Investigation of Low-Temperature Lean Combustion Characteristics in Power Plants with External Heating of Components

An integral part of any open-type gas turbine plant is a low-emission combustion chamber, which is usually two-zone and cooled. One of the ways to reduce emission of harmful substanc-es is organizing low-emission low-temperature lean combustion with external heating of compo-nents. This paper investigates the effect of external heating of air and fuel gas on expansion of the lower combustion limit and stable flame position in a single-zone uncooled combustion chamber of a microgas turbine power plant. Stable position of the flame front in combustion chambers of this type mainly depends on the ratio between the average flow rate of the combus-tible-air mixture and the rate of turbulent combustion. This ratio depends on thermal, gas-dynamic, thermochemical and geometric factors. The purpose of this work is to substantiate the possibility of using the relative flow rate as a generalized characteristic. This goal was achieved in processing a large amount of published experimental data and numerical modeling of low-temperature combustion of lean mixtures. The most significant research result is determination of the range of relative flow rate (gk = 0.3…3.5·10-4 kg⁄s∙N), at which it is possible to ensure sta-ble flame position in a single-zone combustion chamber. Significance of the obtained results lies in the fact that using the relative flow rate makes it possible to quickly determine and analyze the geometric and gas-dynamic parameters and characteristics of turbulent combustion in com-bustion chambers of micro-gas turbine power plants.

COMPUTATIONAL AND EXPERIMENTAL STUDIES OF THE AREA OF SUSTAINABLE COMBUSTION OF NATURAL GAS WITH AIR

One of the rational ways of creating low-emission combustion chambers is the organization of low-temperature lean combustion with external heating of the components before they are fed into the combustion chamber. When organizing lowtemperature lean combustion with large excess air ratios, problems may arise with ensuring a stable position of the flame front. Combustion stability to a large extent depends on the ratio of the average flow rate and the rate of turbulent combustion. The rate of turbulent combustion depends on the composition, pressure and temperature of the components supply and the degree of turbulence in the combustion chamber. The average flow rate depends on the excess air ratio (oxidizer and fuel consumption) and the geometric dimensions of the chamber. Earlier it was shown that when developing a low-emission combustion chamber with low-temperature lean combustion, it is advantageous to use the relative flow rate as a generalized characteristic of the intra-chamber process, which takes into account the consumption, geometric and thermodynamic parameters in the combustion chamber. This work is devoted to the analysis of stable combustion of a fuel composition natural gas + air based on the experimental data available in the public domain by the authors from the University of Michigan (USA). With the help of the methods developed by the authors, the experimental data on the limiting feed rates of the components into the atmospheric burner were processed. The limiting flow rates of air and natural gas, the limiting values of the excess air ratio, the longitudinal values of the speed of the fuel-air mixture and the limiting values of the relative flow rate are obtained and analyzed. Areas of stable combustion by the listed parameters at different degrees of air swirl are graphically presented.

STUDY ON CHARACTERISTICS OF A DOWNHOLE VORTEX JET PUMP

This article analyzes the possibility of increasing the efficiency of using downhole jet pumps by swirling the injected flow. To analyze the peculiarities of the local swirling of injected flow, design and technological parameters in the form of the inclination angle of guiding elements, the diameter of the helical trajectory described by the fluid particles, and the flow rates of the swirling flow are studied. Based on the application of the conservation law of fluid momentum in adjacent jets with a parabolic pressure distribution, equations to determine the pressure characteristic of a jet pump are obtained, taking into account the additional dynamic pressure made by swirling the injected flow. In the process of analyzing the obtained relations, has been set the dependence of the relative pressure growth and the efficiency of the ejection system under the conditions of injected flow swirling on the relative flow rate of a jet pump, and an inversely proportional dependence of the above parameters on its main geometric parameter in the form of the ratio of cross-sectional areas of the mixing chamber and the nozzle.

