scholarly journals Efficiency Reduction in Stirling Engines Resulting from Sinusoidal Motion

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2887 ◽  
Author(s):  
Salvatore Ranieri ◽  
Gilberto Prado ◽  
Brendan MacDonald
Keyword(s):  
Thermal Efficiency ◽  
Thermal Power ◽  
Heat Sources ◽  
Sinusoidal Motion ◽  
Wide Range ◽  
Stirling Engines ◽  
Isothermal Analysis ◽  
The Impact ◽  
Alpha Type ◽  
The Ideal

Stirling engines have a high potential to produce renewable energy due to their ability to use a wide range of sustainable heat sources, such as concentrated solar thermal power and biomass, and also due to their high theoretical efficiencies. They have not yet achieved widespread use and commercial Stirling engines have had reduced efficiencies compared to their ideal values. In this work we show that a substantial amount of the reduction in efficiency is due to the operation of Stirling engines using sinusoidal motion and quantify this reduction. A discrete model was developed to perform an isothermal analysis of a 100cc alpha-type Stirling engine with a 90 ∘ phase angle offset, to demonstrate the impact of sinusoidal motion on the net work and thermal efficiency in comparison to the ideal cycle. For the specific engine analyzed, the maximum thermal efficiency of the sinusoidal cycle was found to have a limit of 34.4%, which is a reduction of 27.1% from Carnot efficiency. The net work of the sinusoidal cycle was found to be 65.9% of the net work from the ideal cycle. The model was adapted to analyze beta and gamma-type Stirling configurations, and the analysis revealed similar reductions due to sinusoidal motion.

Comparative Analysis of EGR and Air Dilution in Spark-Ignited Natural Gas Engines

2017 ◽  
Author(s):  
William Glewen ◽  
Chris Hoops ◽  
Joel Hiltner ◽  
Michael Flory
Keyword(s):  
Natural Gas ◽  
Power Density ◽  
Thermal Efficiency ◽  
Gas Temperature ◽  
Natural Gas Engines ◽  
Cycle Simulation ◽  
Wide Range ◽  
Charge Mixture ◽  
The Impact ◽  
Three Way Catalyst

Industrial natural gas engines are used in a wide range of applications, each with unique requirements in terms of power density, initial cost, thermal efficiency, and other factors. As a result of these requirements, distinct engine designs have evolved to serve various applications. Heavy-duty spark-ignited engines can generally be divided into two broad categories based on their charge characteristics and method of emissions control. Stoichiometric engines are widely used in applications where first cost, absolute emissions and relative engine simplicity are more important than fuel consumption. In most of the developed world, stoichiometric engines are equipped with a three-way catalyst to control emissions of nitrogen oxides (NOx) as well as products of incomplete combustion and raw unburned fuel. Dilution of the charge mixture with excess air reduces the peak combustion gas temperature and associated heat rejection. As a result, lean burn engines are generally able to achieve higher efficiency and power density without inducing excessive component temperatures or end gas knock. NOx formation is mitigated by the reduced gas temperatures, such that most regulatory standards can currently be met in-cylinder. Significant obstacles exist to meeting more stringent future emissions regulations in this manner, however. Another possible strategy is to dilute the charge mixture with recirculated exhaust gas. This offers similar benefits as air dilution while maintaining the ability to use a three-way catalyst for emissions after-treatment. While similar principles apply in either case, the choice of diluent can have a significant impact on knock resistance, emissions formation, thermal efficiency, and other parameters of importance to engine developers and operators. This work aimed to examine the unique characteristics of EGR and air dilution from a thermodynamic and combustion perspective. A combination of cycle simulation tools and experimental data from a single-cylinder test engine was applied to demonstrate the impact of diluent properties on a fundamental level, and to illustrate departures from idealized behavior and practical considerations specific to the development of combustion systems for spark-ignited natural gas engines.

scholarly journals SYSTEM OF AUTOMATIC CONTROL OF THE LEVEL OF STEAM POWER GENERATORS ON THE BASIS OF THE REGULATION CIRCUIT WITH SMOOTHING OF THE SIGNAL

2021 ◽  
Vol 22 (1) ◽  
pp. 287-297
Author(s):  
Dilnoza Umurzakova
Keyword(s):  
Automatic Control ◽  
Water Level ◽  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Steam Generators ◽  
Wide Range ◽  
Steam Boilers ◽  
The Impact

