scholarly journals A Queueing Model of Multiprogrammed Computer Systems Under Full Load Conditions

1977 ◽  
Vol 24 (2) ◽  
pp. 222-240 ◽  
Author(s):  
Alexandre Brandwajn
Keyword(s):  
Computer Systems ◽  
Queueing Model ◽  
Full Load ◽  
Load Conditions

Maneuverability of a pusher and barge system under empty and full load conditions

2017 ◽  
Vol 23 (3) ◽  
pp. 464-482
Author(s):  
Masaaki Sano ◽  
Hironori Yasukawa ◽  
Akio Okuda ◽  
Tomohiro Hamaguchi
Keyword(s):  
Full Load ◽  
Load Conditions

Oil Ring Design Influence on Lube Oil Consumption of SI Engines

2004 ◽  
Author(s):  
Andre´ Ferrarese ◽  
Fernando F. Rovai
Keyword(s):  
Thermal Stability ◽  
The Other ◽  
Oil Consumption ◽  
Ring Type ◽  
Full Load ◽  
Sealing Capacity ◽  
Other Hand ◽  
Actual Use ◽  
Si Engines ◽  
Load Conditions

2-piece and 3-piece oil ring designs were tested in dynamometer and vehicles in order to evaluate the ring type influence on lube oil consumption of spark ignited (SI) engines. The dynamometer tests were executed according a typical durability cycle of SI engines. This cycle is predominantly in full load conditions. Under these conditions, 2-piece oil ring design showed lower lube oil consumption than 3-piece. Two different vehicle tests were also run: urban and mountain circuits. The purpose of the urban circuit test was to simulate the actual use of the engine. The mountain circuit was selected to verify the rings behavior under motoring conditions. In vehicle tests, 3-piece showed lower or equivalent oil consumption than 2 piece, which disagreed with the dynamometer tests. This difference can be explained by the better side sealing capacity of the 3-piece oil ring. On the other hand, 2-piece oil rings present better conformability, important for applications with larger bore distortion. So, the most appropriate application of oil ring type depends on the load and speed conditions, in which the engine would predominantly operate. Ring wear and thermal stability are compared using bench and vehicle tests.

Prediction of unstable full load conditions in a Francis turbine prototype

2022 ◽  
Vol 169 ◽  
pp. 108666
Author(s):  
João Gomes Pereira ◽  
Elena Vagnoni ◽  
Arthur Favrel ◽  
Christian Landry ◽  
Sébastien Alligné ◽  
...  
Keyword(s):  
Francis Turbine ◽  
Full Load ◽  
Load Conditions

scholarly journals Design of Experiments Applied to Francis Turbine Draft Tube to Minimize Pressure Pulsations and Energy Losses in Off-Design Conditions

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3894
Author(s):  
Arthur Favrel ◽  
Nak-Joong Lee ◽  
Tatsuya Irie ◽  
Kazuyoshi Miyagawa
Keyword(s):  
Draft Tube ◽  
Pressure Fluctuations ◽  
Internal Flow ◽  
Francis Turbine ◽  
Energy Losses ◽  
Geometrical Parameters ◽  
Cfd Simulations ◽  
Part Load ◽  
Full Load ◽  
Load Conditions

This paper proposes an original approach to investigate the influence of the geometry of Francis turbines draft tube on pressure fluctuations and energy losses in off-design conditions. It is based on Design of Experiments (DOE) of the draft tube geometry and steady/unsteady Computational Fluid Dynamics (CFD) simulations of the draft tube internal flow. The test case is a Francis turbine unit of specific speed Ns=120 m-kW which is required to operate continuously in off-design conditions, either with 45% (part-load) or 110% (full-load) of the design flow rate. Nine different draft tube geometries featuring a different set of geometrical parameters are first defined by an orthogonal array-based DOE approach. For each of them, unsteady and steady CFD simulations of the internal flow from guide vane to draft tube outlet are performed at part-load and full-load conditions, respectively. The influence of each geometrical parameter on both the flow instability and resulting pressure pulsations, as well as on energy losses in the draft tube, are investigated by applying an Analysis of Means (ANOM) to the numerical results. The whole methodology enables the identification of a set of geometrical parameters minimizing the pressure fluctuations occurring in part-load conditions as well as the energy losses in both full-load and part-load conditions while maintaining the requested pressure recovery. Finally, the results of the CFD simulations with the final draft tube geometry are compared with the results estimated by the ANOM, which demonstrates that the proposed methodology also enables a rough preliminary estimation of the draft tube losses and pressure fluctuations amplitude.

scholarly journals Performance of Multiclass Computer Systems Using Fuzzy Queueing Model

1996 ◽  
Vol 8 (5) ◽  
pp. 947-957
Author(s):  
Jung Bok JO ◽  
Yasuhiro TSUJIMURA ◽  
Mitsuo GEN ◽  
Genji TAMAZAKI
Keyword(s):  
Computer Systems ◽  
Queueing Model

