• Title/Summary/Keyword: Heat Release Ratio

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Analysis of Heat Quantity in CNG Direct Injection Bomb(1) : Homogeneous Charge (CNG 직접분사식 연소기에서의 열량해석(1) :균질급기)

  • 최승환;전충환;장영준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.17-23
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    • 2004
  • A cylindrical constant volume combustion bomb is used to investigate the combustion characteristics and to analyze the heat quantity of homogeneous charge methane-air mixture under various initial pressures, excess air ratios and ignition times. As the overall pressure increase, the values of maximum combustion pressure, maximum heat release rate and cumulative heat release have been increased. But it is not very meaningful to compare with some values such as maximum combustion pressure, maximum heat release rate and cumulative heat release for different overall pressure due to the different heat energy of supplied fuel. So the each value is needed to be compared with normalized value, which is divided by the entered fuel energy. To analyze the heat quantity, some definitions including the CHR ratio, the UHC ratio and the HL ratio are needed and are calculated. As the overall pressure increase, the CHR ratios and the UHC ratios have been decreased, while the HL ratios have been increased. The CHR ratio of 300 ms has the higher value than that of 10000ms, and the HL ratios of 300 ms have a lower value.

Advanced One-zone Heat Release Analysis for IDI Diesel Engine (IDI 디젤기관의 개선된 단일영역 열발생량 계산)

  • Kim Gyu-Bo;Jeon Choung-Hwan;Chang Young-Jun;Lee Suk-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.7
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    • pp.1101-1110
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    • 2004
  • An one-zone heat release analysis was applied to a 4 cylinder indirect injection diesel engine. The objective of the study is to calculate heat release accurately considering the effect of specific heat ratio. heat transfer and crevice model and to find out combustion characteristics of an indirect diesel engine considering the effect of the pressures in main and swirl chambers. Especially specific heat ratio indicating combustion characteristics is adapted. instead of that indicating matter properties, which has been used in former studies Moreover by adaption of blowby model, cylinder gas mass became accurately calculated. Therefore, with ideal gas equation, calculating cylinder gas temperature, it was found to affect heat transfer loss and heat release. Determining heat transfer constants $C_1$. $C_2$ as 0.6 respectively. the integrated gross heat release values were predicted well for the measured value at various engine speed, full load operating conditions. The curve of heat release rate was similar to SI engine rather than DI engine. That is originated from that swirl chamber reduce an instant combustion which occurs in DI engine due to ignition delay on early stage of combustion.

ICE GROSS HEAT RELEASE STRONGLY INFLUENCED BY SPECIFIC HEAT RATIO VALVES

  • Lanzafame, R.;Messina, M.
    • International Journal of Automotive Technology
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    • v.4 no.3
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    • pp.125-133
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    • 2003
  • Several models for the evaluation of Gross Heat Release from the internel combustion engine (ICE) are often used in literature. One of these is the First Law - Single Zone Model (FL-SZM), derived from the First Law of Thermodynamic. This model present a twice advantage: first it describes with accuracy the physic of the phenomenon (charge heat release during the combustion stroke and heat exchange between gas and cylinder wall); second it hat a great simplicity in the mathematical formulation. The evaluation of Heat Release with the FL-SZM is based on pressure experimental measurements inside the cylinder, and ell the assumption of several parameters as the specific heat ratio, wall temperature, polytropic exponent for the motored cycle evaluation, and many others. In this paper the influence of gases thermodynamic properties on Cross Heat Release has been esteemed. In particular the influence of an appropriate equation for k=k(T) (specific heat ratio vs. temperature) which describes the variations of gases thermodynamic properties with the mean temperature inside the cylinder has been evaluated. This equation has been calculated by new V order Logarithmic Polynomials (VoLP), fitting experimental gases properties through the least square methods.

A Study on the Calculation of Heat Release Rate to Compensate the Error due to Single Zone Assumption in Diesel Engines (단일 영역 모델 열발생율 계산 방법의 개선에 관한 연구)

  • Kim Ki-Doo;Yoon Wook-Hyeon;Ha Ji-Soo;Ryu Seung-Hyup
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.7
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    • pp.1063-1071
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    • 2004
  • Accurate heat release analysis of cylinder pressure data is important for evaluating performance in the development of diesel engine However, traditional single zone first law heat release model(SZM) has significant limitations due to the simplified assumption of uniform charge and neglecting local temperature inside cylinder during combustion process. In this study. heat release rate based on single zone heat release model has been evaluated by comparison with computational analysis results using Fire code which is based on multi-dimensional model(MDM). To overcome limitations due to simplicity of single zone assumption. especially the influence of specific heat ratio on gross heat release has been esteemed and newly suggested were the equation $\gamma$= $\gamma$(${T/T}_{max}$) which describes the variations of gases thermodynamic properties with mean temperature and maximum mean temperature inside cylinder Single zone heat release model applied with this equation is shown to give very good results over whole range of operating conditions when compared with computational analysis results based on multi-dimensional model.

One-zone heat release analysis for IDI diesel engine (IDI 디젤기관의 단일영역 열발생량 계산)

  • Lee, S.Y.;Kim, G.B.;Choi, S.H.;Jeon, C.H.;Chang, Y.J.;Chun, K.M.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.830-836
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    • 2001
  • An one-zone heat release analysis was studied for a 4 cylinder indirect diesel engine. The object of the study is to calculate the heat release accurately including the effect of specific heat ratio, heat transfer and crevice volume and to find out combustion characteristics of an indirect diesel engine cosidering the effect of both pressure in the main and swirl chambers. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions.

