Well, I have been lurking around and asking a few questions, but I guess I will go ahead and start a build thread to document the project
I am a senior at Auburn University studying mechanical engineering. I have had a passion for exploring God's creation ever since I was young when my family would go on camping trips, hikes, and bike rides. Growing up my passions have only grown, I have become enthusiastic about mountain biking, backpacking, fly fishing, climbing, and other fun outdoor activities! I have had the opportunity to ride my bike on some great terrain in Alabama (my home state) as well as Wyoming, Virginia, and British Columbia. While biking is one of my favorite outdoor activities, I have also gotten to see some amazing places backpacking, and fly fishing. I have also developed a passion for photography and videography over the years and am not an expert, but I really enjoying capturing beautiful scenes and adventures.
Early in the fall 2015 semester, Jonathan and I decided we needed to do something big with our lives. We both had dreamed of a road trip across the country for years, but we wanted to do much more than just satisfy all of our desires for adventure and recognition. We decided to make the main focus of our trip bringing glory to our God and Savior.
We both have a zeal for exploring God’s creation and we are both studying mechanical engineering and nearing graduation. So we decided to make good use of our passions and talents on this trip. After a series of events consisting of everything from prayer filled consideration to Jonathan’s crazy ideas to job fairs at auburn, we decided on the ‘big thing’ that God was leading us to do with our lives. We decided to buy a school bus, design a system that would enable us to use waste vegetable oil as fuel, and explore the country seeking God’s glory the whole way.
November 2nd, 2015:
We bought a bus.
Its a 1997 International 3800 with a 7.3 liter t444e turbocharged diesel with around 140k. The chassis is a bluebird conventional handicapped chassis. 2600 dollars and It came with a wheelchair lift which we later sold (cha-ching!). It is going to be perfect for our conversion.
Handicap bus, only had 4 or 5 rows of seats
The project can best be divided into at least 3 main parts, filtration system, veggie conversion, and RV conversion.
We are both in engineering so we did extensive planning/designing of our filtration system and veggie oil conversion..
In order to run the bus on waste vegetable oil, we determined we needed to filter the wasted oil to 10 micron absolute. By increasing the viscosity of the oil with heat and simulating a gravitational acceleration of 4,265 m/s^2 on the oil using a centrifuge, we were able to drastically speed up the settling velocity.
Terminal velocity of a sphere falling through a fluid given by stokes law:
Rho_p: density of particle
Rho_f: density of fluid
Mu: Dynamic viscosity of fluid
g: Local gravitational acceleration
For a 50 micron particle in rapeseed oil at 24 C, the settling velocity is as follows:
Mu = 78.8 cP = .0788 kg/m*s
Rho_p = 1200 kg/m^3
Rho_f = .9073 g/mL = 907.3 kg/m^3
G = 9.81 m/s^2
R = 2.5e-5 m
V_s = 5.06 e -6 m/s = .3036 mm/min
For the same particle at 70 C and gravitational acceleration of 4,625 m/s^2
V_s = .00963 m/s = 578 mm/min
::end of technical stuff::
We designed and manufactured the centrifuge using parts from the rear axle of a jeep for the bowl and shaft. The centrifuge uses an electric motor that spins at 1,750 rpm and exerts an acceleration 435 times greater than earth's gravitational acceleration, the oil forcing unwanted particles and water to the wall of the bowl and allowing clean oil to be sprayed out the top. This oil is then collected in a sump where a control system allows it to be pumped out through a filter and into a clean oil tank. The system is protected from overflow using a 107db alarm.
Not the best picture but its all I have, it has performed great, filtered 550 gallons so far in 2 days. We got all our vegetable oil from some local folks who were getting out of the veggie oil thing, they were very nice and helpful
layout of the filtration process:
After researching, we determined if we could get vegetable oil to be similar in viscosity to diesel fuel, we could effectively use it as fuel. This means the vegetable oil must be heated to a temperature of around 175 F before it can be injected. After many revisions, we arrived at a design. The concept of the design is as follows:
-Start the engine on diesel fuel
-Allow engine to heat up
-Use hot engine coolant (180-200 F) in a closed heat exchanger with vegetable oil
-Use filter heater to warm oil as it passes through filter
-Ensure that vegetable oil has been appropriately heated
To achieve this, we used two fuel tanks along with a series of valves, this can be seen in the following figure:
We opted to do 2 separate filters where veggie will never enter the stock filter, we did this because the stock fuel bowl is HUGE and would be tricky to clear all the veggie out of it.
Scored a stock tank out of a similar bus about 1.5 hours from where I live:
We tested the system the day we plumbed it and believe it or not, everything worked with no issues! We were well in the temperature range we needed to be in (70-80 C) to maintain a viscosity similar to that of diesel. We are using a flat plate heat exchanger with insulation wrapped around it along with a filter heater.
Goals for the RV conversion are as follows:
-Sleep up to 5 on the bus
-Store adventure gear, notably, 2 dirtbikes, 4 mountain bikes, 2 kayaks
-Outdoor grill, Gas/electric, and stove plumbed to propane
-Seamless electrical system, able to plug into shore or run use batteries
-Always have 110v ac and 12v dc available.
-Small living area
-Space for compact filtration system
We were able to get a gas/electric fridge, converter, lots of wiring and outlets, sink, air conditioner, and miscellaneous other things all for free from this rotting camper that was at my grandfathers farm.
We also scored some nice 12x1 pine that has been awesome for the conversion.
The layout is as follows: a double bunk in the back passenger side, top bunk only in back driver side. underneath this bunk will be a filtration system and storage. infront of the top bunk is a bathroom and fridge, then across from that is the kitchen. In the front of the bus will be a living area with a couch, navigators table and, for our trip, we wil be taking a 275 gal tote full of oil.
here are some pics of what has been done so far:
The bunks have a nice large storage area under each one, it worked out very nice! Not sure how many of yall have these gas/electric fridges, but ours only works if it is very level.. bit of a pain but its nice when the bus is level anyway.
I designed the electrical system such that all the switching is done automatically when you hook up. We have a 30 amp system.
So yah, that is pretty much where we are, I have been working on installing the electrical recently and I am very close to finishing it up. Hopefully everything works as we plan!
Just the other day we cleaned it out real nice and put Christmas lights in it and a tv and propane stove... it was a good time, watched a movie then woke up to bacon. Cant wait till we get things a little more permanent. Its gunna be fun.
Well if anyone made it this far reading... cheers to you! and thanks for checking it out, hopefully more details will come in the following weeks, everything has to be done by may 14 or so but I don't have ample time to work on it.
more pics here