combustion and emission characteristics of bio diesel
TRANSCRIPT
(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.