Numerical Investigation of Heat Transfer Characteristics of Supercritical CO_2 Tube in Combustion Chamber of Coal-Fired Boiler
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摘要
To achieve compact structure, light weight, and high thermal efficiency for the coal-fired boiler, the supercritical CO_2 power cycle has been considered as one of the promising alternatives in the coal-fired power conversion system. One of the major problems concerning fossil fuel powered plants is the safety of the water wall in boiler design. In this work, the heat transfer characteristics of the supercritical CO_2 tube in the combustion chamber were determined through the low Reynolds number k-ε model, the gas real model and the P-1 radiation model. The study covered the supercritical CO_2 tube and the fins, and the annulus flue gas passage was also included. The wall temperature and the heat transfer coefficient were compared against those obtained from the experiments. Based on the examinations of the calculated flow and turbulence fields, the distributions of the velocity and the temperature inside the supercritical CO_2 tube in the combustion chamber were resolved numerically. Moreover, the effects of the heat transfer coefficient on the heat transfer characteristics were also discussed. And it was numerically focused on the influence of the inclined angle on the flow and the heat transfer of the supercritical CO_2 tube. The results show that the heat transfer coefficient keeps namely constant as the increasing inclined angle. It would help to better understand the heat transfer mechanism of unique characteristics of supercritical CO_2 above the pseudo-critical temperature, which may provide the corresponding theoretical basis on the optimization design of the coal-fired boiler.
To achieve compact structure, light weight, and high thermal efficiency for the coal-fired boiler, the supercritical CO_2 power cycle has been considered as one of the promising alternatives in the coal-fired power conversion system. One of the major problems concerning fossil fuel powered plants is the safety of the water wall in boiler design. In this work, the heat transfer characteristics of the supercritical CO_2 tube in the combustion chamber were determined through the low Reynolds number k-ε model, the gas real model and the P-1 radiation model. The study covered the supercritical CO_2 tube and the fins, and the annulus flue gas passage was also included. The wall temperature and the heat transfer coefficient were compared against those obtained from the experiments. Based on the examinations of the calculated flow and turbulence fields, the distributions of the velocity and the temperature inside the supercritical CO_2 tube in the combustion chamber were resolved numerically. Moreover, the effects of the heat transfer coefficient on the heat transfer characteristics were also discussed. And it was numerically focused on the influence of the inclined angle on the flow and the heat transfer of the supercritical CO_2 tube. The results show that the heat transfer coefficient keeps namely constant as the increasing inclined angle. It would help to better understand the heat transfer mechanism of unique characteristics of supercritical CO_2 above the pseudo-critical temperature, which may provide the corresponding theoretical basis on the optimization design of the coal-fired boiler.
To achieve compact structure, light weight, and high thermal efficiency for the coal-fired boiler, the supercritical CO_2 power cycle has been considered as one of the promising alternatives in the coal-fired power conversion system. One of the major problems concerning fossil fuel powered plants is the safety of the water wall in boiler design. In this work, the heat transfer characteristics of the supercritical CO_2 tube in the combustion chamber were determined through the low Reynolds number k-ε model, the gas real model and the P-1 radiation model. The study covered the supercritical CO_2 tube and the fins, and the annulus flue gas passage was also included. The wall temperature and the heat transfer coefficient were compared against those obtained from the experiments. Based on the examinations of the calculated flow and turbulence fields, the distributions of the velocity and the temperature inside the supercritical CO_2 tube in the combustion chamber were resolved numerically. Moreover, the effects of the heat transfer coefficient on the heat transfer characteristics were also discussed. And it was numerically focused on the influence of the inclined angle on the flow and the heat transfer of the supercritical CO_2 tube. The results show that the heat transfer coefficient keeps namely constant as the increasing inclined angle. It would help to better understand the heat transfer mechanism of unique characteristics of supercritical CO_2 above the pseudo-critical temperature, which may provide the corresponding theoretical basis on the optimization design of the coal-fired boiler.
引文
[1]Bourke P.J.,Pulling D.J.,Gill L.E.,Denton W.H.,Forced convective heat transfer to turbulent CO2 in the supercritical region.International Journal of Heat and Mass Transfer,1970,13(8):1339-1348.