Thermo-Economic Analysis of an Intercooled, Reheat and Recuperated Gas Turbine for Cogeneration Applications: Part II — Part-Load Operation

2001 ◽  
Author(s):  
R. Bhargava ◽  
G. Negri di Montenegro ◽  
A. Peretto
Keyword(s):  
Economic Analysis ◽  
Gas Turbine ◽  
The Other ◽  
Load Range ◽  
Part Load ◽  
Full Load ◽  
Performance Loss ◽  
Low Load ◽  
Cogeneration System ◽  
Load Conditions

The knowledge of off-design performance for a given gas turbine system is critical particularly in applications where considerable operation at low load setting is required. This information allows designers to ensure safe operation of the system and determine in advance thermo-economic penalty due to performance loss while operating under part-load conditions. In this paper, thermo-economic analysis results for the intercooled, reheat (ICRH) and recuperated gas turbine, at the part-load conditions in cogeneration applications, have been presented. Thermodynamically, a recuperated ICRH gas turbine based cogeneration system showed lower penalty in terms of electric efficiency and Energy Saving Index over the entire part-load range in comparison to the other cycles (non-recuperated ICRH, recuperated Brayton and simple Brayton cycles) investigated. Based on the comprehensive economic analysis for the assumed values of economic parameters, this study shows that, a mid-size (electric power capacity 20 MW) cogeneration system utilizing non-recuperated ICRH cycle provides higher return on investment both at full-load and part-load conditions, compared to the other same size cycles, over the entire range of fuel cost, electric sale and steam sale values examined. The plausible reasons for the observed trends in thermodynamic and economic performance parameters for four cycles and three sizes of cogeneration systems under full-load and part-load conditions have been presented in this paper.

Investigation Into a “Steam Whirl” Which Affected HP Rotors of 300 MW Steam Turbines

2007 ◽  
Author(s):  
Janusz Kubiak Sz. ◽  
Dara Childs ◽  
M. Rodri`guez ◽  
J. C. Garci´a
Keyword(s):  
Steam Turbine ◽  
The Other ◽  
Steam Turbines ◽  
Full Load ◽  
The Past ◽  
Instability Effect ◽  
Valve Opening ◽  
Rotordynamic Forces ◽  
Rotor Model ◽  
Load Conditions

In the past, several 300 MW steam turbine rotors were affected by vibrations, which appeared at bearing #1 during load conditions. At certain loads, vibrations of the #1 bearing increased considerably. Near full load the amplitude of vibration sometimes reduced to acceptable levels. Practically, the phenomena were partially cured by trim balancing of the HP rotor, readjusting the valve opening characteristics and by correction of the clearances in the sealing system. The results are briefly summarized. On the other hand, the simulation of the various parameters using rotordynamic codes was conducted to explain the phenomena analytically. In this part, the rotordynamic rotor model was constructed and the following simulations were carried out: rotor bearing instability, effect of the destabilizing steam forces on the rotor at the first row, effect of the seal rotordynamic forces and the valve opening sequence on the rotor stability. All results were analyzed to present general conclusions.

Thermoeconomic Analysis of an Intercooled, Reheat, and Recuperated Gas Turbine for Cogeneration Applications—Part II: Part-Load Operation

2002 ◽  
Vol 124 (4) ◽  
pp. 892-903 ◽  
Author(s):  
R. Bhargava ◽  
G. Negri di Montenegro ◽  
A. Peretto
Keyword(s):  
Gas Turbine ◽  
The Other ◽  
Safe Operation ◽  
Load Range ◽  
Part Load ◽  
Full Load ◽  
Performance Loss ◽  
Low Load ◽  
Cogeneration System ◽  
Load Conditions

The knowledge of off-design performance for a given gas turbine system is critical particularly in applications where considerable operation at low load setting is required. This information allows designers to ensure safe operation of the system and determine in advance thermoeconomic penalty due to performance loss while operating under part-load conditions. In this paper, thermoeconomic analysis results for the intercooled reheat (ICRH) and recuperated gas turbine, at the part-load conditions in cogeneration applications, have been presented. Thermodynamically, a recuperated ICRH gas turbine-based cogeneration system showed lower penalty in terms of electric efficiency and Energy Saving Index over the entire part-load range in comparison to the other cycles (nonrecuperated ICRH, recuperated Brayton and simple Brayton cycles) investigated. Based on the comprehensive economic analysis for the assumed values of economic parameters, this study shows that a midsize (electric power capacity 20 MW) cogeneration system utilizing nonrecuperated ICRH cycle provides higher return on investment both at full-load and part-load conditions, compared to the other same size cycles, over the entire range of fuel cost, electric sale, and steam sale values examined. The plausible reasons for the observed trends in thermodynamic and economic performance parameters for four cycles and three sizes of cogeneration systems under full-load and part-load conditions have been presented in this paper.

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