A Parametric Analysis Microcomputer Model for Evaluating the Thermodynamic Performance of a Reciprocating Brayton Cycle Engine

1989 ◽  
Vol 111 (4) ◽  
pp. 587-594 ◽  
Author(s):  
G. A. Tsongas ◽  
T. J. White
Keyword(s):  
Pressure Ratio ◽  
Piston Compressor ◽  
Significant Loss ◽  
Maximum Temperature ◽  
Specific Work ◽  
Operating Characteristics ◽  
Turbine Engine ◽  
Pressure Losses ◽  
Thermodynamic Performance ◽  
Input Parameters

A novel Brayton open-cycle engine is under development. It operates similarly to a gas turbine engine, but uses reciprocating piston compressor and expander components. The design appears to have a number of advantages, including multifuel capability, the potential for lower cost, and the ability to be scaled to small sizes without significant loss in efficiency. An interactive microcomputer model has been developed that analyzes the thermodynamic performance of the engine. The model incorporates all the important irreversibilities found in piston devices, including heat transfer, mechanical friction, pressure losses, and mass loss and recirculation. There are 38 input parameters to the model. Key independent operating parameters are maximum temperature, compressor rpm, and pressure ratio. While the development of the model and its assumptions are outlined in this paper, the emphasis is on model applications. The model has demonstrated itself to be a powerful tool for evaluating engine thermal efficiency, net specific work, and power. It can be used to analyze the performance of individual engine designs, to generate performance “maps” that graphically represent engine operating characteristics, and to perform sensitivity analysis to compare the relative effects of various input parameters. Examples of each of these model applications are discussed. Recommendations for model improvements and for further engine development work are made. The need for better experimental data to verify some critical model assumptions is stressed.

An Assessment of the Performance of Closed Cycles With and Without Heat Rejection at Cryogenic Temperatures

1996 ◽  
Author(s):  
A. Agazzani ◽  
A. F. Massardo ◽  
T. Korakianitis
Keyword(s):  
Heat Exchangers ◽  
Power Plants ◽  
Cycle Performance ◽  
Maximum Temperature ◽  
Specific Work ◽  
Cryogenic Temperatures ◽  
Temperature Minimum ◽  
Thermodynamic Performance ◽  
Cycle Systems ◽  
Near Term

This paper presents optimized cycle performance that can be obtained with systems including a Closed Cycle Gas Turbine (CCGT). The influence of maximum temperature, minimum temperature and recuperator effectiveness on cycle performance is illustrated. Several power-plant arrangements are analyzed and compared based on: thermodynamic performance (thermal efficiency and specific work); enabling technologies (available at present); and developing technologies (available in the near term or future). The work includes the effects of utilization of high temperature ceramic heat exchangers and of coupling of CCGT systems with plants vaporizing Liquid Hydrogen (LH2) or Liquefied Natural Gas (LNG). Given the versatility of energy addition and rejection sources that can be utilized in closed gas-cycle systems, the thermodynamic performance of power plants shown in this paper indicate the remarkable capabilities and possibilities for closed gas-cycle systems.

Experimental Study on Pressure Losses in Porous Materials

2018 ◽  
Author(s):  
Giacomo Fantozzi ◽  
Mats Kinell ◽  
Sara Rabal Carrera ◽  
Jenny Nilsson ◽  
Yves Kuesters
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Turbine Engine ◽  
Geometrical Properties ◽  
Pressure Losses ◽  
Technological Advances ◽  
Pore Radius Distribution ◽  
Engine Components ◽  
Test Objects

Recent technological advances in the field of additive manufacturing have made possible to manufacture turbine engine components characterized by controlled permeability in desired areas. These have shown great potential in cooling application such as convective cooling and transpiration cooling and may in the future contribute to an increase of the turbine inlet temperature. This study investigates the effects of the pressure ratio, the thickness of the porous material and the hatch distance used during manufacturing on the discharge coefficient. Moreover, two different porous structures were tested and in total 70 test objects were investigated. Using a scanning electron microscope, it is shown that the porosity and pore radius distribution, which are a result from the used laser power, laser speed and hatch distance during manufacturing, will characterize the pressure losses in the porous sample. Furthermore, the discharge coefficient increases with increasing pressure ratio, while it decreases with increasing thickness to diameter ratio. The obtained experimental data was used to develop a correlation for the discharge coefficient as a function of the geometrical properties and the pressure ratio.