The purpose of this article is to develop high-quality combined automatic control systems (ACS) for the water level in the drum of steam boilers of thermal power plants (TPPs), which can significantly improve the quality of regulation and increase the efficiency of TPPs in a wide range of load changes. To improve the quality of water level control in the drum of steam generators of nuclear power plants with a pressurized water-cooled power reactor (PWPR), it is proposed to use a combined automatic control system based on a control loop with a correcting PI-controller tuned to a symmetrical optimum, with smoothing the reference signal and device compensation of the most dangerous internal and external measurable disturbances. A technique has been developed for assessing the impact of changes in the quality characteristics of transients of combined self-propelled guns by the water level in the drum of steam boilers and steam generators on the safety, reliability, durability, and efficiency of thermal power equipment of thermal power plants. Comparison was made of direct indicators of the quality of three ACS (typical and three-pulse, digital system with an observer state, and the proposed combined ACS). The simulation results of transients of the proposed and typical three-pulse self-propelled guns confirmed the advantages of the first. ABSTRAK: Artikel ini bertujuan bagi membina sistem kombinasi automatik (ACS) berkualiti tinggi bagi aras air dalam drum dandang stim tenaga terma logi kuasa (TPP). Ini dapat meningkatkan mutu peraturan dan meningkatkan kecekapan TPP secara signifikan dengan pelbagai perubahan beban. Bagi meningkatkan kualiti kawalan aras air dalam drum penjana wap loji kuasa tenaga nuklear dengan reaktor berpendingin air bertekanan (PWPR). Gabungan sistem kawalan automatik berdasarkan gelung kawalan dengan pembetulan PI telah dicadangkan dan diselaraskan simetri secara optimum, dengan melancarkan isyarat rujukan dan pembetulan peranti dari gangguan yang boleh diukur dari dalam dan luar. Satu teknik telah dibina bagi menilai kesan perubahan ciri kualiti transien gabungan berjentera pada aras air di tong dandang stim dan drum penjana wap pada keselamatan, kebolehpercayaan, ketahanan dan kecekapan peralatan tenaga terma loji janakuasa. Perbandingan dibuat pada kualiti tiga ACS (sistem digital khas dan tiga signal dengan keadaan pemerhati dan gabungan ACS yang dicadangkan). Hasil sistem simulasi transien yang dicadangkan dan tiga signal biasa berjentera mengesahkan kelebihan pada yang pertama.

scholarly journals Analisa Isolasi Pipa Generator Mesin Stirling Tipe Alpha Sudut Fasa 180°

2021 ◽  
Vol 6 (1) ◽  
pp. 1-7
Author(s):  
Dhimas Satria ◽  
Rina Lusiani ◽  
Erny Listijorini ◽  
Aswata
Keyword(s):  
Heat Loss ◽  
Phase Angle ◽  
Stirling Engine ◽  
Compression Process ◽  
Stirling Cycle ◽  
Compression Speed ◽  
Stirling Engines ◽  
Pipe Insulation ◽  
Alpha Type ◽  
The Ideal

This research is a development of previous research, where in the previous research, a design innovation was carried out on an alpha-type stirling engine by making the phase angle to 180o, with the aim of reducing the effect when the cold cylinder is compressed, because the phase angle currently used is (90o) with disadvantages, namely the cold cylinder is perpendicular to the top, so that the compression process against gravity. But in previous studies, the generator pipe was too long, causing a lot of energy or heat loss (heat loss) so that the compression speed was small. So that in the research, innovated and analyzed the pipe insulation of alpha-type stirling engine generators, alpha-type stirling engines, 180o phase angle. The research method used is to use the thermodynamic approach with Schmidt theory and the theory of the ideal cycle stirling engine. while the simulation is done using the Ideal Stirling Cycle Calculator. Results investigated shows that providing insulation on the generator pipes of an alpha-type stirling engine for an alpha-type stirling engine with a 180o phase angle is proven to reduce a lot of energy or heat loss (heat loss) due to too long generator pipes, with a heat loss value ratio of 226.66 W for the pipe. generator that uses insulation whose value is smaller than the value of the heat loss when the generator pipe without using isocation is 1,584.12 W.

scholarly journals THE ELECTROFILTER ASH OF GACKO THERMAL POWER PLANT AS TECHNOGENIC RAW MATERIAL AND THE IMPACT OF ASH WASTE PILEON THE ENVIRONMENT

2016 ◽  
Vol 1 (15) ◽  
Author(s):  
Ljiljana Crnogorac ◽  
Boško Vuković
Keyword(s):  
Coal Combustion ◽  
Power Plants ◽  
New Technologies ◽  
Thermal Power ◽  
Raw Material ◽  
Significant Progress ◽  
Negative Effects ◽  
Wide Range ◽  
The Impact ◽  
Made In