Determination of mass flow characteristics of supersonic axisymmetric nozzle diaphragms in modeling variable duties of low-consumption turbines

В работе приводятся обобщающие зависимости коэффициентов расхода сопловых аппаратов со сверхзвуковыми осесимметричными соплами в широком диапазоне изменения определяющих геометрических и режимных параметров. Предложена двухпараметрическая функция, учитывающая влияние расположения сопел в сопловом аппарате и степени конфузорности дозвуковой части осесимметричного сопла на коэффициент расхода. Показано слабое влияние на коэффициент расхода относительного радиуса закругления стенки в узкой части сопла и относительной длины дозвуковой части сопла в области их оптимальных значений определенных по минимуму потерь кинетической энергии. Переменные режимы работы сопла учитываются зависимостью относительного коэффициента расхода в функции от числа Рейнольдса в критическом сечении сопла. Полученные в работе эмпирические зависимости позволяют использовать их при моделировании переменных режимов и многорежимной оптимизации малорасходных турбин. The research presents generalizing dependences of mass flow rates in supersonic axisymmetric nozzle diaphragms n a wide range of variation of the governing geometric and operating parameters. A two-parameter function is proposed that takes into account the influence of the location of the nozzles in the nozzle apparatus and the degree of compression of the flow of the subsonic part of the nozzle on the mass flow rate. It is shown that the relative radius of rounding of the nozzle wall in the vicinity of the throat section and the relative length of the subsonic part of the nozzle in the region of their optimal values determined by the minimum of kinetic energy losses have a weak effect on the flow rate. Variable duties of nozzle operation are taken into account by the dependence of the relative flow rate as a function of the Reynolds number in the throat of the nozzle. The empirical dependencies obtained in this work make it possible to use them in modeling variable modes and multi-mode optimization of low-consumption turbines.

Increase fish protective efficiency constructions of meliorative water intake

The article solves the problem of increasing the level of protection of juvenile fish to a standard indicator by the modernization of individual elements of fish protection of ameliorative water intake of irrigation systems. The design of an integrated fish-protecting structure with a logging boom adapted to hydrology and the rhythm of migration of juvenile fish from irrigation sources has been proposed. The results of studies on a physical model, taking into account the costs of the reclamation system, show an increase in the efficiency of the combined fish protection structure with a harbor for reclamation water intakes in the range of 78,5–84,0 %, depending on the relative flow rate on the shelf of the sanctuary.

The Improvement of the Mathematical Model of the Work Process of Borehole Ejection Systems

The article presents the sequence of deriving the equations which characterize the hydraulic system of jet pumps that carry out suction and injection-suction bottom flushing while drilling the production wells. The nature of flow distribution in the borehole ejection systems of the suction and injection-suction types is analyzed. The analysis is carried out taking into consideration the peculiarities of the calculation of branched hydraulic systems. While studying the movement of the flows in the bottom circulation circuits, the authors take into account the equation of the balance of the flow-rate at nodal points and hydraulic losses in parallel parts of the system. The developed mathematical models are based on the study of the changes in hydrodynamic pressures which occur in characteristic sections of a jet pump. The pressure ratio of mixed, injected and operating flows is presented as non-dimensional relative pressure of the ejection system. The dependence of non-dimensional relative pressure on the relative flow rate determines the characteristic of the hydraulic system of a jet pump. The relative flow rate or injection ratio of a jet pump is defined as the ratio of flow rate to injected and work flow. While analyzing the developed mathematical models, the authors specify the relation between the design and operating parameters of a jet pump. These parameters ensure its operation with maximum efficiency. Based on the study of the influence of the correlation between the diameters of the jet pump nozzles and the flushing system of the bit, the authors specify parameters which are optimal in terms of energy performance. The article provides the example of graphical determination of the operating point of a pumping unit. This determination is based on a simultaneous solution of the equations of the characteristics of the jet pump and the hydraulic system in which it operates. The improved techniques allow to predict the mode parameters of ejection systems and to determine the size of flowing part of the jet pump. They provide maximum energy performance of its workflow.

