A Reevaluation of the Holzwarth Gas Turbine Cycle for Use in Small Power Plants

2001 ◽  
Author(s):  
Osvaldo José Venturini ◽  
Sebastião Varella
Keyword(s):  
Gas Turbine ◽  
Temperature Variation ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Constant Pressure ◽  
Specific Work ◽  
Brayton Cycle ◽  
Small Power ◽  
The One ◽  
Gas Turbine Cycle

The purpose of this work is to analyze a gas turbine working under a cycle similar to the one proposed, by the Dr. Holtzwarth, at the beginning of the last century, showing its potentiality, mainly when applied to small power turbines. The method for analysis is based in the quasi-steady thermodynamic equilibrium principle, where the effects of the pressure and temperature variation, due to the intermittent combustion, are considered. Conclusions are presented considering the increase of the thermal efficiency and the available specific work, resulting from the constant volume combustion, when compared with those of a turbine operating under constant pressure combustion (Brayton Cycle). These results are obtained using actual curves of operation for the compressor and the turbine and, as well as, the “matching” of them.

scholarly journals Thermodynamic Analysis of Different Configurations of Combined Cycle Power Plants

2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Slight Effect ◽  
Turbine Engine ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency

<p class="1Body">Several modifications have been made to the simple gas turbine cycle in order to increase its thermal efficiency but within the thermal and mechanical stress constrain, the efficiency still ranges between 38 and 42%. The concept of using combined cycle power or CPP plant would be more attractive in hot countries than the combined heat and power or CHP plant. The current work deals with the performance of different configurations of the gas turbine engine operating as a part of the combined cycle power plant. The results showed that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance.</p>

Study on Primary and Secondary Heat-Transport Systems for Sodium-Cooled Fast Reactor

2013 ◽  
Author(s):  
Alexey Dragunov ◽  
Eugene Saltanov ◽  
Igor Pioro ◽  
Glenn Harvel ◽  
Brian Ikeda
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Transport ◽  
Fast Reactor ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Power Conversion ◽  
Gas Turbine Cycle ◽  
Steam Cycle

One of the current engineering challenges is to design next generation (Generation IV) Nuclear Power Plants (NPPs) with significantly higher thermal efficiencies (43–55%) compared to those of current NPPs to match or at least to be close to the thermal efficiencies reached at fossil-fired power plants (55–62%). The Sodium-cooled Fast Reactor (SFR) is one of the six concepts considered under the Generation IV International Forum (GIF) initiative. The BN-600 reactor is a sodium-cooled fast-breeder reactor built at the Beloyarsk NPP in Russia. This concept is the only one from the Generation IV nuclear-power reactors, which is actually in operation (since 1980’s). At the secondary side, it uses a subcritical-pressure Rankine-steam cycle with heat regeneration. The reactor generates electrical power in the amount of 600 MWel. The reactor core dimensions are 0.75 m (height) by 2.06 m (diameter). The UO2 fuel enriched to 17–26% is utilized in the core. There are 2 loops (circuits) for sodium flow. For safety reasons, sodium is used both in the primary and the intermediate circuits. Therefore, a sodium-to-sodium heat exchanger is used to transfer heat from the primary loop to the intermediate one. In this work major parameters of the reactor are listed. The actual scheme of the power-conversion heat-transport system is presented; and the results of the calculation of thermal efficiency of this scheme are analyzed. Details of the heat-transport system, including parameters of the sodium-to-sodium heat exchanger and main coolant pump, are presented. In this paper two possibilities for the SFR in terms of the power-conversion cycle are investigated: 1. a subcritical-pressure Rankine-steam cycle through a heat exchanger (current approach in Russian and Japanese power reactors); 2. a supercritical-pressure CO2 Brayton gas-turbine cycle through a heat exchanger (US approach). With the advent of modern super-alloys, the Rankine-steam cycle has progressed into the supercritical region of the coolant and is generating thermal efficiencies into the mid 50% range. Therefore, the thermal efficiency of a supercritical Rankine-steam cycle is also briefly discussed in this paper. According to GIF, the Brayton gas-turbine cycle is under consideration for future nuclear power reactors. The supercritical-CO2 cycle is a new approach in the Brayton gas-turbine cycle. Therefore, dependence of the thermal efficiency of this SC CO2 cycle on inlet parameters of the gas turbine is also investigated.

scholarly journals The Constant Volume Gas Turbine Cycle According to Karavodine

1982 ◽  
Author(s):  
H. Vandermeulen
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Constant Pressure ◽  
Constant Volume ◽  
Theory And Practice ◽  
Pressure Cycle ◽  
Basic Distinction ◽  
Overall Performance ◽  
The One ◽  
Gas Turbine Cycle

The basic distinction between the constant volume cycle and the well known constant pressure cycle for gas turbines is the method of heat supply, which necessitates a system of combustion chamber valves to contain the fluid. The object of the proposed cycle analysis, which is mainly based on the fundamental laws of mass and energy, will consider a solution for the discrepancies between the former theory and practice of constant volume gas turbines. The overall performance characteristics which emerge from this analysis show the distinct superiority of the one-valve Karavodine cycle. Evaluation by experiment for this cycle variant shows, however, besides a refinement of the model, a marginal superiority in performance for the Brayton gas turbine at low pressure ratios. Any application could probably be justified by incorporating it in Brayton turbines to diminish starting power and to improve part load performance.

