Ethanol based low-temperature combustion in CI engines. Uses dual fuel technology to reduce NOx emissions and soot emissions. Advanced technology using ethanol as base fuel and diesel as ignition fuel so as to reduce the temperature inside the combustion chamber by 100-degree Celsius.

1. ETHANOL BASED LOW TEMPERATURE
COMBUSTION;
AN ADVANCED TECHNOLOGY FOR IC
ENGINES
SACHINLAL A V
S8 M2
ROLL NO:37
Guided by,
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2. CONTENTS
 Current relevance of Ethanol based LTC in IC engines
 Low temperature combustion strategy(LTC)
 Premixed pilot assisted combustion(PPAC)
 Comparison of different fuels
 Experimental setup
 Findings
 Conclusion
 Challenges in adopting Ethanol based LTC technology
 Merits
 Demerits
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3. Current relevance of Ethanol based LTC in IC
engines
 Recent recommendations by NITI Aayog(National Institution for
Transforming India) on adoption of ethanol as well as methanol
based fuel in transport vehicles rather than succumbing on Lithium
battery powered electric vehicles.
 Renewable feedstocks and high octane rating make ethanol an
alternative fuel.
 Ethanol is very cost effective and is easily available and also causes
less emissions compared to gasoline and diesel.
 Employing the use of electric vehicles in India is not a cost effective
sustainable solution as lithium is not an easily available material.
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4. Moreover switching to electric powered transportation would
require extensive charging infrastructure across the entire nation.
Battery manufacturing plants will cause a major environmental
hazard if not disposed properly.
There will be increased imports from china for battery
aggregates(due to lower expertise in battery manufacturing) thus
obviously widening the trade deficit in favour of china.
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5.  LTC engines have great potential to achieve high thermal efficiency
and ultra-low emissions of NOx and PM.
 LTC engines operate on the same fundamental principle as a four-
stroke engine and use basic elements of CI and SI engines.
 In a LTC engine, during the intake stroke, an early homogeneous
fuel–air mixture is introduced.
After intake valve closing (IVC), the piston starts to compress the
fuel–air mixture, which increases the in-cylinder temperature and
pressure. As the piston approaches TDC, charge attains auto-ignition
conditions.
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LTC in IC engines

6.  Auto-ignition in LTC engine occurs simultaneously at several
locations throughout the engine cylinder, and these locations are
called hot spots.
 This quick heat release causes pressure rise in a significantly shorter
time span compared to conventional combustion, while the peak
cylinder local and global temperature still remains significantly
lower.
In summary, LTC consists of the following steps:
(a)Preparation of a highly dilute fuel–air mixture using EGR (Exhaust
gas recirculation)to control combustion and the heat release rate.
(b) At the end of the compression stroke, fuel–air mixture temperature
approaches auto-ignition temperature, leading to simultaneous
spontaneous ignition of entire charge in the cylinder at several
locations.
(c) Precise control of heat release rate (HRR) to achieve trade-off
between combustion efficiency and emissions.
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7. Pre-mixed pilot assisted combustion(PPAC)
It is a novel technique for attaining the Low temperature
combustion in compression ignition (CI) engines.
It involves pre-mixing the air with fuel before ignition fuel
injection using a pilot fuel injector(PFI).
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8. Comparison of different fuels
Diesel
 Volatility--very low
 Auto ignition quality(AI) –very high
 Enthalpy of vaporisation(ΔH) –very low
Ethanol
 Volatility--very high
 Auto ignition quality(AI) –very low
 Enthalpy of vaporisation(ΔH) –very high
From this comparison it is evident that ethanol can be used as a better fuel since it
have low auto ignition quality(The cetane number is 8-11) and excellent
evaporation characteristics.
So for better combustion efficiency and low emission we can select ethanol as
bulk fuel and diesel as an ignition fuel(high auto ignition ,cetane no is 48-50)
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9. Experimental setup
For the current experimental setup ethanol was used as the bulk fuel
and diesel as ignition fuel
Experiment was conducted on a single stroke CI engine having a
compression ratio of 18.2:1.
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Schematic of experimental setup

