Full Load Operation Research Articles

Conversion of a small size passenger car to hydrogen fueling: simulation of full load performance

Abstract Hydrogen offers a valid choice when considering zero emissions transport. This alternative fuel is well suited for spark ignition (SI) engines and it can be implemented with relatively minor changes in terms of added components. Initial evaluations of feasibility with respect to available space for the fuel tank revealed that it is possible to convert a small size passenger car to hydrogen fueling and maintain a range comparable to the fully electric alternative. Peak power assessment showed that additional boosting was required compared to gasoline operation, close to the limit of compressor surge. As a result, the present study extended the engine speed range so as to evaluate full load performance levels that can be obtained when using hydrogen. 0D/1D simulation was applied for simulating power unit output as well as related control parameters. A dedicated laminar flame speed sub-model was implemented for including fuel chemistry effects. Predicted combustion phasing showed the required changes in ignition timing when switching fuels and revealed that the engine could be operated close to stoichiometry when using hydrogen. A reduction of torque was calculated at low engine speed, even if peak power ratings were practically the same as with gasoline fueling.

Development, Construction, Operation and Maintenance of Shouhang Dunhuang 100 MW Molten Salt Solar Power Tower Plant

The Shouhang Dunhuang 100 MW molten salt solar power tower plant is the first 100 MW-scale commercial demonstration project in China. The plant started to break ground in October 2016, was completed and connected to the grid for power generation in December 2018, and achieved full-load operation in June 2019. This paper comprehensively introduces the development, design, and construction process of the project as well as its operation and maintenance over the past five years, and shares experiences and lessons learned from the project.

Managing a Major Lube Oil Leak on a 150 MW Steam Turbine Power Plant

This paper focuses on the management of a major lube oil leak from bearing box No. 2 at the Sumsel-5 Power Plant. The steam turbine, a super high-pressure has been operational since April 2016. Overhauls in 2019 and 2023 addressed issues such as wear on oil deflectors, abnormal gland sealing clearances, and oil sealing wear. However, oil leakage persisted, necessitating further interventions. Rectification efforts included replacing oil deflectors, adjusting clearance, installing additional venting lines, the addition of a fiber gasket at bearing box No. 2 aimed to reduce and manage oil leakage. These measures resulted in a significant reduction in the oil leakage rate, from approximately 2826 ml/hr to 75 ml/hr during full load operation, representing a decrement of around 97.3%. Additionally, the frequency of lube oil top-ups decreased dramatically, leading to substantial cost savings for the plant. From a safety and environmental perspective, rectification measures mitigated fire hazards and reduced oil wastage, minimizing environmental impact. Regular monitoring of lubrication oil quality further ensures operational reliability. Although complete elimination of the oil leak was not achieved, the turbine continues to operate smoothly under manageable oil leakage conditions.

Applicability of Variable-Geometry Turbocharger for Diesel Generators under High Exhaust Back Pressure

The exhaust back pressure of diesel engines is becoming increasingly higher nowadays. In order to keep discharging exhaust unhindered and operating smoothly under high exhaust back pressure, a large reduction in engine maximum brake output is often observed, as well as increased fuel consumption and lower combustion efficiency with heavy exhaust smokes. In our previous study, “Applicability of Reducing Valve Timing Overlap for Diesel Engines under High Exhaust Back Pressure”, a reduced valve timing overlap of 12 °CA partially improves the brake output and BSFC for a fixed-geometry turbocharged diesel engine under high exhaust back pressures. A potential solution for restoring the brake output under high exhaust back pressures could be the use of variable-geometry turbochargers. In this study, a variable-geometry turbocharger is applied to a diesel engine to study the engine performance characteristics and applicability, especially the further improvement of brake output and the brake-specific fuel consumption of the engine. Continuing with the results of our previous research, a basic setting of 12 °CA for the valve timing overlap is set up for the subsequent engine performance simulations in this study (using GT-Power SW). Via simulation, exhaust back pressures of 25 kPa, 45 kPa, and 65 kPa gauge are studied for a turbocharged diesel engine. The results for the engine parameters, including brake output, brake-specific fuel consumption, compressor outlet temperature, turbine inlet temperature, intake air mass flow rate, and exhaust mass flow rate are analyzed. The results of the variable-geometry turbocharger, including turbocharger speed, pressure ratios and efficiencies of compressor and turbine are also analyzed. The results indicate that the brake output and brake-specific fuel consumption are effectively improved under full-load operation with an adequate variable-geometry turbocharger rack position. Operable ranges of rack position are also set up for different back pressures.

