(ENE-562:Biomaass Energy and application)

Lakhanlal(ENE17014)

M.Tech Student

Deptt. of Energy, TezpurUniversity

Combustion and Emission

characteristics of Bio-Diesel

Importance of Bio-Diesel

The crude oil price is fluctuating in the world market (

India’s domestic crude oil is able to meet only 23% of

the requirement (National policy on Bio-fuel,govt.

policy)

New Bio-fuel policy of GOI has set target of 20%

blending in petrol as well as diesel (New Bio-fuel

policy,govt. policy)

It will enhance our energy security as well as

strengthen economy

1. Inlet valve closes after BDC

2. Exhaust valve closes after the TDC

It increases the efficiency of the process.

Can you imagine the charge entering in to the cylinder even if

the piston has started moving upward??

Ramming Effect!!!

Fig.1

Properties of Bio-Diesel Blends:Karanja

Biodiesel

Kinematic

viscosity

(mm2 /sec)

ν

Heating

value

(MJ/kg) HV

Flash point

(°C) FP

Density

(kg/L) ρ

Cetane

number

B0 2.71 42.5 55 0.836 51.00

B20 4.01 41.5 65 0.849 51.70

B40 5.23 39.9 77 0.858 52.82

B60 6.72 38.7 88 0.862 53.15

B80 8.19 37.0 101 0.878 53.86

B100 9.60 35.9 114 0.900 54.53

Source(Nantha Gopal and Thundil Karupparaj 2015)

Table 1

Brake specific fuel consumption:

The brake specific fuel consumption (BSFC) is the actual mass of fuel

consumed to produce 1 kW power output in an hour.

The more quantum of Bio-Diesel as well as its blends is required to

produce 1 kW power.

*Source(Nantha Gopal and Thundil Karupparaj 2015)

Fig. 2

Brake thermal efficiency: It shows the percentage of fuel energy converted into

useful energy

At lower engine load Bio-Diesel and its blends are more efficient than

petro diesel but at higher load Diesel is most efficient among them.

*Source(Nantha Gopal and Thundil Karupparaj 2015)

Fig. 3

Fig.4:Maximum cylinder pressure for different fuels

Peak cylinder pressure occurs closer to TDC for all biodiesel blends and diesel fuels at

low load operations. As the load increases, the peak cylinder pressure occurs relatively

later for all fuels.

*Source(Michael Greenstone 2016)

Bio-diesel:Emission vs % blend

1.Other major pollutant except NOx reduces with increase in blending.

2. PME 100 reduced 45% of UBHC emissions when compared to diesel at

full load condition.

3. NOxemission of PME 100 is increased by 26% when compared to diesel

at rated load

*Source(Fernando, Hall et al. 2006)

Fig 5: Emission vs % blend

•SO2,UBHC, PM and CO2 emission is not a problem for Bio-

Diesel.

But main issue is increased NOx emission.

•causes breathing problems, headaches, chronically reduced lung

function, eye irritation, loss of appetite and corroded

teeth(Hoekman and Robbins 2012).

•Indirectly, it can affect humans by damaging the ecosystem.

•NOx emission becomes important as BSVI norms will going to

cut it by 68%(.06g/Km.) (Business Standard 2017)

•Now the questions is why more NOx with Bio-Diesel??

Bio-Diesel do not have any bound Nitrogen with them. They are

just the simple methyl esters(Palash, Kalam et al. 2013).

Mechanism of NOx formation:

Zeldovich(Thermal mechanism): NOx formation takes

place at temperature greater than 1700K. Residence time

and concentration of Nitrogen and Oxygen also have an

influence on production of Nox. (Hoekman and Robbins 2012).

Prompt or Fenimore reaction : When hydro-carbon

fragment react with atmospheric Nitrogen, prompt NOx is

formed. (Ren and Li 2011)

There are other mechanisms also: Fuel NOx emission, N2O

Pathway mechanism and NNH mechanism. (Hoekman and Robbins

2012)(Fernando, Hall et al. 2006)

NOx Emission related to Physical properties:

Lower viscosity leads to lower NOx emission.(Nettles-Anderson and Olsen 2009)(Yuan and Hansen 2009)(Kegl 2006)

The density of Bio-diesel is higher than the petro diesel, so for a given volume more bio-diesel will be inside the cylinder which will increase the NOx emission.(Ban-Weiss, Chen et al. 2007)(Alptekin and Canakci 2008)(McCormick, Graboski et al. 2001)

The higher saturated fatty acids biodiesel such as coconut, palm and tallow produce less NOx than mineral diesel . (Senatore, Buono et al. 2015)

The NOx concentration is considered as a strong function of fuel surface tension. It has been found that the increase in surface tension will result in increases in NOxemissions.(Gopinath, Puhan et al. 2010)

Injection advance is more in biodiesel(.75-2.3 degree) it results in more Nox formation and can be controlled by reducing injection advance by 3-4 degree. (McCormick, Graboski et al. 2001)

Nox reducing Technology: 3-way catalytic converter, EGR, Introducing amonia in to cylinder, Injecting Urea, Injecting water (Palash, Kalam et al. 2013)

Conclusion

Bio-Diesel is a good fuel for CI engines if the Nox

emission can be controlled.

There are ways to control Nox emission.

The stress of GOI on bio-diesel will definitely lead

us to have reliable and clean fuel technology.