Experimental investigation of the effect of gaseous fuel injector geometry on the pollutant formation and thermal characteristics of a micro gas turbine combustor

Nozari, Mohammadreza; Tabejamaat, Sadegh; Sadeghizade, Hasan; Aghayari, Majid

doi:10.1016/j.energy.2021.121372

Cited by 15 publications

(7 citation statements)

References 27 publications

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“…Reduced-temperature combustion is typically accomplished by premixing the fuel with su cient excess air that the ame temperature is reduced to a value at which thermal nitrogen oxides production is minimal, typically a temperature below approximately 1800 K [1,2]. At these lower ame temperatures, however, the rate of combustion may be insu cient to prevent localized or global blow-off or extinction, particularly under conditions of turbulent ow [3,4]. Flame anchoring and ame stability therefore become problematic at the lower ame temperatures required for truly low-nitrogen oxides lean-premixed combustion [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…At these lower ame temperatures, however, the rate of combustion may be insu cient to prevent localized or global blow-off or extinction, particularly under conditions of turbulent ow [3,4]. Flame anchoring and ame stability therefore become problematic at the lower ame temperatures required for truly low-nitrogen oxides lean-premixed combustion [3,4]. Thus, achievable nitrogen oxides reduction is limited.…”

Section: Introductionmentioning

confidence: 99%

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WITHDRAWN: The importance of cavities to the stabilization of methane flames in micro-structured combustion systems

Chen

2022

Preprint

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Modeling computations are performed to highlight the importance of cavities to the stabilization of methane flames in micro-structured combustion systems. The effects of different design factors on flame stability are investigated. A dimensionless number analysis is performed to better understand the heat transfer characteristics of the burner. The results indicate that the recirculating, hot combustion products continuously contact and ignite the incoming fuel-air mixture, thus anchoring the flame in the vicinity of the recirculation region. When a cavity is used, the flame is anchored because the cavity induces recirculation of hot combustion products within the combustor. Combustion is stabilized and flame stability is improved by recirculation of hot combustion products induced by the cavity structure. An additional effect of the cavity is to direct the incoming fuel-air mixture outwards toward the walls of the combustor, thus rapidly diffusing the mixture into the combustor, making effective use of the combustor's volume. At low flame temperatures, long combustor residence times are needed for combustion completion in the gas phase. Flame stabilization is dependent upon speed of the fuel-air mixture entering the combustion region where propagation of the flame is desired. A sufficiently low velocity must be retained in the region where the flame is desired in order to sustain the flame. A region of low velocity in which a flame can be sustained can be achieved by causing recirculation of a portion of the fuel-air mixture already burned thereby providing a source of ignition to the fuel-air mixture entering the combustion region. However, the fuel-air mixture flow pattern, including any recirculation, is critical to achieving flame stability. The inlet velocity and wall thermal conductivity are vital in determining the flame stability of the burner. Faster ignition and more efficient heat transfer can be achieved, but the design is challenging due to the loss of flame stability.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

WITHDRAWN: The importance of cavities to the stabilization of methane flames in micro-structured combustion systems

Chen

2022

Preprint

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“…The term C p is the mean heat capacity at inlet and exhaust temperatures. 61 Here, the total mass flow rate of the oxidizer and fuel is also the mass flow rate of the product stream as presented in Equation (38b).…”

Section: Reaction Modelmentioning

confidence: 99%

“…

italicPattern factor goodbreak= \frac{T_{maximum} - T_{average}}{T_{average} - T_{inlet}}

TP of the exhaust gasses refers to the power generated by the combustor due to combustion and is expressed in Equations () and (), where

{\dot{m}}_{italicair italicor oxidizer}

and

m_{fuel}

correspond to oxidizer and fuel mass flow rates, respectively. The term

C_{p}

is the mean heat capacity at inlet and exhaust temperatures 61 . Here, the total mass flow rate of the oxidizer and fuel is also the mass flow rate of the product stream as presented in Equation ().

italicThermal power goodbreak= ((), {\dot{m}}_{normala italicir italicor oxidizer} goodbreak+ {\dot{m}}_{fuel}) goodbreak\times C_{p} goodbreak\times ((), T_{italicaverage, italicoutlet} goodbreak- T_{inlet})

{\dot{m}}_{product} goodbreak= {\dot{m}}_{italicair italicor oxidizer} goodbreak+ {\dot{m}}_{fuel}

…”

