Development Of Combustor Research Articles

Development of super-clean diesel engine and combustor using nonthermal plasma hybrid aftertreatment

One of important and successful environmental applications of atmospheric-pressure corona discharge or plasma is electrostatic precipitator (ESP), which have been widely used for coal- or oil-fired boilers in electric power plants and particulate matter control emitted from industries such as glass melting furnace system, etc. In the ESPs, steady high voltage is usually applied to a pair of electrodes (at least, one of these has sharp edge). Unsteady pulsed high voltage is often applied for the collection of high-resistivity particulate matter (PM) to avoid reverse corona phenomena which reduce the collection efficiency of the ESPs. It was found that unsteady high voltage can treat hazardous gaseous components (NOx, SOx, hydrocarbon, and CO, etc.) in the exhaust gas, and researches were shifted from PM removal to hazardous gases aftertreatment with unsteady corona discharge induced plasmas. In the paper, recent results on diesel engine and industrial boiler emission controls are mainly reviewed among these our research topics.

The Effects of High Pressure Gas Burner Parameters on Thermal Efficiency for 2014 International Conference on Machining, Materials and Mechanical Technology (IC3MT)

The KB 5 high pressure gas burners are popularly and widely used at the food stands in Thailand. The gas burner models are of various properties depending on the each factory’s design. The differences of the designs affect the Liquid Petroleum Gas (LPG) consumption to a different extent. This study aimed to evaluate the parameters: the degrees of outer and inner ports; and the number of outer and inner ports of high pressure gas burners which are sold in Thailand. The thermal efficiency was tested with reference to the Standard Industrial stoves in household with liquid petroleum gas (TIS 2312-2549). The result showed that, by increasing the degrees of outer ports from 45 to 80, the thermal efficiency increased by 0.24%; while by increasing the degrees of inner ports from 50 to 60, the thermal efficiency increased 0.11%. By increasing the number of the outer ports from 35 to 38, the thermal efficiency increased 0.44%; while by increasing the number of inner ports from 9 to 15, the thermal efficiency increased by 0.22%. The development of high pressure gas burners should focus on adjusting the degrees and number of inner and outer ports for the overall improvement of the thermal efficiency.

Development of a cylindrical burner comprising multiple pairs of opposing partially premixed or inverse diffusion flames

A cylindrical burner was developed to combine extensive firing limits, high combustion efficiencies, and low NOx emissions from partially premixed or inverse diffusion flames by setting multiple pairs of circumferentially opposing jets (of concentric fuel and air streams). Normal strain rates as high as 1600 s−1 in addition to transverse strain rates of 640 s−1 were combined with a cross-flow impact and elliptical jet dispersion such that a turbulent kinetic energy peak of 15.4 m2/s2 was produced. The fuel/air mixing was enhanced and the peak temperature was reduced due to the stimulation of cross-flow wake zones and the axis switching of the elliptical jets. Partially premixed methane/air combustion of 12 opposing mixtures at Φ=1.5 led to NOx reduction to 0.36 g/kg fuel via controlling the flow residence time and adjusting the separation between the premixing and diffusion zones of each flame. As elliptical ports are used, the NOx concentrations decreased to 4 ppm with an aspect ratio of 3.0. Increasing the ratio between the diameter of the jets and their axial separation decreased the CO and HC emissions respectively to 489 ppm and 0.019%. Upon having opposing inverse diffusion flames, the blowout stability limit reached a maximum value of 53.2 m/s. With a separation of 4.0 cm, the NOx emissions reached a minimum level of 25 ppm by increasing the momentum flux ratio between the cross-flow air jet and the opposing jets to 1.5. By optimizing the cross-flow/primary air velocity ratio and the primary air/fuel jet diameter ratio, the CO and HC emissions were respectively minimized to 721 ppm and 0.039%. The velocity fluctuations indicated that increasing the opposing jets increases the turbulent kinetic energy and decreases the smallest scales of turbulence.

Development of a high-temperature and high-uniformity micro planar combustor for thermophotovoltaics application

The micro-thermophotovoltaic (TPV) power generator is an important solid-state energy conversion system which utilizes high-temperature photons to generate electricity by the photovoltaics effect. Micro-combustor is an important component in this system. In order to obtain high system efficiency, a micro-combustor with high-temperature, high-uniformity and high-efficiency is strongly desired. Here we report a micro planar combustor with the desired features. The planar combustor is fabricated with two numerically optimized baffles which form a heat recirculation chamber. The thermal energy of the hot reacting gas could be utilized to preheat the fresh gas. The performances of the combustor under various operating conditions are investigated experimentally. Numerical simulation is performed to identify the flow field and mass fraction distribution in the planar combustor. A peak combustor wall temperature as high as 1354K is achieved with superior uniformity. By incorporating the designed micro planar combustor into the micro-TPV system, a system efficiency of 4.1% could be obtained. This system efficiency is twice higher than the system with only conventional planar combustor. As a result, the development of the planar combustor with baffles could pave a way to the development of high-performance of the micro-TPV system.

