Research Reports

Single Tank WVO systems and blending SVO WVO to thin it.

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Research Reports

Postby John Galt » Tue Mar 04, 2008 10:40 pm

Using Unmodified Vegetable Oils as a Diesel Fuel Extender –

This paper is a review of literature concerning using vegetable oils as a
replacement for diesel fuel. The term vegetable oils as used in this paper refers to
vegetable oils which have not been modified by transesterification or similar processes to
form what is called biodiesel. The oils studied include virgin and used oils of various
types including soy, rapeseed, canola, sunflower, cottonseed and similar oils. In general,
raw vegetable oils can be used successfully in short term performance tests in nearly any
percentage as a replacement for diesel fuel. When tested in long term tests blends above
20 percent nearly always result in engine damage or maintenance problems. Some
authors report success in using vegetable oils as diesel fuel extenders in blends less than
20 percent even in long term durability studies. Degumming is suggested by one author
as a way to improve use of raw oils in low level blends. It is apparent that few, if any,
engine studies using low-level blends of unmodified vegetable oils, < 20%, have been

Many studies have been done at the University of Idaho and elsewhere involving
vegetable oils as a primary source of energy. Particularly, during the early 1980's,
studies were completed that tested the possibility of using unmodified vegetable oils as a
replacement for diesel fuel.
There is no question that vegetable oil can be placed in the tank of a diesel
powered vehicle and the engine will continue to run and deliver acceptable performance.
Some vegetable oils, such as rapeseed oil, have very high viscosity and thus may starve
the engine for fuel when operated at 100 percent. Most studies show that power and fuel
economy, when compared to operation on diesel, are proportional to the reduced heat of
combustion of the vegetable oil fuel.
Despite the success when diesel engines are operated on vegetable oil for short
term performance tests, the real measure of success when using vegetable oil as a diesel
fuel extender or replacement depends primarily on the performance of vegetable oils in
engines over a long period of time. Thus many researchers have been involved in testing
programs designed to evaluate long term performance characteristics. Results of these
studies indicated that potential hazards such as stuck piston rings, carbon buildup on
injectors, fuel system failure, and lubricating oil contamination (Pratt, 1980) existed
when vegetable oils were used as alternative fuels. This effect diminishes as the blend
of vegetable oil in diesel is decreased. The question of this literature review is to
determine if there is a blend level at which vegetable oil in the unmodified form can be
used as a diesel fuel extender. Throughout this paper when the term vegetable oil or the
name of a particular vegetable oils is used, such as canola, it refers to the unmodified