10. Components in the experimental setup
Ethanol fuel supply system
1. Port fuel injection system (PFI)
2. Dynamometer for measuring torque of engine
3. Diesel common rail injection system
4. Exhaust gas recovery (EGR) valve
5. EGR cooler
6. Mass air flow sensor (MAF)
7. Intake surge tank
8. Exhaust surge tank
9. Back pressure valve
10.Emission gas analysers
11.Intake gas analysers
12.AVL 415S smoke meter
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11.  Ethanol was injected into intake manifold using port injection system
calibrated with ethanol fuel delivery at an injection timing of 10degree
(during intake stroke) ATDC(after top dead centre).
 Diesel fuel was directly injected into cylinder using common rail injection
system.
 Anhydrous ethyl alcohol and ultra low sulphur diesel (ULSD) was used for
the experiment.
 The quantity of ethanol at any point of engine operation is defined using a
term called ethanol fraction.
Ethanol fraction:- It is defined as the ratio of energy contributed by ethanol
quantity to total energy input from both fuels.
All testing was carried out at 1500 rpm.
The targeted NOx and soot emissions are 0.2g/KWh and 0.01g/KWh.
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12. Findings
Effect of ethanol fraction (EF)
The test was started with EF of 0.29 and a constant IMEP of 9.8 bar was
maintained. The EF was increased and the heat release rate profile is shown for
different EF values.
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Effect of EF on HRR

13. The heat release rate profile(HRR) corresponding to lower EF values
of 0.29-0.45 shows that a peak in HRR can be observed.
But as the EF is increased 0.45-0.65 lower HRR peak can be obtained
which significantly reduce the temperature in engine cylinder
The corresponding emission profiles for an increase in EF value is
shown in diagram below.
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Effect of ethanol fraction on emission
level

14.  It is observed that by increasing the EF from 0.5 to a higher value the soot
emissions reduce below 0.01g/KWh.
 The reduction in NOx emissions can also be seen ,this is due to
 The higher the ethanol quantity , high is the rate of evaporation and since the
energy absorbed by ethanol fuel during evaporation is very high it reduces the
temperature inside the engine cylinder causing fewer NOx emissions due to
apparently high activation energy needed for NOx formation.
 But the UHC(unburnt hydrocarbon emission ) increase initially but then attain a
constant value due to homogenous combustion of ethanol at higher EF values.
 We can also observe the corresponding decrease in pressure rise rate(PRR) with
increasing EF, thus reducing the compression work.
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Effect of ethanol on PRR

15. Cylinder cooling
The high enthalpy of vaporisation and low boiling point of ethanol
help to reduce the peak compression pressures in cylinder which in
turn decreases the overall temperature in the cylinder (a decrease of
100K can be achieved). This can be attributed by a overall reduction in
cylinder pressure with increased EF value of 0.6 from 0.3.
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16. CONCLUSION
A Low temperature combustion strategy was employed to study the
effects of using an ethanol-diesel combination in a single cylinder CI
engine.
Higher ethanol fraction can reduce the cylinder temperature to a lower
value that can reduce the soot and NOx emissions with significant
thermal efficiency of 42-44% .
Diesel fuel is used only as the ignition fuel in the experiment and it was
observed that about 41% of total fuel is contributed by diesel for an
efficient soot and NOx free emissions, while ethanol fraction of 0.6-0.65
can result in an efficient combustion.
But it was observed that UHC emissions are higher but it can be
managed using exhaust gas treatment.
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17. Challenges in ethanol based LTC technology
LTC does not offer precise control over the start of combustion
across wide range of engine speeds and loads.
LTC regime suffers from load limitations and can be
implemented only at low-to-medium loads.
Lower in-cylinder temperature in case of LTC impedes post-
oxidation of HCs and conversion of CO to CO2. Thus, LTC
basically suffers from the problem of high HC and CO
emissions.
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18. MERITS
 Ultra low soot and NOx emissions can be attained with diesel like thermal
efficiency.
 Since it adopt a low temperature combustion radiative heat losses from the
engine cylinder is very less
 The work of compression is reduced due to considerable decrease in cylinder
pressure at high EF.
 Fuel consumption rate can be decreased to a considerable value.
DEMERITS
 Precise control over start of combustion cannot be achieved over a wide range
of engine loads.
 Lower in-cylinder temperature in case of LTC impedes post-oxidation of HCs
and conversion of CO to CO2. Thus, LTC basically suffers from the problem
of high HC and CO emissions.
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19. REFERENCES
1. Asad U, Zheng M, Han X, Reader GT, Wang M (2008) Fuel injection
strategies to improve emissions and efficiency of high compression ratio
diesel engines. SAE Int J Eng 1:1220– 1233
2. Asad U, Divekar P, Zheng M, Tjong J (2013) Low temperature
combustion strategies for compression ignition engines: operability
limits and challenges. SAE Technical paper 2013-01-0283
3. Kimura S, Ogawa H, Matsui Y, Enomoto Y (2002) An experimental
analysis of low-temperature and premixed combustion for simultaneous
reduction of NOx and particulate emissions in direct injection diesel
engines. Int J Engine Res 3:249–259
4. Akhilendra Pratap Singh,Avinash Kumar Agarwal (2018) Low-
Temperature Combustion: An Advanced Technology for Internal
Combustion Engines
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