Micro Gas Turbine With Ceramic Rotor

Author(s):  
Hiro Yoshida ◽  
Takayuki Matsunuma ◽  
Norihiko Iki ◽  
Yoshio Akimune ◽  
Hiroshi Hoya

A series of operation tests by using a desktop size gas turbine has been successfully carried out. In the first step of the tests, we have concentrated ourselves on the operation at elevated temperatures. Thus the duration of the bench test at each rotation speed was set to be 1 minute. The baseline machine is J-850 (Sophia Precision, Co., Ltd.) originally made for model airplanes. In this study, we replaced an INCONEL 713C alloy turbine rotor with 5.5 cm diameter into a type SN235 ceramic rotor (Kyocera Corporation). Mixture of 70% white kerosene and 30% gasoline was used as the fuel. The running test was made at the rotational speeds up to 140,000 r.p.m. in the atmospheric air. The basic performance of the small gas turbine was found as follows: At 140,000 r.p.m., 1) the turbine inlet temperature was estimated to be higher than 1,200. This estimation was supported by the observation of the partially melted INCONEL alloy nozzle located before the ceramic rotor. But the ceramic rotor revealed no damages. 2) The compression ratio and the thrust of the ceramic rotor turbine attained at 140,000 r.p.m. were 3 and 100 N, respectively. 3) Total energy level of the exhaust gas jet was 240 kW at the same rotation speed. Experiences learned from the present running tests suggest that the small gas turbine system employed in this study could be a useful tool to quicken the cycle of R & D of micro ceramic gas turbines with reasonable costs.

Author(s):  
Takayuki Matsunuma ◽  
Hiro Yoshida ◽  
Norihiko Iki ◽  
Takumi Ebara ◽  
Satoshi Sodeoka ◽  
...  

A series of operation tests of a ceramic micro gas turbine has been successfully carried out. The baseline machine is a small single-shaft turbojet engine (J-850, Sophia Precision Corp.) with a centrifugal compressor, an annular type combustor, and a radial turbine. As a first step, an Inconel 713C alloy turbine rotor of 55 mm in diameter was replaced with a ceramic rotor (SN-235, Kyocera Corporation). A running test was conducted at rotational speeds of up to 140,000 rpm in atmospheric air. At this rotor speed, the compression pressure ratio and the thrust were 3 and 100 N, respectively. The total energy level (enthalpy and kinetic energy) of the exhaust gas jet was 240 kW. If, for example, it is assumed that 10% of the total power of the exhaust jet gas was converted into electricity, the present system would correspond to a generator with 24 kW output power. The measured turbine outlet temperature was 950°C (1,740°F) and the turbine inlet temperature was estimated to be 1,280°C (2,340°F). Although the ceramic rotor showed no evidence of degradation, the Inconel nozzle immediately in front of the turbine rotor partially melted in this rotor condition. As a second step, the Inconel turbine nozzle and casing were replaced with ceramic parts (SN-01, Ohtsuka Ceramics Inc.). The ceramic nozzle and case were supported by metal parts. Through tests with the ceramic nozzle, it became evident that one of the key technologies for the development of ceramic gas turbines is the design of the interface between the ceramic components and the metallic components, because the difference between the coefficients of linear thermal expansion of the ceramic and metal produces large thermal stress at their interface in the high-temperature condition. A buffer material made of alumina fiber was therefore introduced at the interface between the ceramic and metal.


Author(s):  
Lei Fu ◽  
Yan Shi ◽  
Qinghua Deng ◽  
Zhenping Feng

For millimeter-scale microturbines, the principal challenge is to achieve a design scheme to meet the aerothermodynamics, geometry restriction, structural strength and component functionality requirements while in consideration of the applicable materials, realizable manufacturing and installation technology. This paper mainly presents numerical investigations on the aerothermodynamic design, geometrical design and overall performance prediction of a millimeter-scale radial turbine with rotor diameter of 10mm. Four kinds of turbine rotor profiles were designed, and they were compared with one another in order to select the suitable profile for the micro radial turbine. The leaving velocity loss in micro gas turbines was found to be a large source of inefficiency. The approach of refining the geometric structure of rotor blades and the profile of diffuser were adopted to reduce the exit Mach number thus improving the total-static efficiency. Different from general gas turbines, micro gas turbines are operated in low Reynolds numbers, 104∼105, which has significant effect on flow separation, heat transfer and laminar to turbulent flow transition. Based on the selected rotor profile, several micro gas turbine configurations with different tip clearances of 0.1mm, 0.2mm and 0.3mm, respectively; two different isothermal wall conditions; and two laminar-turbulent transition models were investigated to understand the particular influence of low Reynolds number. These influences on the overall performance of the micro gas turbine were analyzed in details. The results indicate that these configurations should be included and emphasized during the design process of the millimeter-scale micro radial turbines.


