Ignition Delay in Dual Fuel Engines: An Extended Correlation for Gaseous Fuels

Author(s):  
A. Bilcan ◽  
M. Tazerout ◽  
O. Le Corre ◽  
A. Ramesh

Abstract Agricultural & municipal waste and wood residues can be easily converted to biogas or producer gas and used for producing heat and power. The main problem with these fuels is their low energy content. This is due to the presence of certain non-combustible gases like CO2 and N2 in these fuels. The use of these gases in SI engines is associated with problems like unstable operation and high levels of HC and CO emissions. Gaseous fuel can be easily used with good efficiencies and low emissions in diesel engines running in the dual-fuel mode. In dual-fuel engines, these gaseous fuels are inducted along with air and ignited after compression by a small spray of diesel called the pilot. The presence of these gases alters the thermodynamic properties of the intake charge and significantly influence the ignition delay of the pilot diesel fuel and hence the performance of the engine. The aim of this paper is to modify an existing correlation for ignition delay in a dual-fuel engine to incorporate the effects of the gaseous fuel concentration and composition on the polytropic index. An ignition delay correlation of a biogas dual-fuel engine was modified so that it can be used with any primary fuel. The polytropic index was assumed to be a function of the ratio of specific heats. Further, the effect of injection timing on ignition delay was included. The adapted model was introduced in a simulation program and the results of ignition delay were compared with those given in the literature for a dual-fuel engine. In addition, the correlation was used to predict the ignition delay of the pilot fuel when biogas, LPG, natural gas and producer gas were treated as primary fuels. The results obtained with the new correlation have been compared with experimental values from a LPG-diesel dual fuel engine. The comparison was also made for a biogas dual fuel engine. Errors less than 10% were obtained for both of the fuels between the experimental measurements and simulation results.

Author(s):  
Ahmed Al-Sened ◽  
Hesameddin Safari ◽  
Mojtaba Keshavarz ◽  
Ghasem Javadirad

Knock is well recognized as a destructive phenomenon to be avoided when running dual fuel engines. Typically, it occurs at high loads and high ambient temperatures and its onset has always been difficult to predict, particularly where multiple fuels are present. In a dual fuel engine, knock can occur from either the diesel or the gaseous fuel and it is recognised that the ratio of diesel fuel mass to gaseous fuel mass is an important index in determining which type of knock is predominant. This paper describes the development of a two-zone predictive model for the onset of knock in a dual fuel engine. Prediction of spark knock onset is the main objective of present work. A 9-step short mechanism with 11 chemical species, developed specifically for modelling dual fuel operation, is used to determine the chemical reactivity of the end-gas zone. The contribution of pilot diesel fuel combustion is taken into account by a heat release model. Chemical equilibrium is assumed for the burned gas zone. Simulation results predict the point of knock-limited BMEP and its dependency on operating parameters such as air intake temperature, boost pressure, start of pilot fuel injection timing and compression ratio. The results were first validated against some published engine analysis data and also some in-house performance prediction data. Secondly, a known dual-fuel development engine was simulated. Finally, the performance of an engine which had been converted from diesel to dual fuel during its service life was modeled but commercial constraints prevent the identification of this engine within this paper. However, good agreement with existing performance data was demonstrated in all these cases.


Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5663 ◽  
Author(s):  
Mahantesh Marikatti ◽  
N. R. Banapurmath ◽  
V. S. Yaliwal ◽  
Y.H. Basavarajappa ◽  
Manzoore Elahi M Soudagar ◽  
...  

The present work is mapped to scrutinize the consequence of biodiesel and gaseous fuel properties, and their impact on compression-ignition (CI) engine combustion and emission characteristics in single and dual fuel operation. Biodiesel prepared from non-edible oil source derived from Thevetia peruviana belonging to the plant family of Apocynaceaeis. The fuel has been referred as methyl ester of Thevetia peruviana (METP) and adopted as pilot fuel for the effective combustion of compressed gaseous fuel of hydrogen. This investigation is an effort to augment the engine performance of a biodiesel-gaseous fueled diesel engine operated under varied engine parameters. Subsequently, consequences of gas flow rate, injection timing, gas entry type, and manifold gas injection on the modified dual-fuel engine using conventional mechanical fuel injections (CMFIS) for optimum engine performance were investigated. Fuel consumption, CO, UHC, and smoke formations are spotted to be less besides higher NOx emissions compared to CMFIS operation. The fuel burning features such as ignition delay, burning interval, and variation of pressure and heat release rates with crank angle are scrutinized and compared with base fuel. Sustained research in this direction can convey practical engine technology, concerning fuel combinations in the dual fuel mode, paving the way to alternatives which counter the continued fossil fuel utilization that has detrimental impacts on the climate.


