Thermophotovoltaic power conversion from a heat-recirculating micro-emitter

Park, J.H.; Lee, S.I.; Wu, H.; Kwon, Oh Chae

doi:10.1016/j.ijheatmasstransfer.2012.05.001

Cited by 53 publications

(20 citation statements)

References 17 publications

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“…Adiabatic flame corresponds to flame formed without heat losses along the outer walls Vlachos, 2003 andZimont, 2015). The maximum temperature is higher than the adiabatic flame temperature for stoichiometric propane-air mixtures due to heat transfer from the hot combustion products and the inner walls to the incoming cold reactants, namely as a result of preheating (Belmont et al, 2013 and2015;Park et al, 2012). Prior to the flame, large temperature gradients exist in the transverse direction.…”

Section: Computation Schemementioning

confidence: 99%

Flame Stability of Propane-Air Premixed Combustion in Heat-Recirculation Micro-Combustors

Chen¹,

Song²,

Gao³

et al. 2016

Frontiers in Heat and Mass Transfer

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The flame stability of single-pass heat-recirculation micro-combustors was investigated using computational fluid dynamics and compared to singlechannel micro-combustors with respect to critical heat loss coefficient and total power loss. The effect of wall thermal conductivity was also explored. The simulations show that heat recirculation profoundly affects blowout because of preheating of the cold incoming gases but has only minimal effect on extinction. In the limit of low-conductivity walls, the heat-recirculation micro-combustor is much more stable than the single-channel microcombustor. Under certain conditions, the heat recirculation micro-combustor can operate with room-temperature inlet and outlet streams and moderate outer wall temperatures while exhibiting high thermal and combustion efficiency.

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Section: Computation Schemementioning

confidence: 99%

Flame Stability of Propane-Air Premixed Combustion in Heat-Recirculation Micro-Combustors

Chen¹,

Song²,

Gao³

et al. 2016

Frontiers in Heat and Mass Transfer

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“…According to Park et al (2012), the efficiency of a micro combustor in converting the heat produced from combustion to electrical energy is significantly affected by the inlet velocity. This fact is due to the temperature variation with respect to the inlet velocity.…”

Section: Effects Of the Inlet Velocity And Equivalence Ratiomentioning

confidence: 99%

A numerical study of propane-air combustion in meso-scale tube combustors with concentric rings

Munir

Mikami

2015

JTST

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Dwindling energy resources and strong demand for better power sources as compared to conventional batteries have sparked research interest in micro power generation. The invention of state-of-the-art electronic devices requires more energy capacity, shorter charging period and light in weight, characteristics of which batteries lack. Therefore, in recent years micro power generation systems have been seen as a potential alternative to batteries owing to the obvious advantages that it has. It is essential to fully understand the underlying factors that affect the combustion stability in meso and micro-scale combustors. One of the popular methods to examine these factors is by performing numerical simulations. This paper demonstrates an axisymmetric two-dimensional steady state numerical simulation of propane-air combustion in meso-scale cylindrical tube combustors with concentric rings. The inner diameter of the tube is set to 3.5 mm and the wall thickness is specified to 0.7 mm. The concentric rings are placed between the unburned and burned gas region. The main function of these rings is to act as a flame holder where a stable flame can be easily established. The wall thermal conductivity in the unburned and burned gas region is varied from 1 W/m/K to 1000 W/m/K and the results in terms of gas, inner wall, outer wall surface temperature distribution, the blowout limits and combustion efficiency are analyzed and presented. In addition, the effect of the inlet velocity and the equivalence ratio is also investigated. The results show that the inlet velocity and equivalence ratio have significant impacts on the flame temperature, which in turn change the wall temperature distribution. Although the wall thermal conductivity has minimal effect on the flame temperature, both inner and outer wall surface temperature are greatly affected. Consequently, this variation of wall temperature contributes to the significant changes on the blowout limits. It is also shown that the combustion efficiency is influenced by the wall thermal conductivity of the combustors.

