本研究之目的為針對缸內直噴引擎建立氫燃料均質充壓點火操作所需之參數，並建立相關數值模擬技術。首先藉由詳細化學反應模型，假設缸內油氣呈理想均質混合，以零維反應動力計算分析相關參數對於點火時點之影響。於引擎轉速2000 rpm，需使用進氣預熱使燃氣於均質充壓點火操作模式發生自燃點火。且所需進氣預熱溫度隨壓縮比、當量比增加而減少，隨壁面熱損值以及廢氣導回比增加而增加。點火時點隨當量比、壓縮比、進氣溫度增加而提前，隨壁面平均熱損量以及廢氣導回比增加而延後，且壁面熱損對於極貧油之燃氣影響較為顯著。但進氣溫度提高也造成NO排放大幅增加及壓力增加率的上升。過高之壓力增加率意味於實際應用上爆震發生之機率提高。為有效減少排氣中氮氧化物，並考量引擎效能，適宜之氫燃料HCCI引擎操作當量比約於0.3至0.5。我們並進一步運用三維暫態計算流體力學模擬結合詳細化學反應模型之反應動力計算，進行燃燒模擬，以了解其燃燒特性。透過比較三種不同壁面熱傳條件(絕熱、等溫、暫態熱傳)所得之模擬結果發現，HCCI易受缸內三維流場及溫度分佈影響，造成局部高溫和自由基累積而提前點火。暫態熱傳模型所預測之缸內最高溫較等溫壁面條件為高，缸壓較大，點火時點較為提前。模擬結果也發現於HCCI模式操作時缸內極易產生爆震。並於不同進氣預熱溫度之模擬結果發現，於高壓縮比(17.8)之引擎幾何，可於進氣溫度300 K條件下，成功進行氫燃料均質充壓點火操作模式。而缸內直噴HCCI操作模式，可搭配降低進氣預熱溫度與使用廢氣導回，以成功進行缸內直噴氫燃料均質充壓點火操作模式。

The operation of a hydrogen-fuelled HCCI engine is studied using zero-dimensional chemical kinetic and three-dimensional transient computation fluid dynamic simulations with detailed chemistry. The 0-D kinetic analysis shows that the temperature of the intake air has to be preheated to achieve successful ignition for the perfectly mixed charge of an ideal HCCI engine. The required preheat temperature decreases as the compression ratio and equivalence ratio increase and increase as the heat loss rate and EGR rate increase. The start of combustion advances as the compression ratio, equivalence ratio and intake temperature increase and retard as the heat loss rate and and EGR rate increase. But the high intake temperature will enhance the NO emission increase. The optimal operating equivalence ratio appears to be 0.3-0.5. Since the homogeneous charge assumption for the 0-D simulation is not necessarily valid, we further carry out three-dimensional CFD simulations with a 11 species and 22 steps reaction mechanism to investigate the ignition and combustion characteristics. The results show that the spontaneous ignition does occur as autoignition temperature is achieved, and the ignition process is followed by a volumetric heat release in less than 1 °CA.The ignition spots are at regions where the equivalence ratio are close to stoichiometric and close to the center of the cylinder such that wall quenching effects are minimized. 0-D simulation using the same inlet condition as the 3-D calculation shows that HCCI operation is not possible; the result suggests that the temperature and concentration inhomogeneity of the in-cylinder charge create local regions suitable for ignition. The high compression ratio engine geometry for the intake temperature equals to 300 K will achieve successful ignition for of an HCCI engine operation. In order to achieve successful ignition for GDI HCCI engine operation, it can combine the methods of reducing the intake temperature and using the EGR.

[1] J. M. G. Antunes, R. Mikalsen and A. P. Roskilly (2008), An investigation of hydrogen-fuelled HCCI engine performance and operation, International Journal of Hydrogen Energy 33(20), 5823-5828.
[2] G. A. Karim (2003), Hydrogen as a spark ignition engine fuel, International Journal of Hydrogen Energy 28(5), 569-577.
[3] C. Liu and G. A. Karim (2008), A simulation of the combustion of hydrogen in HCCI engines using a 3D model with detailed chemical kinetics, International Journal of Hydrogen Energy 33(14), 3863-3875.
