The split-cycle engine: a leap from the four cycle engine?

[Darth_Yuthura]

In recent years, the question of making cars more efficient revolved around changing the use of the internal combustion engine to electric motors. The hybrid as it's called is what diesel trains have been using for decades, but only lately has it gained favor with the public.

 

Problem is that the idea of the plug-in hybrid puts a strain on battery capacity and price of the car. Although it's more reasonable for the long run, there are other solutions to the expense of batteries. Vegetable oil sounds great, but it's only good on a VERY limited scale. Hydrogen is simply too great a waste of effort and overhead energy... that's out.

 

I think the best solution is to perfect and use the split cycle engine in addition to... or in place of a hybrid. It's still on the drawing boards, but the split cycle engine has the advantage of being able to store potential energy as compressed air. That allows for much greater fuel economy than the hybrid idea alone. The catch is that this engine can store energy much cheaper as compressed air than electricity.

 

Instead of always compressing air in the cylinders in the four-cycle process, there are dedicated pistons that provide power, or compress air... they don't do both tasks like in a 4-cycle engine. This creates a two-stroke process that is much more efficient than the standard four-cycle engine. With half the # of power cylinders, they go through only two cycles to double the number of times they're fired per cycle.

 

The Scuderi Engine is the name of the design concept. It is very promising for the future of internal combustion engines because it can theoretically double the efficiency from what it is today. Instead of the complexity and price of an electric hybrid, the split cycle engine is very simple and a cheaper solution to fuel economy.

[Boba Rhett]

Why is hydrogen out? Simply using hydrolysis to disassociate water is not very efficient but there are new technologies that will greatly increase the efficiency of this process. Bombarding the water with it's own resonant frequency, for example, would cause separation.

 

I'm not saying this is bad, I'm just wondering why these other alternatives are being ruled out. I totally agree with the vegetable oil statement. It's only a great setup as long as no one else around you has a car that runs on it too.

[RedHawke]

Hydrogen ain't 'out'!

 

The oil companies might want you to think that way though... so when reading articles beware of who writes them and where they get their paychecks from.

 

Rhett is right about the rest...

[stingerhs]

using ethanol isn't out of the picture, neither. yes, ethanol is less efficient than gasoline, but it both burns cleaner and is renewable. both of those qualities alone make it a suitable alternative to gasoline.

 

the problem is that the world is looking for a replacement, and ethanol isn't going to provide that for larger countries like the US. as an alternative, though, it does help us out in the short term while we pursue the eventual replacement which will be hydrogen-based fuel cells.

 

the concept of the split-cycle is a very good one, but its more than likely too-little-too-late. we need a clean replacement that will solve more than the fuel-efficiency problem. there are environmental concerns at stake as well, and as much i would prefer a big, powerful combustion engine in my car, the environment needs looking after more so than my wallet.

[Darth_Yuthura]

If the split-cycle engine is more efficient, then it gets higher miles per gallon. Ethanol and hydrogen require a massive overhaul from the standard car design. The hybrid and split-cycle engine are practical examples of new cars that are easy to introduce to the market w/out the need to alter the means of providing new fuel sources. Gasoline is going to greatly outlast the life of every car on the road, so the next/last generation of cars should be the most efficient before we start using an alternate fuel.

 

Ethanol could even fuel the split-cycle engine, but it's not logical to use corn ethanol. In order to alleviate 15% of our energy demands, 100% of all corn crops must be devoted to ethanol... Very detrimental to the economy.

 

The split-cycle engine is a more affordable version of a high performance vehicle. Because there would not be batteries required, the car is cheaper and more likely to be demanded than alternatives. This is not solely aimed for the market, but the environment would also benefit more than traditional cars with 4 cycle engines. And even if hydrogen doesn't have a huge overhead cost in the fuel, the cars themselves are WAY too expensive. You might as well buy a hybrid instead.

