1. Experimental investigations of an IC Engine
operating with alkyl esters of Jatropha,
Karanja and Castor seed oil
Sanjay Bajpai, Lalit Mohan Das
Centre for Energy Studies,
Indian Institute of Technology Delhi
1

2. Background

Need for Alternate fuels
- depletion of limited fossil fuel reserves
- greater concern for Climate Change

Importance in Indian context
- energy security
- environment protection
- employment generation

Vegetable oils sources as Alternate Fuel
- edible oils such as sunflower, rapeseed, soybean etc
- non-edible oils such as Jatropha, Karanja, Castor etc
2

3. Vegetable Oils as Alternate to Diesel
Fuels

Straight Vegetable Oils (SVOs) derived from oilseeds are promising alternatives to diesel
fuel and have proven to be advantageous for certain application in specific engines.
However, High viscosity and low volatility are major hindrances for utilising Straight
Vegetable Oil as fuel for wider applications.

Lower blends of SVOs could compensate for reduced lubricity due to desulphurisation of
diesel as an additive.

For higher blends, options are available to improve fuel properties of SVOs for utilisation
in CI engines.

Transesterification converts glycerides into an alkyl ester where alcohol replaces the
glycerine reducing molecular weight and viscosity while increasing cetane number.

Properties of alkyl esters (Bio-diesel) produced by transesterification close to diesel.
3

4. Biodiesel as diesel substitute
Advantages
 Renewable
 Local feedstock
 Low toxicity
 Superior flash point
 Biodegradable
 Negligible sulfur content
 Lower exhaust emissions
Limitations
 Higher feedstock cost
 Inferior storage &
oxidation stability
 Lower volumetric energy
content
 Inferior cold temperature
operability
 Higher NO emissions
x
4

5. Objectives

Application of environmentally benign renewable higher
alcohols for alcoholysis of oils derived from non edible
feedstocks to produce higher alkyl esters

Characterisation of fuel relevant properties of higher alkyl
esters

Assessment of suitability of higher alkyl esters as fuels through
measurement of performance and emission characteristics
5

6. Selection of Test Fuel Components

Feedstocks
Karanja - High yield, high oil content, grows in all soils except dry,
wide range of rainfall
Jatropha - High yield, grows in wasteland, high oil content, withstands
high temperature and low rainfall
Castor - higher lubricity due to unique type of hydroxylated fatty
acid, so high density and viscosity, amenable to chemical
processes, large domestic produce

Alcohols (Carbon Chain length, Degree of unsaturation and Branching of
Chain affect structure of fatty esters)
Methyl Alcohol - low cost, widely used , high yield
Ethyl Alcohol - standardised process for deriving biogenically
Propyl Alcohol - superior cold flow properties
Butyl Alcohol - can be totally bio-based

Fuels selected
Blends of alkyl esters in various proportions with diesel
6

7. Test Fuels

Karanja Oil Methyl Ester (KOME), Karanja Oil Ethyl Ester (KOEE),
Karanja Oil Propyl Ester (KOPE), Karanja Oil Butyl Ester (KOBE)

Jatropha Oil Methyl Ester (JOME), Jatropha Oil Ethyl Ester (JOEE),
Jatropha Oil Propyl Ester (JOPE), Jatropha Oil Butyl Ester
(JOBE)
Castor Oil Methyl Ester (COME), Castor Oil Ethyl Ester (COEE),
Castor Oil Propyl Ester (COPE), Castor Oil Butyl Ester (COBE)


Blends of Alkyl Esters with Diesel (20%, 40%, 60% & 80% )
7

8. Methodology
1.
Preparation and characterisation of Straight Vegetable Oils
2.
Optimize various parameters for the production of alkyl esters
from non-edible Jatropha, Karanja and Castor oil in two stage
process: Acid Treatment followed by Base Catalysed
Transesterification
Formulation of alkyl ester-diesel blends for use as test fuels
3.
4.
Determine fuel properties like calorific value, relative density,
kinematic viscosity, flash point, fire point, cloud point , pour
point etc of various alkyl esters and their blends with diesel
8

9. Methodology
6.
7.
8.
9.
Set up an experimental test rig with necessary
instrumentation for carrying out the performance and
emission tests with alkyl esters- diesel blends.
Experiments at constant speed with different brake load
conditions on experimental test rig with alkyl estersdiesel blends.
Collect, collate, analyse and compare the performance
and exhaust emission data obtained from the above
experimentation for various test fuels
Infer the results to determine technical feasibilty of
selected test fuels for utilisation in CI engines
9