Development of a bench-scale fluidized bed combustor (FBC) for coal and biomas combustion.

The high technological level of equipment for combustion of fuels, as well as the necessity for rational and efficient use of non-renewable energy resources, has resulted demanding requirements that must be fulfilled by equipment for energy production, via combustion. These requirements form the characteristics of Fluidized bed Combustor (FBC). The objective of this work is to design and fabricate a Circulating FBC for the combustion of coal and biomass and present the design criteria considered in the combustion process. The Designed FBC was then tested by combusting coal (Lafia Obi) and biomass (coconut shell) using the relevant ASTM guidelines. For coal combustion, the characteristic quantities measured from the bench-scale fluidized bed combustion include a mean NOx emission of 455.35, 376.69, 323.35 and 277.35 ppm for a coal feed size of 10, 15, 20 and 25 mm respectively. NOx emission from the combustion of coconut shell in fluidized bed is low and further reduced by the introduction of secondary air. Secondary air increases the recoverable energy level from this biomass, while average CO emission was 13,080 16,620 17,040 and 19,140 ppm for a coal feed size of 10, 15, 20 and 25mm. The temperature in the fluidized bed at ≥ 1100oC was sustained.Keywords: Combustion emissions; fluidized-bed combustion; Design; Lafia-Obi Coal Biomass; Temperature.

航空エンジン燃焼器開発における可視化を利用した燃焼安定性診断

航空エンジン燃焼器開発における可視化を利用した燃焼安定性診断

Experimental study of flow dynamics and fuel spray characteristics in Lean Premixed Prevaporized Combustor

Further improving the emission performance of a Lean Premixed Prevaporized (LPP) combustor is a hot topic for gas turbine research. An in-depth understanding of the combustion characteristics is therefore highly desirable. In this paper, the flow fields and fuel spay characteristics in a LPP combustor are experimentally studied by using Particle Image Velocimetry (PIV). The effects of the fuel allocation and pilot atomizer position on fuel spray characteristics are investigated. Experimental results show that: (1) A Primary Recirculation Zone (PRZ), Corner Recirculation Zone (CRZ) and Lip Recirculation Zone (LRZ) are presented in the flow field in a LPP combustor; (2) The width of the primary recirculation zone initially increases along axial direction from the combustor inlet, and starts to decrease after certain distance; (3) When only the pilot atomizer is operated, the fuel spray characteristics is worsened with the increase of fuel flow rate. Locating the pilot atomizer at the throat results is a better fuel spray distribution than locating it at the outlet of the pilot swirler. The present results are useful for future development of the LPP combustor.

Development and Experimental Investigation of a Tubular Combustor for Pyrolysis Oil Burning

The growing demand for more economical and environmentally friendly power generation forces the industry to search for fuels that can replace the conventional fossil fuels. This has led to significant developments in the production of alternative fuels during the last years, which have made them a reliable and relatively efficient source of energy. One example of these alternative fuels is the pyrolysis oil. However, higher viscosity, lower heat content, limited chemical stability, and its ability to create sediment make pyrolysis oil challenging for gas turbines. The OPRA OP16 gas turbine is an all radial single-shaft gas turbine rated at 1.9 MW. The all radial design, together with the lack of intricate cooling geometries in the hot section, makes this gas turbine suitable for operation on these fuels. This paper presents an experimental investigation of pyrolysis oil combustion in a tubular combustor developed, especially for low-calorific fuels. The experiments have been performed in an atmospheric combustion test rig, and the results have been compared to the results obtained from ethanol and diesel combustion. It was found that it was possible to burn pure pyrolysis oil in the load range between 70% and 100% with a combustion efficiency exceeding 99% and without creation of sediments on the combustor inner wall. It was found that the NOx emissions were similar for pyrolysis oil and diesel, whereas the CO emissions were twice as high for pyrolysis oil. A comparison between the air blast nozzle and the pressure nozzle was performed. The air blast nozzle was found to be more suitable due to its better performance over a wider operating range and that it is more resistant to erosion and abrasion. It was found that the maximum allowed droplet size of the pyrolysis oil spray should be about 50–70% of the droplet size for diesel fuel.