Multivariate and hybrid data-driven models to predict thermoelectric power plants fuel consumption

Ensuring the reliable operation of diesel/Heavy fuel oil (HFO) engines in Thermoelectric Power Plants (TPPs) requires constant monitoring and control of operational parameters. Time series forecasting methods can predict physical system characteristics based on historical data, which can help regulate engine operational parameters. Despite the widespread use of these techniques in coal and natural gas powered TPPs, further examination of their application in large diesel/HFO engines in Brazilian TPPs operating under dispatch conditions is needed. This work investigated the fuel consumption generalization capacity of linear, nonlinear, and hybrid prediction models, both considering univariate and multivariate approaches, related to a TPP engine-driven generator in Pernambuco, Brazil. For multivariate model development, exogenous variables were selected based on change of causality overtime analysis, which sought not only to infer the relationship between signals but also to identify the influence regime of each causality during operations. The feature selection step initially identified a performance improvement when eight additional features were used. However, each feature causality throughout the operations indicated that only four signals helped significantly predict consumption in different ways. The exogenous variables introduction to ARIMA and NAR models resulted in significant improvements only to the nonlinear approach, NARX, which could recognize operational disturbances more quickly when compared to other analyzed models. In addition, the application of additive and multivariate hybrid models provided the ability to detect more complex variations and, at the same time, maintain model stability during full-load operation, benefiting from linear and nonlinear characteristics capturing ability related to the combined model.

Investigation of cable current carrying capacity improvement and its effects on transmit power between Egypt and Saudi Arabia project

This paper presents an investigation for current carrying capacity improvement of high voltage cable laid in unfavorable regions crowded with groups of high and extra high voltage power cables. A proposed MATLAB program is developed to predict the ampacity of these cables at 220 kV and 500 kV. The cables are laid in various formats and under various laying conditions. Temperature distribution inside cable layers and through soil layers are studied using a finite element model (FEM) with COMSOL software during full load operation. Calculations are based on Neher-McGrath methods in accordance with IEC 60,287. The results are compared with the manufacturer's technical guarantee. Furthermore, this paper presents a proposed cable ampacity calculation that is applied to determine the ideal cross section area for four circuits of 500 kV underground cables that will serve for future power transmission between Saudi Arabia and Egypt.

Performance optimization of phase change energy storage combined cooling, heating and power system based on GA + BP neural network algorithm

Combined cooling, heating, and power systems present a promising solution for enhancing energy efficiency, reducing costs, and lowering emissions. This study focuses on improving operational stability by optimizing system design using the GA + BP neural network algorithm. By integrating phase change energy storage, specifically a box-type heat bank, the system effectively addresses load imbalance issues by aligning building thermoelectric demand with system output. This approach increases energy storage density, improves space utilization efficiency, and streamlines maintenance. The study evaluates the system's implementation in residential buildings across five climate zones, leveraging the GA + BP neural network algorithm to optimize energy, economic, and environmental aspects. The proposed full-load operation strategy, rather than the traditional hybrid operation strategy, reduces the need for frequent system adjustments, enhancing stability and efficiency. Results show a significant reduction in primary energy consumption, ranging from 7.74 × 103 to 2.08 × 106 kWh across the five cities studied. Energy optimization indexes improve by 0.27 %–3.78 % compared to electricity load operation and 1.94 %–8.58 % compared to thermal load operation. Comprehensive optimization indexes also demonstrate enhancements ranging from 5.78 % to 27.68 % and 2.67 % to 28.22 %, respectively. The full-load operation strategy proves highly effective for energy savings in residential buildings, offering innovative contributions to optimizing combined cooling, heating, and power systems, developing distributed energy systems, and promoting sustainable building development.

