scholarly journals РОЗРОБКА ВИСОКОЕФЕКТИВНОЇ СУДНОВОЇ СИСТЕМИ ОЧИЩЕННЯ ПОВІТРЯ ВІД КРАПЛИННОЇ ВОЛОГИ

2018 ◽  
pp. 42-46
Author(s):  
Анатолій Павлович Шевцов ◽  
Сергій Сергійович Рижков
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Reverse Flow ◽  
Surface Profile ◽  
Working Fluid ◽  
Efficient Design ◽  
Air Cleaning ◽  
Wide Range ◽  
Design Solutions ◽  
Condensed Moisture

It is investigated one of the directions of increasing the technical, economic and environmental characteristics of engines and power plants by air cleaning as a working fluid of condensed moisture. Prospective methods of aerosol medium separation with the help of gradient intensification of transfer processes in boundary layers of multifunctional surfaces are also investigated. Multifunctional surfaces include surfaces with a coefficient of compactness more than 2000 m2/m3, characterized by improved heat exchange and separating properties. A characteristic feature of the developed separating profiles is the combination of a waveform part with flat input and output elements. In the assembly, the separating profiles form the curved channels with a number of successive confuser and diffuser elements. In diffusor elements, there are separating zones with the gas reverse flow. The liquid film resulting from the droplets deposition, falling into these zones, is influenced by the vortices effect that counteracts the film motion in the direction of the main flow and facilitates its flow under the action of gravity. The investigations of gas dynamics and deposition coefficients of the separation profile were performed. The coefficient of droplets deposition for flow rates of 5, 10, 15, 20 m/s in separating profiles with a radius of 5, 10, 15, 20, 25 mm was calculated. It was determined that vortex zones provide full removal of captured water from the smooth surface profile up to the airspeed of 5 m/s. Excess of this speed leads to the removal of part of the water from the vortex zones. Drainage elements are provided for preventing secondary flooding of the flow in flat sections of the separation profile. Design solutions and a generalized scheme of the ship system of air cleaning of condensed moisture for the air flow from 20 to 2000 m3/h were developed. The introduction of filters based on gradient technologies will increase the reliability, the life of the marine power equipment and its elements. This will contribute to the creation of high-efficiency energy-saving technologies and efficient design solutions for a wide range of gradient marine power plant separators.

A Comparison Study for Off-Design Performance Prediction of a Supercritical CO2 Compressor With Similitude Analysis

2019 ◽  
Author(s):  
Yongju Jeong ◽  
Seongmin Son ◽  
Seong kuk Cho ◽  
Seungjoon Baik ◽  
Jeong Ik Lee
Keyword(s):  
Critical Point ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Cycle Performance ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Design Performance ◽  
Wide Range ◽  
Phase Fluid

Abstract Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics. Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.

Systematic Fluid Selection for Organic Rankine Cycles and Performance Analysis for a Combined High and Low Temperature Cycle

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Maximilian Roedder ◽  
Matthias Neef ◽  
Christoph Laux ◽  
Klaus-P. Priebe
Keyword(s):  
Performance Analysis ◽  
Low Temperature ◽  
Power Plants ◽  
Waste Heat ◽  
Selection Process ◽  
Working Fluid ◽  
Temperature Cycle ◽  
Two Stage ◽  
Working Fluids ◽  
Wide Range

The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree-of-freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic, and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination (EC) and tolerance criteria (TC). For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time, the selection process is applied to a two-stage reference cycle, which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature (HT) and a low temperature (LT) cycle in which the condensation heat of the HT cycle provides the heat input of the LT cycle. After the fluid selection process, the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17.4% in the HT cycle with toluene as the working fluid and 6.2% in LT cycle with isobutane as the working fluid. The electric efficiency of the cogeneration plant increases from 40.4% to 46.97% with the both stages of the two-stage ORC in operation.