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Effects of Emulsified Fuel on Combustion Characteristics in a Diesel Engine (디젤기관에 있어서 에멀젼연료 연소특성에 미치는 영향)

  • Lim, J.K.;Cho, S.G.;Hwang, S.J.;Yoo, D.H.
    • Journal of Power System Engineering
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    • v.11 no.1
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    • pp.51-55
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    • 2007
  • A study on combustion characteristics using emulsified fuel in a diesel engine were performed experimentally. In this paper, the experiments were performed at engine speed 1800rpm, emulsion ratios were 0%, 10%, 20%, and main measured items were specific fuel consumption, cylinder pressure, rate of pressure rise, rate of heat release etc. The obtained conclusions were as follows. 1) Specific fuel consumption increased maximum by 19.8% at low load, but was not affected at full load. 2) Rate of pressure rise and rate of heat release were about the same in the case of 10% and 20% of emulsion ratio. 3) Cylinder Pressure increased 9.6%, rate of pressure rise increased 53.4% in case of emulsion ratio 20% at full load. 4) Rate of heat release increased 72.4% in case of emulsion ratio 20% at full load.

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Effects on the Characteristics of Combustion by using Emulsion Fuel in Diesel Engine (디젤기관에 있어서 에멀젼 연료가 연소특성에 미치는 영향)

  • Lim, J.K.;Cho, S.G.;Hwang, S.J.;Yoo, D.H.;Seo, J.W.
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2006.06a
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    • pp.41-42
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    • 2006
  • A study on the combustion characteristics by using Emulsion Fuel in Diesel Engine is performed experimentally. In this paper, the experiments are performed at engine speed 1800rpm, emulsion fuel ratio is 0%, 10%, 20%, and main measured items are specific fuel consumption, pressure, ratio of pressure rise, rate of heat release etc. The obtained conclusions are as follows. 1) Specific fuel consumption increase maximum 19.8% at low load, but is not effected at full load. 2) Ratio of pressure rise and rate of heat release are about the same in the case of 10% and 20% of emulsion fuel ratio. 3) Cylinder Pressure increase 11.7%, ratio of pressure rise increase 60.4% in case of emulsion fuel ratio 20% at full load. 4) Rate of heat release increase 76.9% in case of emulsion fuel ratio 20% at full load.

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Analysis of Heat Quantity in CNG Direct Injection Bomb(2) : Inhomogeneous Charge (CNG 직접분사식 연소기에서의 열량해석(2) : 비균질급기)

  • 최승환;전충환;장영준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.24-31
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    • 2004
  • A cylindrical constant volume combustion bomb is used to investigate the combustion characteristics and to analyzer the heat quantity of inhomogeneous charge methane-air mixture. To analyze the heat quantity, some definitions including the CHR ratio, the UHC ratio and the HL ratio are needed and are calculated. It is shown that the effect of stratification is not significant in case of the overall excess air ratio of 1.1, mainly due to the higher heat loss and lower thermal efficiency compared to those of homogeneous condition. In the case of the overall excess air ratio of 1.4, as the initial charge pressure decreases, the CHR ratio has been decreased while the HL ratio has been increased, Generally, as the initial charge pressure increases, the amount of injection mixture has been decreased and has resulted in lower mean velocity and turbulence intensity for injection mixture. Also, the injected mixture is too rich to result in mixing deficiency in combustion chamber. From these results, it could be possible to acquire the improvement of thermal efficiency and the reduction of heat loss simultaneously through the 2-stage injection in CNG direct injection engine.

Prediction of Spatial Heat Release Rate of Combustion Chamber by Radicals-PLIF (라디칼 PLIF계측을 이용한 연소실의 공간적 열발생율 예측)

  • Choi, G.M.
    • Journal of ILASS-Korea
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    • v.8 no.4
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    • pp.9-16
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    • 2003
  • The Purpose of this study is to investigate the relationships between the local heat release rate and CH concentration have been investigated by numerical simulations of methane-air premixed flames. And simultaneous CH and OH PLIF(Planar Laser Induced Fluorescence) measurement has been also conducted for lean premixed flame as well as for laminar flames. Numerical simulations are conducted for laminar premixed flames and turbulent ones by using PREMIX in CHEMKIN and two dimensional DNS code with GRI mechanism version 2.11, respectively. In the case of laminar premixed flame, the distance between the peak of heat release rate and that of CH concentration is under $91{\mu}m$ for all equivalence ratio calculated in present work. Even for the premixed flame in high intensity turbulence, the distribution of the heat release rate coincides with that of CH mole fraction. For CH PLIF measurements in the laminar premixed flame burner, CH fluorescence intensity as a function of equivalence ratio shows a similar trend with CH mole fraction computed by GRI mechanism. Simultaneous CH and OH PLIF measurement gave us useful information of instantaneous reaction zone. In addition, CH fluorescence can be measured even for lean conditions where CH mole fraction significantly decreases compared with that of stoichiometric condition. It was found that CH PLIF measurements can be applicable to the estimation of the spatial fluctuations of heat release rate in the engine combustion.

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Experimental Study on Heat Release in a Lean Premixed Dump Combustor using OH Chemiluminescence Images (희박 예혼합 덤프 연소기에서 OH 자발광을 이용한 열 방출에 관한 실험적 연구)

  • Moon, Gun-Feel;Lee, Jong-Ho;Jeon, Chung-Hwan;Chang, Young-June
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1146-1151
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    • 2004
  • Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel de-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented for typical locations.

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