AUTHORS: Junjie Chen, Deguang Xu

Download as PDF

ABSTRACT: Transient simulation of the hydrogen-assisted self-ignition of propane-air mixtures under ambient condition were carried out in platinum-coated micro-combustors, using a two-dimensional model with reducedorder reaction schemes, heat conduction in the solid walls, convection and surface radiation heat transfer. The selfignition behavior of the hydrogen-propane mixed fuel is compared for the case of heated feed is analyzed. Simulations indicate that hydrogen can successfully cause self-ignition of propane-air mixtures in catalytic microchannels with a 0.2 mm gap size, eliminating the need for startup devices. The minimum hydrogen composition for propane self-ignition is found to be in the range of 0.8-2.8 % (on a molar basis), and increases with increasing wall thermal conductivity, and decreasing inlet velocity or propane composition. Higher propane-air ratio results in earlier ignition. The ignition characteristics of hydrogen-assisted propane qualitatively resemble the selectively inlet feed preheating mode. Transient response of the mixed hydrogen-propane fuel reveals sequential ignition of propane followed by hydrogen. Front-end propane ignition is observed in all cases. Low wall thermal conductivities cause earlier ignition of the mixed hydrogen-propane fuel, subsequently resulting in low exit temperatures. The transient-state behavior of this micro-scale system is described, and the startup time and minimization of hydrogen usage are discussed.

KEYWORDS: Micro-combustion; Catalytic combustion; Transient combustion modelling; Platinum catalyst; Selfignition;Reduced-order kinetics

REFERENCES:

[1] C. Deng, W. Yang, J. Zhou, Z. Liu, Y. Wang, and K. Cen. Catalytic combustion of methane, methanol, and ethanol in microscale combustors with Pt/ZSM-5 packed beds. Fuel, Vol. 150, pp. 339-346, 2015.

[2] T.A. Wierzbicki, I.C. Lee, and A.K. Gupta. Rh assisted catalytic oxidation of jet fuel surrogates in a meso-scale combustor. Applied Energy, Vol. 145, pp. 1-7, 2015.

[3] J. Lu and C.M. Corvalan. Free-surface dynamics of small pores. Chemical Engineering Science, Vol. 132, pp. 93-98, 2015.

[4] J.A. Federici, E.D. Wetzel, B.R. Geil, and D.G. Vlachos. Single channel and heat recirculation catalytic microburners: An experimental and computational fluid dynamics study. Proceedings of the Combustion Institute, Vol. 32, No. 2, pp. 3011-3018, 2009.

[5] K. Bijjula and D.G. Vlachos. Catalytic ignition and autothermal combustion of JP-8 and its surrogates over a Pt/γ-Al2O3 catalyst. Proceedings of the Combustion Institute, Vol. 33, No. 2, pp. 1801-1807, 2011.

[6] K. Bijjula and D.G. Vlachos. Catalytic ignition and autothermal combustion of JP-8 and its surrogates over a Pt/γ-Al2O3 catalyst. Proceedings of the Combustion Institute, Vol. 33, No. 2, pp. 1801-1807, 2011.

[7] S. Akhtar, J.C. Kurnia, T. Shamim. A threedimensional computational model of H2-air premixed combustion in non-circular microchannels for a thermo-photovoltaic (TPV) application. Applied Energy, Vol. 152, pp. 47- 57, 2015.

[8] M.C. Cameretti and R. Tuccillo. Combustion features of a bio-fuelled micro-gas turbine. Applied Thermal Engineering, Vol. 89, pp. 280- 290, 2015.

[9] P.D. Ronney. Analysis of non-adiabatic heatrecirculating combustors. Combustion and Flame, Vol. 135, No. 4, pp. 421-439, 2003.

[10] S. Yadav, P. Yamasani, and S. Kumar. Experimental studies on a micro power generator using thermo-electric modules mounted on a micro-combustor. Combustion and Flame, Vol. 99, pp. 1-7, 2015.

[11] A. Rezania and L.A. Rosendahl. A comparison of micro-structured flat-plate and cross-cut heat sinks for thermoelectric generation application. Energy Conversion and Management, Vol. 101, pp. 730-737, 2015.

[12] S.E. Hosseini and M.A. Wahid. Investigation of bluff-body micro-flameless combustion. Energy Conversion and Management, Vol. 88, pp. 120- 128, 2014.

[13] L. Zhang, J. Zhu, Y. Yan, H. Guo, and Z. Yang. Numerical investigation on the combustion characteristics of methane/air in a microcombustor with a hollow hemispherical bluff body. Energy Conversion and Management, Vol. 94, pp. 293-299, 2015.

[14] W. Yang, A. Fan, J. Wan, and W. Liu. Effect of external surface emissivity on flame-splitting limit in a micro cavity-combustor. Applied Thermal Engineering, Vol. 83, pp. 8-15, 2015.