[El Sitherino]

Ethanol could even fuel the split-cycle engine, but it's not logical to use corn ethanol. In order to alleviate 15% of our energy demands, 100% of all corn crops must be devoted to ethanol... Very detrimental to the economy.

 

Before I say anything else, may I see where you gathered this from?

[Darth_Yuthura]

Before I say anything else, may I see where you gathered this from?

 

Alright. I got if from a professor at UW Whitewater. Dr. Marcos Dominguez

 

Since I can't exactly 'prove' this to you, then I don't assume this is enough for you. My point is that food prices have climed because ethanol is detracting from other uses for gasoline... you might as well use agriculture for food and just buy oil from overseas to get the most out of your opportunity costs.

[Aash Li]

Ethanol wouldnt be so bad if they had started using sugarcane instead of corn... sugarcane doesnt leech the nutrients out of the ground as fast as corn does. Besides that, sugarcane isnt a food source for people and livestock...

[Darth_Yuthura]

Ethanol wouldnt be so bad if they had started using sugarcane instead of corn... sugarcane doesnt leech the nutrients out of the ground as fast as corn does. Besides that, sugarcane isnt a food source for people and livestock...

 

Switchgrass is better, but still proving problematic. However, even if that is so, the amount of land used for the ethanol production would be better used for solar energy. It's not a fuel in itself, but the battle we face is making the most out of what's available. Ethanol causes pollution by its manufacture and burning, so we should try to use a clean and perfectly renewable energy instead of ethanol.

 

Crops depend heavily upon high soil quality and that is not renewable if we grow crops on the same land all the time. Solar panels will only need a base capital cost and will endure for a lot longer than agricultural land w/little mainianence.

[El Sitherino]

My point is that food prices have climed because ethanol is detracting from other uses for gasoline... you might as well use agriculture for food and just buy oil from overseas to get the most out of your opportunity costs.

 

No, they increased because gas costs a lot, therefore shipments that would have been made cannot. Due to this, prices go up to compensate for the entire fluctuation of the market.

[Astrotoy7]

You engineering types rattle on about engine all you want, but when your're finished, the public wants to know:

 

when will we have flying cars ...like in bladerunner, not those stoopid hoverjet thingys that exist now...

 

mtfbwya

[Darth_Yuthura]

No, they increased because gas costs a lot, therefore shipments that would have been made cannot. Due to this, prices go up to compensate for the entire fluctuation of the market.

 

That's only part of it. When you have to start importing food from other locations to compensate for what has been lost to the production of ethanol... that's when the demand has exceeded the supply. Beef becomes more expensive because corn is more expensive. Corn is more expensive because there is less of it that it has to be imported from elsewhere.

 

Fuel cost DO have an effect, but the demand exceeding the supply is the most significant reason for the rise of fuel prices.

 

Anyway... that is off the subject of the Split-Cycle Engine.

[El Sitherino]

That's only part of it. When you have to start importing food from other locations to compensate for what has been lost to the production of ethanol... that's when the demand has exceeded the supply. Beef becomes more expensive because corn is more expensive. Corn is more expensive because there is less of it that it has to be imported from elsewhere.

Okay, except corn produced for ethanol is completely separate in crops from corn produced for food. There is no loss of corn or corn/cow land. Ask a farmer if you must.

 

Fuel cost DO have an effect, but the demand exceeding the supply is the most significant reason for the rise of fuel prices.

I agree, but I hardly see what that has to do with corn crops that are grown strictly for ethanol

 

Anyway... that is off the subject of the Split-Cycle Engine.

Not entirely, as you proceeded to claim in your opening post that ethanol is not viable. And then backed up this claim with ridiculous arguments about because we're turning corn into fuel, that's less corn for us to eat. Which is highly untrue.

 

However if you wish to get back to the concept of a split-cycle engine; this is a small attempt to push back the time limit on petroleum based fuel, I think money and time would be better invested in finding a new fuel source. Hell, we'd be better off initiating a nationwide bicycle give-away.