A Study on the NOx Reduction Effect by Low-NOx Burner Program and Development Strategy

A Study on the NOx Reduction Effect by Low-NOx Burner Program and Development Strategy

Ab Initio Investigation of the Thermal Decomposition of n-Butylcyclohexane

Environmental and energy security concerns have motivated an increased focus on developing clean, efficient combustors, which increasingly relies on insight into the combustion chemistry of fuels. In particular, naphthenes (cycloalkanes and alkylcycloalkanes) are important chemical components of distillate fuels, such as diesel and jet fuels. As such, there is a growing interest in describing napthene reactivity with kinetic mechanisms. Use of these mechanisms in predictive combustion models aids in the development of combustors. This study focuses on the pyrolysis of n-butylcyclohexane (n-BCH), an important representative of naphthenes in jet fuels. Seven different unimolecular decomposition pathways of C-C bond fission were explored utilizing ab initio/DFT methods. Accurate reaction energies were computed using the high-level quantum composite G3B3 method. Variational transition state theory, Rice-Ramsperger-Kassel-Marcus/master equation simulations provided temperature- and pressure-dependent rate constants. Implementation of these pathways into an existing chemical kinetic mechanism improved the prediction of experimental OH radical and H2O speciation in shock tube oxidation. Simulations of this combustion showed a change in the expected decomposition chemistry of n-BCH, predicting increased production of cyclic alkyl radicals instead of straight-chain alkenes. The most prominent reaction pathway for the decomposition of n-BCH is n-BCH = C3H7 + C7H13. The results of this study provide insight into the combustion of n-BCH and will aid in the future development of naphthene kinetic mechanisms.

Development of Dry Low-NOx Gas-Turbine Combustors Equipped with Multi-Hole Co-Axial Jet Burners for IGCC

Development of Dry Low-NOx Gas-Turbine Combustors Equipped with Multi-Hole Co-Axial Jet Burners for IGCC

331 バイオガス燃料に対応するマイクロガスタービン燃焼器の開発とその燃焼特性の実験的解明(OS15-3 燃焼技術の基礎と応用研究(3),OS15 燃焼技術の基礎と応用研究)

331 バイオガス燃料に対応するマイクロガスタービン燃焼器の開発とその燃焼特性の実験的解明(OS15-3 燃焼技術の基礎と応用研究(3),OS15 燃焼技術の基礎と応用研究)

912 メタンを用いた触媒燃焼装置の開発と製作(GS08-2 その他)

912 メタンを用いた触媒燃焼装置の開発と製作(GS08-2 その他)

Lighting by Biogas Burners: Perspectives on Development in Brazil

The development of efficient components to save energy plays an important role in designing of sustainable solutions. Based on the concept of green energy, gas burners based on porous ceramic structures are interesting technologies to supply heat and lighting by burning even low calorific fuels as biogas. In this work, perspectives on development of porous ceramic burners in Brazil are presented. For this study a mixture of rare earth oxides―yttria (YTR) was selected as raw material, considering the unique luminescence proprieties of rare earth elements. Ceramic nettings with homogeneous morphology were produced by colloidal processing of rare earth powders. The results highlighted the potentiality of these components to be applied as biogas burners.

Development of strand burner for solid propellant burning rate studies

It is well-known that a strand burner is an apparatus that provides burning rate measurements of a solid propellant at an elevated pressure in order to obtain the burning characteristics of a propellant. This paper describes the facilities developed by author that was used in his studies. The burning rate characteristics of solid propellant have be evaluated over five different chamber pressures ranging from 1 atm to 31 atm using a strand burner. The strand burner has a mounting stand that allows the propellant strand to be mounted vertically. The strand was ignited electrically using hot wire, and the burning time was recorded by electronic timer. Wire technique was used to measure the burning rate. Preliminary results from these techniques are presented. This study shows that the strand burner can be used on propellant strands to obtain accurate low pressure burning rate data.

Bayesian analysis of syngas chemistry models

Syngas chemistry modelling is an integral step toward the development of safe and efficient syngas combustors. Although substantial effort has been undertaken to improve the modelling of syngas combustion, models nevertheless fail in regimes important to gas turbine combustors, such as low temperature and high pressure. In order to investigate the capabilities of syngas models, a Bayesian framework for the quantification of uncertainties has been used. This framework, given a set of experimental data, allows for the calibration of model parameters, determination of uncertainty in those parameters, propagation of that uncertainty into simulations, as well as determination of model evidence from a set of candidate syngas models. Here, three syngas combustion models have been calibrated using laminar flame speed measurements from high pressure experiments. After calibration the resulting uncertainty in the parameters is propagated forward into the simulation of laminar flame speeds. The model evidence is then used to compare candidate models for the given set of experimental conditions and results. Additionally, the technique MUM-PCE, an interesting uncertainty minimisation method for kinetics models, has been compared to the Bayesian method for this application to the prediction of syngas laminar flame speeds. This comparison shows the importance of model form error and experimental error representations in the uncertainty quantification context, for these choices significantly affect uncertainty quantification results.