Using a Microfluidics System to Reproducibly Synthesize Protein Nanoparticles: Factors Contributing to Size, Homogeneity, and Stability

The synthesis of Zein nanoparticles (NPs) using conventional methods, such as emulsion solvent diffusion and emulsion solvent evaporation, is often unreliable in replicating particle size and polydispersity between batch-to-batch syntheses. We have systematically examined the parameters for reproducibly synthesizing Zein NPs using a Y-junction microfluidics chip with staggered herringbone micromixers. Our results indicate that the total flow rate of the fluidics system, relative flow rate of the aqueous and organic phase, concentration of the base material and solvent, and properties of the solvent influence the polydispersity and size of the NPs. Trends such as increasing the total flow rate and relative flow rate lead to a decrease in Zein NP size, while increasing the ethanol and Zein concentration lead to an increase in Zein NP size. The solvent property that was found to impact the size of the Zein NPs formed the most was their hydropathy. Solvents that had a hydropathy index most similar to that of Zein formed the smallest Zein NPs. Synthesis consistency was confirmed within and between sample batches. Stabilizing agents, such as sodium caseinate, Tween 80, and Pluronic F-68, were incorporated using the microfluidics system, necessary for in vitro and in vivo use, into Zein-based NPs.

CONCENTRATION OF SINGLE SUPERPHOSPHATE ON CLOGGING OF DRIP EMITTERS

CONCENTRATION OF SINGLE SUPERPHOSPHATE ON CLOGGING OF DRIP EMITTERS DAYANE RODRIGUES GONÇALVES1; PEDRO RÓBINSON FERNANDES DE MEDEIROS1; ELTON CARLOS PEREIRA VIEIRA DE ALENCAR TELES1; GABIANE SOUZA DOS SANTOS1; ROBERTO CASTRO NASCIMENTO1 E FRANCISCO MAX FERNANDES DO NASCIMENTO2 1Colegiado de Pós Graduação em Engenharia Agrícola, Universidade Federal do Vale do São Francisco, Av. Antônio Carlos Magalhães, 510, Country Club, CEP: 48902-300, Juazeiro, BA, Brasil. E-mail: [email protected] 2Colegiado de Graduação em Engenharia Agrícola e Ambiental, Universidade Federal do Vale do São Francisco, Av. Antônio Carlos Magalhães, 510, Country Club, CEP: 48902-300, Juazeiro, BA, Brasil. E-mail: [email protected] 1 ABSTRACT The localized irrigation systems are most suitable to fertigation uses, when compared to sprinkle, but are affected by the clogging of drip emitters, influencing the uniformity of the irrigation system. This study aims to analyze the susceptibility of on-line drippers under fertigation with single superphosphate to the clogging. This study was done at the Irrigation Laboratory of UNIVASF, Juazeiro-BA campus, Brazil. Two on-line non-pressure compensating drippers with different flow rates were used, both with the same operating pressure (150 kPa). The parameters analyzed were mean flow, relative flow rate, standard deviation, coefficient of flow rate variation, the CUC, DU, SUC and HUC, and clogging degree. The results show that the concentration used for single superphosphate showed no risk of clogging of the drip emitters during system runtime. Keyworks: drip irrigation system, non-pressure compensating drippers, application efficiency GONÇALVES, D. R.; MEDEIROS, P. R. F.; TELES, E. C. P. V. A.; SANTOS, G. S.; NASCIMENTO, R. C.; NASCIMENTO, F. M. F. CONCENTRAÇÃO DE SUPERFOSFATO SIMPLES NA OBSTRUÇÃO DE GOTEJADORES 2 RESUMO Os sistemas de irrigação localizada são os mais indicados para uso na fertirrigação quando comparado com a aspersão, porém são afetados pela obstrução influenciando na uniformidade dos mesmos. Este trabalho tem como objetivo analisar a susceptibilidade ao entupimento de gotejadores tipo online sob fertirrigação com superfosfato simples. Esse trabalho foi realizado no Laboratório de Irrigação da UNIVASF, campus Juazeiro- BA. Foram utilizados dois emissores do tipo gotejadores online não autocompensantes com diferentes vazões, ambos com a mesma pressão de serviço (150 kPa). Avaliou- se os parâmetros vazão média, vazão relativa, desvio padrão, coeficiente de variação de vazão, os coeficientes CUC, CUD, CUE e CUH e grau de entupimento. Os resultados demonstram que a concentração utilizada de superfosfato simples não apresentou riscos de obstrução dos emissores durante o tempo de funcionamento do sistema. Palavras chave: irrigação localizada, gotejadores não compensados, eficiência de aplicação