[4] C. M. White, R. R. Steeper and A. E. Lutz (2006), The hydrogen-fueled internal combustion engine: a technical review, International Journal of Hydrogen Energy 31(10), 1292-1305.
[5] J. M. G. Antunes and A. P. Roskilly (2004), The use of H2 on compression ignition engines, Third European Congress on Economics and Management of Energy inIindustry, 6-9 April.
[6] 蔡健勳、吳明勳 氫燃料缸內直噴引擎HCCI操作模式參數分析與數值模擬, 中國機械工程學會第二十六屆全國學術研討會,台灣台南,11月20-21日,2009.
[7] Riso Energy Report 3, Riso National Laboratory, RIS-R-1469S37-41, 2004.
[8] J. Chang, Z. S. Filipi, T.W. Kuo, D. N. Assanis, P. M. Najt and R. B. Rask (2008), Investigation of Mixture Preparation Effects on Gasoline HCCI Combustion Aided by Measurements of Wall Heat Flux, Journal of Engineering for Gas Turbines and Power 130(6), 062806-062809.
[9] S. B. Fiveland and D. N. Assanis (2000), A four-stroke Homogeneous Charge Compression Ignition engine simulation for combustion and performance studies, SAE Paper 2000-01-0332.
[10] H. F. Liu, M. F. Yao, B. Zhang and Z. Q. Zheng (2008), Effects of inlet pressure and octane numbers on combustion and emissions of a homogeneous charge compression ignition (HCCI) engine, Energy & Fuels 22(4), 2207-2215.
[11] M. Canakci (2008), An experimental study for the effects of boost pressure on the performance and exhaust emissions of a DI-HCCI gasoline engine, Fuel 87(8-9), 1503-1514.
[12] H. Machrafi and S. Cavadiasa (2008), An experimental and numerical analysis of the influence of the inlet temperature, equivalence ratio and compression ratio on the HCCI auto-ignition process of Primary Reference Fuels in an engine, Fuel Process Technol 89(11), 1218-1226.
[13] K. H. Lee, V. Gopalakrishnan and J. Abraham (2004), An investigation of the effect of changes in engine operating conditions on ignition in an HCCI engine, Ksme Int J 18(10), 1809-1818.
[14] X. C. Lu, W. Chen and Z. Huang (2005), A fundamental study on the control of the HCCI combustion and emissions by fuel design concept combined with controllable EGR. Part 2. Effect of operating conditions and EGR on HCCI combustion, Fuel 84(9), 1084-1092.
[15] N. P. Komninos, D. T. Hountalas and C. D. Rakopoulos (2007), A parametric investigation of hydrogen hcci combustion using a multi-zone model approach, Energ Convers Manage 48(11), 2934-2941.
[16] S. W. Park and R. D. Reitz (2007), Numerical study on the low emission window of homogeneous charge compression ignition diesel combustion, Combustion Science and Technology 179(11), 2279-2307.
[17] T.Lakshmanan and G.Nagarajan (2009), Performance and Emission of Acetylene-Aspirated Diesel Engine, Jordan Journal of Mechanical and Industrial Engineering 3(2), 125 - 130.
[18] http://wps.com/LPG/WVU-review.html.
[19] J. M. Kuchta (1975), Summary of ignition property of jet fuels and other aircraft combustion fluids,
http://contrails.iit.edu/DigitalCollection/1975/AFAPLTR75-070.pdf. .
[20] A. J. Smallbone, W. Liu, C. K. Law, X. Q. You and H. Wang (2009), Experimental and modeling study of laminar flame speed and non-premixed counterflow ignition of n-heptane, Proceedings of the Combustion Institute 32, 1245-1252.
[21] http://www.weldreality.com/gasdata.htm.
[22] http://www.engineeringtoolbox.com/adiabatic-flame-temperature-d_996.html.
[23] http://en.wikipedia.org/wiki/Heat_of_combustion.
[24] http://en.wikipedia.org/wiki/Lower_heating_value.
[25] J. N. Kim, H. Y. Kim, S. S. Yoon, S. D. Sa and W. T. Kim (2007), Effect of valve timing and lift on flow and mixing characteristics of a CAI engine, Int J Automot Techn 8(6), 687-696.
