power Fluctuation in an Interferometric Fiber-Optic Gyroscope.

An interferometric fiber-optic gyroscope (IFOG) demodulates a rotation signal via interferometric light intensity. However, the working environments of IFOGs typically involve great uncertainty. Fluctuations in temperature, air pressure, electromagnetic field, and the power system all cause the power of the superluminescent diode (SLD) light source to fluctuate as well. In this invited paper, we studied the effects of SLD power fluctuation on the dynamic and static performance characteristics of a gyro system through the use of a light-power feedback loop. Fluctuations of 0.5 mA, 1 mA, and 5 mA in the SLD source entering the IFOG caused zero-bias stability to be 69, 135, and 679 times worse. We established an effective method to monitor power fluctuations of SLD light sources and to compensate for their effects without increasing hardware complexity or system cost. In brief, we established a real-time power-sensing and -compensating system. Experimental results showed that for every 0.1 mA increase in the fluctuation amplitude of the driving current, the zero-bias stability became 4 to 7 times worse, which could be reduced about 95% through the use of SLD power compensation.