What is ignition delay in diesel engine?

Abstract The ignition delay in a diesel engine is defined as the time interval between the start of injection and the start of combustion. This delay period consists of (a) physical delay, wherein atomisation, vaporization and mixing of air fuel occur and (b) of chemical delay attributed to pre-combustion reactions.

What causes ignition delay?

The longer ignition delay can be caused by a number of factors including: lower intake air temperature, lower boost pressure due to turbocharger lag, lower combustion chamber wall temperature and more advanced dynamic injection timing.

What do you mean by ignition delay?

The period between the beginning of fuel injection into an engine cylinder and the begining of combustion.

How do you reduce ignition delay?

Hence, if n 2 is somewhat increased prior to the fuel being exposed to oxygen, the observed ignition delay, τ, should decrease. According to the two energy level system, τ can be decreased simply by increasing the fuel temperature prior to injecting or exposing the fuel to oxygen.

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What is ignition delay in IC engine?

The ignition delay of a compression ignition (CI) engine is defined as the time (or crank angle) interval between the start of injection and start of combustion. … As the delay period increases the maximum rate of pressure rise increases and also engine noise.

Is ignition delay good?

If the ignition delay time is long, the quantity of the fuel injected into the combustion chamber at the instant of its ignition increases, the quantity of vaporized fuel goes up, the fuel-air mixture becomes more homogeneous, and the degree of its chemical preignition preparation (fragmentation and oxidation) improves …

What is difference between ignition lag and ignition delay?

In the internal combustion engine, the time interval between the passage of the spark and the inflammation of the air-fuel mixture. Also known as ignition delay.

How do you check ignition delay?

Ignition delay is calculated as the period from the start of injection to the start of combustion in terms of the crank angle. The ignition delay for diesel, B10, B20, and B100 were 14.94, 14.67, 14.44, and 13.54°CA, respectively, at the rated power output.

Which property of diesel fuel affects the ignition delay?

Cetane number

In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower cetane fuels. Hydrocarbons in decreasing order of ignition quality, i.e., increasing ignition delay, are: n-paraffins, olefins, naphthenes, iso-paraffins and aromatics.

How is ignition delay calculated?

(2), the ignition delay has been expressed as usually [15] in terms of pressure and temperature:(3) τ ( T , p ) = Ap – n exp E a RT where Ea is the activation energy, R is the universal gas constant (8.314 J/mol K), A and n are parameters that are adjusted for each fuel and equivalence ratio, and for the range of …

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How intake temperature affect the ignition delay?

Ignition delay times as a function of initial charge temperature under various charge pressures, 2.1 (○), 1.8 (□), and 1.5 MPa (Δ) for (a) n-heptane, (b) diesel, and (c) iso-octane, respectively. … During temperature sweep experiments, the charge air mass decreases as chamber temperature decreases.

What causes ignition in a diesel engine?

The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to the mechanical compression; thus, the diesel engine is a so-called compression-ignition engine (CI engine).

Why does a diesel engine knock?

Knocking is more or less unavoidable in diesel engines, where fuel is injected into highly compressed air towards the end of the compression stroke. … This sudden increase in pressure and temperature causes the distinctive diesel ‘knock’ or ‘clatter’, some of which must be allowed for in the engine design.

How does octane reduce knock in engine?

Pre-Ignition and Knocking

With lower octane fuels, the air-fuel mixture can also ignite due to this compression. … The leftover fuel from this incomplete ignition causes residue to stick to the inside of the fuel chamber, eventually leading to the sounds from ones engine known as engine knock.

What is self ignition point?

Autoignition or the kindling point is described as the lowest temperatures at which a material will spontaneously ignite under normal ambient condition without an external initiator such as a flame or a spark.

Is a diesel engine combustion?

Diesel combustion. The diesel engine is an intermittent-combustion piston-cylinder device. It operates on either a two-stroke or four-stroke cycle (see figure); however, unlike the spark-ignition gasoline engine, the diesel engine induces only air into the combustion chamber on its intake stroke.

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