scholarly journals Thermodynamic Properties of Real Porous Combustion Reactor under Diesel Engine-Like Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
M. Weclas ◽  
J. Cypris ◽  
T. M. A. Maksoud
Keyword(s):  
Heat Capacity ◽  
Diesel Engine ◽  
Heat Release ◽  
Combustion Chamber ◽  
Free Volume ◽  
Initial Pressure ◽  
Mixture Formation ◽  
Release Process ◽  
Formation Conditions ◽  
Combustion Reactor

Thermodynamic conditions of the heat release process under Diesel engine-like conditions in a real porous combustion reactor simulated in a special combustion chamber were analyzed. The same analyses were performed for a free volume combustion chamber, that is, no porous reactor is applied. A common rail Diesel injection system was used for simulation of real engine fuel injection process and mixture formation conditions. The results show that thermodynamic of the heat release process depends on reactor heat capacity, pore density, specific surface area, and pore structure, that is, on heat accumulation in solid phase of porous reactor. In real reactor, the gas temperature and porous reactor temperature are not equal influenced by initial pressure and temperature and by reactor parameters. It was found that the temperature of gas trapped in porous reactor volume during the heat release process is less dependent on air-to-fuel-ratio than that observed for free volume combustion chamber, while the maximum combustion temperature in porous reactor is significantly low. As found this temperature depends on reactor heat capacity, mixture formation conditions and on initial pressure. Qualitative behavior of heat release process in porous reactors and in free volume combustion chamber is similar, also the time scale of the process.

scholarly journals Characteristics of Flameless Combustion in 3D Highly Porous Reactors under Diesel Injection Conditions

2013 ◽  
Vol 2013 ◽  
pp. 1-22 ◽  
Author(s):  
M. Weclas ◽  
J. Cypris
Keyword(s):  
Heat Capacity ◽  
Specific Surface ◽  
Pore Structure ◽  
Heat Release ◽  
Surface Area ◽  
Free Volume ◽  
Initial Pressure ◽  
Pore Density ◽  
Release Process ◽  
Characteristic Modes

The heat release process in a free volume combustion chamber and in porous reactors has been analyzed under Diesel engine-like conditions. The process has been investigated in a wide range of initial pressures and temperatures simulating engine conditions at the moment when fuel injection starts. The resulting pressure history in both porous reactors and in free volumes significantly depends on the initial pressure and temperature. At lower initial temperatures, the process in porous reactors is accelerated. Combustion in a porous reactor is characterized by heat accumulation in the solid phase of the porous structure and results in reduced pressure peaks and lowered combustion temperature. This depends on reactor heat capacity, pore density, specific surface area, pore structure, and heat transport properties. Characteristic modes of a heat release process in a two-dimensional field of initial pressure and temperature have been selected. There are three characteristic regions represented by a single- and multistep oxidation process (with two or three slopes in the reaction curve) and characteristic delay time distribution has been selected in five characteristic ranges. There is a clear qualitative similarity of characteristic modes of the heat release process in a free volume and in porous reactors. A quantitative influence of porous reactor features (heat capacity, pore density, pore structure, specific surface area, and fuel distribution in the reactor volume) has been clearly indicated.

Experimental and Theoretical Optimization of Combustion Chamber and Fuel Distribution for the Low Emission DI Diesel Engine

2001 ◽  
Author(s):  
Yoshiyuki Kidoguchi ◽  
Michiko Sanda ◽  
Kei Miwa
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Combustion Chamber ◽  
Heat Release Rate ◽  
Release Rate ◽  
Combustion Process ◽  
Mixture Distribution ◽  
Initial Mixture ◽  
Injection Timing ◽  
Initial Heat

Abstract This study investigated the effect of combustion chamber geometry and initial mixture distribution on combustion process in a direct-injection diesel engine by means of experiment and CFD calculation. The high squish combustion chamber with squish lip could produce simultaneous reduction of NOx and particulate emissions with retarded injection timing in the real engine experiment. According to the CFD computation, the high squish combustion chamber with central pip is effective to continue combustion under the squish lip until the end of combustion and the combustion region forms rich and high turbulence atmosphere, which reduces NOx emissions. This chamber can also reduce initial burning because combustion continues under the squish lip. The CFD computation is also carried out in order to investigate the effect of initial mixture distribution on combustion process. The results suggest that mixture distribution affects the history of heat release rate. When fuel is distributed in the bottom or wide region in the combustion chamber, burned gas tends to spread to the cavity center and initial heat release rate becomes high. On the contrary, the high squish combustion chamber with central pip produces lower initial heat release rate because combustion with local rich condition continues long under the squish lip. Diffusion burning is promoted by high swirl motion in this chamber with keeping lower initial heat release rate.