[2]Kurganov V.A.,Kaptilnyi A.G.,Flow structure and turbulent transport of a supercritical pressure fluid in a vertical heated tube under the conditions of mixed convection.International Journal of Heat and Mass Transfer,1993,36(13):3383-3392.
[3]Walisch K.T.,Mtiller M.,Dorfler W.,Trepp C.,The heat transfer to supercritical carbon dioxide in tubes with mixed convection.High Pressure Chemical Engineering,1996,12:199-204.
[4]Liao S.M.,Zhao T.S.,An experimental investigation of convection heat transfer to supercritical carbon dioxide in miniature tubes.International Journal of Heat and Mass Transfer,2002,45(25):5025-5034.
[5]Jiang P.X.,Zhang Y.,Shi R.F.,Experimental and numerical investigation of convection heat transfer of CO2 at supercritical pressures in a vertical mini-tube.International Journal of Heat and Mass Transfer,2008,51(11-12):3052-3056.
[6]Jiang P.X.,Zhang Y.,Zhao C.R.,Shi R.F.,Convection heat transfer of CO2 at supercritical pressures in a vertical mini tube at relatively low Reynolds numbers.Experimental Thermal and Fluid Science,2008,32(8):1628-1637.
[7]Jiang P.X.,Zhang Y.,Xu Y.J.,Shi R.F.,Experimental and numerical investigation of convection heat transfer of CO2 at supercritical pressures in a vertical tube at low Reynolds numbers,International Journal of Thermal Sciences,2008,47(8):998-1011.
[8]Jiang P.X.,Zhao C.R.,Shi R.F.,Chen Y.,Ambrosini W.,Experimental and numerical study of convection heat transfer of CO2 at supercritical pressures during cooling in small vertical tube.International Journal of Heat and Mass Transfer,2009,52(21-22):4748-4756.
[9]Kim D.E.,Kim M.H.,Experimental study of the effects of flow acceleration and buoyancy on heat transfer in a supercritical fluid flow in a circular tube.Nuclear Engineering and Design,2010,240(10):3336-3349.
[10]Kim D.E.,Kim M.H.,Two layer heat transfer model for supercritical fluid flow in a vertical tube.Journal of Supercritical Fluids,2011,58(1):15-25.
[11]Kim D.E.,Kim M.H.,Experimental investigation of heat transfer in vertical upward and downward supercritical CO2 flow in a circular tube.International Journal of Heat and Fluid Flow,2011,32(1):176-191.
[12]Kim H.Y.,Kim H.,Kang D.J.,Song J.H.,Bae Y.Y.,Experimental investigations on a heat transfer to CO2flowing upward in a narrow annulus at supercritical pressures.Nuclear Engineering and Technology,2007,40(2):155-162.
[13]Gnielinski V.,New equation for heat and mass transfer in turbulent pipe and channel flow.International Chemical Engineering,1976,16(2):359-368.
[14]Petrov N.E.,Popov V.N.,Heat transfer and resistance of carbon dioxide being cooled in the supercritical region.Thermal Engineering,1985,32(3):131-134.
[15]Liao S.M.,Zhao T.S.,A numerical investigation of laminar convection of supercritical carbon dioxide in vertical mini/micro tubes.Progress in Computational Fluid Dynamics,2002,2(2/3/4):144-152.
[16]Dang C.B.,Hihara E.,In-tube cooling heat transfer of supercritical carbon dioxide.Part I:Experimental measurement.International Journal of Refrigeration,2004,27(7):736-747.
[17]Kim H.,Kim H.Y.,Song J.H.,Bae Y.Y.,Heat transfer to supercritical pressure carbon dioxide flowing upward through tubes and a narrow annulus passage.Progress in Nuclear Energy,2008,50(2-6):518-525.
[18]Cao X.L.,Rao Z.H.,Liao S.M.,Laminar convective heat transfer of supercritical CO2 in horizontal miniature circular and triangular tubes.Applied Thermal Engineering,2011,31(14-15):2374-2384.
[19]Du Z.X.,Lin W.S.,Gu A.Z.,Numerical investigation of cooling heat transfer to supercritical CO2 in a horizontal circular tube.Journal of Supercritical Fluids,2010,55(1):116-121.