Influences of iso-amyl nitrate oxygenated additive on mahua methyl ester/diesel blends thermal stability and crdi engine performance characteristics

Mahua oil is a remarkable fuel since it has a similar calorific value to diesel and has similar viscosity, flash point, and boiling points to diesel. However, since mahua oil has a lower cetane number than diesel when utilized as a blend, it displays a longer ignition delay and a greater peak heat release rate, resulting in higher NOx emission. To decrease the negative impact of mahua oil on NOx emission, an effort is made to introduce the ignition improver in different proportions (i.e., 5-20% by vol). Due to its higher latent heat, IAN shows some adverse effects on performance and emission outcomes. An investigation is conducted on a CRDI engine using mahua methyl ester blended with diesel by adding oxygenated additives to the engine characteristics. The emissions like HC, CO, and smoke were reduced by 16.32, 23.56, and 23.12%. The improved combustion process increases NOx and CO2 emissions by 13.62 and 19.89%. Also, an increase in HRR and CP values was noticed at full load operation. Additionally, it is observed that the engine’s performance is enhanced using 15% Iso-amyl nitrate (IAN), indicating that the IAN blend is a useful ignition improver for mahua oil and diesel blends.

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.

Design and Analysis of an H-Type Pickup for Multi-Segment Wireless Power Transfer Systems

To tackle the complex wireless power supply requirements in the Automated Material Handling System (AMHS) of semiconductor wafer factories, this paper presents a design method for a magnetic coupling mechanism based on a Multi-Segment Wireless Power Transfer (MSWPT) system for dynamic wireless power supply in segmented track configurations. Firstly, the track is approached using Inductive Power Transfer (IPT) technology combined with an LCC-S resonant structure transmitter (Tx). Following this, the feasibility of the H-type pickup is assessed through magnetic and electrical circuit analyses, which leads to the preliminary determination of the pickup dimensions by means of finite element magnetic and thermal simulations. Furthermore, an analysis of the mutual inductance drop is conducted under various track structure parameters during track crossing and curve negotiation operation conditions. Secondly, a dual-coil winding method is proposed to reduce the insulation stress on the PCB board. Additionally, a method for calculating the wire length and a design process for the overall parameters of the pickup are derived. Finally, two Txs and a 1.5 kW power receiver (Rx) were designed to verify the mutual inductance fall under the aforementioned conditions. During low-speed full-load operations, a constant-voltage output was achieved through the proposed dual-loop PI control strategy, thereby meeting the requirements for a constant-voltage output in industrial applications.

Studi Ekonomis Implementasi Kapasitor Dengan Detuned Reactor Untuk Meningkatkan Efisiensi Faktor Daya

The use of electrical energy plays a vital role in supporting the continuity of production processes in industrial environments. One critical area that heavily relies on electrical power supply is in the planning of installing a capacitor bank with a detuned reactor. The primary objective of this planning is to enhance the power factor (cos φ) from 60% to 85.2% during full-load operations and up to 94% when operating as per demand simulations. The evaluation of power quality from the implementation of the Capacitor with Detuned Reactor is conducted through simulations using ETAP 12.6.0 software.The simulation results from ETAP 12.6.0 produce comparative graphs between buses equipped with the Capacitor with Detuned Reactor and buses without it, both during full-load operational conditions and when only operating in simulations. The information derived from the simulation provides a deeper insight into the impact of installing the capacitor with detuned reactor on power factor and power quality within this industrial environment. With this understanding, further steps can be taken to optimize the electrical power system within the industrial setting.