[Darth_Yuthura]

Okay, except corn produced for ethanol is completely separate in crops from corn produced for food. There is no loss of corn or corn/cow land. Ask a farmer if you must.

 

 

I agree, but I hardly see what that has to do with corn crops that are grown strictly for ethanol

 

 

Not entirely, as you proceeded to claim in your opening post that ethanol is not viable. And then backed up this claim with ridiculous arguments about because we're turning corn into fuel, that's less corn for us to eat. Which is highly untrue.

 

However if you wish to get back to the concept of a split-cycle engine; this is a small attempt to push back the time limit on petroleum based fuel, I think money and time would be better invested in finding a new fuel source. Hell, we'd be better off initiating a nationwide bicycle give-away.

 

I DIDN'T bring up ethanol until someone else did... did I? The point behind the ethanol issue is that the land that normally would grow corn or other animal feed detracts from the amount of food is available. Corn used for cows translates to the price of food... not directly though.

 

If we want to feed ourselves, but produce ethanol, we should stop raising livestock and instead grow crops for humans... not animal feed. In doing so, the US agricultural land would provide more food if the land were used for human consumption. By feeding cows and growing corn for ethanol, we detract what can be used for human consumption. Either skip meats, or skip ethanol... there is no way for both to be done with the limited agricultural land we have.

 

-----

 

However, the issue here is the split-cycle engine. Because of the fairly cheap way of storing potential energy as compressed air, a car with a SCE would be able to store wasted energy that otherwise would have been stored as electricity in a hybrid. Because an air tank is cheaper than batteries, it's more affordable than most hybrids... more ideal for everyone.

[stingerhs]

hey, don't get me wrong. like i said in my post, ethanol is not the solution. if anything, it should be a temporary alternative that will help with problems with supplying gasoline.

 

and as a guy who is really into fast cars, i do like the concept of the split-cycle engine. if it can help to boost power while increasing fuel economy, then i'm all for it. that's why i liked the hybrid concept to a point. while adding an electric motor to a conventional engine does boost the power output, the extra weight of the batteries is detrimental to performance. while the split cycle engine doesn't completely solve the weight problem (air lines, regulators, air tank, etc), it is a considerable improvement over the hybrid.

 

what would help this concept take off would be for one of the major car manufacturers to apply this technology to a sports car of some kind. just think about it: a car that will do 0-60 mph in under 4 seconds and get 30+ mpg. that would turn some heads.

[Darth_Yuthura]

The issue I'm going for is a new concept that can store excess energy in a cheaper way than batteries. Compressed air is a much more affordable way to store energy that otherwise would be lost in a four-cycle engine w/out a generator. Although split-cycle could also be applied to a hybrid, the air tank advantage is reduced and even makes the car more expensive. The idea is to lower the initial cost enough to attract buyers.

[Bimmerman]

First off, please post a link to more information about this engine design. It sounds like a good idea, but without some numbers or further information it sounds like a theoretical design study. I would really like to see some facts about the design before I start believing the hype. From what it sounds like there is nothing new here technology wise that could have prevented it from being in cars before now....so why isn't it? Sources...good.

 

Secondly, as to the idea that the most efficient engines use the least gas....that's not entirely true. The most efficient engines can crank maximum horsepower per quantity of fuel used per displacement-- Honda's Civic Type-R engine cranks out 218 horsepower out of 2 liters and gets mid 20s or better in fuel mileage (japanese market spec). That's an efficient engine. BMW's E46 M3 engine displaces 3.2 liters and puts out 343 horsepower in European trim, all while returning around 20-22mpg average. That is another high efficiency engine. The Corvette Z06 displaces 7 liters, 505 bhp, and has been known to average 25mpg. Also a high-efficiency engine. Formula 1 cars displace 2.4 liters, put out near 800bhp, and return nearly 5mpg at full throttle- yes, that is an incredibly efficient engine.(For reference, my friend's BMW 325i returned 11mpg at an on-track high performance driving school, so 5mpg is astounding.) None of these are aimed at the majority of car buyers, true, but they are illustrative examples.

