Paper 5: A Cycle Analysis Technique for Small Gas Turbines

Author(s):  
C. Rodgers

Aerothermodynamic analysis studies for open Brayton cycles are often conducted treating the component efficiencies as independent variables. However, as maximum output power is decreased and maximum cycle temperature increased, turbomachinery component sizes diminish resulting in lower component efficiencies. A meaningful small gas turbine cycle analysis should, therefore, treat the component efficiencies as dependent variables. A discussion of such a treatment, as employed during the cycle analysis phase of a small gas turbine, is presented. The particular aerodynamic configuration examined is one comprising a single-stage radial compressor and a single-stage radial turbine. Additionally, cycle performance charts for the selected configuration are presented indicating optimum cycle parameter combinations, attainable performance levels, and typical small gas turbine engine weights.

2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan

<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>


Author(s):  
Hironori Arakawa ◽  
Takayuki Suzuki ◽  
Kazufumi Saito ◽  
Shigeru Tamura ◽  
Shinsuke Kishi

The ceramic gas turbine (CGT) engine can achieve higher thermal efficiency, lower pollutant emissions, and has a wider fuel tolerance compared to conventional gasoline and diesel engines. Accordingly, research and development of a 300kW class ceramic gas turbine has been performed in Japan as a national project since FY 1988, under the Agency of Industrial Science and Technology (AIST), which is an agency of the Ministry of International Trade and Industry (MITI). The final target of the project is to achieve 42% thermal efficiency at a Turbine Inlet Temperature (TIT) of 1350°C. At present, two different types of ceramic gas turbines (CGT 301 and CGT 302) are under development and operating tests of prototype engines are being carried out. The CGT 301 features removable ceramic blades joined to a metal rotor disk. This 37 blade hybrid rotor of the high pressure stage was hot spin tested at a TIT of 1350°C and the burst of the blades did not occur at the rated speed. A thermal efficiency of 26.4% was achieved at a TIT 1200°C during the first year of prototype operation. Improvement in component parts is ongoing and as a result, improvements in thermal efficiency are forthcoming. The CGT 302 features a lean premixed low-NOx combustor having a primary diffusion burner, a set of main pre-mixed burners, single fuel injector, and air bypass to control combustion. This combustor showed a lower pressure loss and NOx emissions of 5ppm (O2 = 16%), which is less than the allowable value of 70ppm. Recent operating tests of this engine showed a maximum output power and thermal efficiency of 228kW and 36%, respectively, as of November 1996. For both the CGT 301 and CGT 302, more focused research on CGT materials and components, as well as operating tests at 1350°C TIT, are being carried out in order to reach the final target values.


Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 265 ◽  
Author(s):  
Lei Qi ◽  
Zhitao Wang ◽  
Ningbo Zhao ◽  
Yongqiang Dai ◽  
Hongtao Zheng ◽  
...  

To further improve the cycle performance of gas turbines, a gas turbine cycle model based on interstage bleeding rotating detonation combustion was established using methane as fuel. Combined with a series of two-dimensional numerical simulations of a rotating detonation combustor (RDC) and calculations of cycle parameters, the pressure gain characteristics and cycle performance were investigated at different compressor pressure ratios in the study. The results showed that pressure gain characteristic of interstage bleeding RDC contributed to an obvious performance improvement in the rotating detonation gas turbine cycle compared with the conventional gas turbine cycle. The decrease of compressor pressure ratio had a positive influence on the performance improvement in the rotating detonation gas turbine cycle. With the decrease of compressor pressure ratio, the pressurization ratio of the RDC increased and finally made the power generation and cycle efficiency enhancement rates display uptrends. Under the calculated conditions, the pressurization ratios of RDC were all higher than 1.77, the decreases of turbine inlet total temperature were all more than 19 K, the power generation enhancements were all beyond 400 kW and the cycle efficiency enhancement rates were all greater than 6.72%.


