E81 Final Report

ENGR 081: Thermal Energy Conversion
Biodiesel Production, Evaluation, and
Analysis
Steven Matos-Torres
May 14, 2016

Matos-Torres 2
Table of Contents
Abstract 3
Introduction 3
Procedures 5
Results 9
Discussion 12
Conclusion 14
Works Cited 15
Appendix A 16
Appendix B 19

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Abstract:
This report analyzes how petro diesel fuel compares to two batches of biodiesel fuel. A
diesel test stand is used to collect various engine data for each type of fuel. The purpose of this
project is to recreate aspects of the E90 project Jonathan Martin ’12 did and determine if there
is a significant performance difference when using biodiesel fuel instead of petro diesel. The
main performance metrics used to compare the fuels were torque, engine speed, torque versus
speed, fuel flow, air flow, and fuel to air ratio. This report was able to provide a starting point
for comparison, but issues during experimentation resulted in the loss of the petro diesel fuel
level data, which threw off the comparisons for fuel flow and the fuel to air ratio.
Introduction:
Since the 1970s, the use of diesel fuel in the United States has increased steadily. In
2012 alone, there were 36,343,072,000 gallons of diesel fuel consumed just on highways.1 This
is an alarming, yet unsurprising statistic given that the United States uses more barrels of fuel
per day than any country in the world and more than the China, Japan, and India combined.2
The tremendous consumption of fossil fuels has prompted research and development of
alternative fuels to minimize the long-term effects of using fossil fuels. Biodiesel fuel made from
cooking oil may present itself as an adequate substitute. Biodiesel can be made from virgin or
waste cooking oil. Making this biodiesel fuel from waste cooking oil is important given that over
3 billion gallons of cooking oil are used per year in hotels and restaurants across the United
States.3
1
http://www.americanfuels.net/2014/04/us-on-highway-diesel-fuel-consumption.html
2
http://world.bymap.org/OilConsumption.html
3
https://www3.epa.gov/region9/waste/biodiesel/questions.html

Matos-Torres 4
This project was inspired by Jonathan Martin ’12, who produced biodiesel fuel from
various cooking oils and tested them on the diesel test stand in Hicks. Since there is only one
diesel test stand in Hicks and it would be a shame if biodiesel fuel from waste vegetable oil
ruined it, this project only tested biodiesel produced from virgin vegetable oil and compared
the data to petro diesel.
Two groups of E14 students were integral to this project. One group produced the
second batch of clean biodiesel and a batch of biodiesel from waste vegetable oil. The biodiesel
from waste oil was produced only to experiment with the filtration process and chemically
compare the product with clean biodiesel fuel. The other group was responsible for preparing
the test components of the project and creating a sample MATLAB Script for data acquisition.
This group rewired a multiplexer (figure 1) and made sure all of the transducers produced
voltages (figure 2).
Figure 1 (left): Multiplexer used for data acquisition
Figure 2 (right): Transducers used to relay voltages to the multiplexer
During experimentation, the data for the different types of fuel was varied by manually
changing the speed of the engine from trial to trial with each individual fuel, but similar engine
speeds were used across trials for the different fuels. The engine behavior was also varied by
changing the electrical load the same way during each trial to see how the engine would
respond.

Matos-Torres 5
Procedures:
Producing Biodiesel Fuel:
Find an outlet and plug the stir plate into it. Count 20 pellets of NaOH and put them in a
2L Erlenmeyer flask with approximately 220-230 mL of methanol. Place a two-inch magnetic stir
bar in the Erlenmeyer flask. Put the Erlenmeyer flask on top of the stir plate. Set the stir plate to
“7” and stir until the NaOH completely dissolves. Once the NaOH completely dissolves, remove
the Erlenmeyer flask from the stir plate and add 1L of vegetable (soybean) oil. Cover the flask
with a rubber stopper and place the flask back on top of the stir plate. Let the contents of the
flask stir overnight.
The following day, turn off the stir plate and let the contents settle into two separate
layers. The top layer is the biodiesel fuel. Separate these layers by carefully pouring the layer of
biodiesel into a second 2L Erlenmeyer flask, making sure none of the other layer gets into the
second flask. Measure, in mL, how much biodiesel was separated into the second flask. Add
deionized water to the flask in a quantity that makes a 3:1 ratio of biodiesel to deionized water.
Add distilled vinegar to the flask in a quantity that makes a 2:1 ratio of deionized water to
vinegar. Put the rubber stopper on the flask and shake vigorously for 3 minutes. This completes
the first round of decanting. Repeat this separation and decanting process two more times,
only adding deionized water when decanting. After the third round of decanting, let the
contents settle and separate the layer of biodiesel. This is the final product.
Preparing the Diesel Test Stand:
Locate the power cables for the diesel test stand plug them into their outlets on the
wall. Turn on the computer and log onto the network. Insert the multiplexer into the top slot on

