scholarly journals The swirl number as a method for determining the optimal operating mode of the micro hydro turbine

2021 ◽  
Vol 2119 (1) ◽  
pp. 012160
Author(s):  
D A Suslov ◽  
I V Litvinov ◽  
E U Gorelikov ◽  
S I Shtork
Keyword(s):  
High Efficiency ◽  
Flow Characteristics ◽  
Operating Mode ◽  
Automated System ◽  
Swirl Number ◽  
Hydro Turbine ◽  
Operating Modes ◽  
Partial Load ◽  
Operating Regimes ◽  
Swirled Flow

Abstract The paper presents the data of a detailed study of the flow characteristics behind the runner of an air model of a propeller-type micro hydro turbine with varying operating modes from partial load to severe overload. Detailed measurements of the flow field distributions were carried out using an automated system for contactless optical diagnostics (LDA). The obtained data made it possible to link the identified features of the development of the flow structure when changing the operating mode of the installation with the nature of the evolution of the integral swirl number that determines the state of the swirled flow. Eventually, the work results can be used in the elaboration of recommendations for extending the regulation range of the operating regimes of hydraulic microturbines and providing their high efficiency.

Investigation on Flow Characteristics of Pump-Turbine Runners With Large Blade Lean

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Baoshan Zhu ◽  
Lei Tan ◽  
Xuhe Wang ◽  
Zhe Ma
Keyword(s):  
High Pressure ◽  
High Efficiency ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Control Flow ◽  
Pump Turbine ◽  
Good Efficiency ◽  
Operating Modes ◽  
Partial Load

Frequent changes in the operating modes pose significant challenges in the development of a pump-turbine with high efficiency and stability. In this paper, two pump-turbine runners, one with a large positive blade lean and the other with a large negative lean, are investigated numerically and experimentally. These two runners are designed by using the optimum stacking condition at the high pressure edge (HPE). The experimental and the numerical results show that both runners have good efficiency performances, and pressure fluctuations for the runner with a negative blade lean are much lower than those for the runner with a positive blade lean. The internal flow field analyses clarify the effects of the blade lean on the pressure distribution around the runner blades. In the turbine mode at partial load, the negative blade lean can control flow separation in the high pressure side of the runner and then reduce the pressure fluctuations in the vaneless space.

scholarly journals Flow characterization in an axial micro-hydroturbine model

2021 ◽  
Vol 2127 (1) ◽  
pp. 012002
Author(s):  
D A Suslov ◽  
S I Shtork ◽  
I V Litvinov ◽  
E U Gorelikov
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
High Efficiency ◽  
Swirling Flow ◽  
Flow Characteristics ◽  
Laser Doppler Anemometer ◽  
Operating Conditions ◽  
Swirl Number ◽  
Operation Conditions ◽  
Flow Characterization

Abstract The flow characteristics behind the runner of an air model of a propeller-type micro-hydroturbine were studied in detail by varying the operation conditions from part-load to high overload. The Reynolds number was varied from 3×104 to 9×104, and the swirl number from 0.7 to -0.4. An automated laser-Doppler anemometer (LDA) system for non-contact optical diagnostics was used to perform detailed measurements of the flow field distribution, including the profiles of two components of averaged velocities and pulsations and LDA signal spectra. Based on the results, a correlation was found between the identified features of the development of the flow structure under changing operating conditions of the hydroturbine and the nature of the evolution of the integral swirl number, which determines the state of the swirling flow. This can be used to develop recommendations for expanding the range of regulation of hydroturbine operation while maintaining high efficiency.

scholarly journals Laboratory Modeling of an Axial Flow Micro Hydraulic Turbine

2022 ◽  
Vol 12 (2) ◽  
pp. 573
Author(s):  
Daniil Suslov ◽  
Ivan Litvinov ◽  
Evgeny Gorelikov ◽  
Sergey Shtork ◽  
David Wood
Keyword(s):  
High Efficiency ◽  
Experimental Studies ◽  
Axial Flow ◽  
Operating Mode ◽  
Hydraulic Turbine ◽  
Hydraulic Unit ◽  
Impeller Outlet ◽  
Wide Range ◽  
Operation Control ◽  
Swirled Flow