[20]He S.,Kim W.S.,Jiang P.X.,Jackson J.D.,Simulation of mixed convective heat transfer to carbon dioxide at supercritical pressure.Journal of Mechanical Engineering Science,2004,218(11):1281-1296.
[21]He S.,Jiang P.X.,Xu Y.J.,Shi R.F.,Kim W.S.,Jackson J.D.,A computational study of convection heat transfer to CO2 at supercritical pressures in a vertical minitube.International Journal of Thermal Sciences,2005,44(6):521-530.
[22]He S.,Kim W.S.,Bae J.H.,Assessment of performance turbulence models in predicting supercritical pressure heat transfer in a vertical tube.International Journal of Heat and Mass Transfer,2008,51(19-20):4659-4675.
[23]Huang D.,Wu Z.,Sunden B.,Li W.,A brief review on convection heat transfer of fluids at supercritical pressures in tubes and the recent progress.Applied Energy,2016,162:494-505.
[24]Le M.Y.,Conceptual study of a high efficiency coal-fired power plant with CO2 capture using a supercritical CO2Brayton cycle,Energy,2013,49(1):32-46.
[25]Mecheri M.,Le M.Y.,Supercritical CO2 Brayton cycles for coal-fired power plants,Energy,2016,103:758-771.
[26]Xu J.,Sun E.,Li M.,Liu H.,Zhu B.,Key issues and solution strategies for supercritical carbon dioxide coal fired power plant.Energy,2018,157:227-246.
[27]Askarova A.,Bolegenova S.,Maximov V.,Beketayeva M.,Safarik P.,Numerical modeling of pulverized coal combustion at thermal power plant boilers.Journal of Thermal Science,2015,24(3):275-282.
[28]Yang Y.,Bai W.,Wang Y.,Zhang Y.,Li H.,Yao M.,Wang H.,Coupled simulation of the combustion and fluid heating of a 300 MW supercritical CO2 boiler.Applied Thermal Engineering,2017,113:259-267.
[29]Zhu B.,Xu J.,Wu X.,et al.,Supercritical“boiling”number,a new parameter to distinguish two regimes of carbon dioxide heat transfer in tubes.International Journal of Thermal Sciences,2019,136:254-266.
[2]Kurganov V.A.,Kaptilnyi A.G.,Flow structure and turbulent transport of a supercritical pressure fluid in a vertical heated tube under the conditions of mixed convection.International Journal of Heat and Mass Transfer,1993,36(13):3383-3392.
[3]Walisch K.T.,Mtiller M.,Dorfler W.,Trepp C.,The heat transfer to supercritical carbon dioxide in tubes with mixed convection.High Pressure Chemical Engineering,1996,12:199-204.
[4]Liao S.M.,Zhao T.S.,An experimental investigation of convection heat transfer to supercritical carbon dioxide in miniature tubes.International Journal of Heat and Mass Transfer,2002,45(25):5025-5034.
[5]Jiang P.X.,Zhang Y.,Shi R.F.,Experimental and numerical investigation of convection heat transfer of CO2 at supercritical pressures in a vertical mini-tube.International Journal of Heat and Mass Transfer,2008,51(11-12):3052-3056.
[6]Jiang P.X.,Zhang Y.,Zhao C.R.,Shi R.F.,Convection heat transfer of CO2 at supercritical pressures in a vertical mini tube at relatively low Reynolds numbers.Experimental Thermal and Fluid Science,2008,32(8):1628-1637.
[7]Jiang P.X.,Zhang Y.,Xu Y.J.,Shi R.F.,Experimental and numerical investigation of convection heat transfer of CO2 at supercritical pressures in a vertical tube at low Reynolds numbers,International Journal of Thermal Sciences,2008,47(8):998-1011.
[8]Jiang P.X.,Zhao C.R.,Shi R.F.,Chen Y.,Ambrosini W.,Experimental and numerical study of convection heat transfer of CO2 at supercritical pressures during cooling in small vertical tube.International Journal of Heat and Mass Transfer,2009,52(21-22):4748-4756.
[9]Kim D.E.,Kim M.H.,Experimental study of the effects of flow acceleration and buoyancy on heat transfer in a supercritical fluid flow in a circular tube.Nuclear Engineering and Design,2010,240(10):3336-3349.
[10]Kim D.E.,Kim M.H.,Two layer heat transfer model for supercritical fluid flow in a vertical tube.Journal of Supercritical Fluids,2011,58(1):15-25.