10. Fuel Characterisation
Properties of Straight Vegetable Oils
Oil Properties
Fatty acid composition (%)
I)Palmitic acid C16:0
II)Stearic acid C18:0
III)Oleic acid C18:1
IV)Linoleic acid C18:2
V)Linolenic acid C18:3
VI)Ricinoleic acid C18:3
Specific gravity
Jatropha (Jatropha
curcas)
Karanja (Pongamia
pinnata)
17.11
7.17
46.35
31.72
0.78
-
12.36
8.21
50.92
15.45
2.86
-
0.9
0.8
3.6
3.82
0.8
89.13
0.938
0.955
0.922
Castor (Ricinus
communis)
K. Viscosity (cSt) at 40oC
35.60
28.31
98.16
Flash point (oC)
172
208
237
Calorific value (MJ/kg)
39.211
35.674
36.116
Acid value (mg KOH/gm)
13.44
16.34
21.37
10

11. Fuel Characterisation
Inferences from fuel properties of SVOs






High percentage of oleic and linoleic acids is likely to impart
better low temperature properties and stability to Jatropha oil
compared to Karanja and Castor
Higher viscosity and polyunsaturated character of all three
vegetable oils may affect injection process. Lower specific gravity
and kinematic viscosity of jatropha oil closer to diesel imparts it
better fuel properties.
Higher FFA content in castor oil may lead to higher carbon
residues and deposits
Presence of oxygen reduces calorific value with Jatopha oil being
closest to diesel
All three oils safe to use as flash and fire points are higher
Cloud and pour point of all test fuels less, so less suitable in cold
conditions ( e.g. Cloud point of diesel 6.5 ºC, Karanja 11
13.2ºC Pour
point 3.1ºC Karanja 6.4ºC).

12. Production of Alkyl Esters



Heating mantle
Reaction flask (2 Ltr)
Mechanical Stirrer
Process Parameters





Reaction Temperature
Reaction Duration
Catalyst Concentration
Oil Alcohol Molar Ratio
Stirring Speed
12

13. Optimisation of yield of Alkyl esters

Higher Esters required
- more amount of alcohol
- higher catalyst quantity
- longer reaction duration
- higher reaction temperature


For same feedstock, yield of lower esters was higher than
corresponding higher esters
Yield of Jatropha esters was highest followed by Karanja
and then Castor
13

14. Characteristics of Test Fuels -Density
Effect of blending on Density of Jatropha derived Alkyl Ester- Diesel blends
900
880
840
820
800
780
760
Di
es
el
JO
M
E2
0
JO
M
E4
JO 0
M
E6
0
JO
M
E8
0
JO
M
E1
00
JO
EE
20
JO
EE
4
JO 0
EE
6
JO 0
EE
80
JO
EE
10
0
JO
PE
20
JO
PE
40
JO
PE
6
JO 0
PE
80
JO
PE
10
0
JO
BE
20
JO
BE
4
JO 0
BE
60
JO
BE
JO 80
BE
10
0
Density (Kg/ m3)
860
Effect of blending on Density of Jatropha derived Alkyl -Esters- Diesel blends14

15. Characteristics of Test Fuels - Viscosity
Comparison of Viscosity of Diesel and 100% Alkyl Esters derived from Jatropha, Karanja and Castor
6
5
Viscosity (cSt)
4
3
2
1
0
Diesel
JOME
JOEE
JOPE
JOBE
KOME
KOEE
KOPE
KOBE
COME
COEE
COPE
Comparison of Viscosity of Diesel and 100% Alkyl Esters derived from Jatropha, Karanja and Castor
15
COBE

16. Characteristics of Test Fuels - Carbon Residue
Carbon Residue of various Alkyl Esters
Carbon Residue (% mass)
0.06
0.05
BIS Limit
0.04
0.03
0.02
0.01
0
Methyl Ester
Ethyl Ester
Alkyl Esters
Jatropha
Karanja
Propyl Ester
Butyl Ester
Castor
Carbon Residue of various Alkyl Esters
16

17. Characteristics of Test Fuels- Oxidation Stability
Oxidation Stability of Alkyl Esters derived from Jatropha, Karanja and Castor
9.5
9
Induction Period (hrs)
8.5
8
7.5
7
6.5
6
5.5
5
JOME
JOEE
JOPE
JOBE
KOME
KOEE
KOPE
KOBE
COME
Oxidation Stability of Alkyl Esters derived from Jatropha, Karanja and Castor
COEE
17
COPE
COBE

18. Fuel Characterisation
Inferences from Fuel Properties of Alkyl Esters

Density, viscosity, flash point, sulphur content, carbon residue, sulphated ash, water
content , cetane number, acid value, alcohol content, ester content, total glycerol, free
glycerol and phosphorous content of all blends of all feedstocks conform to IS:15607 .