This article is devoted to detailed experimental studies of the flow behind the impeller of an air model of a propeller-type microhydroturbine in a wide range of operating parameters. The measurements of two component distributions of averaged velocities and pulsations for conditions from part load to strong overload are conducted. It is shown that the flow at the impeller outlet becomes swirled when the hydraulic turbine operating mode shifts from the optimum one. The character of the behavior of the integral swirl number, which determines the state of the swirled flow, is revealed. Information about the flow peculiarities can be used when adjusting the hydraulic unit mode to optimal conditions and developing recommendations to expand the hydraulic turbine operation control range with preservation of high efficiency. This stage will significantly save time at the stage of equipment design for specific field conditions of water resource.

scholarly journals Numerical Analysis of the Cooling Performance in a 7.2 kW Integrated Bidirectional OBC/LDC Module

2019 ◽  
Vol 10 (1) ◽  
pp. 270
Author(s):  
Jung-Hun Noh ◽  
Seong-il Song ◽  
Deog-Jae Hur
Keyword(s):  
Numerical Analysis ◽  
Power Loss ◽  
Low Voltage ◽  
Flow Characteristics ◽  
Operating Mode ◽  
Internal Cooling ◽  
Battery Charger ◽  
Worst Case ◽  
Operating Modes ◽  
Ev Charging

To satisfy increasing demands for ecofriendly vehicles, researchers are now studying electric vehicle (EV)-related technologies. In particular, integrated bidirectional onboard battery charger (OBC)/low-voltage DC–DC converter (LDC) modules are being researched to improve the efficiency of onboard chargers for EV charging applications. In this study, a numerical analysis method is proposed that considers the power loss and heat flow characteristics in the design of a 7.2 kW integrated bidirectional OBC/LDC module. The developed module supports four operating modes depending on the service situation: OBC and LDC single operation, OBC/LDC simultaneous operation, and LDC operation. The mode is selected based on the power system flow. The characteristics of the circuit were analyzed in each of the four modes to compute the heat loss from the major heating elements. The results of a numerical analysis of the internal cooling characteristics showed that the internal temperature was higher in the OBC single operating mode than in the OBC and LDC simultaneous operating mode in which the power loss was the highest. The results emphasize the importance of ensuring that cooling designs consider the characteristics of various modes as well as the worst-case power loss.

scholarly journals Octane Index Applicability over the Pressure-Temperature Domain

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Tommy R. Powell ◽  
James P. Szybist ◽  
Flavio Dal Forno Chuahy ◽  
Scott J. Curran ◽  
John Mengwasser ◽  
...  
Keyword(s):  
High Efficiency ◽  
National Laboratory ◽  
Operating Conditions ◽  
Dominant Factor ◽  
Compression Ignition ◽  
Oak Ridge ◽  
Operating Modes ◽  
Wide Range ◽  
Thermodynamic Conditions ◽  
Si Engines

Modern boosted spark-ignition (SI) engines and emerging advanced compression ignition (ACI) engines operate under conditions that deviate substantially from the conditions of conventional autoignition metrics, namely the research and motor octane numbers (RON and MON). The octane index (OI) is an emerging autoignition metric based on RON and MON which was developed to better describe fuel knock resistance over a broader range of engine conditions. Prior research at Oak Ridge National Laboratory (ORNL) identified that OI performs reasonably well under stoichiometric boosted conditions, but inconsistencies exist in the ability of OI to predict autoignition behavior under ACI strategies. Instead, the autoignition behavior under ACI operation was found to correlate more closely to fuel composition, suggesting fuel chemistry differences that are insensitive to the conditions of the RON and MON tests may become the dominant factor under these high efficiency operating conditions. This investigation builds on earlier work to study autoignition behavior over six pressure-temperature (PT) trajectories that correspond to a wide range of operating conditions, including boosted SI operation, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). A total of 12 different fuels were investigated, including the Co-Optima core fuels and five fuels that represent refinery-relevant blending streams. It was found that, for the ACI operating modes investigated here, the low temperature reactions dominate reactivity, similar to boosted SI operating conditions because their PT trajectories lay close to the RON trajectory. Additionally, the OI metric was found to adequately predict autoignition resistance over the PT domain, for the ACI conditions investigated here, and for fuels from different chemical families. This finding is in contrast with the prior study using a different type of ACI operation with different thermodynamic conditions, specifically a significantly higher temperature at the start of compression, illustrating that fuel response depends highly on the ACI strategy being used.