Vegetable Oil, Diesel Blends as Potential Fuel Sources
Engelman et al. (1978) presented data for 10% to 50% soybean oil fuel blends
used in diesel engines. The initial results were encouraging. They reported at the
conclusion of a 50-hour test that carbon build-up in the combustion chamber was
minimal. For the fuel blends studied, it was generally observed that vegetable oils could
be used as a fuel source in low concentrations. The BSFC and power measurements for
the fuel blends only differed slightly from 100% diesel fuel. Fuel blends containing 60%
or higher concentrations of vegetable oil caused the engine to sputter. Engine sputtering
was attributed to fuel filter plugging. They concluded that waste soybean oil could be
used as a diesel fuel extender with no engine modifications.
Studies in New Zealand by Sims et al. (1981) indicated that vegetable oils,
particularly rapeseed oil, could be used as a replacement for diesel fuel. Their initial
short-term engine tests showed that a 50% vegetable oil fuel blend had no adverse
effects. While in long-term tests they encountered injector pump failure and cold starting
problems. Carbon deposits on combustion chamber components was found to be
approximately the same as that found in engines operated on 100% diesel fuel. These
researchers concluded that rapeseed oil had great potential as a fuel substitute, but that
further testing was required.
Caterpillar (Bartholomew, 1981) reported that vegetable oils mixed with diesel
fuel in small amounts did not cause engine failure. Short-term research showed that
blends using 50/50 were successful, but that 20% vegetable oil fuel blends were better.
Deere and Company (Barsic and Humke, 1981) studied the effects of mixing
peanut oil and sunflower oil with Number 2 diesel fuel in a single cylinder engine. The
vegetable oil blends were observed to increase the amount of carbon deposits on the
combustion side of the injector tip when compared with 100% diesel fuel. The vegetable
oil fuel blends were found to have a lower mass-based heating value than that of diesel
fuel. Fuel filter plugging was noted to be a problem when using crude vegetable oils as
diesel fuel extenders.
International Harvester Company (Fort et al. 1982) reported that cottonseed oil,
diesel fuel blends behaved like petroleum-based fuels in short-term performance and
emissions tests. The experimental fuels performed reasonably well when standards of
judgment were power, fuel consumption, emissions, etc. However engine durability was
an issue during extended use of these fuel blends because of carbon deposits and fueling
system problems.
Other research at International Harvest Company (Baranescu and Lusco, 1982)
was done using three blends of sunflower oil and diesel fuel. Results indicated that the
sunflower oil caused premature engine failure due to carbon buildup. It was noted that
cold weather operation caused fuel system malfunctions.
Worgetter (1981) analyzed the effects of using rapeseed oil as a fuel in a 43-kW
tractor. The goal of running the tractor for 1000 hours on a blend of 50% rapeseed oil
and 50% diesel was never achieved as the test was aborted at about 400-hours due to
unfavorable operating conditions. The use of rapeseed oil in the fuel resulted in heavy
carbon deposits on the injector tips and pistons, which would have caused catastrophic
engine failure if the tests had not been aborted. Upon engine tear down, it was found that
the heavy carbon deposits on the pistons was the cause of the noted power loss and not
the fuel injectors.
Wagner and Peterson (1982) reported mixed results when using rapeseed oil as a
substitute fuel. Attempts to heat the oil fuel mixture prior to combustion exhibited no
measurable improvement in fuel injection. Severe engine damage was noted during
short-term engine testing due to the use of rapeseed oil. A long-term test using a 70%
rapeseed, diesel fuel blend was successful for 850 hours with no apparent signs of wear,
contamination of lubricating oil, or loss of power.
Van der Walt and Hugo (1981) examined the long-term effects of using sunflower
oil as a diesel fuel replacement in direct and indirect injected diesel engines. Indirect
injected diesel engines were run for over 2000 hours using de-gummed, filtered
sunflower oil with no adverse effects. The direct injected engines were not able to
complete even 400 hours of operation on the 20% sunflower oil, 80% diesel fuel mixture
without a power loss. Further analysis of the direct injected engines showed that the
power loss was due to severely coked injectors, carbon buildup in the combustion
chamber, and stuck piston rings. Lubricating oil analysis also showed high piston, liner,
and bearing wear.
Engine Testing by Ziejewski and Kaufman (1982) at Allis Chalmers using a
50/50 blend of sunflower oil and diesel was unsuccessful. Carbon buildup on the
injectors, intake ports, and piston rings caused engine operating difficulties and eventual
catastrophic failure.
Fuls (1983) reported similar findings for indirect and direct injection engines
using 20% sunflower oil, diesel fuel blends. Fuls Emphasized that injector coking was
the problem with using sunflower oil in direct injected diesel engines.
Caterpillar Tractor Co. (McCutchen, 1981) compared engine performance of
direct injection engines to indirect injection engines when fueled with 30% soybean oil,
70% diesel fuel. The results showed that indirect injection could be operated on this fuel
blend while the direct injection engine could not without catastrophic engine failure
occurring. The direct injection engines showed injector coking and piston ring sticking
as a result of using sunflower oil.
An on-farm study using six John Deere and Case tractors by German et al. (1985)
averaged 1300-hours of operation. Carbon deposits on the internal engine components
were greater for the tractors fueled with 50/50 sunflower oil/diesel than for those fueled
with a 25/75 sunflower oil/diesel fuel blend. All the test engines had more carbon buildup
than normally seen in an engine fueled with diesel fuel. The results of this study
indicated that neither of the fuel blends could be use as a replacement for petroleum
based fuels on a permanent basis without shortening engine life.
Peterson et al. (1982) used rapeseed oil as a diesel fuel extender to study the longterm
effects of using vegetable oils as a fuel source. Fuel composed of 70% rapeseed oil
and 30% Number 1 diesel fuel was successfully used to operate a small single cylinder
engine for 850 hours. No adverse operating conditions were reported at the conclusion of
this engine study. A short-term performance test using a 100% sunflower oil caused
severe piston ring gumming and catastrophic engine failure. This study highlighted the
need for significant long-term engine testing before recommendations of using vegetable
oil as a fuel could be made.
Nag et al. (1995) did studies involving the use of seed oils grown natively in
India. Performance tests using fuel blends as great as 50-50 seed oil from the Indian
Amulate plant and diesel fuel exhibited no loss of power. Knock free performance with
no observable carbon deposits on the functional parts of the combustion chamber were
also observed during these tests. Although this seed oil was not yet commercially
available at the time of this study, it was hoped that it soon would be.
Sapaun et al. (1996) reported that studies in Malaysia, with palm oils as diesel
fuel substitutes, exhibited encouraging results. Performance tests indicated that power
outputs were nearly the same for palm oil, blends of palm oil and diesel fuel, and 100%
diesel fuel. Short-term tests using palm oil fuels showed no signs of adverse combustion
chamber wear, increase in carbon deposits, or lubricating oil contamination.
Ryan et al. (1984) characterized injection and combustion properties of several
vegetable oils. The atomization and injection characteristics of vegetable oils were
significantly different from that of diesel fuel due to the higher viscosity of the vegetable
oils. Engine performance tests showed that power output slightly decreased when using
vegetable oil fuel blends. Injector coking and lubricating oil contamination appeared to
be a more dominate problem for oil-based fuels having higher viscosities.
Pestes and Stanislao (1984) used a one to one blend of vegetable oil and diesel
fuel to study piston ring deposits. Premature piston ring sticking and carbon build-up due
to the use of the one to one fuel blend caused engine failure. The severest carbon
deposits were located on the major thrust face of the first piston ring. These investigators
suggested that to reduce piston ring deposits a fuel additive or a fuel blend with less
vegetable oil was needed.
Other studies by Hofman et al. (1981) and Peterson et al. (1981) indicated that while
vegetable oil fuel blends had encouraging results in short term testing, problems occurred
in long-term durability tests. They indicated that carbon build-up, ring sticking, and
lubricating oil contamination was the cause of engine failure when vegetable oils were
used in high percentages (50% or more) as diesel fuel substitutes.
Due to engine durability problems encountered using raw vegetable oils as a fuel
in the early 1980's, most researchers opted to use chemically modified vegetable fuels
more commonly known as biodiesel in place of unrefined vegetable oils. Thus, in recent
years there has been little literature concerning the feasibility of using raw vegetable oils
as a fuel additive.
McDonnell et al. (2000) studied the use of a semi-refined rapeseed oil as a diesel
fuel extender. Test results indicated that the rapeseed oil could serve as a fuel extender at
inclusion rates up to 25%. As a result of using rapeseed oil as a fuel, injector life was
shortened due to carbon buildup. However, no signs of internal engine wear or
lubricating oil contamination were reported.
Many studies involving use of un-modifed vegetable oils in blend ratios with
diesel fuel exceeding 20 percent were conducted in the early 1980’s. Short-term engine
testing indicates that vegetable oils can readily be used as a fuel source when the
vegetable oils are used alone or are blended with diesel fuel. Long-term engine research
shows that engine durability is questionable when fuel blends contain more than 20%
vegetable oil by volume. More work is needed to determine if fuel blends containing less
than 20% vegetable oil can be used successfully as diesel fuel extenders.

Vegetable Oil As A Diesel Replacement Fuel

While power output and tailpipe emissions using plant or animal oils are in most cases comparable with those when running on petroleum diesel fuel, the main problem encountered has been due to the higher viscosity of the triglyceride oils and their chemical instability. These can cause difficult starting in cold conditions, the gumming up of injectors and the coking-up of valves and exhaust. [3]

The viscosity of plant and animal fats and oils varies from hard crystalline solids to light oils at room temperature. In most cases, these ‘oils’ or ‘fats’ are actually a complex mixture of various fatty acids triglycerides, often with the various components having widely varying melting points. This may give the oil or fat a temperature range over which solidification occurs, with the oil gradually thickening from a thin liquid, through to a thick liquid, then a semi-solid and finally to a solid.

High melting points or solidification ranges can cause problems in fuel systems such as partial or complete blockage as the triglyceride thickens and finally solidifies when the ambient temperature falls. [3] While this also occurs with petroleum based diesel, particularly as the temperature falls below about ~ -10 to -5° C for ‘summer’ formulations and ~ -20 to -10° C for ‘winter’ diesels, it is relatively easy to control during the refining process and is generally not a major problem.

Many vegetable oils and some animal oils are ‘drying’ or ‘semi-drying’ and it is this which makes many oils such as linseed, tung and some fish oils suitable as the base of paints and other coatings. But it is also this property that further restricts their use as fuels.

Drying results from the double bonds (and sometimes triple bonds) in the unsaturated oil molecules being broken by atmospheric oxygen and being converted to peroxides. Cross-linking at this site can then occur and the oil irreversibly polymerises into a plastic-like solid. [9]

In the high temperatures commonly found in internal combustion engines, the process is accelerated and the engine can quickly become gummed-up with the polymerised oil. With some oils, engine failure can occur in as little as 20 hours. [10]

The traditional measure of the degree of bonds available for this process is given by the ‘Iodine Value’ (IV) and can be determined by adding iodine to the fat or oil. The amount of iodine in grams absorbed per 100 ml of oil is then the IV. The higher the IV, the more unsaturated (the greater the number of double bonds) the oil and the higher is the potential for the oil to polymerise.

