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Are there any IC cars out there that do regenerative breaking by running the engine as a compressor while slowing down?
Resha Caner said:In actual production? I don't know of any. I worked on a project with Ford that used an accumulator to store brake energy, but I lost track of where they went with it. I don't think it went to production.
RonL said:Check the jake brake, and at the bottom of the page "engine brake"
http://en.wikipedia.org/wiki/Jake_brake
RonL said:I have put a lot of thought into ways to recover energy from, cars and trucks, and to recover and store this much would involve the use of large, and heavy tanks. The reduced payload would not be justified by the energy recovered from compressed air.
RonL said:Looks like i need to work on metrics a little, I'm still old school
I would look at the compression as 24:1 X 14.69 and think i would end up with a max pressure of a little less than 350 psi, and volume of air in cubic feet, determined by number of pistons, and rpm at start of braking and declining as speed slows down.
Socrates knew more than everyone else, because he knew that he didn't know anything. I've got a book, you've got experience. We both know that experience is more valuable.RonL said:Well NateTG, I'll concede to your calculations, but will stick to my statement.
Did some research, and realized I don't know jacks***
, so i have to use what i have, and that is what engineers have tagged with a spec plate, two tanks R-12, rated at 450 PSI @ 650 degrees F., they each weigh about 200 pounds, and are 12" Dia.X 72" long.
How many of these would it take to receive the energy we are talking about?
Will the high temperatures flash your lubricating oils? and how quick can temperature be removed, before the tanks get too weak to handle the pressure. It seems in my simple way of thinking, that in almost every process of handling energy, mechanical or thermal, a large energy movement requires a large weight of material to handle it.
I think i fit into George Clooney's definition of his two friends "dummer than a bag of hammers", but at age 65 i have done a lot of things and still have all my fingers and toes, and i really do read the engineers spec. sheets.
As for compressed air, i have a link to a site that has something i think is really interesting ( a drawing ) i would change it a little, if you are interested I'll post it.
NateTG said:Assuming the engine does 24:1 adiabatic compression, that works out to roughly 232 atmospheres ~ 23 million Newtons per square meter.
Mech_Engineer said:On the plus side, the idea of using a compressor and tank to store energy rather than batteries and a generator is a sound one and is being worked on by other people right now:
http://www.hydraulicspneumatics.com/200/Issue/Article/False/11985/"
Mech_Engineer said:I'm not sure how you come up with this number, but a piston compressor with a compression ratio of 24:1 and an intake absolute pressure of 1 atm (14.7 psi) will only reach a maximum output pressure of 24 atm (352 psi). There's no way it would put out 10 times that without a mulit-stage compression
Mech_Engineer said:I think the problem with compressing air using the engine for regenerative braking would become a problem when you tried to harness that energy on acceleration. You would have to inject the compressed air back into the cylinders, which would cause an extreme lean condition when paired with combustion and could be quite catastrophic (unless the super-compressed air was only used without any combustion in the cylinder).
NateTG said:My original calculation assumed adiabatic compression at 24 to 1 and came up with that factor of 10 due to heating (the calculation is posted above). I don't have any authoritative references, but wikipedia suggests that diesel engines typically get compression heating to 700-900 degrees C or 1000-1200 degrees kelvin, which is a factor of 3-4 in absolute temperature. This led to the revised estimate of 1000 psi.
NateTG said:At least in theory, compression ignition engines are much less sensitive to running lean than spark ignition engines since there's no potential for pre-ignition. (I was under the impression that existing diesel tech allows for running a leaner mix to scale back power.)
Mech_Engineer said:This is true, so it seems that this specific hybrid technology would only be compatible for direct-injection gasoline or diesel engines. Still, the major concern would be exhaust gas temperatures as leaning the mixture out too much could damage the pistons or valves very easily.
It seems to me that a better way to go would be to have a compressor/turbine in-line with the transmission that could handle regeneration and acceleration.
NateTG said:(Still in pie-in-the-sky land.)
Assuming that this is a compression ignition engine, and it's running a dedicated compressor, are there particular downsides to going to 2-stroke diesel?
NateTG said:I was originally thinking this sort of thing would be a relatively simple modification, but reflection on the storage issue especially suggest that it's not that easy.
RonL said:I'm having a hard time getting my brain to take this in, it seems you need to work against a resistance in order to slow the heavy truck, car, or moving object.
RonL said:I think of my shop compressor, and why i need a 5HP motor, and when does it apply it's power. When the process starts, the first draw of amps goes high, kicking the motor and compressor into action, but because the tank is empty, or low in pressure, the amps fall to a low state as little power is needed to push air into the tank, as the pressure builds, the amp draw goes higher and when the tank is at max pressure the motor is working the hardest.
NateTG said:I'm always looking for new and different things. (Not that I'm all that likely to ever accomplish anything with them.)
Regenerative braking is a technology that captures and stores the kinetic energy generated by a vehicle's braking system. This energy is then converted into electricity and stored in a battery for later use.
Regenerative braking works by using an electric motor to slow down the vehicle, instead of relying solely on the traditional friction brakes. As the motor slows the vehicle, it also acts as a generator, converting the kinetic energy into electrical energy.
Regenerative braking can improve fuel efficiency and reduce emissions by using the stored electrical energy to power the vehicle's accessories and assist the engine when accelerating. It can also extend the life of traditional brakes by reducing their usage.
In IC cars with compressor engines, the compressor is used to convert the stored electrical energy into compressed air, which is then used to assist the engine in powering the vehicle. This differs from traditional regenerative braking systems, which use the stored energy to power an electric motor.
While regenerative braking can provide significant benefits, it is not a perfect solution. The amount of energy that can be captured and stored is limited, and the system is most effective in stop-and-go driving situations. It is not as effective at higher speeds and on long downhill slopes.