Matos-Torres 6
the back of the Agilent data acquisition device. Turn on the data acquisition device. Open
MATLAB and load ‘DieselDAQ.m’ (Appendix A). Fill the fuel tank containing the boat (figure 3)
Figure 3: Fuel tank with boat used to measure fuel level
with the fuel to be tested. **WARNING**: If testing biodiesel, make sure there is petro diesel in
the other fuel tank since the engine MUST be started with petro diesel.
Starting the Engine:
Locate the hose used for engine cooling and turn the water on. Check the valves leading
to engine from the fuel tank and only open the petro diesel valve. Move the throttle to the
“Start” position. Locate the removable crank handle underneath the engine. Place the crank
handle in the opening next to the “Oil” cap. Locate the small, silver lever on the left side of the
engine. Push and hold the lever away from the throttle. While holding the lever, crank the
engine until the flywheel spins well. Let go of the lever and stop cranking. Remove crank
handle. Allow engine to run for approximately one minute.
Testing the Fuel:
For the petro diesel test, go to the computer and run ‘DieselDAQ.m’ in MATLAB. For the
biodiesel test, close the petro diesel valve and immediately open the biodiesel valve. Allow
engine to run for approximately one minute. Go to the computer and run ‘DieselDAQ.m’ in

Matos-Torres 7
MATLAB. During all trials, keep an eye on the data MATLAB outputs in the command window.
After the fifth data point recorded, flip the first switch to vary the electrical load with one 100W
lightbulb (figure 4). After the tenth data point,
Figure 4: First switch flipped to turn on one 100W lightbulb
flip the second switch to change the electrical load to three 100W lightbulbs (figure 5). After the
Figure 5: Second switch flipped to turn on three 100W lightbulbs
fifteenth data point, flip the third switch to change the electrical load to six 100W lightbulbs
(figure 6).

Matos-Torres 8
Figure 6. Third switch flipped to turn on six 100W lightbulbs
Once ‘DieselDAQ.m’ finishes its trial, turn off the lightbulbs by undoing all three switches in
reverse order to minimize the electrical load on the engine.
Stopping the Engine:
The engine MUST be stopped with petro diesel as its fuel source. If trying to stop after a
biodiesel test, close the biodiesel valve and immediately open the petro diesel valve. Allow the
engine to run for 10 minutes with petro diesel to ensure all of the biodiesel is out of the engine.
Move the throttle to the “Stop” position.

Matos-Torres 9
Results:
The following plots represent only the last trial conducted in my experimentation. See
Appendix B for the MATLAB Script used to analyze the fuels.
Figure 7: Torque of the diesel engine for the three types of diesel fuel
Figure 8: Engine speed for the three types of diesel fuel

Matos-Torres 10
Figure 9: Scatter plot of the torque versus engine speed for the three types of diesel fuel
Figure 10: Fuel flow for each of the three types of diesel fuel

Matos-Torres 11
Figure 11: Air flow through the engine for each of the three diesel fuels
Figure 12: Fuel to Air ratio within the engine for each of the three diesel fuels