While some oils have a low IV and are suitable without any further processing other than extraction and filtering, the majority of vegetable and animal oils have an IV which may cause problems if used as a neat fuel. Generally speaking, an IV of less than about 25 is required if the neat oil is to be used for long term applications in unmodified diesel engines and this limits the types of oil that can be used as fuel. Table 1 lists various oils and some of their properties.

The IV can be easily reduced by hydrogenation of the oil (reacting the oil with hydrogen), the hydrogen breaking the double bond and converting the fat or oil into a more saturated oil which reduces the tendency of the oil to polymerise. However this process also increases the melting point of the oil and turns the oil into margarine.

As can be seen from Table 1, only coconut oil has an IV low enough to be used without any potential problems in an unmodified diesel engine. However, with a melting point of 25°C, the use of coconut oil in cooler areas would obviously lead to problems. With IVs of 25 – 50, the effects on engine life are also generally unaffected if a slightly more active maintenance schedule is maintained such as more frequent lubricating oil changes and exhaust system decoking. Triglycerides in the range of IV 50 – 100 may result in decreased engine life, and in particular to decreased fuel pump and injector life. However these must be balanced against greatly decreased fuel costs (if using cheap, surplus oil) and it may be found that even with increased maintenance costs that this is economically viable.

All of these problems can be at least partially alleviated by dissolving the oil or hydrogenated oil in petroleum diesel ( to reduce the IV to 20)

Table 1 Oils and their melting point and Iodine Values [11]

Oil Approx. melting Iodine

point °C Value

Coconut oil 25 10

Palm kernel oil 24 37

Mutton tallow 42 40

Beef tallow 50

Palm oil 35 54

Olive oil -6 81

Castor oil -18 85

Peanut oil 3 93

Rapeseed oil -10 98

Cotton seed oil -1 105

Sunflower oil -17 125

Soybean oil -16 130

Tung oil -2.5 168

Linseed oil -24 178

Sardine oil 185

abstracted from:
Vegetable Oil As A Diesel Replacement Fuel
Phillip Calais* and AR (Tony) Clark**
* Environmental Science, Murdoch University, Perth, Australia,
** Western Australian Renewable Fuels Association Inc,

Results of engine and vehicle testing of semi-refined rapeseed oil

The renewed interest in environmentally compatible fuels has led to the choice of rapeseed oil as the main alternative to diesel fuel in Europe. The objective of this research was to produce and test an economic and high quality non-esterified rapeseed oil suitable for use as a diesel fuel extender. This was achieved by acidified hot water degumming combined with filtration to five microns. This rapeseed oil, designated as a Semi Refined Oil (SRO), has a high viscosity in comparison with diesel. Hence SRO fuel can only be used as a diesel fuel extender, with inclusion rates of up to 25 %.

SRO proved to be a suitable diesel fuel extender, at inclusion rates up to 25 %, when used with direct injection combustion systems (viz. tractor type engines). Power output (at 540 rev/min at the power take off shaft) was reduced by c. 0.06% for every 1% increase in SRO inclusion rate, and brake specific fuel consumption (BSFC) increased by c. 0.14% per 1% increase in SRO inclusion rate (viz. a 25% SRO/diesel blend had a 1.5% decrease in power and a 3.5% increase in BSFC compared with diesel). These values are in accordance with the lower energy density of rapeseed oil fuels compared with diesel. Chemical and viscosity analysis of engine lubrication oil (after c. 170 hours per fuel tested), including metal contamination as an indicator of engine wear occurring, showed that there was no measurable effect on engine lubricating oil due to SRO inclusion in diesel oil.

Abstracted from:
Results of engine and vehicle testing of semi-refined rapeseed oil
Kevin P. McDonnell, Shane M. Ward & Paul B. McNulty
University College Dublin, Dept of Agricultural & Food Engineering, Earlsfort Terrace.Dublin 2, Ireland.
John Galt
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Postby John Galt » Sun Apr 05, 2009 12:48 am

Performance of rapeseed oil blends in a diesel engine

The concept that 100% vegetable oil cannot be used safely in a direct-injection diesel engine for long periods of time has been stressed by many researchers. Short-term engine tests indicate good potential for vegetable oil fuels. Long-term endurance tests may show serious problems in injector coking, ring sticking, gum formation, and thickening of lubricating oil. These problems are related to the high viscosity and non volatility of vegetable oils, which cause inadequate fuel atomization and incomplete combustion. Fuel blending is one method of reducing viscosity.

This paper presents the results of an engine test on three fuel blends. (75D-25R, 50D-50R, 25D-75R) Test runs were also made on neat rapeseed oil and diesel fuel as bases for comparison. There were no significant problems with engine operation using these alternative fuels. The engine ran well on these fuels after warm-up. The engine performance with the blends was comparable with the baseline test for diesel fuel. There was significant improvement in thermal efficiency and hydrocarbon (HC) emissions, compared with diesel fuel, when running on vegetable oil fuels.The test results showed increases in brake thermal efficiency as the amount of rapeseed oil in the blends increases. Reduction of power-output was also noted with increased amount of rapeseed oil in the blends. Test results include data on performance and gaseous emissions.

Continuous exhaust sampling and a hot-flame ionization detector (FID) with a heated line system were used to measure the HC emissions. The vegetable oil fuels offered a net reduction in HC emissions compared with diesel-fuel operation. The data show an average unburned hydrocarbon emission level of 435 ppm with 100% diesel fuel. With 75% diesel-25% rapeseed oil it reduces to 180 ppm, with 50% diesel-50% rapeseed oil it reduces to 160 ppm, with 25% diesel-75% rapeseed oil it reduces to 200 ppm, and with 100% rapeseed oil it reduces to 150 ppm. It's notable that the first 25% of rapeseed oil reduces the HC emissions by 42%.

Crankcase oil analyses showed a reduction in viscosity. Friction power was noted to increase as the amount of diesel fuel in the blend increases.

Abstracted from:
Performance of rapeseed oil blends in a diesel engine

O. M. I. Nwafor and G. Rice
Department of Engineering, University of Reading, Whiteknights, Box 225, Reading, UK, RG6 2AY


Algis Butkus 1, Saugirdas Pukalskas 2, Zenonas Bogdanovičius 3
Dept of Automobile Transport, Vilnius Gediminas Technical University,
J. Basanavičiaus g. 28, LT-03224 Vilnius, Lithuania
E-mails: 1, 2, 3
Received 1 December 2006; accepted 1 February 2007
Abstract. After Lithuania’s accession to the EU it is very important to use a larger amount of renewable fuel. Based
on economic and environmental considerations in Lithuania, we are interested in studying the effects of turpentine
contents in the blended turpentine–diesel fuel on the engine performance and pollutant emission of compression ignition
(CI) engine. Therefore, we used engine test facilities to investigate the effects on the engine performance and pollutant
emission of 5 % turpentine in the fuel blend. The tests were carried out in the laboratory on an engine dynamometer
of the car Audi 1Z and tractor D21 diesel engines. The experimental results showed that turpentine used in
the fuel blend for these diesel engines had a positive influence on the engine performance and exhaust emission.

