SciFest 2012, CIT
Mayfield Community School
Biodiesel additives – is viscosity a factor?
Timeframe: Spring 2012-04-19
Alan O’Keeffe, Thomas O’Donoghue, Alex O’Sullivan
Team:
Introduction
We are three second year students in Mayfield Community School. Some of our
friends were in SciFest last year and we wanted to try it this year.
The idea
Our science teacher told us about people who were using cooking oil instead of diesel
in their car’s engines and some of the problems around doing it. When we talked to
him about doing a science project, he suggested we could look into some of the
science around this and maybe use one of our datalogger sensors to do it.
Vegetable alternatives to diesel fuel
When we entered our project we put ‘biodiesel’ in the title because we thought any
vegetable oil in a diesel engine is ‘biodiesel’. Then we found out that it’s not that
simple.
You could burn any vegetable cooking oil in a diesel engine. The problem is you
could do a lot of damage to it. One of the big problems is viscosity.
Viscosity is a fluid’s resistance to flow. Diesel flows a lot more easily than vegetable
oil.
We found out there are three ways to use the vegetable oil:

Pure Plant Oil – we are calling this the raw oil.

Waste Vegetable Oil – we are calling this the cooked oil.

Biodiesel – this is when you mix a fat or vegetable oil with alcohol. This
causes a reaction that changes the oil into a thing called an ester. This is good
for the engine.
All of these can be mixed with ordinary diesel.
1
SciFest 2012, CIT
Mayfield Community School
We didn’t have time to make proper biodiesel and anyway we just needed to look at
the viscosity, so we are really only looking at raw oil and cooked oil in this project.
So we wanted to look at the viscosity of raw oil, cooked oil and diesel. Then we
wanted to see how the viscosity changed if we mix the cooking oil with diesel. We
heard of someone using a 50:50 mix of cooking oil and diesel so we decided to use
that mix.
Sensors
Our school has a sensor that counts drops. It sounds easy but it’s actually very clever.
It uses light. Thicker liquids and thinner liquids will show up differently on a graph
when you get them to drop through the sensor. We actually had to spend a fair bit of
time getting the right apparatus to make the oil go into drops so we could measure
them and we are still thinking up ways to improve this.
Apparatus
We used small, recycled bottles from the school shop for the oil samples.
Retort stands to hold the sensors, the droppers and the filter funnels
Filter funnels and filter paper
Pasco Explorer GLX Datalogger, Drop Counter Sensor and Laptop.
Small beakers
Hot water, detergent and paper roll for cleaning up
Alex drew a diagram and our teacher took photographs. They are at the end.
Procedure
1. First we collected our test samples. We got two different kinds of cooking oil
from home. Alan’s Mam used sunflower oil and Alex’s Mam used rapeseed
oil. We brought in one bottle of the raw oil and one bottle of the oil after it
was used to cook our dinner. We got some green diesel from the school
caretaker.
2
SciFest 2012, CIT
Mayfield Community School
2. Then we set up the filter funnels to filter the used cooking oil in case there
were any bits left in it. Then we thought it would be a good idea to filter the
raw ones as well.
3. We set up the GLX and the drop counter sensor and practiced with it. We had
a lot of problems getting a good dropper working. The best dropper was a
glass one with a very small opening but it did not hold a lot of liquid so we
ended up combining it with a plastic 3ml pipette with the top cut off. Even
then most of the diesel just ran through it. We are still thinking about ways to
get a better dropper but we didn’t have enough time before SciFest.
4. After that we measured out our samples of oil and put them through the drop
counter.
5. Then we measured out the oil mixed 50:50 with the diesel and put them
through the drop counter.
6. Then we got our teacher to help us put everything in graphs.
7. Our teacher helped us do the headings for the report and with the layout and
the spelling. Thanks Sir .
3
SciFest 2012, CIT
Mayfield Community School
Results
The datalogger only shows two runs at a time on it’s graph screen so we used our
teachers laptop to put all of our results onto graphs. You have to run software called
DataStudio on the laptop but it allows you to control the GLX so you can run the
whole experiment from the laptop.
Measuring Viscosity
The first graph shows the way each of the oils dropped through the drop counter. You
can use the slope of the lines to show their viscosity. The diesel looks a bit funny
because we need to improve the dropper.
Figure 1: 5 Oils – Viscosity
4
SciFest 2012, CIT
Mayfield Community School
Sunflower Oil
The next graph shows how raw sunflower oil and cooked sunflower oil compare to
diesel. You can see that the sunflower oil gets more viscous after you cook it.
Figure 2: Sunflower Oils and Diesel