[26] J. Kashdan and G. Bruneaux (2006), Mixture preparation and combustion in an optically-accessible HCCI, diesel engine, Oil Gas Sci Technol 61(1), 25-42.
[27] L. Cao, A. Bhave, H. Su, S. Mosbach, M. Kraft, A. Dris and R. M. McDavid (2009), Influence if injection timing and piston bowl geometry on PCCI combustion and emissions, ,SAE Paper 2009-01-1102.
[28] Z. Wang, S. J. Shuai, J. X. Wang and G. H. Tian (2006), A computational study of direct injection gasoline HCCI engine with secondary injection, Fuel 85(12-13), 1831-1841.
[29] CD-adapco, STAR-CD Version 4.08 Methodology, 2007.
[30] CD-adapco, es-ice Version 2.02 User Guide, 2007.
[31] E. Tahry and H. Sherif (1983), k-epsilon equation for compressible reciprocating engine flows, AIAA Journal of Energy 7, 345-353.
[32] V. Yakhot and S. A. Orszag (1986), Renormalization group analysis of turbulence–I：Basic theory, , J. Scientific Computing 1, 1-51.
[33] W. Rodi (1979), Influence of buoyancy and rotation on equations for the turbulent length scale, Proc. 2nd Symp. on Turbulent Shear Flows.
[34]王敬文、曾文業、吳明勳、李訓谷、林大惠、陳榮洪 汽油缸內直噴引擎之燃燒室流場動態三維數值模擬，中華民國第十四屆車輛工程學術研討會，台灣雲林，10月30日,2009.
[35] 王敬文, 汽油缸內直噴引擎之燃燒室流場數值模擬與分析，國立成功大學機械工程學系碩士論文，2009.
[36] R. I. Issa (1986), Solution of the Implicitly Discretized Fluid-Flow Equations by Operator-Splitting, Journal of Computational Physics 62(1), 40-65.
[37] M. A. Leschziner (1980), Practical evaluation of three finite difference schemes for the computation of steady-state recirculating flows, Computer Methods in Applied Mechanics and Engineering 23, 293-312.
[38] K. Y. M. Lai (1983), Numerical analysis of fluid transport phenomena, PhD Thesis, University of London.
[39] J. Li, Z. Zhao, A. Kazakov and F. L. Dryer (2004), An updated comprehensive kinetic model of hydrogen combustion, International Journal of Chemical Kinetics 36(10), 566-575.
[40] R. K. Hanson and S. Salimian (1984), Survey of rate constant in the N/H/O system, Combustion and Chemistry 6, 361-421.
[41] A. A. Konnov (2004), Refinement of the Kinetic Mechanism of Hydrogen Combustion, Khimicheskaya Fizika 23(8), 5-18.
[42] T. Morel and R. Keribar (1985), A model for predicting spatially and time resolved convective heat transfer in bowl-in-piston combustion chambers, SAE paper 850204.
[43] E. J. Lyford-Pike and J. B. Heywood (1984), Thermal boundary layer thickness in the cylinder of a spark-ignition engine, International Journal of Heat and Mass Transfer 27(10), 1873-1878.
[44] W. Sutherland (1985), The viscosity of gases and molecular force, Philosophical Magazine Series 5 36(223), 507-531.
[45] P. O. A. L. Davies and M. J. Fisher (1964), Heat Transfer From Electrically Heated Cylinders, Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences 280(1383), 486-527.
[46] R. H. D. Winterton (1998), Where did the Dittus and Boelter equation come from ?, International Journal of Heat and Mass Transfer 41, p. 809.
[47] E. Giacomazzi, B. Favini, C. Bruno, F. R. Picchia and N. Arcidiac (2003), LES of H2/CH4/Air turbulent non-premixed, In European Combustion Meeting, 25-28 October,Orleans, France.
[48] 蔡健勳、吳明勳 氫燃料均質充量壓燃引擎點火特性之三維暫態反應流模擬與分析,中華民國第二十屆燃燒與能源學術研討會,台灣台南,3月20日,2010.