Matos-Torres 12
Discussion:
For all of the data analysis, “Batch 1” referred to the batch of biodiesel fuel I made and
“Batch 2” referred to the batch of biodiesel fuel the E14 group made. Only the last trial was
analyzed because accessing the data from previous trials was a challenge. When analyzing the
data, I realized I saved all of the data in three files, one for each fuel. Because of this, MATLAB
was only able to import the data for last trial in each file.
Figure 7 showed the engine had comparable torques for the petro diesel and both
batches of biodiesel when subjected to the same electrical load variation. Batch 1 had two large
spikes in torque during the trial that neither of the other two fuels had. I compared the torques
from my data to the torques in Jonathan Martin’s E90 and noticed he had some of the same
spikes in torque for his biodiesel fuel. He noted that this could be caused by the engine wobble.
Figure 8 showed the engine speed (RPM) with each of the fuels. The petro diesel and
Batch 2 had similar trends as the electrical load increased. The engine speed with these two
fuels decreased as the load increased, which was expected since the throttle remained constant
did not change during the trial. The petro diesel finished approximately 80 RPM slower than it
began. Batch 2 finished approximately 40 RPM slower than it began. Batch 1 was the oddball
when analyzing the engine speed. Batch 1 actually had a large increase in engine speed at the
beginning of the trial relative to the other two fuels. The engine speed oscillated a noticeable
amount with Batch 1 and even finished the trial approximately 15-20 RPM higher than it began,
which should not have happened. Because the other trials were not analyzed, I am uncertain if
this is an anomaly or if Batch 1 displayed this behavior repeatedly.

Matos-Torres 13
Figure 9 compared the torque to the engine speed for each fuel. This comparison
unveiled a significant behavioral difference for the fuels. Even though the petro diesel had the
largest total change in RPM, the torque was more consistent and tightly grouped in the scatter
plot. Both batches of biodiesel had erratic torque behavior when compared to the engine
speed. The spikes in torque noticed in Figure 7 for Batch 1 played a role in the erratic behavior
shown in Figure 9. Differences in the chemical composition of the biodiesel batches may have
contributed to this erratic behavior.
Figure 10 recorded the fuel flow for each of the fuels. It appeared that the boat was
stuck during the petro diesel trial and I did not notice it at the time. Because of this, the fuel
flow and fuel to air ratio for the petro diesel were irrelevant. Batch 1 and Batch 2 provided
useful fuel flow data, though. The data showed an increase in fuel flow as the electrical load
increased. Batch 2 had several large oscillations in its fuel flow. Chemical differences, such as
viscosity, combustion temperature, and composition may have contributed to the differences in
fuel flow. During a visual comparison of the two batches, I observed that Batch 1 was a lot
brighter in color and not as translucent as Batch 2. I noticed Batch 1 appeared to be more
viscous than Batch 2 due to how easily Batch 2 moved when the flasks were swirled.
Figure 11 compared the air flow recorded for each fuel. The air flows were comparable
in behavior for each fuel. Each oscillated similarly, but the petro diesel had lower minimum air
flow values, which may have been since the petro diesel ran at a lower engine speed than the
two batches of biodiesel.
Figure 12 compared the fuel to air ratio for each fuel. At first glance, the batches of
biodiesel appeared to have significantly different fuel to air ratios. If you exclude the time

Matos-Torres 14
intervals where Batch 2 had large spikes in fuel flow in Figure 10, Batch 1 and Batch 2 had very
similar fuel to air ratios. The plot of the ratios even had similar oscillation shapes, which meant
the engine reacted to the varying electrical load in comparable ways with both batches of
biodiesel.
Whenever I expand this project for my E90 next year, I would do several things
differently. To reduce the possibility of the boat getting stuck during a trial, I would clean the
fuel tanks to remove any accumulation of fuel stuck to the walls and bottom. Afterwards, I
would recalibrate all of the transducers and the orifice meter since this project assumed all of
Jonathan’s calibrations from 2012 were still accurate four years later. I would personally make
all of the biodiesel fuel to ensure the same procedures were used. One piece of equipment to
invest in would be a separatory funnel to simplify the decanting process. Expanding this project
would mean doing mass spectrometry and/or gas chromatography to chemically compare
petro diesel and the batches of biodiesel fuel. Another aspect I want to incorporate is filtration
of waste vegetable oil to chemically compare the filtered oil to virgin vegetable oil and
determine the best method of treating the filtered oil when producing biodiesel fuel.
Conclusion:
The purpose of this project was to recreate aspects of the E90 project Jonathan Martin
’12 did and determine if there was a significant performance difference when using biodiesel
fuel instead of petro diesel. Data was collected by running the diesel test stand with petro
diesel and two batches of biodiesel fuel. There appeared to be slight performance differences in
the limited torque, engine speed, fuel flow, and air flow data analyzed.

