scholarly journals A Useful Equation for Gas Turbine Design

2018 ◽  
Vol 140 (03) ◽  
pp. S52-S53
Author(s):  
Lee S. Langston
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Gas Turbine ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Nonlinear Superposition ◽  
Transient Conditions ◽  
One Dimensional ◽  
Turbine Design

This article presents three different gas turbine phenomena and design cases. The sketch in the article shows a schematic of a combined cycle powerplant consisting of a Brayton cycle (gas turbine) whose exhaust provides energy to a Rankine cycle (steam turbine). Frequently, one can use simple but exact one-dimensional (1D) heat conduction solutions to estimate the heat loss or gain of gas turbine components under transient conditions. These easy-to-use solutions are found in most undergraduate heat transfer texts. The article suggests that those three widely different gas turbine phenomena and design cases all have the simple, nonlinear superposition form.

scholarly journals Why We Need Nuclear Power Plants

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Gen Iv

The major growth in the electricity production industry in the last 30 years has centered on the expansion of natural gas power plants based on gas turbine cycles. The most popular extension of the simple Brayton gas turbine has been the combined cycle power plant with the Air-Brayton cycle serving as the topping cycle and the Steam-Rankine cycle serving as the bottoming cycle for new generation of nuclear power plants that are known as GEN-IV. The Air-Brayton cycle is an open-air cycle and the Steam-Rankine cycle is a closed cycle. The air-Brayton cycle for a natural gas driven power plant must be an open cycle, where the air is drawn in from the environment and exhausted with the products of combustion to the environment. This technique is suggested as an innovative approach to GEN-IV nuclear power plants in form and type of Small Modular Reactors (SMRs). The hot exhaust from the AirBrayton cycle passes through a Heat Recovery Steam Generator (HSRG) prior to exhausting to the environment in a combined cycle. The HRSG serves the same purpose as a boiler for the conventional Steam-Rankine cycle [1].

Electrical Power Generation: Fossil Fuels

2017 ◽  
Author(s):  
Peter Rez
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Fossil Fuels ◽  
Turbine Blades ◽  
Electrical Power ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Steam Temperature

Nearly all electrical power is generated by rotating a coil in a magnetic field. In most cases, the coil is turned by a steam turbine operating according to the Rankine cycle. Water is boiled and heated to make high-pressure steam, which drives the turbine. The thermal efficiency is about 30–35%, and is limited by the highest steam temperature tolerated by the turbine blades. Alternatively, a gas turbine operating according to the Brayton cycle can be used. Much higher turbine inlet temperatures are possible, and the thermal efficiency is higher, typically 40%. Combined cycle generation, in which the hot exhaust from a gas turbine drives a Rankine cycle, can achieve thermal efficiencies of almost 60%. Substitution of coal-fired by combined cycle natural gas power plants can result in significant reductions in CO2 emissions.

Analysis of a Combined Cycle Plant Using a Small Particle Receiver to Drive a Primary Brayton Cycle

2015 ◽  
Author(s):  
Matthew Miguel Virgen ◽  
Fletcher Miller
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Small Particle ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Efficiency Gains ◽  
Steam Cycle

All current commercial CSP plants operate at relatively low thermodynamic efficiency due to lower temperatures than similar conventional plants and due to the fact that they all employ Rankine conversion cycles. We present here an investigation on the effects of adding a bottoming steam power cycle to a hybrid CSP plant based on a Small Particle Heat Exchange Receiver (SPHER) driving a gas turbine as the primary cycle. Due to the high operating temperature of the SPHER being considered (over 1000 Celsius), the exhaust air from the primary Brayton cycle still contains a tremendous amount of exergy. While in the previous analysis this fluid was only used in a recuperator to preheat the Brayton working fluid, the current analysis explores the potential power and efficiency gains from instead directing the exhaust fluid through a heat exchanger to power a Rankine steam cycle. Not only do we expect the efficiency of this model to be competitive with conventional power plants, but the water consumption per kilowatt-hour will also be reduced by nearly two thirds as compared to most existing concentrating solar thermal power plants as a benefit of having air as the primary working fluid, which eliminates the condensation step present in Rankine-cycle systems. Coupling a new steam cycle model with the gas-turbine CSP model previously developed at SDSU, a wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP combined cycle gas turbine (CCGT) plant. Due to the generalized nature of the bottoming cycle modeling, and the varying nature of solar power, special consideration had to be given to the behavior of the heat exchanger and Rankine cycle in off-design scenarios. The trade-offs of removing the recuperator for preheating the primary fluid are compared to potential overall power and efficiency gains in the combined cycle case.

