So I don't know if this would be worth the effort, but I've been kicking this idea around for a while.


Steam needs a heat source, ICE engines get hot. Why not use the heat from the engine to run a steam motor that generates electricity?


I don't know of any hybrids that run off battery alone. but with a regular engine and a steam engine going, shouldn't that get close to charging up the batteries?


Is it worth the weight penalty?

 

A couple of flaws I see off the bat....

1. Added weight AND SPACE of the steam engine and the water storage required for creating the steam. I imagine you'd need to carry ALOT of water to run a steam engine.
2. To produce the steam, you need to heat water. "Heating" involves the transfer of heat. Taking heat from the engine, at least in the winter months might result in the ICE having to come back on to get the engine up to operating temps. That would waste fuel.
3. Efficiency of a steam engine. I don't know how efficiently a steam engine produces electricity and whether that efficiency is a match for the motor/generators in today's hybrids.

 

This sounds a little like getting free hot water out of the wood stove you use to heat the house. I know it's not the same, but I ried putting a copper water coil in my heater, and could barely get any heat out of it for the house.

If you suck heat away from the engine, there's bound to be a penalty of some sort. Probably reduced efficiency because the engine can't get up tp proper operational temperature. ....and then there's the weight penalty.

 

Steam compounding (more likely a Sterling cycle, a closed loop engine using other than water as the working fluid) could generate considerable power. The issue is the weight and packaging. Another issue is the slow response of any external combustion engine. One possible application could be an APU (Aux power unit) to run generators and keep the battery charged. A more likely application would be HD trucks and buses, where the extra efficiency could be more easily recover the up-front cost.

So, the problems to be engineered out:

1. Packaging the condenser. Hard to find real estate with adequate air flow, without mucking up the Cx of the vehicle.
2. Packaging the evaporator or working fluid generator. Most likely source would be the engine exhaust, downstream of the cat-con. Decent amount of heat there at heavy loads, but at light loads, not so much. Dealing with the corrosives in the exhaust will be a materials challenge. Ditto on fully condensing the water in the exhaust.
3. Figuring out the working fluid. Water (or compounds containing it) may work, but again, the issue of materials comes up. Other fluids may present venting toxicity issues (like from collisions). Ideal fluid has high heat of vaporization, low corrosiveness, is not toxic, and cheap. Again, a materials issue.
4. Safety in collisions. Having a high-pressure system (needed for decent efficiency) compromised in a collision brings a whole boatload of safety concerns. Steam burns are a b***h. Keep in mind that your car cooling system runs at low pressures (<15 psi) and it can still parboil you if it's rapidly depressurized. Having a working fluid at 3-500 PSI flash could create some major burns.
5. Cost. Making the whole system cheap enough and marketing it in a way that shows a reasonable payback period. With consistently high fuel prices, this would become easier.

Again, none are anything but engineering problem

 

Let's forget about mehcanical systems and their losses, and focus on something semiconductor/solid-state: http://www.sciencedaily.com/releases...0603110849.htm Thermoelectric generators would use exhaust and/or coolant system heat, low weight, and low maintenance. Then again, the inventor of the SuperSoaker might have a better idea: http://www.spectrum.ieee.org/mar08/6079

-J

 

If those devices can be manufactured at a reasonable cost, it would offer tremendous bonus for a Hybrid drivetrain, as the electricity generated could charge the battery, reducing the load on the ICE. Overall efficiency improvement would truly be a bonus, as the energy is discarded today.

This would kill the Flowmaster business model though.