DESEMPENHO DE GOTEJADORES APLICANDO PERCOLADO DE ATERRO SANITÁRIO DILUÍDO

DESEMPENHO DE GOTEJADORES APLICANDO PERCOLADO DE ATERRO SANITÁRIO DILUÍDO FRANCISCO DE OLIVEIRA MESQUITA1; SANDRA MARIA CAMPOS ALVES2; RAFAEL OLIVEIRA BATISTA2; TARCÍSIO BATISTA DANTAS2 E LUIZ DI SOUZA3 1 Departamento de Ciências Ambientais e Tecnológicas, UFERSA, câmpus Pau dos Ferros-RN, BR 226, km 405, Bairro São Geraldo, CEP: 59900-000 – Pau dos Ferros, RN, Brasil. E-mail: [email protected]; 2 Departamento de Ciências Ambientais e Tecnológicas, UFERSA câmpus Mossoró-RN, Avenida Francisco Mota, no 572, Bairro Costa e Silva, CEP: 59625-900-Mossoró,RN,Brasil.E-mail:[email protected], [email protected]; 3 Departamento de Química, UERN câmpus Mossoró, Rua Professor Antônio Campos, s/n, BR 110, km 48, Bairro Costa e Silva, CEP: 59600-000 - Mossoró, RN, Brasil. E-mail: [email protected] 1 RESUMO O percolado de aterro sanitário possui quantidades apreciáveis de nutrientes que podem ser utilizados na produção de biomassa para fins energéticos. Objetivou-se neste trabalho analisar os indicadores de desempenho de gotejadores aplicando percolado de aterro sanitário diluído, bem como os principais fatores de obstrução e a qualidade do percolado. O experimento foi montado no esquema de parcelas subdivididas, tendo nas parcelas os tipos de gotejadores (G1-não autocompensante; G2 - autocompensante, G3 - autocompensante e G4 - autocompensante) e nas subparcelas os tempos de operação (0, 20, 40, 60, 80, 100, 120, 140 e 160 h), com quatro repetições. A vazão relativa (QR), a redução da vazão relativa (RQR) e os atributos físico-químicos e microbiológicas do percolado de aterro sanitário diluído, foram obtidos a cada 20 h, até completar 160 h de operação em todas as unidades de irrigação. Os valores de QR e RQR do gotejador G1 diferiram estatisticamente dos valores dos gotejadores G2, G3 e G4. O gotejador G1 foi o mais susceptível à obstrução, enquanto os gotejadores G2, G3 e G4 foram mais resistentes ao entupimento. Palavras-chave: resíduos urbanos, lixiviado, emissores, obstrução. MESQUITA, F. O.; ALVES, S. M. C.; BATISTA, R. O.; DANTAS, T. B.; SOUZA, L. D.PERFORMANCE OF DRIPPERS OPERATING WITH DILUTED LANDFILL LEACHATE 2 ABSTRACT The landfill leachate has appreciable amounts of nutrients that can be used to produce biomass for energy purposes. The objective of this work is to analyze the drip performance indicators applying diluted leachate landfill well as the main obstruction factors and the leachate quality. The experiment was set up on split-plot scheme with kind drippers (G1 - non-pressure compensated; G2 - pressure compensated; G3 - pressure compensated; and G4 - pressure compensated) in the plot and operating times (0, 20, 40, 60, 80, 100, 120, 140 and 160 h) in subplots, with four replications. The relative flow rate (QR), the reduction of relative flow (RQR) and physicochemical and microbiological characteristics of the landfill leachate diluted were obtained every 20 h until the completion of 160 h of operation in all irrigation units. The QR and RQR values of the dripper G1 differed significantly from the values found in G2, G3, and G4 drippers. The G1 dripper was the most susceptible to obstruction while the G2, G3, and G4 drippers were more resistant to clogging. Keywords: municipal waste, leachate, emitters, clogging.