 

My 1995 Subaru Legacy would be an example of a non-efficient engine- 2.2L four cylinder, 135 horsepower, and I average 22mpg including highway. My driving style is partly to blame, but the best I have seen is 25mpg in mixed driving while emulating the driving prowess of a 90 year old pensioner.

 

And for a personal example of high efficiency, I recently drove a 1994 BMW 325i (2.5 L inline 6 cylinder engine, 190 horsepower) back from Utah averaging 85-90mph(with some triple digit spurts) and averaged 32.4mpg from Ticaboo until I hit traffic in Denver. All the current hoopla of "we have 7 models that get better than 30mpg highway" is the same kind of marketing idiocy saying you need cars with a) cupholders or b) more than two cupholders. 30 mpg is not an accomplishment, it is embarrasing for a mass-market oriented vehicle not to obtain. Unless it is American, apparently.

 

It is trivially easy to make a low horsepower car with great fuel economy, but that engine is not very energy efficient. Lots of power from small displacement using little fuel is one way of measuring high efficiency. It is more expensive to make a good engine than an engine that has acceptable power but good mileage, hence why nobody associates power per fuel used per displacement as the measure of efficiency. Some small cars do get great mileage with good power for the engine. Most....don't.

 

None of these engines are turbocharged or supercharged, that's a completely different matter.

 

Now the point was made that hydrogen requires massive changes in vehicle design.....that is flat out, entirely wrong. Honda has the FCX, Toyota has something similar. Both of those are hydrogen fuel cell vehicles, converting hydrogen into electricity. The car isn't redesigned for the powertrain, only the engine/motor driving the transmission is different along with the packaging. Hydrogen does not even require the fuel cell route either, despite everything that the media/honda/toyota/etc want you to believe.

 

BMW has a fully production car, built on the assembly line with the rest of the 7 series, that can run on either gasoline or hydrogen in the same engine!!! That means, hydrogen is a workable fuel for internal combustion. BMW's engineers say that if they did not have to tune the car to run on both fuels they could have gotten over 600 horsepower from the 6 liter V12 with astoundingly good fuel economy-- high efficiency. Two ways to go about the same task.

 

Now as for hybrids, sure they get good mileage, but they are no more efficient than a small VW Jetta/Golf TDI diesel- worse fuel mileage in many cases in fact. And those batteries aren't good for the environment either. Hybrids aren't the mileage champs that the news/political windbags/automakers/toyota want you to think either- the Euro market only VW Polo was tested to get 71 mpg on the same route a Prius got 43 mpg. If hybrids were diesel/electric they'd be worth the extra coin, but as is, I see them as nothing more than a way to feel good about the environment by spending more than you needed to.

 

As for ethanol....HAHAHAHAHA. Bad idea. The only thing ethanol is good for is in turbocharged engines, since the chemical characteristics of ethanol allow you to make much more power out of the same amount of fuel. Otherwise, given the 33% less power and mileage from ethanol, it's not worth it unless the price is 33% less.

 

As a parting thought: you may have heard about hypermiling recently. The only thing I will say is DO NOT DO THIS!!! Tailgating semi's, running stop signs, turning off your engine while going downhill(and therefore losing power assisted brakes, steering, etc) is a good way to kill or injure yourself and others. Hypermiling is for fools. Please don't do it. Burn the extra gallon to get there safely, a hospital visit is much more than a mere $4 for a gallon of gas.

 

Sorry for the long post/rant. Vehicle\Racecar Design is my specialty.

[Darth_Yuthura]

I stand by what I said earlier by the word 'efficient.' By having a dedicated firing and compression piston, the engine only gets a marginal increase in efficiency. Some designs of split-cycle engines don't live up to the most efficient 4-cycle engines... but those cannot store potential energy as compressed air. All the air compression immediately is used for the combustion.