4. Conclusions
1. Addition of 5 % of lighter fuel fractions to diesel
fuel reduced engine exhaust smoke by 10…20 % in
both Diesel engines.
2. Turpentine easily form mixtures (without any supplements)
with diesel fuel.
3. Decrease of specific fuel consumption be for diesel
fuel blends with 5 % of turpentine was caused by
faster evaporation and combustion of the blend particles
as compared with pure diesel fuel.
4. Small amount of turpentine additive to diesel fuel
would increase the cost of the fuel blend only by
3…5 %.

Stories of favorable results with various additives, including acetone, turpentine, mineral spirits, paint thinner, naptha, kerosene, stove oil, jetA, and gasoline:

Performance of direct-injection off-road diesel engine on rapeseed oil
LABECKAS Gvidonas (1) ; SLAVINSKAS Stasys (1) ;
Author(s) Affiliation(s)
(1) Department of Transport and Power Machinery, Lithuanian University of Agriculture, Student Str. 15, P.O. Box 53067, Kaunas Academy, LITUANIE
This article presents the comparative bench testing results of a naturally aspirated, four stroke, four cylinder, water cooled, direct injection Diesel engine operating on Diesel fuel and cold pressed rapeseed oil. The purpose of this research is to study rapeseed oil flow through the fueling system, the effect of oil as renewable fuel on a high speed Diesel engine performance efficiency and injector coking under various loading conditions. Test results show that when fueling a fully loaded engine with rapeseed oil, the brake specific fuel consumption at the maximum torque and rated power is correspondingly higher by 12.2 and 12.8% than that for Diesel fuel. However, the brake thermal efficiency of both fuels does not differ greatly and its maximum values remain equal to 0.37-0.38 for Diesel fuel and 0.38-0.39 for rapeseed oil. The smoke opacity at a fully opened throttle for rapeseed oil is lower by about 27-35%, however, at the easy loads its characteristics can be affected by white colored vapors. Oil heating to the temperature of 60 °C diminishes its viscosity to 19.5 mm2 s-1 ensuring a smooth oil flow through the fuel filter and reducing the brake specific energy consumption at light loads by 11.7-7.4%. Further heating to the temperature of 90 °C offers no advantages in terms of performance. Special tests conducted with modified fuel injection pump revealed that coking of the injector nozzles depends on the engine performance mode. The first and second injector nozzles that operated on pure oil were more coated by carbonaceous deposits than control injector nozzles that operated simultaneously on Diesel fuel.
Journal Title
Renewable energy ISSN 0960-1481
2006, vol. 31, no6, pp. 849-863 [15 page(s) (article)] (16 ref.)
Elsevier Science, Oxford, ROYAUME-UNI (1991) (Revue)
Thermal efficiency ; Motor fuel consumption ; Performance ; Alternative motor fuel ; Rapeseed oil ; Direct injection ; Renewable energy ; Cold ; Diesel fuel ; Diesel engine ;
Last edited by John Galt on Mon Apr 13, 2009 12:36 pm, edited 1 time in total.
John Galt
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Postby jburke » Mon Apr 13, 2009 9:26 am

hi john,

the link doesn't work.
his is where it sends me: ... ize=larger
"...." a problem?
maybe use
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Postby John Galt » Mon Apr 13, 2009 12:40 pm

dead link --- deleted
John Galt
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Postby 240Volvo » Tue Apr 14, 2009 12:38 pm

I have some interesting research to post, but it is in PDF format. How can I attach it?

1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby SunWizard » Tue Apr 14, 2009 1:37 pm

240Volvo wrote:I have some interesting research to post, but it is in PDF format. How can I attach it?

You can't attach it, you need to put it on the web somewhere, and post the link to it.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby 240Volvo » Tue Apr 14, 2009 6:27 pm

Thanks, Sunwizard. Below is a study published in 2005 of a single tank system that ran for 265,000KM in the study. I cannot access the original PDF from the web, but I copied the text and offer it below. First I will give the conclusion, then the entire paper (minus tables and diagrams, etc., could not be copied, sorry). I have to post in segments as it is too long

Basically, they took a CDI Mercedes and put a webasto-type pre-heater, heated injector nozzles, FPHE, etc and drove it 265,000KM around northern Europe, tore the engine down and found that it was fine.

The conclusions are summarised as follows:
1. Using rapeseed oil in CD engines leads to shot- and long-term problem which can be overcome by applying a set of modifications of fuel delivery and injection system. The bench scale spray and injection studies provide sufficient information to elaborate type of modification which needs to be performed.
2. Oil pre-heating up to 60°C enables safe engine operation and does not require major engine modifications. To amend the rapeseed oil delivery, the replacement of existing fuel lines as well as filter is required. Increasing rapeseed oil injection pressure or its temperature improves atomisation and therefore enhances combustion. A new type of engine oil was applied and the
3. Close investigation of the injector performance showed that rapeseed oil at 60°C provides a similar injector performance, however featured but a noticeable injection delay.
4. A modification of a Mercedes Benz 220 C-class had been performed and the engine test did not revealed significant faults for 265,000 km of the car’s driving. The long-driving test revealed the power loss about 10 % and the fuel consumption increase within 2-4 %.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby 240Volvo » Tue Apr 14, 2009 6:35 pm