[11]Kim D.E.,Kim M.H.,Experimental investigation of heat transfer in vertical upward and downward supercritical CO2 flow in a circular tube.International Journal of Heat and Fluid Flow,2011,32(1):176-191.
[12]Kim H.Y.,Kim H.,Kang D.J.,Song J.H.,Bae Y.Y.,Experimental investigations on a heat transfer to CO2flowing upward in a narrow annulus at supercritical pressures.Nuclear Engineering and Technology,2007,40(2):155-162.
[13]Gnielinski V.,New equation for heat and mass transfer in turbulent pipe and channel flow.International Chemical Engineering,1976,16(2):359-368.
[14]Petrov N.E.,Popov V.N.,Heat transfer and resistance of carbon dioxide being cooled in the supercritical region.Thermal Engineering,1985,32(3):131-134.
[15]Liao S.M.,Zhao T.S.,A numerical investigation of laminar convection of supercritical carbon dioxide in vertical mini/micro tubes.Progress in Computational Fluid Dynamics,2002,2(2/3/4):144-152.
[16]Dang C.B.,Hihara E.,In-tube cooling heat transfer of supercritical carbon dioxide.Part I:Experimental measurement.International Journal of Refrigeration,2004,27(7):736-747.
[17]Kim H.,Kim H.Y.,Song J.H.,Bae Y.Y.,Heat transfer to supercritical pressure carbon dioxide flowing upward through tubes and a narrow annulus passage.Progress in Nuclear Energy,2008,50(2-6):518-525.
[18]Cao X.L.,Rao Z.H.,Liao S.M.,Laminar convective heat transfer of supercritical CO2 in horizontal miniature circular and triangular tubes.Applied Thermal Engineering,2011,31(14-15):2374-2384.
[19]Du Z.X.,Lin W.S.,Gu A.Z.,Numerical investigation of cooling heat transfer to supercritical CO2 in a horizontal circular tube.Journal of Supercritical Fluids,2010,55(1):116-121.
[20]He S.,Kim W.S.,Jiang P.X.,Jackson J.D.,Simulation of mixed convective heat transfer to carbon dioxide at supercritical pressure.Journal of Mechanical Engineering Science,2004,218(11):1281-1296.
[21]He S.,Jiang P.X.,Xu Y.J.,Shi R.F.,Kim W.S.,Jackson J.D.,A computational study of convection heat transfer to CO2 at supercritical pressures in a vertical minitube.International Journal of Thermal Sciences,2005,44(6):521-530.
[22]He S.,Kim W.S.,Bae J.H.,Assessment of performance turbulence models in predicting supercritical pressure heat transfer in a vertical tube.International Journal of Heat and Mass Transfer,2008,51(19-20):4659-4675.
[23]Huang D.,Wu Z.,Sunden B.,Li W.,A brief review on convection heat transfer of fluids at supercritical pressures in tubes and the recent progress.Applied Energy,2016,162:494-505.
[24]Le M.Y.,Conceptual study of a high efficiency coal-fired power plant with CO2 capture using a supercritical CO2Brayton cycle,Energy,2013,49(1):32-46.
[25]Mecheri M.,Le M.Y.,Supercritical CO2 Brayton cycles for coal-fired power plants,Energy,2016,103:758-771.
[26]Xu J.,Sun E.,Li M.,Liu H.,Zhu B.,Key issues and solution strategies for supercritical carbon dioxide coal fired power plant.Energy,2018,157:227-246.
[27]Askarova A.,Bolegenova S.,Maximov V.,Beketayeva M.,Safarik P.,Numerical modeling of pulverized coal combustion at thermal power plant boilers.Journal of Thermal Science,2015,24(3):275-282.
[28]Yang Y.,Bai W.,Wang Y.,Zhang Y.,Li H.,Yao M.,Wang H.,Coupled simulation of the combustion and fluid heating of a 300 MW supercritical CO2 boiler.Applied Thermal Engineering,2017,113:259-267.
[29]Zhu B.,Xu J.,Wu X.,et al.,Supercritical“boiling”number,a new parameter to distinguish two regimes of carbon dioxide heat transfer in tubes.International Journal of Thermal Sciences,2019,136:254-266.