During the working of thermal power plants, due to technological process of coal combustion, wastematter, which takes up large areas of land, degrades and pollutes the environment, is created. In the lastyears, a significant progress has been made in the world in researching new technologies thatimplement technogenic materials which have wide range of optimal economic use.An example for thisis electrofilterash which is, as technogenic raw material,largly and more often used in building industry.This resulted in decreasing negative effects of ash which was deposited considerably on ash waste piles.The use of ash for different industry purposes decreases the costs, increases a company's profitandremoves the negative effects on the environment and human health.

scholarly journals Comparative analysis of the Allam cycle and the cycle of compressorless combined cycle gas turbine unit

2020 ◽  
Vol 209 ◽  
pp. 03023
Author(s):  
Mikhail Sinkevich ◽  
Anatoliy Kosoy ◽  
Oleg Popel
Keyword(s):  
Comparative Analysis ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Thermal Power ◽  
District Heating ◽  
Combined Cycle ◽  
Working Fluid ◽  
District Heating System ◽  
Wide Range

Nowadays, alternative thermodynamic cycles are actively studied. They allow to remove CO2, formed as a result of fuel combustion, from a cycle without significant energy costs. Calculations have shown that such cycles may meet or exceed the most advanced power plants in terms of heat efficiency. The Allam cycle is recognized as one of the best alternative cycles for the production of electricity. Nevertheless, a cycle of compressorless combined cycle gas turbine (CCGT) unit is seemed more promising for cogeneration of electricity and heat. A comparative analysis of the thermal efficiency of these two cycles was performed. Particular attention was paid to ensuring equal conditions for comparison. The cycle of compressorless CCGT unit was as close as possible to the Allam cycle due to the choice of parameters. The processes, in which the difference remained, were analysed. Thereafter, an analysis of how close the parameters, adopted for comparison, to optimal for the compressorless CCGT unit cycle was made. This analysis showed that these two cycles are quite close only for the production of electricity. The Allam cycle has some superiority but not indisputable. However, if cogeneration of electricity and heat is considered, the thermal efficiency of the cycle of compressorless CCGT unit will be significantly higher. Since it allows to independently regulate a number of parameters, on which the electric power, the ratio of electric and thermal power, the temperature of a working fluid at the turbine inlet depend. Thus, the optimal parameters of the thermodynamic cycle can be obtained in a wide range of operating modes of the unit with different ratios of thermal and eclectic powers. Therefore, the compressorless CCGT unit can significantly surpass the best steam turbine and combined cycle gas turbine plants in district heating system in terms of thermal efficiency.

Introduction of Environmental Measures in the Heat Power Industry of the Central Ecological Zone of the Baikal Natural Territory

2018 ◽  
Vol 22 (7) ◽  
pp. 20-25 ◽  
Author(s):  
B.G. Saneev ◽  
I.Yu. Ivanova ◽  
E.P. Maysyuk ◽  
T.F. Tuguzova
Keyword(s):  
Renewable Energy Sources ◽  
Thermal Power ◽  
Economic Assessment ◽  
Heat Sources ◽  
Energy Prices ◽  
Protection Measures ◽  
Carrier Medium ◽  
Environmental Measures ◽  
The Impact ◽  
The Town

Presented the results of calculations of emissions of pollutants into the atmosphere from heat sources and their comparison with the permissible values for Lake Baikal basins. The ecological ranging of the territory made it possible to determine the areas of greatest emissions: Slyudyansky, North Baikal and the town of Severobaikalsk. As potential directions to reduce anthropogenic impact from heat source proposed: improving the system for cleaning off gases: transition to more environmentally friendly energy carrier medium, as well as renewable energy sources. For each of the directions of environmental protection measures, the areas of rational use were identified and the reduction of emissions of harmful substances into the atmosphere during their implementation. Considered only the possible environmental effect from the introduction of particular direction to reduce the impact on the atmosphere of thermal power facilities, without taking into account the technical and economic assessment of environmental measures, the identification of legislative measures, the development of preferential tariffs, energy prices and other financial and economic mechanisms.

scholarly journals Optimized Piston Motion for an Alpha-Type Stirling Engine

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 700 ◽  
Author(s):  
Robin Masser ◽  
Abdellah Khodja ◽  
Mathias Scheunert ◽  
Karsten Schwalbe ◽  
Andreas Fischer ◽  
...  
Keyword(s):  
Waste Heat ◽  
Stirling Engine ◽  
Piston Motion ◽  
Performance Improvements ◽  
Engine Model ◽  
Wide Range ◽  
The Individual ◽  
Parameter Values ◽  
The Impact ◽  
Alpha Type

The Stirling engine is one of the most promising devices for the recovery of waste heat. Its power output can be optimized by several means, in particular by an optimized piston motion. Here, we investigate its potential performance improvements in the presence of dissipative processes. In order to ensure the possibility of a technical implementation and the simplicity of the optimization, we restrict the possible piston movements to a parametrized class of smooth piston motions. In this theoretical study the engine model is based on endoreversible thermodynamics, which allows us to incorporate non-equilibrium heat and mass transfer as well as the friction of the piston motion. The regenerator of the Stirling engine is modeled as ideal. An investigation of the impact of the individual loss mechanisms on the resulting optimized motion is carried out for a wide range of parameter values. We find that an optimization within our restricted piston motion class leads to a power gain of about 50% on average.