Gas Turbine With Constant Volume Heat Addition

2010 ◽  
Author(s):  
S. Can Gu¨len
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Fossil Fuel ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Heat Addition ◽  
Volume Heat

Increasing the thermal efficiency of fossil fuel fired power plants in general and the gas turbine power plant in particular is of extreme importance. In the face of diminishing natural resources and increasing carbon emissions that lead to a heightened greenhouse effect and greater concerns over global warming, thermal efficiency is more critical today than ever before. In the science of thermodynamics, the best yardstick for a power generation system’s performance is the Carnot efficiency — the ultimate efficiency limit, set by the second law, which can be achieved only by a perfect heat engine operating in a cycle. As a fact of nature this upper theoretical limit is out of reach, thus engineers usually set their eyes on more realistic goals. For the longest time, the key performance benchmark of a combined cycle (CC) power plant has been the 60% net electric efficiency. Land-based gas turbines based on the classic Brayton cycle with constant pressure heat addition represent the pinnacle of fossil fuel burning power generation engineering. Advances in the last few decades, mainly driven by the increase in cycle maximum temperatures, which in turn are made possible by technology breakthroughs in hot gas path materials, coating and cooling technologies, pushed the power plant efficiencies to nearly 40% in simple cycle and nearly 60% in combined cycle configurations. To surpass the limitations imposed by available materials and other design considerations and to facilitate a significant improvement in the thermal efficiency of advanced Brayton cycle gas turbine power plants necessitate a rethinking of the basic thermodynamic cycle. The current paper highlights the key thermodynamic considerations that make the constant volume heat addition a viable candidate in this respect. First using fundamental air-standard cycle formulas and then more realistic but simple models, potential efficiency improvement in simple and combined cycle configurations is investigated. Existing and past research activities are summarized to illustrate the technologies that can transform the basic thermodynamics into a reality via mechanically and economically feasible products.

Thermal efficiency of direct, inverse and sCO 2 gas turbine cycles intended for small power plants

Energy ◽  
2016 ◽  
Vol 100 ◽  
pp. 66-72 ◽  
Author(s):  
Manuel Valdés ◽  
Rubén Abbas ◽  
Antonio Rovira ◽  
Javier Martín-Aragón
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Small Power

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.

scholarly journals Potentials for Pressure Gain Combustion in Advanced Gas Turbine Cycles

2019 ◽  
Vol 9 (16) ◽  
pp. 3211
Author(s):  
Nicolai Neumann ◽  
Dieter Peitsch
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Specific Work ◽  
Turbine Cooling ◽  
Turbine Efficiency ◽  
Optimization Study ◽  
Pressure Gain Combustion ◽  
Reduce Emissions ◽  
Secondary Air ◽  
Gas Turbine Cycle

Pressure gain combustion evokes great interest as it promises to increase significantly gas turbine efficiency and reduce emissions. This also applies to advanced thermodynamic cycles with heat exchangers for intercooling and recuperation. These cycles are superior to the classic Brayton cycle and deliver higher specific work and/or thermal efficiency. The combination of this revolutionary type of combustion in an intercooled or recuperated gas turbine cycle can, however, lead to even higher efficiency or specific work. The research of these potentials is the topic of the presented paper. For that purpose, different gas turbine setups for intercooling, recuperation, and combined intercooling and recuperation are modeled in a gas turbine performance code. A secondary air system for turbine cooling is incorporated, as well as a blade temperature evaluation. The pressure gain combustion is represented by analytical-algebraic and empirical models from the literature. Key gas turbine specifications are then subject to a comprehensive optimization study, in order to identify the design with the highest thermal efficiency. The results indicate that the combination of intercooling and pressure gain combustion creates synergies. The thermal efficiency is increased by 10 percentage points compared to a conventional gas turbine with isobaric combustion.

