Was thinking about this on the way into work this morning. The amount of heat that comes off the engine would be a great source of energy if it could be recycled. However, car manufacturers haven't found a way of recycling it just yet.

I found an article that say Honda was trying it but they couldn't compact it down enough or make it cost efficient to make it worthwhile to put into production cars.

It seems to me from looking at current energy saving methods, heat seems to be the next big step (and not just engine heat). Other methods are based on aerodynamics or recycling kinetic energy.

First thing that came to my mind was the nuclear scenario where heated roads in water produce steam. It could work for a car if you concentrated the heat into a small enough space but the additional equipment would increase weight and size. I can't imagine tons of steam being produced either so efficiency vs cost is likely to be a factor.

Heat recycling the way forward? I couldn't find many in-depth articles on this sadly which surprised me.

I suppose if a pipe from the rear of exhaust pipe system was fed into the car, that would save it's occupants from breathing clean air, that someone else could use??

Apologise for stupid statement, must be that time of the month. LOL

IIRC i read an article a few years ago that BMW were investigating using the heat from the exhaust to heat water that would drive a steam turbine.

I think the steam turbine would then suppliment the power of the engine. Not heard anything about it since.

What do you know; search and you shall find. http://www.gizmag.com/go/4936/

There was also something i read about a 6 stroke cycle. The idea being that the engine deliberatly runs hot, and after the exhaust stroke it injects water. This instantly turns to steam and you end up with another power stroke.

article; http://www.damninteresting.com/the-six-stroke-engine

Edited 17 May, 201115 yr by apinner

I suppose it's the size of the heat exchanger equipment. The engine produces heat all over really and the exhaust is probably the best point to collect that heat at becuase the temp will be higher and access is more convenient.

But then what do you do with that heat? electrical systems probably don't add that much to the mpg of a car unless you are running an AC unit at full whack in the desert. the cost of the heat exchanger might be more than the fuel it would save in the lifetime of the car.

An electric car could use the power but won't produce any heat to collect.

When you talk about roads I had a thought a while back that they could include ground sourced heap pumps in roads when they lay them. Roads heat up in the sun and from the wheels of cars passing. You could potential turn your motorways into power stations if it could be passed efficiently to the grid.

http://www.icax.co.uk/asphalt_solar_collector.html

If any company was going to pioneer something like this it was going to be BMW.

Problem with heat is that it can't directly power the engine. combination of heat and water always seems to be option. Therefore more complex, more expensive etc.

Given heat exchange boilers are now increasingly being installed in homes and businesses instead of gas equivalents for about 3 years, be surprised if we didnt see something in our cars soon.

If it could be incorporated into F1 with their hefty budgets first......

Water injection in to the cylinders has been used.

The problem is the temperature of the water is not quite hot enought to be useful.

If it was above 100 C it would be more useful it could be used as steam and then feed back in to the cooling system when the steam/hot water was used.

Need oils to work at 150-200 C plus.

Higher compression ratios was always the route to higher thermal effeciency and slower engine revs so heat was not rejected until it had done all the work it could.

Ideally you would want no cylinder cooling at all ie actually an insulated jacket but components currently cannot operate at those temperature without seizing.

Nice technical thoughts

F1 would certainly be a place to start. Temperatures are even higher there, not to mention budgets!

I think temperatures are hot enough for energy collection of some type, but the technology is too bulky or expensive right now.

Would make a good university thesis for someone this topic :p

Ceramic engines. Then the whole crankcase could be made a semi-conductor translating heat directly into electrical energy using the Peltzier effect. Gains, a constant KERS reserve whilst the engine was running. Other benefits, weight saving on the engines themselves and with the disappearance of massive cooling system, especially on F1. And engines that could stand higher temperatures and pressures without failing.

Due to the number and complexity of components in modern recipricating piston engines there are too many heat paths and energy losses to deal with. Needs simplicification. W-A-N-K-E-L or several clutch connected mini W-A-N-K-E-L-S, or eccentric in-line W-A-N-K-E-L-S attached to a crankshaft (Shades of the early aircraft rotary engines) ?

Make final drive all electric, so that W-A-N-K-E-L operates in a highly tuned state as a fixed RPM generator.

W-A-N-K-E-L design has 3 combustions for each crankshaft rotation and, by virtue of the mass of the piston, could be persuaded to run on a wider range of fuels (Wide Cut).

That's me done, I'm all out of euphemisms.

Perhaps this is the opportunity for NASA to reverse the favour done by F1 on CF panels.

Nick

Edited 20 May, 201115 yr by Clunkclick

Love W*nkel Engine cars and bikes. Reciprocating engines are so 19th century but investment needs to go in to it.