Ancillary Services Potential for Flexible Combined Cycles

2021 ◽  
Author(s):  
Alberto Vannoni ◽  
Jose Angel Garcia ◽  
Weimar Mantilla ◽  
Rafael Guedez ◽  
Alessandro Sorce
Keyword(s):  
Electricity Market ◽  
Gas Turbines ◽  
High Efficiency ◽  
Combined Cycle ◽  
Ancillary Services ◽  
Ancillary Service ◽  
Spinning Reserve ◽  
Service Market ◽  
Partial Load ◽  
Ancillary Services Market

Abstract Combined Cycle Gas Turbines, CCGTs, are often considered as the bridging technology to a decarbonized energy system thanks to their high exploitation rate of the fuel energetic potential. At present time in most European countries, however, revenues from the electricity market on their own are insufficient to operate existing CCGTs profitably, also discouraging new investments and compromising the future of the technology. In addition to their high efficiency, CCGTs offer ancillary services in support of the operation of the grid such as spinning reserve and frequency control, thus any potential risk of plant decommissioning or reduced investments could translate into a risk for the well-functioning of the network. To ensure the reliability of the electricity system in a transition towards a higher share of renewables, the economic sustainability of CCGTs must be preserved, for which it becomes relevant to monetize properly the ancillary services provided. In this paper, an accurate statistical analysis was performed on the day-ahead, intra-day, ancillary service, and balancing markets for the whole Italian power-oriented CCGT fleet. The profitability of 45 real production units, spread among 6 market zones, was assessed on an hourly basis considering local temperature, specific plant layouts, and off-design performance. The assessment revealed that net income from the ancillary service market doubled, on average, the one from the day-ahead energy market. It was observed that to be competitive in the ancillary services market CCGTs are required to be more flexible in terms of ramp rates, minimum environmental loads, and partial load efficiencies. This paper explores how integrating a Heat Pump and a Thermal Energy Storage within a CCGT could allow improving its competitiveness in the ancillary services market, and thus its profitability, by means of implementing a model of optimal dispatch operating on the ancillary services market.

Three Spool High Efficiency Small Scale Gas Turbine Concept

2017 ◽  
Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Small Scale ◽  
Inlet Temperature ◽  
Substantial Impact ◽  
Electrical Efficiency ◽  
Partial Load ◽  
Reciprocating Engines

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.

scholarly journals Computational study of smoke flow control in garage fires and optimization of the ventilation system

2009 ◽  
Vol 13 (1) ◽  
pp. 69-78
Author(s):  
Milos Banjac ◽  
Barbara Nikolic
Keyword(s):  
Computational Study ◽  
Ventilation System ◽  
Operating Mode ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Start Time ◽  
Combustion Dynamics ◽  
Operating Modes ◽  
Smoke Flow ◽  
Emergency Operating

With the aim of evaluating capabilities of a ventilation system to control the spread of smoke in the emergency operating mode, thereby providing conditions for safe evacuation of people from a fire-struck area, computational fluid dynamics simulation of a fire in a semi-bedded garage was conducted. Using the experimental results of combustion dynamics of a passenger car on fire, optimal positions of ventilation openings were determined. According to recommendations by DIN EN 12101 standard, the operating modes of a ventilation system were verified and optimal start time of the smoke extraction system was defined.

scholarly journals Modernization of a frequency-controlled asynchronous electric drive system

2019 ◽  
pp. 25-33
Author(s):  
I. V. Shestakov ◽  
N. R. Safin
Keyword(s):  
Energy Efficiency ◽  
Electric Drive ◽  
Asynchronous Motor ◽  
Operating Mode ◽  
Voltage Source ◽  
Sinusoidal Voltage ◽  
Pulse Width Modulated ◽  
Operating Modes ◽  
Asynchronous Electric Drive ◽  
Research Show

The paper introduces the results of mathematical simulation of the operating modes of an asynchronous motor when powered by a sinusoidal voltage source and a width-modulated voltage pulse source. The study shows the possibilities of increasing the energy efficiency of an asynchronous electric drive. Findings of research show the feasibility of studying the switching of the motor power source from a pulse width-modulated voltage to a sinusoidal voltage source in the nominal operating mode in order to increase the energy efficiency of the electric drive

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