The Optimal Intercooling of Compressors by a Finite Number of Intercoolers

1992 ◽  
Vol 114 (3) ◽  
pp. 255-260 ◽  
Author(s):  
P. Vadasz ◽  
D. Weiner
Keyword(s):  
Finite Number ◽  
Pressure Ratio ◽  
Optimal Number ◽  
Specific Work ◽  
Relative Pressure ◽  
Correction Factors ◽  
Isothermal Compression ◽  
Compression Process ◽  
Pressure Losses ◽  
The Ideal

Intercooling of compressors is necessary for an efficient process. Among the optimal criteria required, minimizing the compression-specific work is one of the more commonly used. Upon ideal conditions, such a criterion leads to an isothermal compression whose importance is purely theoretical, since it requires an infinite number of intercoolers. In this paper the evaluation of correction factors to the well-known relations of the optimal location of intercoolers in a compression process and its corresponding work of compression was performed for a general compression process which accounts for pressure losses and other irreversibilities as well. As a result of including the pressure losses in the equations, a finite number of intercoolers is evaluated as optimum. The results, although qualitatively expected, show a quantitative nonempirical figure of the optimal number of intercoolers as a function of the terminal pressure ratio and as a function of the relative pressure losses. The ideal conditions are evaluated and verified as a particular case by assuming no pressure losses. In practice, these results can be used as an upper limit for technoeconomical optimization processes.

scholarly journals Analyses of a High Pressure Ratio Intercooled Direct Brayton Helium Gas Turbine Cycle for Generation IV Reactor Power Plants

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
A. Gad-Briggs ◽  
P. Pilidis ◽  
T. Nikolaidis
Keyword(s):  
Power Plants ◽  
Pressure Ratio ◽  
Business Case ◽  
Sensitivity Analyses ◽  
Critical Parameters ◽  
Processing Plant ◽  
Specific Work ◽  
Pressure Losses ◽  
Cycle Efficiency ◽  
Very High

The intercooled cycle (IC) as an alternative to the simple cycle recuperated (SCR) and intercooled cycle recuperated (ICR) is yet to be fully analyzed for the purpose of assessing its viability for utilization within Generation IV nuclear power plants (NPPs). Although the benefits are not explicitly obvious, it offers the advantage of a very high overall pressure ratio (OPR) in the absence of a recuperator. Thus, the main objective of this study is to analyze various pressure ratio configurations, the effects of varying pressure ratio including sensitivity analyses of component efficiencies, ambient temperature, component losses and pressure losses on cycle efficiency, and specific work of the IC, including comparison with the SCR and ICR. Results of comparison between the IC and the SCR and ICR derived that the cycle efficiencies are greater than the IC by ∼4% (SCR) and ∼6% (ICR), respectively. However, the pressure losses for IC are lower when compared with the SCR and ICR. Nonetheless, heat from the turbine exit temperature of the IC can be used in a processing plant including the possibility of higher turbine entry temperatures (TETs) to significantly increase the cycle efficiency in a bid to justify the business case. The analyses intend to bring to attention an alternative to current cycle configurations for the gas-cooled fast reactors (GFRs) and very-high-temperature reactors (VHTRs), where helium is the coolant. The findings are summarized by evaluating the chosen pressure ratio configurations against critical parameters and detailed comparison with the SCR and ICR.

scholarly journals Effect of radial inflow distortion on the performance of a highly loaded tandem stage

2021 ◽  
pp. 095765092110316
Author(s):  
Amit Kumar ◽  
AM Pradeep
Keyword(s):  
Pressure Ratio ◽  
Pressure Rise ◽  
Adverse Pressure Gradient ◽  
Significant Loss ◽  
The Novel ◽  
Weight Optimization ◽  
Turbine Engine ◽  
Stall Margin ◽  
Engine Size ◽  
Highly Loaded

Engine size and weight optimization have always been high-priority design objectives for designers. Compressors occupy a relatively large part of the gas turbine engine. Owing to the adverse pressure gradient in the compressor, achieving the required pressure ratio within fewer stages has been a challenging task for compressor designers. Tandem blading is one of the novel concepts, which could be used to increase the pressure ratio by means of higher flow turning through the blade passages. This paper presents the performance characteristics of a tandem stage based on results from experiments and numerical analyses. The investigation is further extended to analyze the effect of a radial hub and tip distortion on the performance of the tandem stage. The experimental results are very well supported with some interesting numerical results, particularly near the hub and tip region. It is observed that the tandem stage demonstrates higher pressure rise and stall margin under clean inflow. The tandem stage is also observed to be more sensitive to radial distortion leading to a significant loss in the total pressure and the stall margin.