[15] J. Lee, S. Jeon, and Y. Kim. Multi-environment probability density function approach for turbulent CH4/H2 flames under the MILD combustion condition. Combustion and Flame, Vol. 162, No. 4, pp. 1464-1476, 2015.

[16] A. Veeraragavan and C.P. Cadou. Flame speed predictions in planar micro/mesoscale combustors with conjugate heat transfer. Combustion and Flame, Vol. 158, No. 11, pp. 2178-2187, 2011.

[17] J.A. Badra and A.R. Masri. Catalytic combustion of selected hydrocarbon fuels on platinum: Reactivity and hetero-homogeneous interactions. Combustion and Flame, Vol. 159, No. 2, pp. 817-831, 2012.

[18] A. Brambilla, C.E. Frouzakis, J. Mantzaras, A. Tomboulides, S. Kerkemeier, and K. Boulouchos. Detailed transient numerical simulation of H2/air hetero-/homogeneous combustion in platinum-coated channels with conjugate heat transfer. Combustion and Flame, Vol. 161, No. 10, pp. 2692-2707, 2014.

[19] D.G. Norton and D.G. Vlachos. Hydrogen assisted self-ignition of propane/air mixtures in catalytic microburners. Proceedings of the Combustion Institute, Vol. 30, No. 2, pp. 2473- 2480, 2005.

[20] D.G. Norton, E.R. Wetzel, and D.G. Vlachos. Fabrication of single-channel catalytic microburners: Effect of confinement on the oxidation of hydrogen/air mixtures. Industrial & Engineering Chemistry Research, Vol. 43, No. 16, pp. 4833-4840, 2004.

[21] N. Michelon, J. Mantzaras, and P. Canu. Transient simulation of the combustion of fuellean hydrogen/air mixtures in platinum-coated channels. Combustion Theory and Modelling, Vol. 19, No. 4, pp. 514-548, 2015.

[22] N. Fernandes, Y.K. Park, and D.G. Vlachos. Transient simulation of the combustion of fuellean hydrogen/air mixtures in platinum-coated channels. Combustion and Flame, Vol. 118, No. 1-2, pp. 164-178, 1999.

[23] O. Deutschmann, L.I. Maier, U. Riedel, A.H. Stroemman, and R.W. Dibble. Hydrogen assisted catalytic combustion of methane on platinum. Catalysis Today, Vol. 59, No. 1-2, pp. 141-150, 2000.

[24] Y. Zhang, J. Zhou, W. Yang, M. Liu, and K. Cen. Effects of hydrogen addition on methane catalytic combustion in a microtube. International Journal of Hydrogen Energy, Vol. 32, No. 9, pp. 1286-1293, 2007.

[25] G. Landi, A. Di Benedetto, P.S. Barbato, G. Russo, and V. Di Sarli. Transient behavior of structured LaMnO3 catalyst during methane combustion at high pressure. Chemical Engineering Science, Vol. 116, pp. 350-358, 2014.

[26] V. Seshadri and N.S. Kaisare. Ignition strategies for fuel-mixtures in microburners. Combustion Theory and Modelling, Vol. 14, No. 1, pp. 23- 40, 2010.

[27] J. Mantzaras, R. Bombach, and R. Schaeren. Hetero-/homogeneous combustion of hydrogen/air mixtures over platinum at pressures up to 10 bar. Proceedings of the Combustion Institute, Vol. 32, No. 2, pp. 1937-1945, 2009.

[28] P.M. Struk, J.S. T’ien, F.J. Miller, and D.L. Dietrich. Transient numerical modeling of catalytic channels using a quasi-steady gas phase. Chemical Engineering Science, Vol. 119, pp. 158-173, 2014.

[29] X. Zheng and J. Mantzaras. An analytical and numerical investigation of hetero-/homogeneous combustion with deficient reactants having larger than unity Lewis numbers. Combustion and Flame, Vol. 161, No. 7, pp. 1911-1922, 2014.

[30] G. Pizza, J. Mantzaras, C. Frouzakis, A. Tomboulides, and K. Boulouchos. Suppression of combustion instabilities of premixed hydrogen/air flames in microchannels using heterogeneous reactions. Proceedings of the Combustion Institute, Vol. 32, No. 2, pp. 3051- 3058, 2009.

[31] D.G. Norton, E.D. Wetzel, and D.G. Vlachos. Thermal management in catalytic microreactors. Industrial & Engineering Chemistry Research, Vol. 45, No. 1, pp. 76-84, 2006.

[32] M. Schultze, J. Mantzaras, F. Grygier, and R. Bombach. Hetero-/homogeneous combustion of syngas mixtures over platinum at fuel-rich stoichiometries and pressures up to 14 bar. Proceedings of the Combustion Institute, Vol. 35, No. 2, pp. 2223-2231, 2015.