Oxidation stability is relatively low for higher alkyl esters. The choice of feedstock does not
made much difference.

Density of all alkyl esters blends higher than diesel. Density of higher alkyl esters higher
for the same blend percentage. Jatropha blends have lowest density followed by
corresponding blends of Karanja and then Castor.

Calorific value of all alkyl esters and their blends lower than neat diesel. The gap widened
for higher blends. Jatropha derived alkyl esters blends possess higher calorific value
compared to corresponding Karanja and Castor derived alkyl esters blends. Higher alkyl
esters had relatively lesser calorific values.
18

19. Fuel Characterisation
Inferences from Fuel Properties of Alkyl
Esters

Transesterification process improves the fuel properties of the oil with respect to density,
calorific value, viscosity, flash point, cloud point and pour point.

Lower alkyl esters of Jatropha in lower blends has closest distillation temperature,
oxidation stability, calorific value and density characteristics to diesel compared to any
other blend of Jatropha or any feedstock followed by lower blends of Karanja.

Jatropha oil derived esters have lowest cloud point followed by Karanja and then Castor.
Higher alkyl esters of Jatropha and Karanja have similar low temperature operability as
lower alkyl esters. Castor derived alkyl esters may not give similar cold operability.

Higher alkyl esters of Jatropha up to relatively higher blends and karanja at relatively
lesser blends with diesel are likely to give comparable performance to methyl esters.
19

20. Engine Selection

Direct Injection
- Stationary Application
- Mixture Formation

Widely used for
- Agriculture application
- Decentralised Energy generation
20

21. Engine Specifications
Model: AV1 (Kirloskar Make)

No. of cylinders
One

Bore x Stroke
80 x 110 mm

Cubic Capacity
0.553 lit

Compression Ratio
16.5 : 1

Rated Output as per BS5514/ISO 3046/IS 10001
3.7 kW(5.0 hp) at 1500 rpm.

SFC at rated hp/1500 rpm
245 g/kWh(180 g/bhp-hr)

Lub Oil Consumption
1.0 % of SFC max.

Lub Oil Sump Capacity
3.3 lit.

Fuel Tank Capacity
6.5 lit

Fuel Tank re-filling time period
Every 6 hours engine running at rated output

Engine Weight(dry) w/o flywheel
114 kg

Weight of flywheel
33kg – Standard

Rotation while looking at the flywheel
Clockwise. Optional – Anticlockwise

Power Take-off
Flywheel end. Optional-Gear end half or full speed

Starting
Hand start with cranking handle.
21

22. Schematic diagram of test set up for DI diesel engine
AMPLIFIER
WATER
FLOW TANK
WATER INLET
TEMPRATURE
AIR SURGE
TANK
FUEL
TANK
PRESSURE
TRANSDUCER
PHOTOCELL
FUEL
METER
GAS
ANALYSER
& SMOKE
METER
SILENCER
ENGINE
EDDY CURRENT
DYNAMOMETER
J
U
N
C
T
I
O
N
COMPUTER
EGT
AMPLIFIER
WATE
R OUT
MAGNETIC
PICK UP
CHARGE
AMPLIFIER
WATER
OUTLET
TEMPERATURE
B
O
X
LOAD
CONTROLLER
22

23. Parameters measured by Experimental Setup
Air Mass Flow
Coolant water inlet
temperature
Coolant water engine
outlet temperature
Exhaust Gas
Temperature
Engine
Engine Speed
Crank Movement
Eddy Current
Dynamometer
Fuel consumption
Engine Load
Load
controller
D
A
T
A
A
C
Q
U
I
S
I
T
I
O
N
S
Y
S
T
E
M
COMPUTER
23

24. Test Matrix for Short Term Engine
Performance and Emissions
Sl.No.
Variables
Types of variables studied
Details of variables studied
1
Independent
1. Fuels used
Jatropha, Karanja, Castor methyl, ethyl, propyl, butyl
esters and their blends with Diesel
Diesel
100% neat
Alkyl Ester– Diesel blends (v/v), %
2. Load
2
Dependent
20%,40%,60%,80% and 100% blends of methyl, ethyl,
propyl and butyl esters of Jatropha, Karanja and Castor
0% , 20%, 40%, 60%, 80%, 100%
1. Brake Specific Fuel Consumption (BSFC)
At 0% , 20%, 40%, 60%, 80%, 100% load
2. Brake Thermal Efficiency (BTE)
At 0% , 20%, 40%, 60%, 80%, 100% load
3. Exhaust Gas Temperature
At 0% , 20%, 40%, 60%, 80%, 100% load
4. Engine Exhaust Emissions Carbon
monoxide (CO), Hydrocarbon (HC),
Nitrogen oxides (NOx), Smoke ( Opacity %)
At 0% , 20%, 40%, 60%, 80%, 100% load
24