 

The split cycle also has the advantage of two modes for using energy that otherwise would have been wasted when the car is idle.

 

1)The air compression piston can function for the purpose of filling the pressurized air tank, but the firing piston does not operate. This is used to convert kinetic energy from the car to compressed air.

 

2)When the car's air tank is filled, the compressed air can be used instead of the compression piston. Because the compression piston isn't operating, the engine can generate more power with the engine not having to compress air in this mode.

 

This is not exactly a more 'efficient' engine, but this design allows for a cheaper alternative to batteries to store excess energy or to obtain better milage.

 

Google 'split-cycle engine.' You'll get it from:

 

wardsauto.com

autofieldguide.com

motortrend.com

[RedHawke]

Ethanol and hydrogen require a massive overhaul from the standard car design.

Hydrogen certainly does not... my evidence is in my driveway 4-5 days a week.

 

 

Looks very much like a normal Ford Focus to me... the technology will be made into cars we are comfortable with already.

 

The split-cycle engine is interesting as a possible stop-gap measure, but we seriously need to re-think the use of fossil fuels altogether. Even Hydrogen isn't perfect but at least you aren't consuming anything finite in the fuel cell process.

 

As always, this is just my...

[Darth_Yuthura]

The split-cycle engine is interesting as a possible stop-gap measure, but we seriously need to re-think the use of fossil fuels altogether. Even Hydrogen isn't perfect but at least you aren't consuming anything finite in the fuel cell process.

 

Where do you think that hydrogen comes from? How do you think that hydrogen came from water and into your tank?

 

Although it is not itself a fossil fuel, the energy that produced the hydrogen came mostly from coal or natural gas. And in producing hydrogen, it resulted in a huge investment of energy that is wasted like electricity is lost when transmitted over a long distance.

 

Hydrogen isn't a fuel in itself like nuclear, coal, or oil. It's more like another means of transmitting energy that came from another source. In fact, a hydrogen economy is worse than what we already have... because it increases our energy demands more than it is.

[Darth_Yuthura]

One other thing:

 

How much did that hydrogen fuel-cell powered vehicle cost? I've heard upwards of over $100 grand. The split cycle engine is a more affordable and more realistic solution to the hybrid electric. Fuel cells may be the only fuel in the future, but the present belongs to the internal combustion engine. It will slowly whittle away, but that's still a long way off.

 

I agree it's better to switch from fossil fuels to another source of renewable energy, but fuel cells are not economic... at least not for a long time.

[RedHawke]

Where do you think that hydrogen comes from? How do you think that hydrogen came from water and into your tank?

 

Although it is not itself a fossil fuel, the energy that produced the hydrogen came mostly from coal or natural gas. And in producing hydrogen, it resulted in a huge investment of energy that is wasted like electricity is lost when transmitted over a long distance.

Fossil fuels are where the oil companies make hydrogen from, yes.

 

But it isn't the only, or logical, source of hydrogen, here is Sac our state electrical utility (SMUD) has a Hydrogen fueling station that uses only its own solar power and makes the hydrogen on the spot, with a 0 carbon footprint (meaning no fossil fuels expended to make it).

 

They are working on versions you can install in your home that do something similar (the projected size of a refrigerator), imagine that. Now feel free to believe what you want (or what propaganda the oil companies want you to believe), but I have seen differently, that the technology is quite viable, and something that we indeed should pursue.

 

Is hydrogen the be-all-end-all? No. But it is far, far better than what we currently are using... and something the oil companies are fighting tooth-and-nail, for their very survival.

 

Edit: The costs for these vehicles will be a little higher in the beginning (like any new technologies), but they will more than likely settle into what the markets will allow. (This was the answer I got BTW when I asked about the price. )

 

Edit2: Since this thread is about the split cycle engine I will cease for now as we are getting somewhat off topic.