Worked with Norton on their W*nkel bikes and always wanted an RX8 but it needs to be single rotor and turbocharged and then should do reasonable fuel consumption. Super compact, no reciproating losses and bearing loads. Use water injection shortly after ignition to convert cylinder and rotor heat in to power.

Mazda going to continue with W*nkel I heard.

Filling car up would be 25 litres of fuel and 25 litres of water say. Water injection (sometime with added methanol) used in P47, FW 190s in WW2 and gave a significant amount of extra power.

Across all areas of economic activity the last 20 years has been characterised by commercial exploitation of engineering and scientific ideas originating many years before such as the w-A-N-K-E-L. Through commercial exploitation they've literally squeezed the last drop of lemon juice out of the existing fruit. Time to develop a new fruit.

What's needed now is some heavy weight investment in research in new technolgies.

They've been talking about ceramic engines for the last 30 years. Stop talking, start doing.

Something for VW to re-gain its reputation on.

Nick

Edited 20 May, 201115 yr by Clunkclick

Rotary engines are effectively petrol 2-smokes without the oil consumption. Due to low torque, high revs and frankly rubbish combustion chamber shaping, they can't come close to matching the thermal efficiency of diesels.

I seem to remember Saab having a system that stored engine heat for several hours in order to start a warm engine which would be more economical. I haven't heard anything more so I think it must have died

Rotary engines are effectively petrol 2-smokes without the oil consumption. Due to low torque, high revs and frankly rubbish combustion chamber shaping, they can't come close to matching the thermal efficiency of diesels.

Rotarys can be petrol or diesel. Elongated combustion chamber disadvantage can be largely over come by forced induction. Rotarys reve better as there are no reciprocating losses. Higher piston speeds mean combustion chambers are becoming much over square hence heading towards same place as rotary. Rotarys are super compact hence used all the way for model aircraft to tug boats.

Tip seals were the big problem but largely over come by using more exotic materials like titanium.

When I was involved with Norton's rotary that police used and Hislop (you are still remembered Steve) used for IoM it was an amazing bit of kit. Felt like a 12 cylinder or like a gas turbine. The over reving over standard engine was unbelievable hence its IoM win. Same with RX7 etc, paper over standard was amazing as doubling its standard rev limit was easily possible.

Let us hope new Mazda rotary is really something and get used in RX9 and MX5.

Edited 28 May, 201115 yr by lol

There is a lot of research happening looking at doing just this with slow speed diesels on ships. Similar concept to what gadgetman mentions. They are looking to use the cooling fluid to extract heat from. From what I gather there are 2 areas they are looking at, power generation and auxiliary air con applications. I don’t know how efficient they are or how big the boilers would need to be but these would be the main draw backs from what understand.

I’ve got 2 friends in the final year at Uni doing Marine Engineering who have just written thesis’s on just these topics. From what I gather some of the PHD research staff are looking into it also.

I agree with Ken diesels are the place to start at the minute, you can bet if the marine industry start then automotive will follow or visa versa.

Ah interesting. Larger scale application and then condense it downwards into cars. Heat is a tricky one. I believe there is enough heat in coolant fluid or oil to actually make building a car based boiler worthwhile. But using that heat without the majority of it escaping in the first place could be a problem also.

Will have to keep a look out for this type of technology in the marine and automobile industry

Slow speed marine diesels are amazing, thermal effieciency in the 40%. But these engine I use to work on were 5 storeys high, weighed 500 tonnes. Using the heat from the exhaust to create another 1000 hp or so as well as the engine 20,000 hp but it is the space. Heat exchange was the size of a large size plus the steam turbine.

The Fiat Twin Air won the engine if the year and two cylinder petrols and diesels (maybe W*ankel in the Mazda R9) seem to be the way to go with electric systems that produce about half what the internal combustion engine can ie 100KW internal combustion and 50 KW electric. TSI VRS performance with fuel consumption over 50 mpg combined probably.

Edited 28 May, 201115 yr by lol

Rotarys can be petrol or diesel. Elongated combustion chamber disadvantage can be largely over come by forced induction. Rotarys reve better as there are no reciprocating losses. Higher piston speeds mean combustion chambers are becoming much over square hence heading towards same place as rotary. Rotarys are super compact hence used all the way for model aircraft to tug boats.

Tip seals were the big problem but largely over come by using more exotic materials like titanium.

When I was involved with Norton's rotary that police used and Hislop (you are still remembered Steve) used for IoM it was an amazing bit of kit. Felt like a 12 cylinder or like a gas turbine. The over reving over standard engine was unbelievable hence its IoM win. Same with RX7 etc, paper over standard was amazing as doubling its standard rev limit was easily possible.