Performance and emissions assessment under full load operation of an unmodified diesel engine running on biodiesel-based waste cooking oil synthesized using JPW solid catalyst

The current study builds upon the prior research (Mulkan et al., 2023) [1], which successfully created an innovative solid catalyst from discarded jackfruit peel waste (JPW) to produce biodiesel from waste cooking oil (WCO). Expanding on this initial research, our study's primary objective is to assess the performance and emissions attributes of a diesel engine when utilizing blends of WCO biodiesel and conventional diesel fuel under full load conditions, covering engine speeds from 1200 to 2400 rpm. The results show that as engine speed increases, brake-specific fuel consumption (BSFC) decreases by an average of 16.67%–22.69%, while brake thermal efficiency (BTE) increases by 16.67%. Engine torque initially decreases and drops significantly at higher speeds, while brake power (BP) proportionally rises. Notably, substantial reductions in CO emissions (ranging from 6.11% to 48.63%) were observed at all engine speeds compared to pure diesel. However, CO2 and NO emissions generally increased, although some fuel samples demonstrated reductions. Hydrocarbon emissions decreased with higher engine speeds, while smoke opacity increased, with slight reductions observed for specific fuel samples at 1800–2400 rpm. In conclusion, blending WCO biodiesel synthesized using the JPW catalyst with pure diesel results in improved engine performance and reduced exhaust emissions.

Effect of different draft tube designs on the phase resonance in a pump-turbine based on compressible CFD simulation

An investigation into projects with significant noise issues during full-load turbine operation revealed a distinct draft tube elbow design difference compared to more successful projects. This prompted an initiative to explore the impact of draft tube shape on pressure pulsations within the pump-turbine during full-load operation. Various draft tube designs were tested on the same prototype-scale pump-turbine unit using 3D compressible transient simulations. Results indicated increased pressure pulsation amplitude in the spiral casing for the flat elbow draft tube, accompanied by phase shifts that rendered pressure pulsations close to zero at certain locations, converting direct pulsations into indirect ones. Moreover, phase variations in the opposing runner channel aligned with multiples of the rotation period, suggesting possible cancellation of pressure pulsation waves. These improvements were confirmed through contour analysis, which showed reduced negative pressure areas in the draft tube, minimized pressure differences, and more uniform and stable streamlines. This study analyses the influence of draft tube shape on internal flow field pressure fluctuations, offering theoretical insights for enhancing pump turbine stability and guiding further research.

Numerical Assessment of a Rich-Quench-Lean Staging Strategy for Clean and Efficient Combustion of Partially Decomposed Ammonia in the Constant Pressure Sequential Combustion System

Abstract In a future energy system prospective, predictably dominated by (often) remote and (always) unsteady, nondispatchable renewable power generation from solar and wind resources, hydrogen (H2) and ammonia (NH3) have emerged as logistically convenient, chemically simple and carbon-free chemicals for energy transport and storage. Moreover, the reliability of supply of a specific fuel feedstock will remain unpredictable in the upcoming energy transition period. Therefore, the ability of gas turbine combustion systems to seamlessly switch between very disparate types of fuels must be ensured, aiming at intrinsically fuel-flexible combustion systems, i.e., capable of operating cleanly and efficiently with novel carbon-free energy vectors like H2 and NH3 as well as conventional fossil fuels, e.g., natural gas or fuel oils (back-up feedstock). In this context, a convenient feature of Ansaldo's constant pressure sequential combustion (CPSC) system, resulting in a fundamental advantage compared to alternative approaches, is the possibility of controlling the amount of fuel independently fed to the two combustion stages, depending on the fuel reactivity and combustion characteristics. The fuel-staging strategy implemented in the CPSC system, due to the intrinsic characteristics of the auto-ignition stabilized reheat flame, has already been proven able of handling fuels with large hydrogen fractions without significant penalties in efficiency and emissions of pollutants. However, ammonia combustion is governed by widely different thermo-chemical processes compared to hydrogen, requiring a considerably different approach to mitigate crucial issues with extremely low flame reactivity (blow-out) and formation of significant amounts of undesired pollutants and greenhouse gases (NOx and N2O). In this work, we present a fuel-flexible operational concept for the CPSC system and, based on unsteady Reynolds-Averaged Navier–Stokes (uRANS) and large eddy simulation (LES) performed in conjunction with detailed chemical kinetics, we explore for the first time full-load operation of the CPSC architecture in a Rich-Quench-Lean (RQL) strategy applied to combustion of partially-decomposed ammonia. Results from the numerical simulations confirm the main features of ammonia-firing in RQL operation already observed from previous work on different combustion systems and suggests that the CPSC architecture has excellent potential to operate in RQL-mode with low NOx and N2O emissions and good combustion efficiency.

