Control in Partial Load Operation

2022 ◽  
pp. 119-154
Author(s):  
Adrian Gambier
Keyword(s):  
Partial Load

scholarly journals Structural Response of a Single-Stage Centrifugal Compressor to Fluid-Induced Excitations at Low-Flow Operating Condition: Experimental and Numerical Study

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4292
Author(s):  
Kirill Kabalyk ◽  
Andrzej Jaeschke ◽  
Grzegorz Liśkiewicz ◽  
Michał Kulak ◽  
Tomasz Szydłowski ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Structural Response ◽  
Flow Coefficient ◽  
Low Flow ◽  
Dynamic Strain ◽  
Duct Acoustics ◽  
Numerical Noise ◽  
Partial Load ◽  
Compressor Impeller

The article describes an assessment of possible changes in constant fatigue life of a medium flow-coefficient centrifugal compressor impeller subject to operation at close-to-surge point. Some aspects of duct acoustics are additionally analyzed. The experimental measurements at partial load are presented and are primarily used for validation of unidirectionally coupled fluid-structural numerical model. The model is based on unsteady finite-volume fluid-flow simulations and on finite-element transient structural analysis. The validation is followed by the model implementation to replicate the industry-scale loads with reasonably higher rotational speed and suction pressure. The approach demonstrates satisfactory accuracy in prediction of stage performance and unsteady flow field in vaneless diffuser. The latter is deduced from signal analysis relying on continuous wavelet transformations. On the other hand, it is found that the aerodynamic incidence losses at close-to-surge point are underpredicted. The structural simulation generates considerable amounts of numerical noise, which has to be separated prior to evaluation of fluid-induced dynamic strain. The main source of disturbance is defined as a stationary region of static pressure drop caused by flow contraction at volute tongue and leading to first engine-order excitation in rotating frame of reference. Eventually, it is concluded that the amplitude of excitation is too low to lead to any additional fatigue.

Exergy Analysis of a Hybrid Micro Gas Turbine Fuel Cell System Based on Existing Components

2012 ◽  
Author(s):  
D. P. Bakalis ◽  
A. G. Stamatis
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Exergy Analysis ◽  
Cell System ◽  
System Component ◽  
Utilization Factor ◽  
Fuel Cell Stack ◽  
Micro Gas Turbine ◽  
Partial Load ◽  
Set Up

A hybrid system based on an existing recuperated microturbine and a pre-commercially available high temperature tubular solid oxide fuel cell is modeled in order to study its performance. Individual models are developed for the microturbine and fuel cell generator and merged into a single one in order to set up the hybrid system. The model utilizes performance maps for the compressor and turbine components for the part load operation. The full and partial load exergetic performance is studied and the amounts of exergy destruction and efficiency of each hybrid system component are presented, in order to evaluate the irreversibilities and thermodynamic inefficiencies. Moreover, the effects of various performance parameters such as fuel cell stack temperature and fuel utilization factor are investigated. Based on the available results, suggestions are given in order to reduce the overall system irreversibility. Finally, the environmental impact of the hybrid system operation is evaluated.

Computational Study of Pump Turbine \u2013 Partial Load Operation

2021 ◽  
Author(s):  
Muhannad Altimemy ◽  
Justin Caspar ◽  
Alparslan Oztekin
Keyword(s):  
Computational Study ◽  
Pump Turbine ◽  
Partial Load

Energieeffizienz beim Spanen/Energy efficiency at machining - Investigations about the influence of minimun quantity lubrication (MQL) at final cutting

2017 ◽  
Vol 107 (05) ◽  
pp. 352-358
Author(s):  
S. Prof. Simon ◽  
S. Wichmann ◽  
A. Brill
Keyword(s):  
Energy Efficiency ◽  
Minimum Quantity Lubrication ◽  
Stress Conditions ◽  
Cutting Performance ◽  
Workpiece Material ◽  
Load Range ◽  
University Of Technology ◽  
Partial Load ◽  
Longitudinal Turning

Von der Brandenburgischen Technischen Universität (BTU) sind in Zusammenarbeit mit der TU Liberec Untersuchungen zur Verbesserung der Energieeffizienz an spanenden Werkzeugmaschinen durchgeführt worden. Im Gegensatz zu bereits durchgeführten Untersuchungen wurde der Fokus hier auf das Belastungsverhalten im Teillastbereich gerichtet. Die durchgeführten Untersuchungen beschränkten sich auf das Längsdrehen mit geringen Schnitttiefen. Als Werkstoffe kamen ein Baustahl und ein Vergütungsstahl zum Einsatz. Durch die Bestimmung der Leerlaufleistung der verwendeten Drehmaschine waren tatsächliche Aussagen über die Schnittleistung möglich. Für das Ermitteln des Wirkungsgrades wurden auch die Schnittleistungen bei verschiedenen Drehzahlen aufgenommen. Alle weiteren Spanungsbedingungen blieben für die Untersuchungen konstant. Im Ergebnis der Untersuchung bestätigte sich das Potenzial der Minimalmengenschmierung. Der Wirkungsgrad verbesserte sich durchschnittlich um 5 %. Beachtenswert ist der Einfluss des Einstellwinkels. Hier liegt das Optimierungspotenzial der Energieeffizienz in Summe bei 14 %. Die Untersuchungen ergaben weiterhin eine hohe Korrelation von Spanungsbedingungen, Werkstückwerkstoff und verwendetem Schmiermittel.   The Brandenburg University of Technology has carried out investigations in cooperation with the technical University of Liberec to improve the energy efficiency of cutting machine tools. In contrast to investigations already carried out, the focus here was on the loading behavior in the partial load range. The investigations carried out were limited to longitudinal turning with low cutting depths. A structural steel and a tempering steel were used as materials. By determining the no-load power of the used lathe, actual statements about the cutting performance were possible. For the determination of the efficiency, the cutting performance was recorded at different speeds. All further stress conditions remained constant for the investigations. As a result of the investigation, the potential of minimum quantity lubrication was confirmed. The efficiency improved by an average of 5 %. The influence of the angle of setting was remarkable. The optimization potential of energy efficiency was at 14 %. The investigations also revealed a high correlation between stress conditions, workpiece material and lubricant used.

Trade-Off Design Analysis of Operating Pressure and Temperature in PEM Fuel Cell Systems

1999 ◽  
Author(s):  
Frano Barbir ◽  
Bhaskar Balasubramanian ◽  
Jay Neutzler
Keyword(s):  
Fuel Cell ◽  
Cell Polarization ◽  
Propulsion System ◽  
Automotive Application ◽  
Total Efficiency ◽  
Operating Voltage ◽  
Operating Pressure ◽  
Surprising Result ◽  
Partial Load ◽  
Full Power

Abstract The paper presents the results of an optimization study of an automotive fuel cell propulsion system equipped with a fuel reformer. Based on a set of fuel cell polarization curves determined experimentally by running a prototype fuel cell stack at a variety of operating pressures and temperatures, a numerical steady state model was used to determine the optimal operating pressure and temperature. The optimization criteria were the size of individual components and the entire propulsion system as well as its total efficiency at both full power and partial load. The results suggested that an automotive system should be operated at relatively high pressure (308 kPa), but an expander must be used to recover most of the power used for compression. A surprising result of this analysis is that a relatively low temperature (∼60°C) results in smallest heat rejection equipment if neutral water balance is mandated. The efficiency of the system is about 33% at full power and about 38% at 25% of the load. Higher efficiencies may be achieved by selecting a higher fuel cell operating voltage, but that would result in larger fuel cell stacks, which may be a limiting factor for automotive application with the state-of-the-art fuel cells.

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.

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