[33] S.R. Deshmukh and D.G. Vlachos. CFD simulations of coupled, countercurrent combustor/reformer microdevices for hydrogen production. Industrial & Engineering Chemistry Research, Vol. 44, No. 14, pp. 4982-4992, 2005.

[34] J. Zetterberg, S. Blomberg, J. Gustafson, J. Evertsson, J. Zhou, E.C. Adams, P.-A. Carlsson, M. Aldén, and E. Lundgren. Spatially and temporally resolved gas distributions around heterogeneous catalysts using infrared planar laser-induced fluorescence. Nature Communications, Vol. 6, Article number: 7076, 2015.

[35] A. Brambilla, C.E. Frouzakis, J. Mantzaras, R. Bombach, and K. Boulouchos. Flame dynamics in lean premixed CO/H2/air combustion in a mesoscale channel. Combustion and Flame, Vol. 161, No. 5, pp. 1268-1281, 2014.

[36] G.P. Gauthier, G.M.G. Watson and J.M. Bergthorson. Burning rates and temperatures of flames in excess-enthalpy burners: A numerical study of flame propagation in small heatrecirculating tubes. Combustion and Flame, Vol. 161, No. 9, pp. 2348-2360, 2014.

[37] N.S. Kaisare and D.G. Vlachos. Extending the region of stable homogeneous micro-combustion through forced unsteady operation. Proceedings of the Combustion Institute, Vol. 31, No. 2, pp. 3293-3300, 2007.

[38] S.K. Som and U. Rana. Wall heat recirculation and exergy preservation in flow through a small tube with thin heat source. International Communications in Heat and Mass Transfer, Vol. 64, pp. 1-6, 2015.

[39] R. Carroni, T. Griffin, J. Mantzaras, and M. Reinke. High-pressure experiments and modeling of methane/air catalytic combustion for power generation applications. Catalysis Today, Vol. 83, No. 1-4, pp. 157-170, 2003.

[40] P.-A. Bui, E.A. Wilder, D.G. Vlachos, and P.R. Westmoreland. Hierarchical reduced models for catalytic combustion: H2/Air mixtures near platinum surfaces. Combustion Science and Technology, Vol. 129, No. 1-6, pp. 243-275, 1997.

[41] M.S. Mettler, G.D. Stefanidis, and D.G. Vlachos. Enhancing stability in parallel plate microreactor stacks for syngas production. Chemical Engineering Science, Vol. 66, No. 6, pp. 1051-1059, 2011.

[42] M. Schultze and J. Mantzaras. Hetero/homogeneous combustion of hydrogen/air mixtures over platinum: Fuel-lean versus fuelrich combustion modes. International Journal of Hydrogen Energy, Vol. 38, No. 25, pp. 10654- 10670, 2013.

[43] C.H. Kuo and P.D. Ronney. Numerical modeling of non-adiabatic heat-recirculating combustors. Proceedings of the Combustion Institute, Vol. 31, No. 2, pp. 3277-3284, 2007.

[44] J. Wan, A. Fan, H. Yao, and W. Liu. Effect of thermal conductivity of solid wall on combustion efficiency of a micro-combustor with cavities. Energy Conversion and Management, Vol. 96, pp. 605-612, 2015.

[45] R.J. Kee, F.M. Rupley, E. Meeks, and J.A. Miller. Chemkin: a Fortran chemical kinetics package for the analysis of gas-phase chemical kinetics, Report No. SAND96-8216, Technical Report, Sandia National Laboratories, 1996.

[46] M.E. Coltrin, R.J. Kee, F.M. Rupley, and E. Meeks. Surface Chemkin: a Fortran package for analyzing heterogeneous chemical kinetics at a solid surface/gas-phase interface, Report No. SAND96-8217, Technical Report, Sandia National Laboratories, 1996.

[47] R.J. Kee, G. Dixon-Lewis, J. Warnatz, M.E. Coltrin, and J.A. Miller. A Fortran computer code package for the evaluation of gas-phase multicomponent transport properties, Report No. SAND86-8246, Technical Report, Sandia National Laboratories, 1996.

[48] N.S. Kaisare, G.D. Stefanidis, and D.G. Vlachos. Comparison of ignition strategies for catalytic microburners. Proceedings of the Combustion Institute, Vol. 32, No. 2, pp. 3027- 3034, 2009.

[49] W. Choi, S. Kwon, and H.D. Shin. Combustion characteristics of hydrogen-air premixed gas in a sub-millimeter scale catalytic combustor. International Journal of Hydrogen Energy, Vol. 33, No. 9, pp. 2400-2408, 2008.