Author(s):  
Greg Beshouri ◽  
Gerry Fischer

Abstract In the late 1980’s Enterprise Engine Company performed a single cylinder test of micro-pilot high pressure direct injection as a retrofit technology for conventional dual fuel engines. While that testing demonstrated a number of benefits for this technology, non-technical considerations led to the use of low pressure Pre-Combustion Chamber (PCC) micro-pilot technology as the retrofit technology instead. Thirty years later, when the automotive components of the PCC micro-pilot system were no longer available, the opportunity again arose to test the capabilities of an off the shelf high pressure direct injection micro-pilot system as a retrofit technology for a conventional dual fuel engine. Single cylinder and full engine testing of the high pressure direct injection micro-pilot injection confirmed the results of the 1980’s testing. The test results also corroborated modern analytical and experimental testing of high pressure pilot technology. In particular, the interaction between the diesel pilot and primary fuel gas charge is very complex and sometimes counterintuitive. Likewise performance optimization requires careful balance of injection timing, injection quantity and fuel gas air/fuel ratio. Even then, exhaust gas methane emissions remain counterintuitive. This paper reviews modern single cylinder and full engine test results focusing on optimization parameters for high pressure direct injection micro-pilot for retrofit and new engine applications.


1999 ◽  
Author(s):  
G. H. Abd Alla ◽  
H. A. Soliman ◽  
O. A. Badr ◽  
M. F. Abd Rabbo

Abstract A quasi-two zone predictive model developed in the present work for the prediction of the combustion processes in dual fuel engines and some of their performance features. Methane is used as the main fuel while employing a small quantity of liquid fuel (pilot) injected through the conventional diesel fuel system. This model emphasizes the effects of chemical kinetics activity of the premixed gaseous fuel on the combustion performance, while the role of the pilot fuel in the ignition and heat release processes is considered. A detailed chemical kinetic scheme consists of 178 elementary reaction steps and 41 chemical species is employed to describe the oxidation of the gaseous fuel from the start of compression to the end of expansion process. The associated formation and concentrations of exhaust emissions are correspondingly established. This combustion model is able to establish the development of the combustion process with time and the associated important operating parameters such as pressure, temperature, rates of energy release and composition. Predicted values for methane operation show good agreement with corresponding previous experimental values over a range of operating conditions mainly associated with high load operation.


2012 ◽  
Vol 5 (4) ◽  
pp. 350-356 ◽  
Author(s):  
N. R. Banapurmath ◽  
V. S. Yaliwal ◽  
R. S. Hosmath ◽  
P. G. Tewari

2003 ◽  
Vol 125 (3) ◽  
pp. 827-836 ◽  
Author(s):  
G. A. Karim

In the dual fuel engine much of the energy release comes from the combustion of the gaseous fuel while only a small amount of diesel liquid fuel provides ignition through timed cylinder injection. Such operation with optimum conversion methods has the potential to provide operational characteristics that are comparable or superior to those of the corresponding diesel or spark ignition engines. These characteristics may be realized only if sufficiently effective measures can be ensured both for the avoidance of knock, usually at high loads, and incomplete gaseous fuel utilization at relatively light loads. An objective of this contribution is to demonstrate that the main effort needed to overcome the problems associated with the operation of gas fueled dual fuel engines is via a better control of the relatively complex processes of combustion. Both experimental and analytical modeling procedures for effecting optimum improvement to the combustion process are described.


1966 ◽  
Vol 181 (1) ◽  
pp. 453-466 ◽  
Author(s):  
G. A. Karim ◽  
S. R. Klat ◽  
N. P. W. Moore

The paper describes some aspects of the findings of an investigation which was initiated mainly to obtain a better understanding of the phenomenon of knock under dual-fuel operation and to determine the effect of various operating parameters on the knock-free performance limits and the nature of these limits. Some common gaseous fuels such as methane, propane, ethylene, acetylene, hydrogen and some of their mixtures were used as the main fuels. A method is suggested to relate changes in the knock-limited power output of a dual-fuel engine with the intake temperature of the charge and the nature of the main fuel used.


2011 ◽  
Vol 2 (4) ◽  
pp. 403-413 ◽  
Author(s):  
N. R. Banapurmath ◽  
V. S. Yaliwal ◽  
Satish Kambalimath ◽  
A. M. Hunashyal ◽  
P. G. Tewari

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