Journal of KONES Internal Combustion Engines 2005, vol. 12, 1-2

M. T. Bialkowski *, T. Pekdemir * , R. Reuben *
M. Brautsch ** , D. P. Towers *, G. Elsbett ***
* School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland **Environmental Engineering Department, University of Applied Sciences, Amberg-Weiden Germany
***ELSBETT Technologie GmbH, Thalmassing Germany;
A Common-rail Diesel Injection (CDI) Bosch system was modified to operate on neat rapeseed oil (RSO) in a single tank mode. The performed modifications were derived from the fundamental and comparative injection studies. Laser droplet sizing, high-speed imaging and the Acoustic Emission (AE) tests combined with the basic bench scale experiments were employed to define the main direction of modifications. The RSO pre-heating was found as the most feasible direction of the modification. Some technical constrains were taken into account prior to the modification. The paper indicates on the main direction of the modification and evaluates the preliminary results of the CDI engine tests. Cold start, deposit formation, engine oil deterioration and drivability of a Mercedes Benz 220 C-class car had been investigated to assess the modification. The injection system did not exhibit the same magnitude of undesired effects as previously recorded in similar test with DI Diesel engines. A long-term drive tests provided very promising results on which further modification could be based. The engine test and inspection revealed that RSO pre-heating of successfully alters its properties enabling its successful use in a CDI system.
1. Introduction
Unstable situation on the crude oil market resulting in an unpredictable price rise, as well
as an increasing effort to seek for Diesel substitutes led to an interest in using neat vegetable oils. With the recent popularity of the cultivation of oilseed rape in the European Union (in UK it is currently the third most-widely grown crop), rapeseed oil (RSO) is the most obvious candidate for evaluation as a Diesel fuel substitute. Particularly, cold pressed RSO is emerging as a potentially viable alternative to diesel fuel. Whilst longer-term engine tests confirmed the satisfactorily operation of larger-cylinder IDI (indirect injection) engines when fuelled with rapeseed oil [7] a number of problems associated with the use of rape-seed oil in DI (direct injection) engines and small-cylinder IDI engines were identified in [7, 26, 30, 21, 9].
The difference in viscosity, surface tension and density between RSO and Diesel is anticipated to have an adverse effect on the combustion of RSO in most of existing Diesel engines. Additionally poor fuel flow, filter clogging [1, 31] and engine oil deterioration [28] would complete the list. There have been a number of literature suggestions how to reduce the viscosity of rapeseed oil and thus to alleviate these problems [12,24, 27, 32].
Broader research work on performance of Diesel engines running on rapeseed oil were presented by Hemmerlein et al. [10], Peterson [28] who evaluated winter rapeseed oil as a Diesel fuel and by others investigators [2, 22, 27]. The results revealed very satisfactory
short-term emission results concerning CO, HC, N Oxand soot. As in previous investigations [2, 22, 27], lower maximum temperature in the combustion chamber, lower emission of nitrogen oxides and soot were reported. Despite the successful tests when Diesel engines were working on plant oils for a short time, the actual real assessment of such success needs to be measured in long-term operational periods. Recent studies and engine tests showed difficulties in direct fuelling Diesel engines caused mainly by higher viscosity of RSO, which leads to a decrease of engine performance [21, 29, 1, 20, 9]. Despite the successful use of RSO and its derivatives in the IDI Diesel engines presented by Hemmerlein [10] and in [14], similar application in the DI engines is still highly problematic manifesting in so-called “short-” and “long-term” problems [1, 25]. However, the number of successful modifications of IDI engines as well as some attempts on DI showed that RSO could help create a sustainable and cheap source of mechanical energy. Theoretical work of modelling of plant oil atomisation in DI engines has already been performed [23] to provide the fundamental information required for the modification. The latest development of CDI engines indicates a high performance and efficiency together with deep emission reduction. Considering all promising results of other DI engines operating on RSO it can be expected that modifications of the CDI system would enable it to operate on RSO and hence create a very efficient and sustainable Diesel powered energy source. Nevertheless recent operation of the CDI engines on RSO has been problematic due to different physical properties of the oil, which badly influence fuel delivery, spray development and therefore reduction of the air/fuel mixture.
The long-term problems manifest in coking tendencies, carbon deposit formation, start-up and engine oil deterioration [1].
The CR injection process finely controlled by an electronic control unit does not overcome spray obstruction and therefore needs to be redesigned. To improve atomisation the injection system requires modification derived from fundamental spray pattern characteristics, droplet sizing tests and broad engine tests. In order to improve atomisation of RSO parameters like penetration, spray cone angle and drop size distribution under different injection fuel pressure and temperature need to be assessed similarly to studies performed for diesel in [13, 17, 3, 19] or its alternative [18]. Such studies could provide the necessary basic experimental data to characterise the mechanism responsible for deficiency during RSO combustion in CR engines and this has been defined as the aim of the present paper.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby 240Volvo » Tue Apr 14, 2009 6:36 pm

2. Problem definition
Reviews of the available resources on Diesel engines modifications, the preliminary tests in which an unmodified CDI engine was run [1] and the analysis of the bench scale experimental results [11] directed the authors to form the following conclusions. These were grouped as a recognised problem together with its expected solution and a mean to meet it:
1. Quantities o f injected fuel limit performance of CDI system and result in overall engine effectiveness. Due to differences in viscosity, density and surface tension, injected
volumes of RSO are expected to be different from Diesel. Injection process requires more
thoroughly studies considering fuel metering under the rail pressure oscillations.
Investigation of the oil metering is expected to provide information about the alternation
of injected quantities by applying higher injection pressure or RSO temperature.
2. The use of RSO in CDI poses a few challengesto injection system operation due to higher density and viscosity. The filter clogging is one of the common problems. Hence, several experiments should be performed to investigate the influence of RSO flow across a fuel filter at different fuel temperatures. RSO and the fuel filter pre-heating and alternative filter replacement should overcome the clogging problem.
3. Spray characteristic of RSO is expected to be significantly different in terms of spray penetration, cone angle and drop size distribution. The poorer spray atomisation is expected to be the main reason of incomplete combustion. Studies of these parameters should pro-vide information if there is any feasible way to improve the spray characteristic without modifying the injector.
4. Fuel flow inside the injector is expected to be sensitive to different fuel properties as originally designed for Diesel. Especially, higher viscosity and surface tension would reduce the fuel flow in the injector and therefore lead to the injection delay (hesitation)
and shortening of the effective duration of injection. The acoustic emission experiments are expected to verify this phenomenon. Measurements at varying fuel temperature and pressure should provide information if the injection delay could be overcome by the increased fuel temperature of the injection pressure.
The defined problems were looked in series of various experiments utilising different techniques. The aim was to provide enough information to determine a set of technical changes required for modification of a CDI.
3. Experimental details
Studies of RSO characteristics in a CDI system in comparison to Diesel were performed.
The tests involved investigation of RSO flow and injection sampling, spray characterisation, droplets sizing and acoustic emission probing. The experiments were carried out using a Bosch CDI. The injection port was designed to accommodate a commercial, seat-hole Mercedes (A6110700587) common-rail injector (0.18 mm bore-diameter). A schematic presentation of the experimental system is illustrated in Figure 1. Samples of cold pressed RSO and calibration oil (exhibits the same physical properties as Diesel) named here as standard oil (SO) were used in experiments at different oil temperatures.
Figure 1. Schematic presentation of the experimental rig (the injection stand and the spray chamber), 1-fuel tank, 2-fuel electric heater, 3-fuel water cooler, 4-low pressure fuel pumps, 5- heat exchangers, 6-fuel filters, 7-high pressure pump, 8-transmission, 9-electric motor, 10-rail, 11-rail pressure control valve, 12-pressure valve controller, 13-rail fuel temperature indicator, 14-rail pressure indicator, 15-rail- pressure sensor, 16-nozzle port, 17-spray chamber, 18-gas cylinder, 19-in-flow gas heater, 20-fuel return, 21-cooling water inlet, 22-cooling water outlet

