Supercar Engine Part Deux

I've refined my ideas for the engines quite a bit.

After doing some thermodynamic calculations and expansion energy calculations, I have come to the conclusion that approximately 9.7% of the energy in C17H32O2 is expansion and the other 90.3% is thermal. Note that this does not include standard kinetic energy for being above 0K or nuclear energy, etc.

I chose the molecule C17H32O2 because I found that Biodiesel is composed of oils in the C12 to C22 range, with a certain percentage C, H, and O by weight. Using molar masses I coverted this mass ratio into a molar ratio and determined the molar formula for the average biodiesel molecule. (Inherent is the assumption of a linear or at least guassian distribution of molecule sizes from C12 to C22.) The particular molecule I chose was a methyl ester. I chose a methyl ester for my calculations based on the fact that biodiesel is formed from Waste Vegetable Oil (WVO) by transesterification to remove sugar parts. Methanol is most often used in this process although Ethanol or propanol could also be used for (apparently) lower yields. So I used this molecule:

CH3OC(O)(CH2)5CH=CH(CH2)7CH3

C17H32O2

This is a mono-unsaturated methyl ester and I think it is representative enough of Biodiesel for my calculations.

At any rate, the thermal energy contained is important enough to worry about, as the mechanical energy of expansion is about 1/10th as much. However, the mechanical energy is enough that we don't want to throw it away either!

First we build a standard diesel engine that burns biodiesel. Most of our modification has to do with the intake, exhaust, and cooling systems that support this engine. However, one of the main modifications is that it is now a "medium speed" diesel engine which runs at a fixed rpm to produce a specific frequency of alternating current. This current is then fed into our supercapacitor stack (SCS).

Instead of a regular cooling system, we are going to cool the engine block, exhaust, and oil all through heat exchangers. This heat is then transferred to hosing which contains an organic fluid which boils at 50-60'C. This boiling fluid is used in a steam turbine arrangement to produce further power. The electrical power from the steam turbine is also funneled into the SCS.

Because we are scavenging more energy from the same amount of fuel we can spend a bit of our margin to make our system cleaner and more efficient. We can do this by installing an oxygen condenser. Our exhaust, once cooled, is run through an oxygen condenser. CO2, N2 and H2O are released to the ambient environment while O2 is recirculated into the "air intake" (which is actually an "oxygen intake." Biodiesel does not contain nitrogen yet NOx are produced by diesel engines. This is the oxidization of N2 present in the air and which enters through the air intake. By providing a 90%+ combustion atmosphere we can reduce or eliminate NOx and also provide quick and complete combustion. Higher cetane fuels ignite earlier in the timing of a diesel and thus allow more complete combustion by the time the stroke has finished. By having 90%+ oxygen instead of ~21% oxygen we can allow even fuller and more complete combustion. This type of system could well be marketed in north america as a "clean diesel." One of the reasons diesel engines are unpopular in north america is the common perception that they are dirty. Biodiesel is, in fact, quite clean and an excellent solvent. As a result the system described above would, in fact, be an extremely clean running engine, producing only CO2 and H2O with no NOx or SOx produced.

The SCS, or supercapacitor stack, is an integral part to this system. It is a decent way to get multiple sources of energy converging. Supercapacitors currently do not have the energy density required to be the energy source for a vehicle. However, unlike batteries, supercapacitors have a high power density. This allows a SCS to act as a great power source for electric motors directly attached to wheels. A SCS would actually be fairly heavy but research in this area is advancing quickly. It may be true that a SCS could be reasonably weighted... I have not yet done any calculations. I would first calculate the maximal reasonable acceleration required, then the electrical draw by the motors, then calculate what is required of the SCS. It would likely be that either a larger diesel (and hence heat) engine is required or a larger SCS is required as an energy buffer. Some equilibrium between these sizes would likely yield optimal conditions. Naturally the draw will be larger for larger vehicles, such as passenger trucks, but these vehicles also have more space and weight capacity for a SCS than a commuter vehicle. I see this design as scalable.