Author(s):  
Takane Itoh ◽  
Hidetomo Kimura

Under the ongoing seven-year program, designated “Research and Development of Automotive Ceramic Gas Turbine Engine (CGT Program)”, started in June 1990. Japan Automobile Research Institute. Inc. (JARI) is continuing to address the issues of developing and demonstrating the advantageous potentials of ceramic gas turbines for automotive use. This program has been conducted by the Petroleum Energy Center (PEC) with the financial support of MITI. The basic engine is a 100 kW, single-shaft regenerative engine having a turbine inlet temperature of 1350°C and a rotor speed of 110,000 rpm. In the third year of this program, the experimental evaluation of the individual engine components and various assembly tests in a static thermal test rig were continued. Exhaust emissions were also measured in a performance test rig for an initially designed pre-mixed, pre-vaporized lean (PPL) combustor. A maximum speed of 130,700 rpm was obtained during hot spin tests of delivered ceramic turbine rotors, which was almost the same level as during cold spin tests. A dynamic thermal test including a centrifugal compressor, a ceramic radial turbine rotor and all the ceramic stationary hot parts was initiated.


1987 ◽  
Vol 109 (1) ◽  
pp. 1-7 ◽  
Author(s):  
I. G. Rice

This paper presents a heat balance method of evaluating various open-cycle gas turbines and heat recovery systems based on the first law of thermodynamics. A useful graphic solution is presented that can be readily applied to various gas turbine cogeneration configurations. An analysis of seven commercially available gas turbines is made showing the effect of pressure ratio, exhaust temperature, intercooling, regeneration, and turbine rotor inlet temperature in regard to power output, heat recovery, and overall cycle efficiency. The method presented can be readily programmed in a computer, for any given gaseous or liquid fuel, to yield accurate evaluations. An X–Y plotter can be utilized to present the results.


Author(s):  
Norihiko Iki ◽  
Hirohide Furutani ◽  
Sanyo Takahashi

The mirror gas turbine proposed by Tsujikawa and Fujii extends the applications of turbo machinery. The characteristic component of a mirror gas turbine is a thermal generator, which is a kind of “inverted Brayton cycle”. The operating sequence of the thermal generator is reverse that of an ordinary gas turbine, namely, the hot working fluid is first expanded, and then cooled, compressed, and finally exhausted. In this work, we investigated the theoretical feasibility of inserting a thermal generator to a small reheat gas turbine of 30–100kW classes. Using process simulator software, we calculated and compared the thermal efficiency of this reheat gas turbine to that of a micro gas turbine under several conditions, turbine inlet temperature. This comparison showed that the performances of the both gas turbines are significantly influenced by the performance of the heat exchanger used for the recuperator. The efficiency of the micro gas turbine is also improved by using water injection into the compressor to cool the inlet gas. The resulting thermal efficiency of this reheat gas turbine is about 7% higher than that of a micro gas turbine with the same power unit.


Author(s):  
Valentina Zaccaria ◽  
Mario L. Ferrari ◽  
Konstantinos Kyprianidis

Abstract Micro gas turbine engines in the range of 1–100 kW are playing a key role in distributed generation applications, due to the high reliability and quick load following that favor their integration with intermittent renewable sources. Micro-CHP systems based on gas turbine technology are obtaining a higher share in the market and are aiming at reducing the costs and increasing energy conversion efficiency. An effective control of system operating parameters during the whole engine lifetime is essential to maintain desired performance and at the same time guarantee safe operations. Because of the necessity to reduce the costs, fewer sensors are usually available than in standard industrial gas turbines, limiting the choice of control parameters. This aspect is aggravated by engine aging and deterioration phenomena that change operating performance from the expected one. In this situation, a control architecture designed for healthy operations may not be adequate anymore, because the relationship between measured parameters and unmeasured variables (e.g. turbine inlet temperature or efficiency) varies depending on the level of engine deterioration. In this work, an adaptive control scheme is proposed to compensate the effects of engine degradation over the lifetime. Component degradation level is monitored by a diagnostic tool that estimates performance variations from available measurements; then, the information on the gas turbine health condition is used by an observer-based model predictive controller to maintain the machine in a safe range of operation and limit the reduction in system efficiency.