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“…A group at Sungkyunkwan University also conducted plenty of works on micro TPV systems [35][36][37]. As shown in Figure 1.14, the cylindrical micro-combustor has an annular shield that enables the exhaust gas to preheat the incoming fresh mixture.…”

Section: Previous Work 131 Development Of the Micro-power Devicesmentioning

confidence: 99%

“…Li et al at National Cheng Kung University [38,39] developed a mesoscale high-flame-luminescence 14: Heat-recirculating micro-combustor and array of GaSb cells developed at Sungkyunkwan University [37]. Introduction TPV power system combining the utilisation of the radiation in both visible and near-infrared region to improve the system overall efficiency.…”

Section: Previous Work 131 Development Of the Micro-power Devicesmentioning

confidence: 99%

“…Past work on experimental micro/mesoscale combustion revealed a range of interesting flame features such as flames with repetitive extinction and ignition (FREI) [127] and various unstable flame patterns [63,65], demonstrated the enhancement of flame stability limits [66,[138][139][140], as well as developed prototype systems for electrical power generation [36,37,141]. However, experimental works have inherent difficulties in obtaining spatially resolved measurements at small scales.…”

Section: Introductionmentioning

confidence: 99%

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Micro/mesoscale combustion based portable power generating system

Kang¹

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Micro/mesoscale combustion-driven power generation is a promising alternative to replace traditional batteries for powering small scale electronics owing to its much higher energy densities. However, the considerable heat losses from the combustor walls due to the dramatically increased surface-tovolume ratio, as well as the short flow residence time at small scales pose a technical challenge in stabilising the flame inside the micro/mesoscale combustor. On the other hand, the significantly enhanced flame-wall thermal coupling at small scales can also lead to some unique flame characteristics.Recently, solid state power conversion of the heat released in the micro/mesoscale combustor such as thermoelectric (TE) and thermophotovoltaic (TPV) has been favoured over traditional power conversion methods such as micro-turbines. This is due to the excessive mechanical and viscous losses that rotating machinery suffers from upon miniaturisation.One of the main aims of this thesis is to perform numerical simulations to investigate the fundamental aspects of micro/mesoscale combustion, such as micro-flame behaviours of propagation and stabilisation, the conditions under which flame dynamics occur and the choices that suppress them. A set of modelling techniques that gives guidelines and practices for performing the time-accurate micro/mesoscale combustion simulations has been developed through investigation. Knowledge on standard and well-accepted numerical methods in literature are collected in a cohesive document. The less well-established modelling choices have been thoroughly evaluated and discussed.Using the developed numerical models, the effects of hydrogen and carbon monoxide addition on premixed methane/air flame dynamics is investigated. Results show that the flame instabilities which exist in pure methane/air flames could be effectively suppressed via a small amount of additives. Deep understanding of the underlying physics and chemistry has been gained. The effects of wall temperature profiles on the simulated micro-flame behaviours are also studied. The role of the combustion heat release and the gas-solid heat transfer in determining the micro-flame propagation speed is identified.Experimental works are also carried out, towards a full system demonstration for micro-power generation. The focus is placed on the "wall thermal engineering" on the improvement of the combustor performance and power output. The thermally-orthotropic pyrolytic graphite for the combustor wall material is explored. Compared to an isotropic material of stainless steel, a widened flame stability limit with pyrolytic graphite is demonstrated. Moreover, a uniform and moderate temperature distribution over the combustor surface is achieved, which is favourable for thermoelectric power conversion applications. Meanwhile, a novel, compact mesoscale thermophotovoltaic power generating system using a combination of porous media combustion and a simple band-pass filtering method is developed. The use of the porous media effectively enh...

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Thermophotovoltaic power conversion from a heat-recirculating micro-emitter

Cited by 53 publications

References 17 publications

Flame Stability of Propane-Air Premixed Combustion in Heat-Recirculation Micro-Combustors

Flame Stability of Propane-Air Premixed Combustion in Heat-Recirculation Micro-Combustors

A numerical study of propane-air combustion in meso-scale tube combustors with concentric rings

Micro/mesoscale combustion based portable power generating system

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