Matos-Torres 15
Works Cited
"American Fuels." U.S. On-Highway Diesel Fuel Consumption. Mike Gregory, 9 Apr. 2014. Web.
13 May 2016. <http://www.americanfuels.net/2014/04/us-on-highway-diesel-fuel-
consumption.html>.
"Learn About Biodiesel." US Environmental Protection Agency. N.p., 27 Apr. 2016. Web. 14 May
2016. <https://www3.epa.gov/region9/waste/biodiesel/questions.html>.
"Petroleum Consumption - World Statistics and Charts as Map, Diagram and Table." Petroleum
Consumption / Countries of the World. N.p., 18 Jan. 2016. Web. 13 May 2016.
<http://world.bymap.org/OilConsumption.html>.

Matos-Torres 16
Appendix A: DieselDAQ.m
%% DieselDAQ.m
% Reads data from diesel engine test stand, outputs engine variables to txt
% file, plots variables.
%
% Based on significant contributions from the E90 project done by
% Jonathan Martin '12 and pieces of the oveneval.m script used by Steven
% Matos-Torres '17, Cole Fox '17, Graham Lesko '17, and Cooper Woolston '17
% for the E14 Oven Lab.
%% Set calibration values
clear;clf;
format compact;
% define coefficients
AirSlope = 0.478; % in. H20/mV; calculating airflow and pressure difference
FlowCoeff = 1.0456; % PPH*(diff. psi)'2; calculating airflow
WaterSlope = 9.992; % mL/s/Hz; calculating waterflow
FuelSlope = -32.48; % mL/V; calculating fuel flow
FuelEmpty = -4.836; % V @ 0 mL; voltage when fuel reservoir empty
TorqueSlope = 9.777; % lb-ft/mV; calculating engine torque
Torquelnt = -10.78; % lb-ft @ 0 mV; initial engine torque
%% Preallocate arrays for variables to be measured (for performance)
t1 = clock; % set clock
b=20; % number of elements in each array = total number of data points to be
taken
n=20; % number of snapshots taken for torque
ti=zeros(size(b)); % Time array
EngineSpeed=zeros(size(b)); % Engine Speed array
tachometer=zeros(size(b)); % Tachometer array
FuelLevel=zeros(size(b)); % Fuel Level array
WaterIn=zeros(size(b)); % Water In array
WaterOut=zeros(size(b)); % Water Out array
AirFlow=zeros(size(b)); % Air Flow array
WaterFlow=zeros(size(b)); % Water Flow array
TorqueSnap=zeros(size(b,n)); % b-by-n array holding snapshots of torque
EngineTorque=zeros(size(b)); % mean values of Torque for each b
%% Open link with Agilent DAQ board
% USB interface applies only to Keysight 34972A LXI Data Acquisition / Switch
% Unit. Use GPIB0 interface otherwise.
daq = visa('agilent','USB0::0x0957::0x2007::my49021465::0::INSTR');
fopen(daq);
% Get file info from user
filnam = input('Name of file to hold data: ','s');
fid = fopen(filnam, 'at');
%% Thermocouple readings being set to variables
% Takes user input to name the data sequence
DSEQ=input('ENTER THE NAME OF THIS TEST: ','s');
% Prepare output file
fprintf(fid,'nn'); % insert two blank lines between current and previous
test
fprintf(fid,'%s', 'TEST=',DSEQ);
% create headings in command window and output txt file
fprintf(' %7s%7s%7s%7s%7s%7s%7s%7s%7s','Index','Time',...
'EngSpd','WtrIn','WtrOut','WtrFlw',...
'PrsDif','AirFlw','FuelLv');
fprintf(fid,'n %7s%7s%7s%7s%7s%7s%7s%7s%7s','Index','Time',...