Let us hope new Mazda rotary is really something and get used in RX9 and MX5.

There is so much nonsense in this that I don't know where to start!

Ok, I never said there was any technical reason for not building a rotary diesel (other than possibly tip sealing, but I don't know enough to comment meaningfully there). What I did say was that rotaries are effectively on a 2-stroke cycle.

Forced induction does not make a flame front advance faster, so an injector or ignitor in the middle of a long thin chamber is still not going to light off the ends faster. Nor will it cause the heat losses through the long walls to be smaller.

Controlling piston speeds affects bore (and/or number of cylinders). It does not affect chamber shape for a good (fast, complete, clean) burn.

"Tip seals were the problem" - Very true, but titanium seals are a desperate attempt to find a solution!

There is so much nonsense in this that I don't know where to start! ;)Ok, I never said there was any technical reason for not building a rotary diesel (other than possibly tip sealing, but I don't know enough to comment meaningfully there). What I did say was that rotaries are effectively on a 2-stroke cycle. Forced induction does not make a flame front advance faster, so an injector or ignitor in the middle of a long thin chamber is still not going to light off the ends faster. Nor will it cause the heat losses through the long walls to be smaller.

Controlling piston speeds affects bore (and/or number of cylinders). It does not affect chamber shape for a good (fast, complete, clean) burn.

"Tip seals were the problem" - Very true, but titanium seals are a desperate attempt to find a solution!

The word "stroke" has no meaning in W*nkels, like all internal combustion engines it has an induction, compression, power and exhaust phase. Flame front speed is easier to promote in a forced induction engine as beneificial turbulence and more consistent density is easier to achieve. Over square piston engine have further for the flame front to travel than under square engine, hence Alfa adoption of twin plugs in their over square engines.

Looks like R9 will not be turbo'd unfortunately but larger capacity by wider rotors, maybe for racing.

I'm pretty sure BMW are looking at bring residual heat recycling in to their cars in the next couple of years. The last I heard about it was a form of electrical recycling using a clever (aren't they always) catalyst type thingie that turns heat into leccy. I guess it would power minor systems or possibly recharge the battery. Personally I just like a warm car, so would be happy with the heat being pumped around some radiators

The word "stroke" has no meaning in W*nkels, like all internal combustion engines it has an induction, compression, power and exhaust phase. Flame front speed is easier to promote in a forced induction engine as beneificial turbulence and more consistent density is easier to achieve. Over square piston engine have further for the flame front to travel than under square engine, hence Alfa adoption of twin plugs in their over square engines.

Well, if you're going to make up your own lexicon rather than use a standard one (performing all 4 of your "phases" once per revolution per combustion volume is defiend as being a 2-stroke cycle), and change the laws of physics to suit yourself (maximum speed of combustion of a given fuel in compressed air at given pressure is a constant in the real World) then there is no point in my continuing this conversation!

Mazda and Audi considering rotary engine partnership - report - FYI (w*nk*l) Engine could be used in production A1 e-tron

The last partnership between Germany and Japan didn't end well, but a new report is indicating that Audi and Mazda are considering a w*nkel engine alliance.

Inside Line says the two companies have had informal talks to explore the possibility of joining forces to develop rotary engines. While it may seem odd that Audi would be interested, the A1 e-tron features a 20 PS (15 kW / 20 hp) range-extending ****el engine.

In related news, Mazda has reportedly developed a new laser ignition system for rotary engines. Details are limited, but the system eliminates the need for spark plugs and allows for better engine sealing as well as reduced CO2 emissions. The engine would likely debut in the successor to the RX-8, but a source indicated that a launch hasn't been green-lighted and the company is seeking funding.

Read more: http://www.worldcarfans.com/111061034082/mazda-and-audi-considering-rotary-engine-partnership--#ixzz1OxBMqlo2

Edited 11 June, 201115 yr by lol

I wonder if you could build a Stirling engine that would run off the heat of an exhaust? This then could run a generator and say power a motor.

I wonder if you could build a Stirling engine that would run off the heat of an exhaust? This then could run a generator and say power a motor.

I was just going to pipe in and mention that!!

Either run it from the exhaust or use the excess heat that would normally go to the radiator.

I was just going to pipe in and mention that!!

Either run it from the exhaust or use the excess heat that would normally go to the radiator.

The size and extra weight of the device has been the main problem. Using a reverse of the fridge cycle and both cylinder and exhaust heat but we need more engine bay space which needs to be achieved by using one or two cylinder petrol or w*nkel engines which are more compact than 4 cylinder and above or diesel engines.

It will have to complete with hybrid technology for cost and space and is likely to loose over that technology it seems to be likely.

Edited 8 July, 201114 yr by lol