Investigation of the Performance of a Three Stage Combined Power Cycle for Electric Power Plants

2019 ◽  
Author(s):  
Pereddy Nageswara Reddy ◽  
J. S. Rao
Keyword(s):  
Power Plant ◽  
Electric Power ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Atmospheric Air ◽  
Power Cycle

Abstract A three stage combined power cycle with a Brayton cycle as the topping cycle, a Rankine cycle as the middling cycle and an Organic Rankine Cycle (ORC) as the bottoming cycle is proposed in the present investigation. A two-stage Gas Turbine Power Plant (GTPP) with inter-cooling, reheating and regeneration based on the Brayton cycle, a single-stage Steam Turbine Power Plant (STPP) based on the Rankine cycle, and a two-stage ORC power plant with reheating based on ORC with atmospheric air as the coolant is considered in the present study. This arrangement enables the proposed plant to utilize the waste heat to the maximum extent possible and convert it into electric power. As the plant can now operate at low sink temperatures depending on atmospheric air, the efficiency of the combined cycle power plant increases dramatically. Further, Steam Turbine Exhaust Pressure (STEP) is positive resulting in smaller size units and a lower installation cost. A simulation code is developed in MATLAB to investigate the performance of a three stage combined power cycle at different source and sink temperatures with varying pressure in heat recovery steam boiler and condenser-boiler. Performance results are plotted with Gas Turbine Inlet Temperature (GTIT) of 1200 to 1500 °C, Coolant Air Temperature (CAT) of −15 to +25 °C, and pressure ratio of GTPP as 6.25, 9.0 and 12.25 for different organic substances and NH3 as working fluids in the bottoming ORC. Simulation results show that the efficiency of the three stage combined power cycle will go up to 64 to 69% depending on the pressure ratio of GTPP, GTIT, and CAT. It is also observed that the variation in the efficiency of the three stage combined power cycle is small with respect to the type of working fluid used in the ORC. Among the organic working fluids R134a, R12, R22, and R123, R134a gives a higher combined cycle efficiency.

Integration of a Pressurized-Air Solar Receiver Array to a Gas Turbine Power Cycle for Solar Tower Applications

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Peter Poživil ◽  
Aldo Steinfeld
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Rankine Cycle ◽  
Power Input ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Receiver Array ◽  
Solar Receiver

The thermal performance of an array of pressurized-air solar receiver modules integrated to a gas turbine power cycle is analyzed for a simple Brayton cycle (BC), recuperated Brayton cycle (RC), and combined Brayton–Rankine cycle (CC). While the solar receiver's solar-to-heat efficiency decreases at higher operating temperatures and pressures, the opposite is true for the power cycle's heat-to-work efficiency. The optimal operating conditions are achieved with a preheat stage for a solar receiver outlet air temperature of 1300 °C and an air cycle pressure ratio of 9, yielding a peak solar-to-electricity efficiency—defined as the ratio of the net cycle work output divided by the solar radiative power input through the receiver's aperture—of 39.3% for the combined cycle configuration.

Microprocessor Silicon Die Temperature Prediction by Simplified Boundary Conditions

2015 ◽  
Author(s):  
Koji Nishi ◽  
Tomoyuki Hatakeyama ◽  
Shinji Nakagawa ◽  
Masaru Ishizuka
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Boundary Conditions ◽  
Thermal Resistance ◽  
Hot Spot ◽  
Three Dimensional ◽  
Thermal Design ◽  
Target Temperature ◽  
One Dimensional ◽  
Thermal Network

The thermal network method has a long history with thermal design of electronic equipment. In particular, a one-dimensional thermal network is useful to know the temperature and heat transfer rate along each heat transfer path. It also saves computation time and/or computation resources to obtain target temperature. However, unlike three-dimensional thermal simulation with fine pitch grids and a three-dimensional thermal network with sufficient numbers of nodes, a traditional one-dimensional thermal network cannot predict the temperature of a microprocessor silicon die hot spot with sufficient accuracy in a three-dimensional domain analysis. Therefore, this paper introduces a one-dimensional thermal network with average temperature nodes. Thermal resistance values need to be obtained to calculate target temperature in a thermal network. For this purpose, thermal resistance calculation methodology with simplified boundary conditions, which calculates thermal resistance values from an analytical solution, is also introduced in this paper. The effectiveness of the methodology is explored with a simple model of the microprocessor system. The calculated result by the methodology is compared to a three-dimensional heat conduction simulation result. It is found that the introduced technique matches the three-dimensional heat conduction simulation result well.