25. Results of Engine Performance
Brake Specific Fuel Consumption (BSFC)
BSFC comparison of 20% and 100% Alkyl Esters at full load
0.3
0.2
0.15
0.1
0.05
JO
JO
el
M
E2
0
M
E1
0
JO 0
EE
JO 20
EE
10
JO 0
PE
JO 20
PE
10
JO 0
BE
2
JO 0
BE
10
KO 0
M
E
KO 2 0
M
E1
0
KO 0
EE
KO 20
EE
10
KO 0
PE
KO 20
PE
10
KO 0
BE
KO 2 0
BE
10
CO 0
M
E
CO 20
M
E1
0
CO 0
EE
CO 20
EE
10
CO 0
PE
CO 20
PE
10
CO 0
BE
CO 20
BE
10
0
0
Di
es
BSFC (kg/ kWh)
0.25
Blends
BSFC comparisons of 20% and 100% Alkyl Esters at full load
25

26. Results of Engine Performance
Brake Specific Fuel Consumption (BSFC)

All alkyl esters derived from all the three feedstocks and their blends
demonstrated higher BSFC than diesel. This is due to lower calorific value
of alkyl ester blends

Karanja derived alkyl esters showed lower BSFC compared to Jatropha and
Castor. However difference was marginal which shows limited effect of
feedstock.

BSFC difference between diesel and blends was larger for part loads and
the gap narrowed with increasing loads.

For all three feedstocks, methyl esters demonstrated lowest BSFC followed
by ethyl esters, propyl esters and butyl esters. The deviation from diesel
BSFC was least for 20% blends and increased with blend percentage. This
implies that structural features of the alcohol moiety that comprise fatty
esters affect BSFC.
26

27. Results of Engine Performance
Brake Thermal Efficiency (BTE)
BTE of Diesel and Jatropha Alkyl Ester blends at full load
38.3
38.1
37.9
BTE
(%)
37.7
37.5
37.3
37.1
36.9
Diesel
36.7
36.5
Jatropha 20
Jatropha 40
Methyl Ester
Jatropha 60
Ethyl Ester
Jatropha 80
Propyl Ester
BTE of Diesel and Jatropha Alkyl Ester blends at full load
Jatropha 100
Butyl Ester
27

28. Results of Engine Performance
Brake Thermal Efficiency (BTE)
BTE of Diesel and Karanja Alkyl Ester blends at full load
38.5
37.5
37
36.5
KO
ME
2
KO 0
ME
4
KO 0
ME
6
KO 0
ME
KO 80
ME
10
KO 0
EE
20
KO
EE
4
KO 0
EE
6
KO 0
EE
8
KO 0
EE
10
KO 0
PE
2
KO 0
PE
40
KO
PE
6
KO 0
PE
8
KO 0
PE
10
KO 0
BE
2
KO 0
BE
4
KO 0
BE
60
KO
BE
8
KO 0
BE
10
0
el
36
Di
es
BTE (%)
38
Blends
BTE of Diesel and Karanja Alkyl Ester blends at full load
28

29. Results of Engine Performance
Brake Thermal Efficiency (BTE)
BTE of Diesel and Castor Alkyl Ester blends at full load
38.5
38
BTE
(%)
37.5
37
36.5
36
35.5
Di
e
CO s el
M
E
C O 20
M
E
CO 40
M
E
CO 60
M
CO E80
M
E1
0
CO 0
EE
CO 2 0
EE
CO 4 0
EE
CO 60
EE
CO 80
EE
1
CO 00
PE
CO 2 0
PE
CO 4 0
PE
CO 60
PE
CO 80
PE
1
CO 00
BE
CO 2 0
BE
CO 4 0
BE
6
CO 0
BE
CO 80
BE
10
0
35
Blends
BTE of Diesel and Castor Alkyl Ester blends at full load
29

30. Results of Engine Performance
Brake Thermal Efficiency (BTE)



Jatropha derived ethyl and methyl esters showed higher BTE
than corresponding blends of Karanja and Castor, which could
be attributed to better fatty acid characteristics of Jatropha.
BTE is generally higher for higher blends, higher loads and
higher alkyl esters.
Engine operating on Castor oil based propyl and butyl esters
demonstrated marginally higher BTE than Karanja and
Jatropha. This could be due to prominent effect of enhanced
lubricity of higher alkyl esters.
30

31. Inferences from Performance Studies

The brake thermal efficiency (BTE) improves when diesel engine is fueled with
diesel-biodiesel blends of Jatropha and Karanja. Higher alkyl esters blends
demonstrate higher thermal efficiency.