Studija o projektovanju sistema dizel pumpi za gašenje požara za stambenu zgradu

Currently, on-site diesel firefighting pump systems are significantly necessary for high-rise buildings. This study presents a process for designing diesel fire pump systems for high-rise buildings using AVL BOOST software associated with mechanical calculations. The Kirloskar CPHM 80/32 pump and DESSUN 4DSP-75 diesel engine were selected based on preliminary calculations to match the requirements of Vietnamese standards for a 79-meter building. AVL BOOST software has been used to simulate the full load performance characteristic of the engine; then, a partial load characteristic is determined for the adequate pump that requires input power at a rated speed of about 2975 rpm. The transmission consists of the propeller drive, and flanges were designed to connect the engine and pump. The findings show that utilizing AVL BOOST software is considerably helpful in determining the engine's partial load characteristics, saving time and costs. This study contributes a foundation for practical research to calculate and design the firefighting pump mechanical systems in high-rise buildings.

Impact of thermal swing piston top land coatings on gasoline engine performance and raw emissions

Upcoming legislations aim to significantly reduce carbon dioxide and hydrocarbon emissions compared to current regulations. Accordingly, options have to be evaluated to not only convert the raw emissions in a catalytic converter, but also to reduce the raw emissions from the combustion process in the first place. Therefore, thermal piston top land coatings, which lead to an oscillating piston surface temperature were investigated on a single cylinder research engine using a gasoline RON95E10 fuel. Measurements were conducted at a compression ratio of 12.2 and a long Miller intake event. In this manuscript the results achieved with yttria stabilized zirconia in comparison to an uncoated piston are displayed. Significant effects of the coatings on the indicated efficiency could be observed mainly at low engine speeds and loads due to the high share of fuel energy in the wall heat losses and incomplete combustion. At these operating points, the reduction of wall heat losses can almost be fully transferred into indicated efficiency, leading to an increase in indicated efficiency of 6.3% by the yttria stabilized zirconia coating. At higher engine speeds and loads, the advantage in indicated efficiency vanishes and a decrease of 0.5% can be observed. Near full load operation the indicated efficiency slightly lower. However, the effects of a thermal swing coating on combustion efficiency and wall heat losses strongly depend on the operation conditions.

Numerical assessment of water injection for improved thermal efficiency and emissions control in a medium-duty hydrogen engine for transportation applications

The existing political environment and the growing worries about climate change have resulted in the imposition of stringent regulations on traditional propulsion systems reliant on fossil fuels. While new technologies are being investigated to substitute internal combustion engines, their current technological advancement necessitates further development and refinement in order to emerge as a viable alternative to the conventional internal combustion engine. The utilization of hydrogen-powered internal combustion engines has showcased their capacity to rapidly achieve complete decarbonization in the transportation industry. However, these engines continue to encounter limitations regarding their operational range that need to be addressed. The utilization of EGR for controlling combustion instabilities and mitigating NOx formation still has significant limitations in operating at high engine loads, mainly affecting the boost requirements for reaching high power densities. The present work evaluates the potential of substituting the EGR dilution with a water injection system for reaching full load operation on a conventional diesel engine, assuming the minimum modifications required for it to work under H2 combustion. The study is carried out assuming a multi-cylinder engine representing the medium- to high-duty transport sector. The evaluation includes a comparison of the engine performance and emissions obtained when using EGR and water injection at full load, comparing the requirements of the boost system for both strategies to reach power densities of 24 bar of BMEP equivalent to modern diesel applications. The results show that WI allows for significantly reduced boost pressure requirements lowering intake pressure by up to 1 bar, while achieving very similar engine efficiency and a reduction of NOx emissions around 80%, resulting a similar effectiveness compared with EGR. Additionally, WI provides additional prevention against undesired autoignition.

