Heat-Recirculating Combustor Using Porous Inert Media for Mesoscale Applications

Marbach, Timothy; Agrawal, Ajay K.

doi:10.2514/1.14547

Cited by 23 publications

(6 citation statements)

References 11 publications

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“…A variety of porous burner designs have been proposed by many researchers. The studies concluded that internal heat recirculation within porous burner results in extended the flammability limits [21][22][23][24][25][26][27]. They are useful comprehensive review papers in this area [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Experimental study of combustion of low-calorific producer gas from small scale biomass gasification within porous burner

Jirakulsomchok¹,

Wongchang²,

Prasartthong³

2021

Journal of Thermal Engineering

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The aim of this experimental study is to investigate the combustion low-calorific producer gas within porous burner. The small scale downdraft biomass gasification for rural area was performed to produce gaseous fuel. Three types of wood in Thailand were used as raw materials to produce producer gas, i.e. Acacia-mangium, White popinac and Eucalyptus. The low heating values of producer gas were in the range of 3800-4232 kJ.kg -1 that are difficult to burn in conventional burner. Tapered and bilayer porous burners were used to overcome this limitation. The effects of air preheating modes, equivalence ratio and firing rate on thermal structure and pollutant emission were revealed. The results showed that the complete combustion with low emission of low-calorific producer gas was accomplished with low firing rate in the range of 2.8 -3 kW. Both CO and NO x emission were less than 160 ppm for all of tests. The combustion within tapered porous burner emitted small CO emission nearly zero for all of equivalence ratios. The tar reduction was 99.5% by combustion within porous burner.

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Section: Introductionmentioning

confidence: 99%

Experimental study of combustion of low-calorific producer gas from small scale biomass gasification within porous burner

Jirakulsomchok¹,

Wongchang²,

Prasartthong³

2021

Journal of Thermal Engineering

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“…Additionally, studies [8][9][10][11] have shown the importance of wall conduction in heat recirculation to reactants in such configurations. Use of porous inert medium (PIM) of high surface area per unit volume was considered by Takeno and other researchers [12][13][14] as well as Marbach and Agrawal [15] to obtain excess enthalpy combustion. Takeno and Sato [12] showed that a ceramic rod introduced in the flame, extracted heat from the products and conducted it backwards towards the cold reactants.…”

Section: Introductionmentioning

confidence: 99%

“…Takeno and Sato [12] showed that a ceramic rod introduced in the flame, extracted heat from the products and conducted it backwards towards the cold reactants. Marbach and Agrawal [15] used a configuration in which reactants flowed counter-current to the hot products through an annulus filled with PIM and combustion took place near another PIM kept internally. Such configurations, however, may result in increased overall weight of the assembly, higher pressure losses, and appearance of hot spots.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from the absence of any porous material, the new design differed from the Marbach and Agrawal [15] configuration in that the combustion reactions occurred in the annular zone instead of the combustor core, and reactants and products flowed co-current to each other. The annular microcombustor had a much smaller surface area per unit volume (~364 m -1 based on outer surface area) in comparison to other configurations [12,15] using PIM for flame stabilization and it also suffered from smaller pressure losses. Hydrogen (H 2 ) can combust at very small length scales [17].…”

Section: Introductionmentioning

confidence: 99%

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Effects of combustor geometry on hydrogen–air premixed flame combustion in an annular microcombustor

Jejurkar

Mishra

2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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Heat losses at the walls and heat release are two competitive rate processes in microcombustion, and a microcombustor design must balance them appropriately for optimal performance. The primary objective of this work was to study the effects of some design variables on the processes influencing microcombustor characteristics and performance. A new compact and lightweight premixed hydrogen–air annular microcombustor was studied using a detailed computational fluid dynamics model validated against experimental data from literature. Heat reflux and flame stabilization were achieved by inserting a hollow tube in the combustion zone, which was also thermally isolated to reduce heat losses. It was found that the flame structure was insensitive to the thickness of inner tube, while wall temperature was not. On the other hand, a compact flame was obtained for larger aspect ratios, and wall temperature field did not alter significantly. Performance improved marginally with a higher thermal conductivity hollow tube. However, larger aspect ratio resulted in inferior thermal performance and non-isothermal walls. Thus, a configuration with smaller aspect ratio and thin-walled inner tube, possibly with a high thermal conductivity, was found to be desirable for good thermal performance. Finally, the model predictions indicated suitability of the design for intended applications.

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“…Extensive work has been conducted on miniature scale micro combustion including the MIT microengine project to realize a compact, reliable, and efficient micro combustion device [49][50][51][52][53][54][55][56], and numerous studies are still underway to address the challenges. Due to the potential high energy densities achievable with a hydrocarbonbased power generator, the study on micro combustion engines is still regarded as one of the promising frontiers of MEMS [48].…”

mentioning

confidence: 99%

An integrated electromagnetic micro-turbo-generator supported on encapsulated microball bearings

Beyaz

Hanrahan

Feldman

et al. 2012

2012 IEEE 25th International Conference on Micro Electro Mechanical Systems (MEMS)

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This dissertation presents the development of an integrated electromagnetic microturbo-generator supported on encapsulated microball bearings for electromechanical power conversion in MEMS (Microelectromechanical Systems) scale. The device is composed of a silicon turbine rotor with magnetic materials that is supported by microballs over a stator with planar, multi-turn, three-phase copper coils. The microturbo-generator design exhibits a novel integration of three key technologies and components, namely encapsulated microball bearings, incorporated thick magnetic materials, and wafer-thick stator coils. Encapsulated microball bearings provide a robust supporting mechanism that enables a simple operation and actuation scheme with high mechanical stability. The integration of thick magnetic materials allows for a high magnetic flux density within the stator. The wafer-thick coil design optimizes the flux linkage and decreases the internal impedance of the stator for a higher output power. Geometrical design and device parameters are optimized based on theoretical analysis and finite element simulations. A microfabrication process flow was designed using 15 optical masks and 110 process steps to fabricate the micro-turbogenerators, which demonstrates the complexity in device manufacturing. Two 10 pole devices with 2 and 3 turns per pole were fabricated. Single phase resistances of 46Ω and 220Ω were measured for the two stators, respectively. The device was actuated using pressurized nitrogen flowing through a silicon plumbing layer. A test setup was built to simultaneously measure the gas flow rate, pressure, rotor speed, and output voltage and power. Friction torques in the range of 5.5-33µNm were measured over a speed range of 0-16krpm (kilo rotations per minute) within the microball bearings using spin-down testing methodology. A maximum per-phase sinusoidal open circuit voltage of 0.1V was measured at 23krpm, and a maximum per-phase AC power of 10µW was delivered on a matched load at 10krpm, which are in full-agreement with the estimations based on theoretical analysis and simulations. The micro-turbogenerator presented in this work is capable of converting gas flow into electricity, and can potentially be coupled to a same-scale combustion engine to convert high-density hydrocarbon energy into electrical power to realize a high-density power source for portable electronic systems.

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Heat-Recirculating Combustor Using Porous Inert Media for Mesoscale Applications

Cited by 23 publications

References 11 publications

Experimental study of combustion of low-calorific producer gas from small scale biomass gasification within porous burner

Experimental study of combustion of low-calorific producer gas from small scale biomass gasification within porous burner

Effects of combustor geometry on hydrogen–air premixed flame combustion in an annular microcombustor

An integrated electromagnetic micro-turbo-generator supported on encapsulated microball bearings

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