5
SciFest 2012, CIT
Mayfield Community School
The next graph shows how the viscosity of raw sunflower oil and cooked sunflower
oil changed after we mixed it 50:50 with diesel. The diesel made the viscosity lower
but the change in the raw sunflower oil was way bigger. If we made a better dropper,
the lines of the mixes would look better.
Figure 3: How the viscosity changes in the sunflower oils after you mix them with diesel.
6
SciFest 2012, CIT
Mayfield Community School
Rapeseed Oil
The next graph just shows the viscosity of raw and cooked rapeseed oil compared to
diesel. Just like the sunflower oil, the rapeseed oil is more viscous after you cook it.
Figure 4: Rapeseed Oils and Diesel
Now we are going to show you what happened when we mixed the raw and the
cooked rapeseed oil with diesel. Just like the sunflower oil, the viscosity went lower
when you mixed them with diesel and just like the sunflower oil, the raw rapeseed oil
changed way more than the cooked rapeseed oil.
7
SciFest 2012, CIT
Mayfield Community School
Figure 5: How the Rapeseed Oils change after you mix them with diesel.
8
SciFest 2012, CIT
Mayfield Community School
Analysis and Conclusion
Even though there is a problem with the dropper when the oils are not very viscous
like diesel, you can still see from the graphs that when you mix diesel with both of the
cooking oils, the viscosity goes down. That makes them better to use in a diesel
engine. As well as that, you can see from the graphs that the raw vegetable oil mixed
with diesel is better than the cooked vegetable oil mixed with diesel. It was the same
for the sunflower oil and the rapeseed oil.
So is viscosity a factor?
Yes, but now we know that it isn’t that simple.
We need to design a better dropper and it would be a good idea for another project to
see how the temperature of the vegetable oil changes the viscosity.
References
Websites
www.fueleconomy.gov/feg/biodiesel.shtml
http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/biodiesel.htm
www.oilgae.com
Vegetable Oil Facts
Vegetable oil comes from vegetables, but it is carried more in the seeds than it is in the fruit of
the plant itself. Some plants like the avocado store its oils in the fruit itself instead of storing
starches and sugars in it like most other vegetables. Vegetable oils are made either coldpressed such as olive and sesame, and they are also refined. Refined oils include safflower
or canola.
Vegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at
room temperature, and fats are solid. Chemically, both fats and oils are composed of
triglycerides, as contrasted with waxes which lack glycerin in their structure. Although many
plant parts may yield oil, in commercial practice, oil is extracted primarily from seeds.
If you frequently cook in the kitchen then you are probably familiar with using oil. Oil is used
as an ingredient and is also used for frying. One of the most common cooking oils is
vegetable oil, but do you really know what that is? Do you know what oils are best used for
frying or the proper way to store it? Here you will find different types of common cooking oils
and the proper use of each of them.
Vegetable Oil: Vegetable Oil is probably the most commonly used of all the oils. It can be
found frequently for use in recipes and can also be used for frying. Vegetable oil is actually a
blend of several oils, such as corn, soybean, palm and sunflower.
9
SciFest 2012, CIT
Mayfield Community School
Canola Oil: Canola oil has been said to be one of the most healthy of the cooking oils
because of its low saturated fat content and high mono unsaturated fat. It is commonly used
in frying, but only with medium frying temperatures, about 450 degrees F.
Corn Oil: Corn oil is relatively low on both saturated and mono unsaturated fats. It is popular
in margarine and used in both frying and baking. It should only be used when frying on
medium temperatures.
Sunflower Oil: Sunflower Oil is low in saturated fat and high in Vitamin E. Many food
manufacturers are recognizing the health benefits of sunflower oil and are using it as the
preferred oil in such snack foods as potato chips. It can be used in the home to fry, cook, and
for use in salad dressings.
Olive Oil: There are different varieties of olive oil: extra virgin, virgin, extra light, and refined.
Extra virgin olive oil is the most common of those used. There are many uses for all varieties,
such as stir-frying, cooking, sauteing and as an ingredient in recipes.Olive Oil is also
frequently used in salad oils. It is the most healthy of all the oils as it is high in mono
unsaturated fat which has been shown to help reduce the risk of heart disease. Many people
use it daily in their meals, drizzling it over a wide variety of foods.
Peanut Oil: Peanut oil is a great oil to use when frying in high temperatures. It is a common
oil during the Thanksgiving holiday as many people are using turkey fryers to fry their turkeys,
but can be used anytime when frying.
10