[Boba Rhett]

Hydrogen isn't a fuel? What? When did it stop being one? Was there a vote? What are you talking about? Hydrogen is a flammable gas that contains energy that can be converted to another type of energy. Petrolium is a flammable liquid that can be converted to another type of energy. Fuel is any material that can be burnt or altered in order to obtain energy.

 

The rest of your sentence is equally as mind blowing. Literally. It's blowing my mind. My mind done be gone. Yes, hydrogen is a means of "transmitting" energy that came from another source into another, readily usable, energy source. That's because ALL fuels are a means of "transmitting" energy that came from another source into another, readily usable, energy source.

 

Also worth pointing out, the Americas are to coal as the middle east is to oil. This makes the use of coal plants to generate electricity to, in turn, generate hydrogen all the more appealing for us. Broken down further: A. We have a crap load of coal B. It's easy to make electricity using said coal. C. ??? D. Profit.

 

We could even sidestep the use of fossil fuels all together and use nuclear power plants to generate the required electricity. Broken down further: A. Electricity is one thing we're very good at making. B. We can use electrical energy to generate hydrogen which can then have its energy used to power vehicles more efficiently than the electrical energy was capable of doing itself. This is all, all a game of converting one type of energy into another, more useful type.

 

 

Holy god, I think I'm going to need blood pressure medication prescribed to me just for this thread. Wait, do they make medication specifically for nerd rage now?

[ChAiNz.2da]

Holy god, I think I'm going to need blood pressure medication prescribed to me just for this thread. Wait, do they make medication specifically for nerd rage now?

Why yes, yes they do

 

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[Darth_Yuthura]

Fossil fuels are where the oil companies make hydrogen from, yes.

 

But it isn't the only, or logical, source of hydrogen, here is Sac our state electrical utility (SMUD) has a Hydrogen fueling station that uses only its own solar power and makes the hydrogen on the spot, with a 0 carbon footprint (meaning no fossil fuels expended to make it).

 

They are working on versions you can install in your home that do something similar (the projected size of a refrigerator), imagine that. Now feel free to believe what you want (or what propaganda the oil companies want you to believe), but I have seen differently, that the technology is quite viable, and something that we indeed should pursue.

 

Is hydrogen the be-all-end-all? No. But it is far, far better than what we currently are using... and something the oil companies are fighting tooth-and-nail, for their very survival.

 

Edit: The costs for these vehicles will be a little higher in the beginning (like any new technologies), but they will more than likely settle into what the markets will allow. (This was the answer I got BTW when I asked about the price. )

 

Edit2: Since this thread is about the split cycle engine I will cease for now as we are getting somewhat off topic.

 

With all due respect, companies would find it's way too expensive to use solar power to produce hydrogen. That hydrogen may have come from a renewable source, but it was not economic and undesirable to investors.

 

Despite all the reasons to use solar and wind for energy today, they are simply not economic... because their extreme capital costs result in high interest payments that eclipse the operating costs. That solar power that produced the hydrogen you spoke of... it is not simply propaganda. Although oil companies have all the reason to silence renewable energies, there is not denying that solar and wind bear extreme capital costs and are not always reliable if the weather is bad for conditions.

 

In addition, to provide enough hydrogen to replace gasoline, you would essentially have enough of those stations you mentioned to accommodate everyone in the US. There are very few hydrogen stations as it is and setting something like that up would be an extreme measure. That requires a significant amount of time to implement.

 

In the meantime, gasoline is the predominant fuel in America and we can't look that far into the future if our current needs are not met. Hydrogen is still in its infancy and is not logical in any degree at this time. Instead of a revolution to take place over a short period like with nuclear power, we should use what we have more efficiently and make the transition when it is ready.

 

Hydrogen is a drastic revolution. The split-cycle engine is a simple solution with drastic effects for today's needs.