항공용 가스터빈 연소기 기본 설계 프로그램 개발 : Part 2 - 공기 유량 배분

This study introduces the design methods for air flow distribution at the level of preliminary design, and reviews the typical combustion process and main functions of sub-components of aircraft gas turbine combustors. There are lots of design approaches and empirical equations introduced for air flow distributions at the combustors. It is shown that a decision on which design approaches work for the combustor development is totally dependent upon the objective of engine design, target performance, and so on. The current results suggested for preliminary air flow distributions need to be validated by combustor geometry checkups and performance evaluations for future works.

Characterization of Lean Burn Module Air Blast Pilot Injector With Laser Techniques

For lean burn combustor development in low emission aero-engines, the pilot stage of the fuel injector plays a key role with respect to stability, operability, NOx emissions, and smoke production. Therefore it is of considerable interest to characterize the pilot module in terms of pilot zone mixing, fuel placement, flow field, and interaction with the main stage. This contribution focuses on the investigation of soot formation during pilot-only operation. Optical test methods were applied in an optically accessible single sector rig at engine idle conditions. Using planar laser-induced incandescence (LII), the distribution of soot and its dependence on air/fuel ratio, as well as geometric injector parameters, was studied. The data shows that below a certain air/fuel ratio, an increase of soot production occurs. This is in agreement with smoke number measurements in a standard single sector flame tube rig without optical access. Reaction zones were identified using chemiluminescence of OH radicals. In addition, the injector flow field was investigated with PIV. A hypothesis regarding the mechanism of pilot smoke formation was made based on these findings. This along with further investigations will form the basis for developing strategies for smoke improvement at elevated pilot-only conditions.

Platinum-Nanoparticle-Catalyzed Combustion of a Methanol–Air Mixture

Catalytic combustion is a practical approach to sustain and manage combustion in microreactors. Previous work has demonstrated room-temperature ignition and size-dependent properties of platinum nanoparticles as they related to catalytic combustion of hydrocarbons. This work investigates the use of platinum nanoparticle coatings to combust a stochiometric methanol–air mixture. Platinum nanoparticles with dp = 8 nm were used to coat cordierite substrates with 800 μm wide square channels. Room-temperature ignition of the methanol–air mixture and repeated catalytic cycling were successfully achieved with operational temperatures ranging from 250 to 850 °C. The catalysis reaction was controlled by altering fuel–air flow rates and catalyst mass loading. A nanoparticle stability study indicated a minimal effect of sintering on the combustion behavior and vice versa with repeated catalytic cycling. A product gas analysis indicated that overall methanol conversion rates of up to 60% were achieved with the current design. The results of this work directly contribute to the development of catalytic micrometer-scale combustors.

Development of high intensity low emission combustor for achieving flameless combustion of liquid fuels

This paper presents the experimental and numerical results for a two stage combustor capable of achieving flameless combustion with liquid fuels for different thermal heat inputs of 20, 30, 40 and 60kW and heat release density of 5–15MW/m3. Combustion characteristics and pollutant emissions are studied for three different fuels, kerosene, diesel and gasoline. The influence of droplet diameter on pollutant emissions at all conditions is studied. The fuel and oxidizer are supplied at ambient conditions. The concept of high swirl flows has been adopted to achieve high internal recirculation rates, residence time and increased dilution of the fresh reactants in the primary combustion zone, resulting in flameless combustion mode. Air is injected through four tangential injection ports located near the bottom of the combustor and liquid fuel is injected through a centrally mounted pressure swirl injector. Computational analysis of the flow features shows that decrease in the exit port diameter of the primary chamber increases the recirculation rate of combustion products and helps in achieving the flameless combustion mode. Based on preliminary computational studies, a 30mm primary chamber exit port diameter is chosen for experimental studies. Detailed experimental investigations show that flameless combustion mode was achieved with evenly distributed combustion reaction zone and uniform temperature distribution in the combustor. Pollutant emissions of CO, NOx, CxHy are measured and compared for all operating conditions of different fuels and different thermal inputs. The acoustic emission levels are reduced by 6–8dB as combustion mode shifts from conventional mode to flameless combustion mode.