A Modified, High-Efficiency, Recuperated Gas Turbine Cycle

1988 ◽  
Vol 110 (2) ◽  
pp. 233-242 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Water Flow Rate ◽  
Component Technology ◽  
Pure Substance ◽  
Working Fluid ◽  
Recovery Processes ◽  
Dead State ◽  
Percentage Points ◽  
Wide Range

The thermal efficiency of an intercooled/recuperated cycle may be increased by: (a) evaporatively aftercooling the compressor discharge; and (b) injecting and evaporating an additional amount of water in the recuperator. Comparative computations of such a modified cycle and intercooled/recuperated cycles carried out over a wide range of pressure ratios and turbine inlet temperatures and at two different levels of component technologies show an advantage of over five percentage points in efficiency for the modified cycle. About 60 percent of this improvement results from modification (a) and 40 percent from modification (b). The modified intercooled/recuperated cycle is compared with nonintercooled steam-injected gas turbine systems at each component technology level. The present cycle is found to be superior by about 2.75 percentage points in efficiency and to require a substantially smaller water flow rate. To assist in interpreting those differences, the method of available-work analysis is introduced and applied. This is identical to exergy analysis for systems with a pure-substance working fluid, but differs from the latter for systems using a mixture of pure substances insofar as the thermodynamic dead state is defined for the chemical and phase composition realized at the exhaust conditions of practical engineering devices and systems. This analysis is applied to the heat-recovery processes in each of the three systems considered. It shows that the substantial, fundamental available-work loss incurred by mixing steam and gases in the steam-injected system is the main reason for the superior efficiency of the precent cycle.

Marine steam-gas semi-closed cycle power plant for peak loads

2021 ◽  
Vol 2 ◽  
pp. 21-25
Author(s):  
Vladimir Baranovsky ◽  
Maxim Lipatov
Keyword(s):  
Diesel Engine ◽  
Power Plant ◽  
Power Plants ◽  
High Efficiency ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Closed Cycle ◽  
Peak Loads ◽  
Wide Range ◽  
Gas Power Plant

A wide range of efficient gas turbine engines has been developed at UEC NPO Saturn, Russia. Those engines can be successfully used for developing a marine steam-gas semi-closed cycle power plant to compensate peak loads on ships and vessels. This compact steam-gas power plant will demonstrate high efficiency which doesn’t change significantly depending on the load when compared to conventional steam-gas power plants. Also, this solution can possibly change the diesel engine prevalence among marine power plants.

Computational Fluid Dynamics of a Radial Compressor Operating With Supercritical CO2

2012 ◽  
Author(s):  
Rene Pecnik ◽  
Enrico Rinaldi ◽  
Piero Colonna
Keyword(s):  
Critical Point ◽  
Gas Turbine ◽  
Supercritical Co2 ◽  
High Speed ◽  
Power Plants ◽  
Compressible Flows ◽  
High Efficiency ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Maximum Pressure

The merit of using supercritical CO2 (scCO2) as the working fluid of a closed Brayton cycle gas turbine is now widely recognized, and the development of this technology is now actively pursued. scCO2 gas turbine power plants are an attractive option for solar, geothermal and nuclear energy conversion. Among the challenges which must be overcome in order to successfully bring the technology to the market, the efficiency of the compressor and turbine operating with the supercritical fluid should be increased as much as possible. High efficiency can be reached by means of sophisticated aerodynamic design, which, compared to other overall efficiency improvements, like cycle maximum pressure and temperature increase, or increase of recuperator effectiveness, does not require an increase in equipment cost, but only an additional effort in research and development. This paper reports a three-dimensional CFD study of a high-speed centrifugal compressor operating with CO2 in the thermodynamic region slightly above the vapor-liquid critical point. The investigated geometry is the compressor impeller tested in the Sandia scCO2 compression loop facility [1]. The fluid dynamic simulations are performed with a fully implicit parallel Reynolds-averaged Navier-Stokes code based on a finite volume formulation on arbitrary polyhedral mesh elements. The CFD code has been validated on test cases which are relevant for this study, see Ref. [2,3]. In order to account for the strongly nonlinear variation of the thermophysical properties of supercritical CO2, the CFD code is coupled with an extensive library for the computation of properties of fluids and mixtures [4]. Among the available models, the one based on reference equations of state for CO2 [5,6] has been selected, as implemented in one of the sub-libraries [7]. A specialized look-up table approach and a meshing technique suited for turbomachinery geometries are also among the novelties introduced in the developed methodology. A detailed evaluation of the CFD results highlights the challenges of numerical studies aimed at the simulation of technically relevant compressible flows occurring close to the liquid-vapor critical point. The data of the obtained flow field are used for a comparison with experiments performed at the Sandia scCO2 compression-loop facility.