A Study on the Accurate Calculation Method of Heat-Release Rate in Swirl Chamber Indirect Injection Diesel Engine

1989 ◽  
Vol 203 (4) ◽  
pp. 267-275 ◽  
Author(s):  
J P Liu ◽  
X K Ge ◽  
L X Peng
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Flow Coefficient ◽  
Practical Calculation ◽  
Release Process ◽  
Flow Equations ◽  
Swirl Chamber ◽  
Energy Exchanges

Taking the two chambers of swirl chamber indirect injection diesel engine (SC engine) as two relative but independent thermodynamic systems, this paper builds up thermodynamic equations respectively in the two chambers, together with the mass and enthalpy flow equations describing the mass and energy exchanges between them. This model, based on the synchronous pressure diagrams measured in the two chambers, is used to calculate the thermodynamic state of medium and heat-release process in both of the chambers. Furthermore, with the help of the thermodynamic equivalent system, the calculation of the variable flow coefficient of the connecting passage has been successfully achieved. A Model 6105Q SC engine is taken as a practical calculation example to reveal the combustion pattern of this type of engine. In the last part of this paper, several methods currently used for the heat-release rate calculation have been analysed to show their application field and accuracy.

scholarly journals Investigations on Internal Ballistic Characteristics of Pasty Propellant Rocket Engine

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xinyou Shan ◽  
Yingkun Li ◽  
Xiong Chen ◽  
Yan Wu ◽  
Yong He ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Free Volume ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Rocket Engine ◽  
Initial Pressure ◽  
Internal Ballistic ◽  
Pressure Peak ◽  
Propellant Rocket

Pasty rocket engines have broad application prospects in the aerospace field. To study the internal ballistic characteristics of the pasty propellant rocket engine, the burning surface change model of pasty propellant was built. The calculation program was developed to calculate the pressure evolution in the combustion chamber, and the experiment was carried out based on a pasty propellant rocket test system. The data calculated by the program are in good agreement with the experiment, the error of the initial pressure peak is only 4.02%, and the internal ballistic characteristics of the rocket engine at each stage were analyzed detailly. The effects of ignition delay time, transport pipeline structure, free volume of the combustion chamber, mass flow rate, and flow velocity of the pasty propellant on internal ballistic characteristics of the pasty propellant rocket engine are investigated. The results indicate that when the ignition delay time increases, the pressure rises faster and the initial pressure peak increases obviously. The transport pipe diameter changes from 11.3 mm to 7.4 mm, and the initial combustion time and residual propellant combustion time decreased by 41.3% and 36.0%. The reduction of the free volume of the combustion chamber can reduce the initial pressure peak and the time to reach the equilibrium pressure. The initial pressure spike and equilibrium pressure rise with the increase of the pasty propellant flow velocity. While the ignition transient decreased with the increase of the pasty propellant flow velocity. The internal ballistic properties can be improved by reducing the ignition delay time, the diameter of the transport pipeline, and the free volume of the combustion chamber, or by increasing the mass flow rate of the pasty propellant rocket engine.

scholarly journals Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Fuqiang Bai ◽  
Zuowei Zhang ◽  
Yongchen Du ◽  
Fan Zhang ◽  
Zhijun Peng
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Combustion Process ◽  
Injection Rate ◽  
Injection System ◽  
Nox Emissions ◽  
Release Process ◽  
Common Rail Injection System ◽  
Soot Emissions ◽  
Rate Profile

When multi-injection is implemented in diesel engine via high pressure common rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are the same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid, and wedge) of injection rate profiles were investigated. Modeling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline, rectangle (flat), shape of injection rate can have better balance between NOx and soot emissions than the other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces the highest soot emissions among the five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions were produced by triangle shape due to higher peak injection rate.

Heat release process in three-dimensional macro-cellular SiC reactor under Diesel engine-like conditions

Fuel ◽  
2012 ◽  
Vol 102 ◽  
pp. 115-128 ◽  
Author(s):  
J. Cypris ◽  
L. Schlier ◽  
N. Travitzky ◽  
P. Greil ◽  
M. Weclas
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Three Dimensional ◽  
Release Process ◽  
Macro Cellular
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