Assessing the Potential of Gas-Recuperation in Reheated Gas Turbines Within Combined Gas-Steam Power Plants

2014 ◽  
Author(s):  
Adam Doligalski ◽  
Luis Sanchez de Leon ◽  
Pavlos K. Zachos ◽  
Vassilios Pachidis
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Power Plants ◽  
Current Approach ◽  
Combined Cycle ◽  
Variable Position ◽  
Power Turbine ◽  
Power Generation Systems ◽  
Gas Turbine Cycle

This paper presents a comparative analysis between two different gas turbine configurations for implementation within combined cycle power plants, aiming to downselect the most promising one in terms of thermal efficiency at design point. The analysed gas turbines both feature the same dual-pressure steam bottoming cycle, but differ in the gas turbine cycle itself: the first configuration comprises a single-shaft reheated gas turbine with variable position of the reheater (representative of the current approach of the industry to combined cycle power plants), whilst the second configuration comprises a dual-shaft reheated-recuperated engine with free power turbine. Comparison of the two competing gas turbine configurations is conducted by means of systematic exploration of the combined cycle design space. The analysis showed that the reheated-recuperated configuration delivers higher thermal efficiency than the more conventional reheated (non-recuperated) gas turbine and is identified, therefore, as a competitive option for future combined cycle power generation systems.

Probabilistic Assessment of Thermodynamic Output of an Intercooled-Reheated-Regenerative Brayton Cycle Coupled to Variable Temperature Heat Reservoirs

2013 ◽  
Author(s):  
Vishal Anand ◽  
Krishna Nelanti
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Variable Temperature ◽  
Gas Turbine Engine ◽  
Design Parameters ◽  
Probabilistic Assessment ◽  
Brayton Cycle ◽  
Turbine Engine ◽  
Temperature Heat

The gas turbine engine works on the principle of Brayton cycle. One of the ways to improve the thermal efficiency of gas turbine engine is to make changes in the Brayton cycle. These changes may include intercooling, reheating, regeneration etc. The aim of the present study is to do a probabilistic assessment of the thermal efficiency and the dimensionless power of an intercooled, reheated, regenerative Brayton cycle coupled to variable temperature heat reservoirs. The Spearman’s rank coefficient has been used to find the design parameters which most affect the thermal efficiency and the dimensionless power. The design parameters, such as the effectiveness of the different heat exchangers, the efficiency of turbines and compressors and the heat capacitance rates of the external and the working fluids; have been listed with their relative impact on the thermal efficiency and the dimensionless power. The probabilistic assessment gives us a new insight into the sensitivity of the thermal efficiency and the dimensionless power of the Brayton Cycle with respect to these parameters. It will help the designers/decision makers to allocate the limited resources in a better way with the ultimate aim of making more efficient power plants.

A Feasibility Study on Various Power-Conversion Cycles for a Sodium-Cooled Fast Reactor

2012 ◽  
Author(s):  
Alexey Dragunov ◽  
Eugene Saltanov ◽  
Sergey Bedenko ◽  
Igor Pioro
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Supercritical Pressure ◽  
New Approach ◽  
Heat Regeneration ◽  
Gas Turbine Cycle ◽  
Steam Cycle

One of the current engineering challenges is to design next generation (Generation IV) Nuclear Power Plants (NPPs) with significantly higher thermal efficiencies compared to those of current NPPs to match or at least to be close to thermal efficiencies reached at thermal power plants (43–55%). A Sodium-cooled Fast Reactor (SFR) is one of six concepts considered under the Generation IV International Forum (GIF). This concept is the only one from the Generation IV reactors, which is actually in operation in Russia. In general, there are 3 possibilities for an SFR in terms of the secondary cycle: 1. Subcritical-pressure Rankine-“steam”-cycle through a heat exchanger (current approach used in Russian and Japanese power reactors). 2. Supercritical-pressure Rankine-“steam”-cycle through a heat exchanger (new approach). 3. Supercritical-pressure CO2 Brayton-gas-turbine-cycle through a heat exchanger (US approach). The BN-600 reactor is a sodium-cooled fast-breeder reactor built at the Beloyarsk NPP in Russia. It has been in operation since 1980 and adopts the secondary subcritical-pressure Rankine-“steam”-cycle with heat regeneration. Steam extractions are taken from High-Pressure (HP), Intermediate-Pressure (IP) and Low-Pressure (LP) turbines. The basic method of increasing the thermal efficiency of power plants is to improve it by increasing the operating pressure and temperature. With the advent of modern super alloys, the Rankine-“steam”-cycle has progressed into the supercritical region of the coolant and is generating net efficiencies into the mid 40% range. Calculations of thermal efficiency of a secondary sub- and supercritical-pressure Rankine-“steam”-cycle with heat regeneration are presented in the paper. The Brayton-gas-turbine cycle is under consideration for future nuclear power reactors. The higher operating temperatures will be achieved, the higher thermal efficiency will be. Supercritical CO2 cycle is a new approach in Brayton-gas-turbine cycle. Carbon dioxide has a critical pressure of 7.38 MPa and a critical temperature of 31.0°C, which is significantly less than that of water (22.064 MPa and 373.95°C). However, liquid sodium is more compatible with SC CO2 than with water. Therefore, thermal efficiency of this SC CO2 cycle is also calculated.

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