Experimental Study on Pressure Losses in Porous Materials

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Giacomo Fantozzi ◽  
Mats Kinell ◽  
Sara Rabal Carrera ◽  
Jenny Nilsson ◽  
Yves Kuesters
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Turbine Engine ◽  
Geometrical Properties ◽  
Pressure Losses ◽  
Technological Advances ◽  
Pore Radius Distribution ◽  
Engine Components ◽  
Test Objects

Recent technological advances in the field of additive manufacturing have made possible to manufacture turbine engine components characterized by controlled permeability in desired areas. These have shown great potential in cooling application such as convective cooling and transpiration cooling and may in the future contribute to an increase of the turbine inlet temperature. This study investigates the effects of the pressure ratio, the thickness of the porous material, and the hatch distance used during manufacturing on the discharge coefficient. Moreover, two different porous structures were tested, and in total, 70 test objects were investigated. Using a scanning electron microscope, it is shown that the porosity and pore radius distribution, which are a result from the used laser power, laser speed, and hatch distance during manufacturing, will characterize the pressure losses in the porous sample. Furthermore, the discharge coefficient increases with increasing pressure ratio, while it decreases with increasing thickness to diameter ratio. The obtained experimental data were used to develop a correlation for the discharge coefficient as a function of the geometrical properties and the pressure ratio.

An Assessment of the Performance of Closed Cycles With and Without Heat Rejection at Cryogenic Temperatures

1999 ◽  
Vol 121 (3) ◽  
pp. 458-465 ◽  
Author(s):  
A. Agazzani ◽  
A. F. Massardo ◽  
T. Korakianitis
Keyword(s):  
Heat Exchangers ◽  
Power Plants ◽  
Cycle Performance ◽  
Maximum Temperature ◽  
Specific Work ◽  
Cryogenic Temperatures ◽  
Temperature Minimum ◽  
Thermodynamic Performance ◽  
Cycle Systems ◽  
Near Term

This paper presents optimized cycle performance that can be obtained with systems including a closed cycle gas turbine (CCGT). The influence of maximum temperature, minimum temperature, and recuperator effectiveness on cycle performance is illustrated, Several power-plant arrangements are analyzed and compared based on thermodynamic performance (thermal efficiency and specific work); enabling technologies (available at present); and developing technologies (available in the near term or future). The work includes the effects of utilization of high temperature ceramic heat exchangers and of coupling of CCGT systems with plants vaporizing liquid hydrogen (LH2) or liquefied natural gas (LNG). Given the versatility of energy addition and rejection sources that can be utilized in closed gas-cycle systems, the thermodynamic performance of power plants shown in this paper indicate the remarkable capabilities and possibilities for closed gas-cycle systems.

Numerical Modeling of Heat Transfer and Pressure Losses for Uncooled Gas Turbine Blade Tip: Effect of Tip Clearance and Tip Geometry

2007 ◽  
Author(s):  
Lamyaa A. El-Gabry
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Gas Turbine ◽  
Computational Study ◽  
Numerical Models ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Pressure Losses ◽  
Blade Tip ◽  
Exit Mach Number

A computational study has been performed to predict the heat transfer distribution on the blade tip surface for a representative gas turbine first stage blade. CFD predictions of blade tip heat transfer are compared to test measurements taken in a linear cascade, when available. The blade geometry has an inlet Mach number of 0.3 and an exit Mach number of 0.75, pressure ratio of 1.5, exit Reynolds number based on axial chord of 2.57×106, and total turning of 110 deg. Three blade tip configurations were considered; they are flat tip, a full perimeter squealer, and an offset squealer where the rim is offset to the interior of the tip perimeter. These three tip geometries were modeled at three tip clearances of 1.25, 2.0, and 2.75% of blade span. The tip heat transfer results of the numerical models agree fairly well with the data and are comparable to other CFD predictions in the open literature.

scholarly journals Low-pressure reversible axial fan with straight profile blades and relatively high efficiency

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 593-603 ◽  
Author(s):  
Zivan Spasic ◽  
Sasa Milanovic ◽  
Vanja Sustersic ◽  
Boban Nikolic
Keyword(s):  
Numerical Simulations ◽  
High Efficiency ◽  
Suction Side ◽  
Standard Test ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Blade Profile ◽  
Operating Characteristics ◽  
Axial Fan ◽  
Increase Energy Efficiency

The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.

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