2018 ◽  
Vol 20 ◽  
pp. 78-85 ◽  
Author(s):  
Iacopo Rossi ◽  
Alberto Traverso

In the panorama of gas turbines for energy production, a great relevance is given to performance impact of the ambient conditions. Under the influence of ambient temperature, humidity and other factors, the engine performance is subject to consistent variations. This is true for large power plants as well as small engines. In Combined Cycle configuration, variation in performance are mitigated by the HRSG and the bottoming steam cycle. In a small scale system, such as a micro gas turbine, the influence on the electric and thermal power productions is strong as well, and is not mitigated by a bottoming cycle. This work focuses on the Turbec T100 micro gas turbine and its performance through a series of operations with different ambient temperatures. The goal is to characterize the engine performance deriving simple correlations for the influence of ambient temperature on performance, at different electrical loads. The newly obtained experimental data are compared with previous performance curves on a modified machine, to capture the differences due to hardware degradation in time. An active management of the compressor inlet temperature may be developed in the future, basing on the analysis reported here.


Author(s):  
Koichi Tanaka ◽  
Sazo Tsuruzono ◽  
Toshifumi Kubo ◽  
Makoto Yoshida

Kyocera has been developing various ceramic components for gas turbines under the Ceramic Gas Turbine (CGT) Project funded by the Japanese Government. This project has set a turbine inlet temperature (TIT) of 1350°C as a final target. For 1350°C TIT, we have developed a new silicon nitride material SN281, which has high stress rupture strength at elevated temperatures up to 1500°C. This material has excellent oxidation resistance as well. We have also developed improved sintering and inspection technologies for the use of SN281 as engine components. We are able to fabricate rotors and nozzles of the gas generator turbine (GGT) in good agreement with design geometry requirements, by optimizing sintering conditions. Small defects were also successfully detected by microfocus X-ray radiography. The SN281 rotors have attained 120% of design rotating speed at room temperature.


2021 ◽  
Vol 24 (3) ◽  
pp. 14-20
Author(s):  
Fajri Vidian ◽  
◽  
Putra Anugrah Peranginangin ◽  
Muhamad Yulianto ◽  
◽  
...  

Leaf waste has the potential to be converted into energy because of its high availability both in the world and Indonesia. Gasification is a conversion technology that can be used to convert leaves into producer gas. This gas can be used for various applications, one of which is using it as fuel for gas turbines, including ultra-micro gas ones, which are among the most popular micro generators of electric power at the time. To minimize the risk of failure in the experiment and cost, simulation is used. To simulate the performance of gas turbines, the thermodynamic analysis tool called Cycle-Tempo is used. In this study, Cycle-Tempo was used for the zero-dimensional thermodynamic simulation of an ultra-micro gas turbine operated using producer gas as fuel. Our research contributions are the simulation of an ultra-micro gas turbine at a lower power output of about 1 kWe and the use of producer gas from leaf waste gasification as fuel in a gas turbine. The aim of the simulation is to determine the influence of air-fuel ratio on compressor power, turbine power, generator power, thermal efficiency, turbine inlet temperature and turbine outlet temperature. The simulation was carried out on condition that the fuel flow rate of 0.005 kg/s is constant, the maximum air flow rate is 0.02705 kg/s, and the air-fuel ratio is in the range of 1.55 to 5.41. The leaf waste gasification was simulated before, by using an equilibrium constant to get the composition of producer gas. The producer gas that was used as fuel had the following molar fractions: about 22.62% of CO, 18.98% of H2, 3.28% of CH4, 10.67% of CO2 and 44.4% of N2. The simulation results show that an increase in air-fuel ratio resulted in turbine power increase from 1.23 kW to 1.94 kW. The generator power, thermal efficiency, turbine inlet temperature and turbine outlet temperature decreased respectively from 0.89 kWe to 0.77 kWe; 3.17% to 2.76%; 782 °C to 379 °C and 705°C to 304 °C. The maximums of the generator power and thermal efficiency of 0.89 kWe and 3.17%, respectively, were obtained at the 1.55 air-fuel ratio. The generator power and thermal efficiency are 0.8 kWe and 2.88%, respectively, with the 4.64 air-fuel ratio or 200% excess air. The result of the simulation matches that of the experiment described in the literature.


Author(s):  
Junji Kato ◽  
Masayosi Otsuka ◽  
Katsuhiko Sugiyama

A seven-year program, designated “Research & Development of Automotive Ceramic Gas Turbine Engine (CGT Program)” conducted by Petroleum Energy Center, was started in June 1990 with the object of demonstrating the advantageous potentials of ceramic gas turbines for automotive use. This paper describes the results of an assembly test on the rotating components including a ceramic turbine rotor and a compressor assembled in the ceramic static structure. The preliminary check-out test has been successfully accomplished under the actual engine operating condition of a turbine inlet temperature of 1200°C.


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