26-04-2012, 11:52 AM
ALTERNATIVE FUELS FOR DIESEL ENGINE
Altenative fuels for diesel engine.pdf (Size: 198.15 KB / Downloads: 143)
ABSTRACT:
Diesel is one of the major petroleum product and
most needed fuel to run automobiles, machines in
industries etc. If the usage of diesel in the world
is continued this will cause a crisis of shortage of
fuel in few years Since diesel is exhausting from
nature an alternate fuel supply could be
extremely helpful to replace diesel and stabilize
fuel prices, especially when fuel prices are
fluctuating. Biodiesel could be an excellent
renewable fuel for diesel engines. It is derived from
vegetable oils that are chemically converted into
biodiesel. As the name implies, it is similar to diesel
fuel except that it is produced from crops commonly
grown in, including canola, soybean, sunflower and
jathropa.[1]. These crops are all capable of producing
several gallons of fuel per acre that can power an
unmodified diesel engine. Vegetable oil is converted
into biodiesel through a chemical process that
produces methyl or ethyl ester. After washing and
filtering to meet American Society for Testing and
Materials standards(ASTM), it is usable as an
alternate renewable fuel. The removal of fatty acids
and organic chemicals, esters etc to improve the
properties to match diesel property called as
Transesterification.
Key words: Transesterification, Jatropha
Bio-diesel:-
Biodiesel refers to a vegetable oil- or animal
fat-based diesel fuel consisting of long-chain alkyl
(methyl, propyl or ethyl) esters. Biodiesel is
typically made by chemically reacting lipids.
Biodiesel is meant to be used in standard diesel
engines and is thus distinct from the vegetable and
waste oils used to fuel converted diesel engines.
Biodiesel can be used alone, or blended with petro
diesel(petroleum-derived diesel is increasingly
called petro diesel). Biodiesel can also be used as a
low carbon alternative to heating oil.
Properties of biodiesel
Biodiesel has better lubricating properties and
much higher cetane ratings than today's lower
sulphur diesel fuels. Biodiesel addition reduces
fuel system wear, and in low levels in high
pressure systems increases the life of the fuel
injection equipment that relies on the fuel for its
lubrication. Depending on the engine, this might
include high pressure injection pumps, pump
injectors (also called unit injectors) and injectors.
The calorific value of biodiesel is about 37.27
MJ/kg(mega joules/kg). This is 9% lower than
regular Number 2 petro diesel. Variations in
biodiesel energy density is more dependent on the
feedstock used than the production process. Still
these variations are less than for petro diesel. It
has been claimed biodiesel gives better lubricity
and more complete combustion thus increasing
the engine energy output and partially
compensating for the higher energy density of
petro diesel.
Biodiesel is a liquid which varies in colour —
between golden and dark brown —depending on
the production feedstock. It is immiscible with
water, has a high boiling point and low vapor
pressure. *The flash point of biodiesel (>130 °C,
>266 °F) is significantly higher than that of
petroleum diesel (64 °C, 147 °F) or gasoline
(−45 °C, -52 °F). Biodiesel has a density of ~
0.88 g/cm³, higher than petro diesel ( ~
0.85 g/cm³).
Biodiesel has virtually no sulphur content, and it is
often used as an additive to Ultra-Low Sulphur
Diesel (ULSD) fuel to aid with lubrication, as the
sulphur compounds in petro diesel provide much
of the lubricity.
BENEFITS OF BIO FUEL:
1. Renewable source
2. High cetane number
3. Safe storage and handling due to high
flash point
4. Non drying oil due to lower Iodine value
5. Nontoxic
6. No sulphur content
Selection of oils as fuel.[4]:
In cold weather vegetable oil crystallises, forming
solid wax crystals that can quickly block the fuel
filters. One solution to the all-weather problem
with two-tank kits is to change the filter in winter,
using a 30-micron filter instead of the standard 10-
micron filter (or less), so the wax crystals just go
straight through without blocking the filter and
melt in the injection pump, allegedly without
causing any stress or damage.
Diesel engines last a long time, half a million miles
or more is not unusual, and there are not many
thorough, long-term studies of the effects of using
straight vegetable oil in diesel engines. What is
clear is that "any diesel" is an exaggeration.
1. Some diesel engines are more suitable
than others.
2. Some vegetable oils are better than others.
3. Some injection pumps work better than
others.
4. Some SVO kits are better than others.
5. Some computerised fuel systems don't like
vegetable oil at all.
6. There are doubts about using waste
vegetable oil.
7. There are doubts about using straight
vegetable oil in DI (Direct Injection)
diesels.
The older IDI diesel engines are generally
more suitable for SVO use, especially 1980s
Mercedes and VWs. Newer DI engines can be
converted for SVO use, but not just any SVO
system will do the job properly
Mechanical injection is better for SVO use
than computerized injection. Inline injection
pumps such as most Bosch models are most
suitable for SVO. Rotary pumps should not be
used with SVO systems. Lucas/CAV injection
pumps have had high failure rates running on
SVO.
Avoid SVO systems containing copper parts --
not because the oil will damage the copper but
because the copper will catalyse the oil,
causing it to decompose
Svo-straight vegetable oils.[6]
Jatropha oil used as biodiesel:
In india they use jatropa oil along with this
Karanj oil Madhucha oil Neem oil
Jatropha oil Waste Vegetable oil Rubber
seed oil Animal Tallows Acid Oils (
RiceBran, Palm etc) can be used as bio fuel.
If Jatropha feedstock is used, the fuel will cost
depending on the country approximately US $
0,40 per litre plus tax when applicable.
FEED STOCK PRODUCTION PER HECTARE &
COST
FEEDSTOCK Country Yield/hectare
(kg)
Rate per
barrel(US$)
SOYA OIL USA 375 73
RAPESEED OIL Europe 1000 78
JATROPHA OIL INDIA 3000 43
PALM OIL Malaysia 5000 46
Unlike the first generation biodiesel and bio fuel
crops such as soy or corn, Jatropha is a non-food
crop and can grow in non-agricultural and marginal
lands not suitable for food crops.
1. Jatropha can be grown by using
wastewater too
2. Fertilizer and pesticide requirements, and
crop management costs, are relatively
lower for Jatropha than for many other
energy crops
3. Jatropha is a perennial; hence it needs to
be planted just once and it yields oil for
over 30 years