Brake specific fuel consumption (BSFC) of all selected diesel-biodiesel fuel
blends is more than diesel. BSFC amongst corresponding blends is least for
Karanja followed by Jatropha alkyl esters. BSFC increases with the increase of
alkyl ester percentage in blends for all blends .

Lower blends of Jatropha derived methyl and ethyl esters or Karanja derived
propyl and butyl esters offer a trade-off between BSFC and BTE.
31

32. Results of Engine Emissions
Carbon monoxide (CO)



The CO emissions for all alkyl ester blends are higher than diesel due
to unfavourable properties offsetting above advantages.
CO emissions decrease for diesel and all test fuels with increase in
load up to 80%. At full load CO emissions are higher than 80% load but
lower than all other loads.
CO emissions for Jatropha, Karanja and Castor derived
alkyl esters and blends fall within a narrow range showing
very limited effect of source of alkyl esters. However, the
emissions are much higher for higher alkyl esters showing
effect of alcohol used.
32

33. Results of Engine Emissions
Oxides of Nitrogen (NOx)

NOx emissions decrease with increase in load and are least at 100% due
to supply of more fuel at larger load and relatively less time for
preparation of mixture leading to less temperature rise.

The NOx emissions are higher for higher alkyl esters and higher
than diesel for all alkyl ester blends. This implies that NO x emissions
are affected by alcohol used.

Jatropha derived alkyl esters emit lesser NOx compared to Karanja
and Castor. This implies that NOx emissions are affected by
feedstock.
33

34. Results of Engine Emissions
Hydrocarbons


Methyl esters of Jatropha up to 80% blend and Karanja
up to 40% give lesser HC emissions than diesel at all
loads. Emissions for all castor esters are higher than
diesel.
20% blends of ethyl, propyl and butyl esters give lesser
emissions than diesel for 60% and above loads, HC
emissions relative to diesel increase at lower loads.
This is due to fuller combustion at higher loads and
dominant role of higher oxygen content.
34

35. Results of Engine Emissions
Smoke

Methyl esters of Jatropha up to 60%, ethyl esters up to
40% and butyl and propyl esters up to 20% blends give
emissions comparable to diesel at all loads, though
difference in emissions relative to diesel increase at
higher loads.

The smoke emission increased with biodiesel addition to
diesel fuel.
35

36. Inferences from Emission Results

Smoke, HC, CO and NOx emissions were least for 20% blend of
lower alkyl esters derived from Jatropha followed by Karanja.

While smoke and HC emissions were lesser, CO was
marginally and NOx was significantly higher than diesel for
20% blends of alkyl esters. NOx and CO emissions of 20%
Jatropha oil methyl esters were closest to diesel.
36

37. Conclusions

Ethyl, propyl and butyl esters of Jatropha and Karanja feedstock have
physicochemical properties similar to methyl esters and engine
performance, emission and combustion characteristics were inferior to
methyl esters while operating on these blends.

To get engine performance in close range of diesel, the blending ratio of
higher alkyl esters need to be further reduced below 20%. Lower blends of
higher alkyl esters are expected to give better engine characteristics in close
proximity to diesel overcoming the limitations of bio-diesel, while retaining
the advantages.
20% Jatropha oil methyl esters is optimum blends as per this study. It is also
extrapolated that 5% to 20 % blends of Jatropha or Karanja alkyl esters
have the potential for consideration as viable alternate fuels to existing
options.

37

38. Conclusions

Methyl alcohol proved to be a preferred alcohol for conventional
transesterification ; ethyl, propyl and butyl alcohol can also be used for
producing alkyl esters following conventional process and may have certain
advantages while using newer process such as enzymatic and ultrasonic
transesterification.

Jatropha emerged as preferred feedstock closely followed by Karanja for
producing alkyl esters. The advantages of using Castor feedstock could not be
established.

A trade off between blending proportion and engine performance, emission and
combustion is required to be arrived for utilisation of higher alkyl esters in CI
engines. The blending proportion of higher alkyl esters should be much less than
methyl esters to obtain comparable performance and emission characteristics.
38

39. 39