Table 1 lists full injection conditions and experimental parameters and some properties of used oils.
Two different gases were used in the experiments, which produced in-engine air compression conditions (N SF 6 ) up to maximum pressure equivalent to 4.9 MPa of air.
3.1. Flow and injection tests
The series of tests in which the SO and RSO flow and their injected volume were measured had been performed. The aim of these experiments was to investigate differences in the oils flows through the fuel filter and the injection metering between SO and RSO. The first part of the experiments RSO was preheated up to 30, 40 or 60°C and then pumped through the filter. The flowrate as well as oil temperature were measured after the fuel filter.
The readings were taken every 10 minutes. Two brand new Bosch NG172 (1St) fuel filter were used separately for each oil. Results were compared with the SO flow at 30°C. The injection stand was adopted to measure fuel amounts delivered through the CR nozzle. The experimental setup comprised of the automatic system to collect fuel for a required number of injection or the motor revolutions and the glass burettes wherein fuel was collected. The system allowed producing the appropriate injection pressure and temperature of the tested oil.
The measurements were performed at different frequency and duration of injection for SO and RSO accordingly. The ambient pressure was atmospheric and the ambient temperature was 22°C. The measurements were performed at the injection frequency of 5 Hz. The frequency was chosen as a compromise between the experimental variables and the accuracy of the measurements.
The Table 1 presents in details the experim ental parameters investigated in this part of the research.
Table 1. Fuel properties and the experimental condition
1)Spray characteristics experiments. 2)Injection tests
3.2. Spray penetration and sizing
All the measurements were made in a high-pressure injection chamber which enabled the study of spray behaviour at different injection conditions. Spray penetration lengths and spray cone angle were measured for a wide range of injection pressures and three different fuel injection temperatures: 25, 40 and 60°C, and chamber densities in the range from 3 to 60 kg/m 3
(Table 1). The results of measurements of RSO were compared with the SO spray at
Fueltype/Parameter Standardoil Rapeseedoil
Densityat20°C, [kg/m3] 823.2 921.1
Viscosityat20°C, [mm2/s] 3.81 73.78
Oiltanktemperature, [°C] 20, 30, 25, 40, 50, 60
Injectionpressure1),[MPa] 56.3, 131.3
Injectionpressure2),[MPa] 30, 50, 60, 80, 100
Fuelpre-pressure, [bar] 4.1
In-cylindertemperature, [°C] 20
In-cylinderdensities, [kg/m3] 3, 6, 15, 30, 45, 60
Injectionfrequency, [Hz] 1.01), 3.0, 5.0, 7.0, 10.0
25°C. A Kodak high-speed image analyser (HSC) - model 4540hx was used to capture images of spray. Gamma correction of the images prior to the technique of a threshold value was applied to determine the spray penetration and cone angle. Similar sets of experiments were performed using a Phase Doppler Anemometry instrument to obtain drop size distribution.
Also, measurements of arithmetic, Sauter and De Broukere mean diameters were performed for both RSO and SO. The light source was an Argon-Ion Dantec laser providing beams at two wavelengths, green ( =514.5 nm) and blue ( =488.0nm). The beams were transmitted to the PDA probe through an optical fibre and then focused at the measurement volume at a focal length of 600 mm from the PDA transmitter and 30 mm downstream from the nozzle tip. All the sizing test were performed using two dimensional PDA setup, whereas the raw data processing was carried out with 1D configuration only due to better validation and proper statistical presentation of the drop populations. Details on the experimental setup and the procedure can be found in [5, 6].
3.3. Acoustic emission test
An injector signal with different temporal characteristic was measured using the data acquisition system consisting of a Lead Zirconium Titanate sensor, the signal conditioning circuit, the data acquisition board and the computer equipped with the appropriate software.
The data acquisition system was build and tested at Heriot-Watt University and allowed to use four AE channels. The sensor was placed on the injector side on its body and connected to the preamplifier filtering a bandwidth of 0.1 to 1.2 MHz. The signal conditioning circuit utilised the analogue processing unit to produce raw AE signal with variable gain.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby 240Volvo » Tue Apr 14, 2009 6:37 pm