scholarly journals Benefits of Solar/Fossil Hybrid Gas Turbine Systems

1979 ◽  
Author(s):  
H. S. Bloomfield
Keyword(s):  
Power Systems ◽  
Gas Turbine ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Fuel Saving ◽  
Operational Mode ◽  
Fuel Savings ◽  
Cycle Systems ◽  
Potential Benefits ◽  
Near Term

The potential benefits of solar/fossil hybrid gas turbine power systems were assessed. Both retrofit and new systems were considered from the aspects of: cost of electricity, fuel conservation, operational mode, technology requirements, and fuels flexibility. Hybrid retrofit (repowering) of existing combustion (simple Brayton cycle) turbines can provide near-term fuel savings and solar experience, while new and advanced recuperated or combined-cycle systems may be an attractive fuel saving and economically competitive vehicle to transition from today’s gas- and oil-fired powerplants to other more abundant fuels.

A Cold Heat Transfer Tunnel for Gas Turbine Research on an Annular Cascade

1993 ◽  
Author(s):  
R. F. Martinez-Botas ◽  
A. J. Main ◽  
G. D. Lock ◽  
T. V. Jones
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Region Of Interest ◽  
Secondary Flows ◽  
Test Duration ◽  
Pressure Distributions ◽  
Exit Mach Number ◽  
Nozzle Guide ◽  
Turbine Design ◽  
Annular Cascade

The Oxford University Blowdown Tunnel has been substantially modified to test a large annular cascade of high pressure nozzle guide vanes (mean blade diameter of 1.11 m and axial chord of 0.0673 m). The new transonic facility has been constructed to obtain complete contours of heat transfer coefficient for both the end walls and blade surfaces using the transient liquid crystal technique, to measure pressure distributions and losses, and to study fundamental aspects of boundary layers and secondary flows. The facility allows an independent variation of Reynolds and Mach numbers, providing aerodynamic and heat transfer measurements in the region of interest for gas turbine design. The mass flow rate through the cascade at NGV design conditions (exit Mach number 0.96 and Reynolds number 2.0 × 106) is 38 kg/s and the pressure-regulated test duration exceeds 7 seconds.

Nonlinear Inverse Heat Conduction With a Moving Boundary: Heat Flux and Surface Recession Estimation

1999 ◽  
Vol 121 (3) ◽  
pp. 708-711 ◽  
Author(s):  
V. Petrushevsky ◽  
S. Cohen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fourier Series ◽  
Heat Conduction ◽  
Moving Boundary ◽  
Heat Conduction Problem ◽  
Inverse Heat Conduction Problem ◽  
Variable Order ◽  
Inverse Heat Conduction ◽  
One Dimensional

A one-dimensional, nonlinear inverse heat conduction problem with surface ablation is considered. In-depth temperature measurements are used to restore the heat flux and the surface recession history. The presented method elaborates a whole domain, parameter estimation approach with the heat flux approximated by Fourier series. Two versions of the method are proposed: with a constant order and with a variable order of the Fourier series. The surface recession is found by a direct heat transfer solution under the estimated heat flux.

Part Load Conditions of Complex Cycle Power Plants With Intercooled Gas Turbine

1996 ◽  
Author(s):  
A. Peretto
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Working Conditions ◽  
Power Plants ◽  
Pressure Level ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Part Load ◽  
High Pressure Compressor ◽  
Pressure Compressor

The present paper evaluates the behavior, in design and part load working conditions, of a complex gas turbine cycle with multiple intercooled compression, and the optional preheating of the air at the high pressure compressor outlet by means of the gas turbine outlet hot gas. The results are then compared with those obtained by a Brayton cycle gas turbine, with or without preheating of the air at the high pressure compressor outlet. Subsequently, the performance of complex combined cycles, with intercooled gas turbine as topper and one, two or three pressure level steam cycle as bottomer, in design and part load working conditions is also evaluated. The performance of these complex combined plants is then compared with that obtained by a Brayton cycle gas turbine as topper and one, two or three pressure level steam cycle as bottomer. Part load working conditions are realized by varying either the inlet guide vane angle of the first compressor nozzles or the maximum temperature at the combustor outlet. The study shows that in part load working conditions obtained by varying IGV, the complex cycles, in the examined gas turbine or in the combined cycle power plants, give conversion efficiencies decidedly greater than those obtainable by varying combustor exit temperature. Furthermore it is found that these complex power plant efficiencies, in part load working conditions, are far greater than those obtained by the Brayton cycle gas turbine, or by combined cycle with Brayton cycle gas turbine as topper, if IGV adjustment is adopted. If power variation is obtained with combustor outlet temperature adjustment, the efficiencies of the combined power plants with complex or Brayton cycle gas turbines, are substantially the same, for the same relative power variation.

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