Matos-Torres 17
'EngSpd','WtrIn','WtrOut','WtrFlw',...
'PrsDif','AirFlw','FuelLv');
% Get inital fuel level and time measurements
fprintf(daq, 'MEAS:VOLT:DC? AUTO,(@108)n');
FuelLevel(1) = (str2double(fscanf(daq))-FuelEmpty)*FuelSlope; % mL
for i=2:1:(b+1)
ti(i-1)=etime(clock,t1); % ti is the time in sec
% Tachometer (engine speed) readings
fprintf(daq, 'MEAS:FREQ? MIN,(@101)n');
EngineSpeed(i-1) = 60/8*str2double(fscanf(daq)); % Engine speed - RPM60
Sec/Min, 8 Periods/Rotation
% Temperature readings
fprintf(daq, 'MEAS:TEMP? TC,K,(@104)n');
WaterIn(i-1) = str2num(fscanf(daq)); % deg C
fprintf(daq, 'MEAS:TEMP? TC,K,(@105)n');
WaterOut(i-1) = str2num(fscanf(daq)); % deg C
% Airflow readings from voltage
PressDiff = max([AirSlope*1000*str2num(fscanf(daq)),0]); % in. H20 must
be >= 0 or flow rate will be complex number
AirFlow(i-1) = sqrt(PressDiff*14.7)*FlowCoeff; % PPH
% Waterflow readings from voltage
fprintf(daq, 'MEAS:FREQ? AUTO,(@107)n'); % mL/s
WaterFlow(i-1) = WaterSlope*str2double(fscanf(daq)); % mL/s
% Fuelflow readings from voltage
FuelLevel(i) = (str2num(fscanf(daq))-FuelEmpty)*FuelSlope; % mL
%Because of wobble in engine, torque must be measured many times
for x = 1:1:n
TorqueSnap(i-1,x) = str2num(fscanf(daq));
end
EngineTorque(i-1) = TorqueSlope*1000*mean(TorqueSnap(i-1,:))+Torquelnt;
% Print data in MATLAB window;
fprintf('n %7.0f%7.0f%7.0f%7.1f%7.1f%7.1f%7.1f%7.1f%7.1f',i-1,ti(i-
1),...
EngineSpeed(i-1),WaterIn(i-1),WaterOut(i-1),WaterFlow(i-1),...
PressDiff,AirFlow(i-1),FuelLevel(i-1));
% Print data in output file;
fprintf(fid,'n %7.0f%7.0f%7.0f%7.1f%7.1f%7.1f%7.1f%7.1f%7.1f',i-1,ti(i-
1),...
EngineSpeed(i-1),WaterIn(i-1),WaterOut(i-1),WaterFlow(i-1),...
PressDiff,AirFlow(i-1),FuelLevel(i-1));
%% Plot data
% plot engine speed
subplot(3,2,1)
plot(ti(1:end),EngineSpeed)
title('Engine Speed')
xlabel('sec elapsed')

Matos-Torres 18
ylabel( 'RPM' )
% plot waterin and waterout
subplot(3,2,2)
plot(ti(1:end),WaterIn,ti(1:end),WaterOut)
title('Temperatures')
ylabel('deg C')
legend('Water In','Water Out','Location','West')
legend('boxoff')
% plot airflow
subplot(3,2,3)
plot(ti(1:end),AirFlow)
title('Air Flow')
ylabel('PPH')
% plot waterflow
subplot(3,2,4)
plot(ti(1:end),WaterFlow)
title('Water Flow')
ylabel('mL/s')
% plot fuelflow (fuellevel)
subplot(3,2,5)
plot(ti(1:end),FuelLevel(2:end))
title('Fuel Flow')
ylabel('mL/s')
% plot engine torque
subplot(3,2,6)
plot(ti(1:end),EngineTorque)
title('Engine Torque')
ylabel('lb-ft')
pause(1)
end
% insert new line at the end of output
fprintf('n');
fprintf(fid,'n');
% save output as .mat file
filnam_save = strcat(filnam,'.mat');
save(filnam_save);
% close output txt file
fclose(fid);
fclose(daq); % close connection
delete(daq); % delete connection