4. Results and discussion
The following section presents only the selected results of the performed experiments. It is believed that chosen examples are typical and represent a wider set of results.
4.1. Injection metering and fuel filter clogging
Figure 2(a) illustrates results of a test where RSO was subjected to different temperatures
simultaneously flowing through a fuel filter. At each case, the oil was preheated in the fuel tank, pumped through the filter and diverted to a discharge tank. The figure compares rapeseed oil results with the flow of standard oil at three different tank temperatures i.e. 30,40 and 60°C.
Figure 2. (a) Flow rate of SO and RSO through the filter at different constant fuel temperatures.
(b) Effect of the oil temperature on injected mass for SO and RSO at different injection pressures and oil temperature. (Injection duration - 1 ms, injection frequency 5 Hz)
The figure shows that pre-heating RSO increases the flowrate across the filter. The RSO
flow at 30°C is much lower than in case of SO. The flow is nearly 3 times lower as result of noticeably high viscosity i.e. 35 cP. At 60°C, RSO is close to the SO flow at 30°C. In this case the vegetable oil viscosity was approximately 12 cP in comparison to 4 cP of standard oil. After certain time the oil and system reached a stable temperature and subsequently the flowrate became constant. The experiments were finished after 250 minutes and the fuel filter was inspected. A similar results but for waste cooking oil were presented by Bari et al. [4].
The author investigated oil flows at different temperatures through a filter and compared
with Diesel. A difference in flow rates was about 240 %, i.e. waste cooking oil flow as lower than the conventional Diesel. The results indicate serious flow deterioration of RSO at temperatures lower than 40°C. Oil pre-heating improves radically the flow but the similar flow cannot be reached. RSO subjected to the constant heating and recirculating in the system gets heated slower than SO. This can be due to higher flow properties and poorer heat transfer. Generally, rapeseed oil requires longer pre-heating period to reach desired temperature and this may indicate an extra pre-heating system must be fitted to provide fast and efficient oil heating. It can be concluded that a separate filter heater should be considered to ensure enhanced oil flow through filter.
The injected quantities of standard and rapeseed oil are compared in Figure 2(b) for the
selected injection pressures and in a range of oil temperatures. Three pairs of curves exhibit a general overlook at these two types of oil and changes in injected quantities. The figure shows the rise of injected oil quantities with fuel temperature and injection pressure, but illustrates a combined effect of these two parameters on injection. As the injection pressure and temperature increase the points are getting closer and the pressure effect seems be dominant over the temperature effect. This is manifested in the closed oil curves for each pressure set.
4.2. Spray characterization
Figure 3 illustrates a sample of experimental data in a comparative study. Processing of
the spray development images showed discrepancy between the solenoid valve activation and injection rate.
Figure 3. Spray characterisation at the injection pressures of 93.75 MPa at amb=15.0 kg/m3 of ambient density, for three RSO temperatures: 25, 40 and 60°C and compared with SO at 25°C. (a) Spray penetration and (b) Spray cone angle
This phenomenon was noted for all the injection rates of tested fuels however the delay
phenomenon was longer for RSO. Higher viscosity of RSO results in slower flow within feed passages and therefore higher “hesitation”. In case of low injection pressure ( < 30 MPa) and fuel temperature injection did not result in atomisation at all. The SO values indicate shorter injection delay and in all cases the first detected spray was recorded before 5 10 -4 s. The same trend cannot be observed clearly for RSO. Increased injection pressure slightly reduces injection delay as it was concluded before this does affect the fuel flow inside the nozzle. It can be concluded that in this case the pressure drop across the nozzle is less affected by changes of RSO viscosities and more by momentum forces resulting in penetration values less dependent on temperature. For all investigated cases penetration of RSO spray was less developed in comparison to SO. Spray processing revealed differences in the shape and rate of development of RSO sprays. The temperature increase has some effect on spray development resulting in an increase of penetration due to a reduction of RSO viscosity. Although, the RSO oil spray penetration at 60 °C was observed to be lower than that of SO at 25 °C for all the pressure conditions investigated. It was observed from spray images that increased ambient pressure results in significant reduction of penetration and “richer” and denser fuel spray. It indicates the higher degree of air entrainment and the presence of small vortexes at the edge of the sprays. Shear forces between the stagnant gas and liquid sprays result in such a phenomenon which would contribute to an increase in the mixing and evaporation of RSO droplets as concluded previously by Laguitton et al. [17]. It can be concluded from the data presented in these figures that lower ambient pressure, higher injection pressure and higher fuel temperature render RSO spray characteristics similar to that of SO. The injection pressure effect is more significant and similar to the one reported in [13] performed in the similar range of the injection conditions.
4.3. Droplet sizing
Some selected distribution results of the SO and RSO sizing are shown in Figure 4. Two
general effects on spray were investigated in comparative studies: the injection pressure and oil temperature. Figure 4(a) presents the temperature effect on RSO Sauter mean diameter (D32) with ambient density of 15 kg/m 3 . The RSO curves have been compared with the SO D32ranges (depicted by a grey band in the chart) corresponding to the lowest (37.50 MPa) and highest (131.25 MPa) injection pressure. The chart represents a typical trend recorded for RSO for the whole range of studied ambient pressures (only a selected example is shown here). Results indicated that the aerodynamic resistance of the ambient gas has important role in breaking-up the RSO drops, because of high surface tension and viscosity. It can be seen that the temperature effect leads to reduced D32values of RSO but still higher than SO by 50% on average. Further reduction of D32values was recorded for higher ambient pressures i.e. 45 and 60 kg/m 3 .
Figure 4. (a) Temperature effect on the Sauter mean diameter of RSO and comparison with SO (The ambient density of 15 kg/m3). (b) Effect of fuel injection pressure (at various oil temperatures) on values of the arithmetic, Sauter and De Broukere mean diameter of RSO and SO (The ambient density of 60 kg/m3)
As it can be expected the higher oil temperature and ambient pressure (gas density) results in the deeper reduction of mean diameter. The similar observation was reported in [8] and it can be explained as the result of a reduction of the relative velocity and hence the tendency for drops to break. Figure 4(b) presents the variation of arithmetic, Sauter and De Broukere mean diameter of RSO at 60°C in the comparison to SO injected at 30°C for the higher oil temperature and ambient pressure. The figure clearly shows the effect of injection pressure on droplet mean diameter, which decreased at higher injection pressures. The trend observed is consistent with other measurements reported in the literature [15]. It can be concluded that such observation is caused by an effect of surface tension and viscosity reducing with temperature and the aerodynamic resistance of the ambient gas enhancing the break-up of drops. It needs to be highlighted that the RSO measurements was effected by number of “satellite” drops present close to the measuring point. This might lead to the higher number of large drops present in nearly each drop population. The distributions of droplet size revealed the presence of one pick well representing Gaussian droplet size distribution. It is interesting to notice that RSO distribution showed higher number of small drops but also the larger ones comparing to SO distribution and this effect could be explained using the Lefebvre correlation. Furthermore, close analysis of the injection pictures in relation to the PDA test showed the presence of circulating drops inside vortexes appearing especially at the edge of sprays which may contribute in the higher number of tiny drops. It has been noticed that RSO drop population consists of a significant number of larger drops within a range of 60-120 µm.
Contribution of these large drops in values of D32 and D10 is significant, thus the increased number of small drops does not result in reduced values of mean drop diameters since the noticeable number of large drops is present in the population. An earlier study [16] indicates droplet diameters of Diesel fuel up to 500 µm for much lower injection pressures. In summary, it can be seen that the effect of temperature is pronounced and shows more rapid decrease together with the highest ambient pressure however oil temperature has slightly less effect on distribution than injection pressure. By increasing the ambient gas pressure and oil temperature the RSO distribution curve shifts more towards lower drop ranges. The mean drop size values closely follow or even exceed data of SO.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby 240Volvo » Tue Apr 14, 2009 6:39 pm

4.4. Acoustic emission results
AE tests were performed in the comparative studies to analyse closely the injector performance operating on RSO. As concluded from the spray characterisation results, the RSO spray development exhibits a certain level of hesitation which was associated with the obstruction of oil flow inside the injector channels. Thus, the AE tests were expected to provide information about the internal flow (during the actual injection) of RSO in comparison to SO for various injection and ambient conditions. A summary of the AE results is presented in Figure 5. The Figure 5(a) presents the AE signal recorded for SO and RSO at 30°C and 60°C accordingly. The signals were recorded at the ambient density of 60 kg/m and the injection pressure of 131.25 MPa. The chart confirms a delay shift features the RSO signal but also shows the higher overall energy of the signal. The energy is directly proportional to the “strength” of events taking place inside the injector. The corresponding energy values for the signals were 0.00285255 and 0.00930928 (of arbitrary units) accordingly. The effect of oil temperature on the internal flow is presented in the Figure 5(b) for various infection pressures. As expected, the AE energy on the internal flow rapidly increases with oil temperature exceeding values recorded for SO. The effect does not confirm the results of measurements of injected quantities of RSO. It can be concluded that the energy describes an event which can be associated with the internal flow which one of the components is the effective flow and hence the oil release. Nevertheless, the results confirm that the injection enhancement due to increased oil temperature.
Figure 5. (a) Comparison of the RSO and SO acoustic emission signals. (b) Flow energy con-tents inside the
injector at different oil temperatures
4.5. System modification
Considering the summary of the presented results it can be concluded that the RSO temperature rise would positively contribute in injection and lead to enhanced spray development. Also, the injection improvement could be reached by increasing the injection pressure especially at the low engine load where the low injection pressures are utilised. Despite understanding of the modification steps need to be taken the CR system does not offer a high level of flexibility to apply suggested changes unless the suitable tools are available. Modification of the system becomes especially difficult due to a lack of information of the Engine Control Unit (ECU) and its accessibility. The ECU box incorporates a program which governs the operation of the injection system by collecting and processing incoming signals as well as accordingly responding to them. The ECU code is incorporated in a microprocessor chip and can by accessed only through a specialised tool and altered through a specific interface. It becomes clear then, that any modifications changing the injection regime or conditions must be performed in combination of re-programming the ECU or replacing the existing electronic components. An alternative way is to change mechanical components being used to produce fuel spray. Although, following such way only limited number of changes can be performed. Therefore, a full set of suggested modifications could not be fully implemented and had to be partly applied. Some of the injection parameters like the rate of injection and the injection timing were automatically adjusted by the ECU itself due to its adaptive feature. It has been recognised that the control unit flexibly responded to new properties of the fuel and corrected the injection timing accordingly advancing or delaying ignition. This was performed only in the thermodynamical state of RSO remains unchanged.