Section: Numerical Modelingmentioning

confidence: 99%

Analysis of methane, propane, and syngas oxy‐flames in a fuel‐flex gas turbine combustor for carbon capture

Haque

Nemitallah

Abdelhafez

et al. 2022

Intl J of Energy Research

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Premixed oxy-combustion flames of methane, syngas (CH 4 :CO:H 2 with the molar ratio of 2:1:1), and propane in CO 2 -diluted environment (for carbon capture) are examined in a swirl-stabilized combustor using large eddy simulations (LES) in three-dimensional (3-D) domain. The flame and emission characteristics are examined for the different fuels over a range of equivalence ratios (Φ: 0.34, 0.39, and 0.42), at 60% oxygen fraction (OF), and 2.5 m/s bulk inlet velocity under atmospheric conditions. The results indicate increments in several characteristic parameters that are of special importance for gas turbine combustion applications, including adiabatic flame temperature (T ad ), laminar flame speed (LFS), power density (PD), product formation rate (PFR), Damköhler number (Da), and CO emission, with the increase of Φ whatever the type of fuel. Alternatively, flame thickness (δ) decreases with the increase in Φ for the three fuels. Characteristic "V" shape with almost identical outer recirculation zone (ORZ) is also observed for the three fuels. Among the studied fuels, oxy-methane flames demonstrate highest flame thicknesses, least uniform temperature distribution (highest pattern factor) at combustor outlet, and lowest CO emission level. Oxy-syngas flames show more uniform temperature distribution (lowest pattern factor) at combustor outlet and highest CO emission as compared with the oxy-methane and oxy-propane flames. The oxy-propane flames have higher values of T ad , LFS, PD, PFR, Da, and thermal power (TP) along with lowest flame thickness compared with methane and syngas counterparts. Highlights• Increasing equivalence ratio improves the flame characteristics but increases CO emission.• Fuel type has insignificant effects on shape/size of the outer recirculation zone (ORZ).• Oxy-methane flames showed highest flame thicknesses and pattern factor and lowest CO.

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“…More particularly, micro-structured combustion systems enable the realization of a wide range of micro-machinery componentry for thermodynamic cycling, propulsion, and producing sources of power that achieve high efficiencies of components [15], [16]. Micro-heat exchangers [17], [18], micro-turbines, micro-combustors [19], [20], and other microcomponentry can be developed as thermodynamic micro-modules that could be interconnected in various combinations to construct micro-structured thermodynamic cycles such as micro-gas turbine generators [21], [22], micro-gas turbine engines [23], [24], and a wide range of other thermodynamic cycles [25], [26] in the regime of millimeters. Specifically, micro-structured combustion systems apply to all portable electric power applications for which air is available [27], [28].…”

Section: Introductionmentioning

confidence: 99%

Combustion Characteristics and Flame Stability of a Methane-Air Mixture in Micro-Structured Systems

Chen

2022

Engineering Science & Technology

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Cavities are effective in improving the ability of a flame in micro-structured systems, but the mechanism for increased flame stability remains unclear. Numerical simulations are performed to understand the overall small-scale combustion characteristics of a cavity-stabilized burner. The effects of inlet velocity, equivalence ratio, wall thermal conductivity, channel height, and heat transfer coefficient on flame stability are investigated. A dimensionless number analysis is performed to better understand the heat transfer characteristics of the burner. The results indicate that the cavity structure can induce recirculation of hot products, thereby improving flame stability. The wall thermal conductivity and inlet velocity are vital in determining the flame stability of the burner. Further improvement in flame stability can be achieved using anisotropic walls. Fast flows can cause a blowout and slow flows can cause extinction. There exists an optimum inlet velocity for the greatest flame stability. A critical issue of fuel-rich cases is the loss of combustion efficiency. Combustion at the microscale can offer many advantages. Faster ignition and more efficient heat transfer can be achieved, but the design is challenging due to the loss of flame stability.

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Experimental investigation of the effect of gaseous fuel injector geometry on the pollutant formation and thermal characteristics of a micro gas turbine combustor

Cited by 15 publications

References 27 publications

WITHDRAWN: The importance of cavities to the stabilization of methane flames in micro-structured combustion systems

WITHDRAWN: The importance of cavities to the stabilization of methane flames in micro-structured combustion systems

Analysis of methane, propane, and syngas oxy‐flames in a fuel‐flex gas turbine combustor for carbon capture

Combustion Characteristics and Flame Stability of a Methane-Air Mixture in Micro-Structured Systems

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