Underground Coal Gasification for Power Generation: High Efficiency and CO2-Emissions

2004 ◽  
Author(s):  
Michael S. Blinderman ◽  
Bernard Anderson
Keyword(s):  
Co2 Emissions ◽  
Gas Turbines ◽  
Power Plants ◽  
Coal Gasification ◽  
High Efficiency ◽  
Gas Production ◽  
Western World ◽  
Underground Coal Gasification ◽  
Thick Coal Seam ◽  
Wide Range

Underground Coal Gasification (UCG) is a gasification process carried out in non-mined coal seams using injection and production wells drilled from the surface, enabling the coal to be converted into product gas. The UCG process practiced by Ergo Exergy is called Exergy UCG or εUCG. εUCG was applied in the Chinchilla UCG-IGCC Project in Australia. The IGCC project in Chinchilla, Australia has been under development since July 1999. The project involves construction of the underground gasifier and demonstration of UCG technology, and installation of the power island. Since December 1999 the plant has been making gas continuously, and its maximum capacity is 80,000 Nm3/h. Approximately 32,000 tonnes of coal have been gasified, and 100% availability of gas production has been demonstrated over 30 months of operation. The UCG operation in Chinchilla is the largest and the longest to date in the Western world. The εUCG facility at Chinchilla has used air injection, and produced a low BTU gas of about 5.0 MJ/m3 at a pressure of 10 barg (145 psig) and temperature of 300° C (570° F). It included 9 process wells that have been producing gas manufactured from a 10 m thick coal seam at the depth of about 140 m. The process displayed high efficiency and consistency in providing gas of stable quality and quantity. The results of operations in Chinchilla to date have demonstrated that εUCG can consistently provide gas of stable quantity and quality for IGCC power projects at very low cost enabling the UCG-IGCC plant to compete with coal-fired power stations. This has been done in full compliance with rigorous environmental regulations. A wide range of gas turbines can be used for UCG-IGCC applications. The turbines using UCG gas will demonstrate an increase in output by up to 25% compared to natural gas. The power block efficiency reaches 55%, while the overall efficiency of the UCG-IGCC process can reach 43%. A UCG-IGCC power plant will generate electricity at a much lower cost than existing or proposed fossil fuel power plants. CO2 emissions of the plant can be reduced to a level 55% less than those of a supercritical coal-fired plant and 25% less than the emissions of NG CC.

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.

Fluidic Components for Oscillating Water Column Based Wave Energy Plants

2011 ◽  
Author(s):  
Prasad V. Dudhgaonkar ◽  
V. Jayashankar ◽  
Purnima Jalihal ◽  
S. Kedarnath ◽  
T. Setoguchi ◽  
...  
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
High Efficiency ◽  
Reverse Flow ◽  
Forward Direction ◽  
Oscillating Water Column ◽  
High Impedance ◽  
Energy Plant ◽  
Wide Range ◽  
Fluidic Diode

A bidirectional (oscillating) air flow is central to energy conversion from wave to wire in an oscillating water column based wave energy plant. Several classes of bidirectional turbines, which operate with such an oscillating flow, have been designed and tested with limited efficiencies. A topology which uses fluidic diodes in conjunction with unidirectional turbines is shown to significantly improve the efficiency. The design and test results from several fluidic diodes for such an application are discussed. It is shown that a combination of a fluidic diode and the unidirectional turbine can achieve a very high impedance to reverse flow while having a high efficiency in the forward direction, over a wide range of flow coefficients.