THE IMPACT OF LEADERSHIP PRACTICES TO TEAM MEMBERS’ SATISFACTION

2009 ◽  
Vol 8 (1) ◽  
Author(s):  
Chalimah .
Keyword(s):  
Conflict Resolution ◽  
Leadership Practices ◽  
Hotel Industry ◽  
Leader Behavior ◽  
Team Leader ◽  
Shop Floor ◽  
Team Members ◽  
Top Executives ◽  
Wide Range ◽  
The Impact

eamwork is becoming increasingly important to wide range of operations. It applies to all levels of the company. It is just as important for top executives as it is to middle management, supervisors and shop floor workers. Poor teamwork at any level or between levels can seriously damage organizational effectiveness. The focus of this paper was therefore to examine whether leadership practices consist of team leader behavior, conflict resolution style and openness in communication significantly influenced the team member’s satisfaction in hotel industry. Result indicates that team leader behavior and the conflict resolution style significantly influenced team member satisfaction. It was surprising that openness in communication did not affect significantly to the team members’ satisfaction.

Stress, anxiety, depression and burnout in frontline health care workers during COVID-19 pandemic: a brief systematic review and new data from Russia

2021 ◽  
Author(s):  
Ekaterina Mosolova ◽  
Dmitry Sosin ◽  
Sergey Mosolov
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Female Gender ◽  
Assessment Tools ◽  
Care Workers ◽  
Younger Age ◽  
Wide Range ◽  
Associated Risk Factors ◽  
Anxiety Depression ◽  
The Impact

During the COVID-19 pandemic, healthcare workers (HCWs) have been subject to increased workload while also exposed to many psychosocial stressors. In a systematic review we analyze the impact that the pandemic has had on HCWs mental state and associated risk factors. Most studies reported high levels of depression and anxiety among HCWs worldwide, however, due to a wide range of assessment tools, cut-off scores, and number of frontline participants in the studies, results were difficult to compare. Our study is based on two online surveys of 2195 HCWs from different regions of Russia during spring and autumn epidemic outbreaks revealed the rates of anxiety, stress, depression, emotional exhaustion and depersonalization and perceived stress as 32.3%, 31.1%, 45.5%, 74.2%, 37.7% ,67.8%, respectively. Moreover, 2.4% of HCWs reported suicidal thoughts. The most common risk factors include: female gender, nurse as an occupation, younger age, working for over 6 months, chronic diseases, smoking, high working demands, lack of personal protective equipment, low salary, lack of social support, isolation from families, the fear of relatives getting infected. These results demonstrate the need for urgent supportive programs for HCWs fighting COVID-19 that fall into higher risk factors groups.

A MODELING SYSTEM FOR CLIMATE CHANGE RISK ASSESSMENT, MANAGEMENT AND HEDGING IN COASTAL AREAS

2017 ◽  
Author(s):  
Sergei Soldatenko ◽  
Sergei Soldatenko ◽  
Genrikh Alekseev ◽  
Genrikh Alekseev ◽  
Alexander Danilov ◽  
...  
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Coastal Areas ◽  
Mitigation Strategies ◽  
System Structure ◽  
The Arctic ◽  
Risk Modeling ◽  
Wide Range ◽  
Adverse Weather ◽  
The Impact

Every aspect of human operations faces a wide range of risks, some of which can cause serious consequences. By the start of 21st century, mankind has recognized a new class of risks posed by climate change. It is obvious, that the global climate is changing, and will continue to change, in ways that affect the planning and day to day operations of businesses, government agencies and other organizations and institutions. The manifestations of climate change include but not limited to rising sea levels, increasing temperature, flooding, melting polar sea ice, adverse weather events (e.g. heatwaves, drought, and storms) and a rise in related problems (e.g. health and environmental). Assessing and managing climate risks represent one of the most challenging issues of today and for the future. The purpose of the risk modeling system discussed in this paper is to provide a framework and methodology to quantify risks caused by climate change, to facilitate estimates of the impact of climate change on various spheres of human activities and to compare eventual adaptation and risk mitigation strategies. The system integrates both physical climate system and economic models together with knowledge-based subsystem, which can help support proactive risk management. System structure and its main components are considered. Special attention is paid to climate risk assessment, management and hedging in the Arctic coastal areas.

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