2021 ◽  
Vol 13 (22) ◽  
pp. 12566
Author(s):  
Oleg Bazaluk ◽  
Valerii Havrysh ◽  
Oleksandr Cherednichenko ◽  
Vitalii Nitsenko

Currently, offshore areas have become the hotspot of global gas and oil production. They have significant reserves and production potential. Offshore platforms are energy-intensive facilities. Most of them are equipped with gas turbine engines. Many technologies are used to improve their thermal efficiency. Thermochemical recuperation is investigated in this paper. Much previous research has been restricted to analyzing of the thermodynamic potential of the chemically recuperated gas turbine cycle. However, little work has discussed the operation issues of this cycle. The analysis of actual fuel gases for the steam reforming process taking into account the actual load of gas turbines, the impact of steam reforming on the Wobbe index, and the impact of a steam-fuel reforming process on the carbon dioxide emissions is the novelty of this study. The obtained simulation results showed that gas turbine engine efficiency improved by 8.1 to 9.35% at 100% load, and carbon dioxide emissions decreased by 10% compared to a conventional cycle. A decrease in load leads to a deterioration in the energy and environmental efficiency of chemically recuperated gas turbines.


A method to simulate the gas turbine cycle and performance is developed. This paper intent to describe a digital computer code to make it useful for other researchers. This program is written in Python language for analyzing the steady-state, parametric cycle performance of turbojet engines. This can be used to analyze one- and two-spool turbojet engines without any modification to the basic program. The influence of initial parameters, component characteristics and flight condition on performance characteristics of gas turbine during operation are shown. The program results are compared and validated with those from an existing GSP (Gas Turbine Simulation Program) software. The major advantage of this new method is that it frees the programmer from having to minimize the number of equations which require iterative solution. As a result, some of the approximations normally used in engine simulations can be eliminated. The outcomes of this analysis form a strong base for further analysis to predict the performance of the gas turbine engine with reasonable accuracy for design and fabrication of gas turbine engines using this performance code.


Author(s):  
P. A. Phillips ◽  
Peter Spear

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.


Author(s):  
Robert A. Wilson ◽  
Daniel B. Kupratis ◽  
Satyanarayana Kodali

The Department of Defense and NASA have funded a major gas turbine development program, Integrated High Performance Turbine Engine Technology (IHPTET), to double the power density and fuel economy of gas turbines by the turn of the century. Seven major US gas turbine developers participated in this program. While the focus of IHPTET activity has been aircraft propulsion, the same underlying technology can be applied to water craft and terrestrial vehicle propulsion applications, such as the future main battle tank. For these applications, the gas turbines must be equipped with recuperators. Currently, there is no technology roadmap or set of goals to guide industry and government in the development of a next generation recuperator for such applications.


2016 ◽  
Vol 138 (06) ◽  
pp. 38-43
Author(s):  
Lee S. Langston

This article discusses various fields where gas turbines can play a vital role. Building engines for commercial jetliners is the largest market segment for the gas turbine industry; however, it is far from being the only one. One 2015 military gas turbine program of note was the announcement of an U.S. Air Force competition for an innovative design of a small turbine engine, suitable for a medium-size drone aircraft. The electrical power gas turbine market experienced a sharp boom and bust from 2000 to 2002 because of the deregulation of many electric utilities. Since then, however, the electric power gas turbine market has shown a steady increase, right up to present times. Coal-fired plants now supply less than 5 percent of the electrical load, having been largely replaced by new natural gas-fired gas turbine power plants. Working in tandem with renewable energy power facilities, the new fleet of gas turbines is expected to provide reliable, on-demand electrical power at a reasonable cost.


Author(s):  
C. Rodgers

By the new millennia gas turbine technology standards the size of the first gas turbines of Von Ohain and Whittle would be considered small. Since those first pioneer achievements the sizes of gas turbines have diverged to unbelievable extremes. Large aircraft turbofans delivering the equivalent of 150 megawatts, and research micro engines designed for 20 watts. Microturbine generator sets rated from 2 to 200kW are penetrating the market to satisfy a rapid expansion use of electronic equipment. Tiny turbojets the size of a coca cola can are being flown in model aircraft applications. Shirt button sized gas turbines are now being researched intended to develop output powers below 0.5kW at rotational speeds in excess of 200 Krpm, where it is discussed that parasitic frictional drag and component heat transfer effects can significantly impact cycle performance. The demarcation zone between small and large gas turbines arbitrarily chosen in this treatise is rotational speeds of the order 100 Krpm, and above. This resurgence of impetus in the small gas turbine, beyond that witnessed some forty years ago for potential automobile applications, fostered this timely review of the small gas turbine, and a re-address of the question, what are the effects of size and clearances gaps on the performances of small gas turbines?. The possible resolution of this question lies in autopsy of the many small gas turbine component design constraints, aided by lessons learned in small engine performance development, which are the major topics of this paper.


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