Effect of Impurities on Compressor and Cooler in Supercritical CO2 Cycles

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Ladislav Vesely ◽  
K. R. V. Manikantachari ◽  
Subith Vasu ◽  
Jayanta Kapat ◽  
Vaclav Dostal ◽  
...  
Keyword(s):  
Critical Point ◽  
Carbon Capture ◽  
Nuclear Power ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Compressor Inlet ◽  
Almost All

With the increasing demand for electric power, the development of new power generation technologies is gaining increased attention. The supercritical carbon dioxide (S-CO2) cycle is one such technology, which has relatively high efficiency, compactness, and potentially could provide complete carbon capture. The S-CO2 cycle technology is adaptable for almost all of the existing heat sources such as solar, geothermal, fossil, nuclear power plants, and waste heat recovery systems. However, it is known that optimal combinations of operating conditions, equipment, working fluid, and cycle layout determine the maximum achievable efficiency of a cycle. Within an S-CO2 cycle, the compression device is of critical importance as it is operating near the critical point of CO2. However, near the critical point, the thermo-physical properties of CO2 are highly sensitive to changes of pressure and temperature. Therefore, the conditions of CO2 at the compressor inlet are critical in the design of such cycles. Also, the impurity species diluted within the S-CO2 will cause deviation from an ideal S-CO2 cycle as these impurities will change the thermodynamic properties of the working fluid. Accordingly, the current work examines the effects of different impurity compositions, considering binary mixtures of CO2 and He, CO, O2, N2, H2, CH4, or H2S on various S-CO2 cycle components. The second part of the study focuses on the calculation of the basic cycles and component efficiencies. The results of this study will provide guidance and define the optimal composition of mixtures for compressors and coolers.

Computational Fluid Dynamics of a Radial Compressor Operating With Supercritical CO2

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Rene Pecnik ◽  
Enrico Rinaldi ◽  
Piero Colonna
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Critical Point ◽  
Gas Turbine ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Compressible Flows ◽  
High Efficiency ◽  
Working Fluid ◽  
Maximum Pressure

The merit of using supercritical CO2(scCO2) as the working fluid of a closed Brayton cycle gas turbine is now widely recognized, and the development of this technology is now actively pursued. scCO2 gas turbine power plants are an attractive option for solar, geothermal, and nuclear energy conversion. Among the challenges that must be overcome in order to successfully bring the technology to the market is that the efficiency of the compressor and turbine operating with the supercritical fluid should be increased as much as possible. High efficiency can be reached by means of sophisticated aerodynamic design, which, compared to other overall efficiency improvements, like cycle maximum pressure and temperature increase, or increase of recuperator effectiveness, does not require an increase in equipment cost, but only an additional effort in research and development. This paper reports a three-dimensional computational fluid dynamics (CFD) study of a high-speed centrifugal compressor operating with CO2 in the thermodynamic region slightly above the vapor–liquid critical point. The investigated geometry is the compressor impeller tested in the Sandia scCO2 compression loop facility. The fluid dynamic simulations are performed with a fully implicit parallel Reynolds-averaged Navier–Stokes code based on a finite volume formulation on arbitrary polyhedral mesh elements. In order to account for the strongly nonlinear variation of the thermophysical properties of supercritical CO2, the CFD code is coupled with an extensive library for the computation of properties of fluids and mixtures. A specialized look-up table approach and a meshing technique suited for turbomachinery geometries are also among the novelties introduced in the developed methodology. A detailed evaluation of the CFD results highlights the challenges of numerical studies aimed at the simulation of technically relevant compressible flows occurring close to the liquid–vapor critical point. The data of the obtained flow field are used for a comparison with experiments performed at the Sandia scCO2 compression-loop facility.

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