Matos-Torres 19
Appendix B: DataAnalysis.m
%% Data Analysis
clc
%% Import Data files
petro = importdata('may3petro.mat');
batch1 = importdata('may3batch1.mat');
batch2 = importdata('may3batch2.mat');
%% Torque
T_p = petro.EngineTorque; % Torque for petrodiesel
T_1 = batch1.EngineTorque; % Torque for Batch 1
T_2 = batch2.EngineTorque; % Torque for Batch 2
figure(1)
plot(petro.ti,T_p)
hold on; grid on;
plot(batch1.ti,T_1);
plot(batch2.ti,T_2);
title('Torque Comparison')
xlabel('Time (s)'); ylabel('Torque (lb-ft)');
hold off;
legend('Petro','Batch 1','Batch 2','Location','Best')
%% Engine Speeed
s_p = petro.EngineSpeed; % RPM for petrodiesel
s_1 = batch1.EngineSpeed; % RPM for Batch 1
s_2 = batch2.EngineSpeed; % RPM for Batch 2
figure(2)
plot(petro.ti,s_p)
hold on; grid on;
plot(batch1.ti,s_1);
plot(batch2.ti,s_2);
title('Engine Speed Comparison')
xlabel('Time (s)'); ylabel('Engine Speed (RPM)');
hold off;
%% Torque vs. Speed
figure(3)
scatter(s_p,T_p,'filled')
hold on;
scatter(s_1,T_1,'filled')
scatter(s_2,T_2,'filled')
grid on;
xlabel('Engine Speed (RPM)'); ylabel('Torque (lb-ft)');
title('Torque vs Speed')
hold off;
%% Fuel Flow
fuel_p = petro.FuelLevel(2:end); % mL
fuel_1 = batch1.FuelLevel(2:end); % mL
fuel_2 = batch2.FuelLevel(2:end); % mL
% Calculate fuel flow in mL/s
ff_p(1) = (petro.FuelLevel(2)-petro.FuelLevel(1))/petro.ti(1);
ff_1(1) = (batch1.FuelLevel(2)-batch1.FuelLevel(1))/batch1.ti(1);
ff_2(1) = (batch2.FuelLevel(2)-batch2.FuelLevel(1))/batch2.ti(1);
for i=2:1:20
ff_p(i) = (fuel_p(i)-fuel_p(i-1))/(petro.ti(i)-petro.ti(i-1)); % mL/s
ff_1(i) = (fuel_1(i)-fuel_1(i-1))/(batch1.ti(i)-batch1.ti(i-1));
ff_2(i) = (fuel_2(i)-fuel_2(i-1))/(batch2.ti(i)-batch2.ti(i-1));

Matos-Torres 20
end
figure(4)
plot(petro.ti,ff_p);
hold on
plot(batch1.ti,ff_1)
plot(batch2.ti,ff_2)
hold off
xlabel('Time (s)'); ylabel('Fuel Flow (mL/s)')
title('Fuel Flow')
%% Air Flow
air_p = (petro.AirFlow); %lb/hr
air_1 = (batch1.AirFlow);
air_2 = (batch2.AirFlow);
figure(5)
plot(petro.ti,air_p)
hold on;
plot(batch1.ti,air_1)
plot(batch2.ti,air_2)
hold off
xlabel('Time(s)'); ylabel('Air Flow (lb/hour)');
title('Air Flow Comparison');
%% Fuel to Air Ratio
ratio_p = (3600.*ff_p./5.7)./air_p; % 3600 mL/hr = 5.7 lb/hr
ratio_1 = (3600.*ff_1./5.7)./air_1;
ratio_2 = (3600.*ff_2./5.7)./air_2;
figure(6)
plot(petro.ti,ratio_p)
hold on;
xlabel('Time (s)'); ylabel('lb Fuel/lb Air')
title('Fuel to Air Ratio')
plot(batch1.ti,ratio_1)
plot(batch2.ti,ratio_2)
hold off;

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