The most problematic issue the injection pressure alternation. It has expected that suggested modifications would have been more successful if the injection pressure could have been further increased. Considering feasibility of the suggested solutions a set of modifications was made at Elsbett Company. The modification involved the following major changes to the injection system and the engine:
1. The fuel delivery loop was equipped with a new fuel filter with a filtrating cartridge mesh around. The system comprises an additional backup fuel filter allowing a flexible
interchange in case of fuel delivery through the master one. Conjointly, the filter was pre- heated and an additional hand-pump was build in between the filter and the fuel delivery pump. Filter replacement intervals were set to 10000-15000 km.
2. The fuel delivery system was re-designed and changed to ensure free RSO flow even at low oil temperatures. The low-pressure loop of the system was equipped with the pre-heating unit employing an external Diesel heater. The heater was turned on prior to the start-up and kept running to ensure desired engine block temperature being reached. Since the engine reached appropriate temperature the pre-heating system was switched over and utilised the heat generated during the engine operation. These two heating modes were integrated and controlled automatically according to the ambient temperature.
3. A separate pre-heating system was constructed to ensure additional injectors heating along the injector body. The system utilised the battery power and was controlled by an automatic relay. Injectors heating were integrated with heating inside of the fuel delivery
system. Additionally, glow plugs were replaced with the more efficient ones.
4. The lube oil was replaced by the enhanced engine oil (PLANTMOT) suitable for Diesel engines working on plant oils. The selection on the oil was based on periodical examination of oil samples withdrawn from the engine. The parameters like density, viscosity and epsilon value were measured and compared with a corresponding mineral oil sample.

The output of the modification was studied in a short - and long-term tests and a summary of the results is presented:
1. The car has been successfully operating on RSO for 265,000 km without major problems. Engine inspection did not revealed the deposit build up and a typical lacquer formation on the nozzle tip was not found.
2. The driving test revealed the power loss of approximately 10 % and the fuel consumption increase was around 2 up to 4 %. A significant noise reduction was found due to less “knocking” coming out of the engine.
3. The engine oil tests have not revealed significant volume increase (due to unburned RSO) nor higher concentration of copper.
4. The minimum RSO pre-heating temperature at which successful ignition took place was 20°C. It has been recorded that 45°C ensured fully successful engine ignition.

5. Conclusions
A commercial common-rail injection system had been modified based on various fundamental studies of rapeseed oil. The influence of oil properties has been experimentally tested in different injection and ambient conditions using various experimental techniques.
The conclusions are summarised as follows:
1. Using rapeseed oil in CD engines leads to shot- and long-term problem which can be overcome by applying a set of modifications of fuel delivery and injection system. The bench scale spray and injection studies provide sufficient information to elaborate type of modification which needs to be performed.
2. Oil pre-heating up to 60°C enables safe engine operation and does not require major engine modifications. To amend the rapeseed oil delivery, the replacement of existing fuel lines as well as filter is required. Increasing rapeseed oil injection pressure or its temperature improves atomisation and therefore enhances combustion. A new type of
engine oil was applied and the
3. Close investigation of the injector performance showed that rapeseed oil at 60°C provides a similar injector performance, however featured but a noticeable injection delay.
4. A modification of a Mercedes Benz 220 C-class had been performed and the engine test did not revealed significant faults for 265,000 km of the car’s driving. The long-driving test revealed the power loss about 10 % and the fuel consumption increase within 2-4 %.

6. Acknowledgements
Special thanks need to be addressed to Elsbett Company GmbH and Prof. Markus Brautsch for the CR injection stand and their valuable assistance. Finally, the author would like to thank Dr Krzysztof Nowak from Heriot-Watt for his never-ending scientific and personal support.
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1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
Posts: 127
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Postby jburke » Wed May 20, 2009 7:52 pm

Hi 240Volvo,

It's good to see this report, I think I've seen fragments before.
Sounds like it went well. At 60*C only a few modificatoins were necessary.
I wonder if they are incorporated in the M-B CR Elsbett kits?

The translatoin was a little fuzzy. It sounded like the ECU automatically compensated for the delayed combustion start when using RSO.
That would be great.f No need to advance the timing for RSO.
Posts: 69
Joined: Thu Apr 03, 2008 10:07 am

Postby John Galt » Thu May 21, 2009 9:53 pm

Fuel Properties Profiles of Various Oils and Fats

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John Galt
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Postby 240Volvo » Thu May 21, 2009 10:30 pm

jburke wrote:Hi 240Volvo,

It's good to see this report, I think I've seen fragments before.
Sounds like it went well. At 60*C only a few modificatoins were necessary.
I wonder if they are incorporated in the M-B CR Elsbett kits?

The translatoin was a little fuzzy. It sounded like the ECU automatically compensated for the delayed combustion start when using RSO.
That would be great.f No need to advance the timing for RSO.

Hi, jburke

I don't think that it is a translation, actually, it is just most of the authors are not native english speakers (even those in Edinburgh). I don't know if they are included in the Elsbett MB kit, but I understand that heated injectors nozzles are available in Europe. One of the europeans mentioned this on infopop. I have heard others mention that the MB seems to compensate, so I think that your reading of this is correct. That is the impression I got, as well. I was also of interest to me that they employed a webasto-type block heater.
Last edited by 240Volvo on Fri May 22, 2009 8:13 am, edited 1 time in total.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
Posts: 127
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Location: New Jersey

Postby coachgeo » Fri May 22, 2009 7:15 am

my understanding has been that the older mechanical MB IP's did have the ability to compensate for viscocity.

Im sorry I don't recall the physics behind it not that I totaly understood it when I first came across it. Something about passageways, increased pressures :?:
Life; It's all in the Balance

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