Multi-Objective Experimental Combustor Development Using Surrogate Model-Based Optimization

Abstract The majority of premixed industrial gas turbine combustion systems feature two or more separately controlled fuel lines. Every additional fuel line improves the operational flexibility but increases the complexity of the system. When designing such a system, the goals are low emissions of various pollutants and avoiding lean blowout or extinction. Typically, these limitations become critical under different load conditions of the machines. Therefore, it is particularly challenging to develop combustors for stable and clean combustion over a wide operating range. In this study, we apply the Gaussian process regression machine learning method for application to burner development, with the aim of improving the process, which is often driven by a trial-and-error approach. To do so, a special pilot unit is installed into a full-scale industrial swirl combustor. The pilot features 61 positions of fuel injection, each of which is equipped with an individual valve, allowing to modify the fuel–air mixture close to the flame root in various degrees. In fully automatized atmospheric tests, we use the pilot system to train two surrogate models for different design objectives of the combustor, relevant for full load and part load operation, respectively. Once trained, the models allow for prediction for any possible injection scheme. In combination, they can be used to identify pilot injector configurations with an improved operation range in terms of low NOx emissions and part load stability. The adopted multimodel approach enables combustor design specifically for high operational flexibility of gas turbines, but can also be extended to other similar industrial development processes.

System Design, Optimization and 2nd Law Analysis of a 100 MWe Double Reheat s-CO2 Power Plant at Full Load and Part Loads

Super-critical Carbon dioxide (s-CO2) power plants are considered to be efficient and environmentally friendly compared to the traditional Rankine cycle-based steam power plants and Brayton cycle-based gas turbine power plants. In this work, the system design of a coal-fired 100 MWe double reheat s-CO2 power plant is presented. The system is also optimized for efficiency with turbine inlet pressures and the recompression ratio as the variables. The components needed, mass flow rates of various streams and their pressures at various locations in the system have been established. The plant has been studied based on 1st and 2nd laws at full load and at part loads of 80%, 60% and 40%. Operating parameters such as mass flow rate, pressure and temperature have considerably changed in comparison to full load operation. It was also observed that the 1st law efficiency is 53.96%, 53.93%, 52.63% and 50% while the 2nd law efficiency is 51.88%, 51.86%, 50.61% and 48.1% at 100%, 80%, 60% and 40% loads, respectively. The power plant demonstrated good performance even at part loads, especially at 80% load, while the performance deteriorated at lower loads. At full load, the highest amount of exergy destruction is found in the main heater (36.6%) and re-heaters (23.2% and 19.6%) followed by the high-temperature recuperator (5.7%) and cooler (4.1%). Similar trends were observed for the part load operation. It has been found that the recompression ratio should be kept high (>0.5) at lower loads in order to match the performance at higher loads. Combustion and heat exchange due to finite temperature differences are the main causes of exergy destruction, followed by pressure drop.

Rating and sizing analysis of the solar chimney power plant considering uncertainty in solar radiation and under different load conditions

ABSTRACT The main focus of this research is on modeling and analyzing an industrial-scale solar chimney power plant (SCPP) under actual or realistic conditions. While most of earlier studies considered the steady state kind of solar radiation, this study is based on the assumption of the diffuse and erratic nature of solar energy in calculating the sizing rating of SCPP. Moreover, the use of uncertainties in solar radiations is time-consuming and difficult, and hence a theoretical approach is used to get the required results. Statistics and probability theory concerning solar radiation and weather data of Mumbai, India region are used for said analysis. The best generator rating and daily energy output are determined by taking into consideration variables like chimney height, collector radius, and storage thickness below the absorber plate of SCPP. Based on the aforementioned characteristics, one may construct SCPP sizing curves to yield 136, 435, and 945 kWh energy generation in 24 h period. It is essential to consider the full load and part load operations of the generator in order to prevent the unused kinetic energy linked to low velocity and increased velocity. While the majority of the past research by various researchers was carried out under full-load conditions, this study also addresses half-load situations. The current effort will help manufacturers and the scientific community develop sizing and rating taking into account different sun radiation statistics.