BMW Turbosteamer and Thermoelectric Generator Projects Aim to Harness Heat Energy

[Jason]

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BMW Turbosteamer and Thermoelectric Generator Projects Aim to Harness Heat Energy

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30.08.2011

Munich. Even the most efficient internal combustion engine can only convert about one-third of the energy derived from fossil fuels into the mechanical kinetic energy needed to power a motor vehicle. Over the past few years BMW EfficientDynamics has made great improvements in engine efficiency, for example with technologies such as direct fuel injection, variable valve timing, exhaust-driven turbochargers, brake energy regeneration and the Auto Start Stop function. However, about 60 percent of the generated energy is still lost, half of it being exhaust heat, with the remaining half as heat absorbed by the engine cooling system. Finding ways of recovering this lost heat energy is one of the major goals being pursued by engineers working on BMW EfficientDynamics for the future. That is why the BMW Group is involved in several projects, each with different approaches to utilising dissipated heat energy, and at various levels – in research, pre-production and series development. Among the most promising innovations are the turbosteamer, thermoelectric generator, engine encapsulation and a waste heat exchanger for oil heating.

The Turbosteamer and Thermoelectric Generator (TEG) projects are focused on generating electric current from waste heat to improve overall engine efficiency, but each project follows a different approach and time frame. There is great potential for considerable fuel savings if the electrical energy required by all of the systems in an automobile can be produced using waste heat rather than relying solely on the vehicle's generator. This is another milestone behind the philosophy of BMW EfficientDynamics in achieving increased power and performance while reducing emissions and fuel consumption at the same time.

BMW TURBOSTEAMER – modelled after a power station.

In the Turbosteamer Project research and technology specialists of the BMW Group are working on a heat recovery system that is based on the principle of a steam process.

The process of recovering energy from waste heat is already practised on a large scale in modern power generation plants: large gas and steam power stations combine the principles of a gas turbine and a steam circuit to achieve a significantly higher level of efficiency. The gas turbine process is the first phase of the energy conversion and serves as the source of heat for the downstream steam cycle in the second phase.

The BMW turbosteamer is based on this two-stage stationary power generation method – but reduced in scale and design to form a component that can be used in modern automobile engines.

The first-generation turbosteamer – a maximalist approach.

Researchers proved the feasibility of this technology in December 2005 with the unveiling of the first-generation turbosteamer, which was based on a maximalist approach: they designed a dual-cycle system. The primary element was a high-temperature circuit that employed a heat exchanger to recover energy from the engine exhaust gases. This was connected with a secondary circuit that collected heat from the engine cooling system and combined this heat with the high-temperature heat from the primary circuit to create lower temperature heat.

When this design was laboratory tested on the four-cylinder petrol engines produced by BMW at the time, the dual system boosted the performance of these engines by 15 percent.

The turbosteamer today: smaller and simpler.

In order to further develop the system for use in series production, attention was given to reducing the size of the components and making the system simpler to improve its dynamics and achieve an optimized cost-benefit ratio. Thus researchers focused on designing a component having only one high-temperature circuit.

“A heat exchanger recovers heat from the engine exhaust, and this energy is used to heat a fluid which is under high pressure – this heated fluid then turns into steam, which powers an expansion turbine that generates electrical energy from the recovered heat,” explains Jürgen Ringler, Team Leader for Thermal Energy Converters at BMW Group Research and Technology. For the latest generation of the turbosteamer, engineers developed an innovative expansion turbine based on the principle of the impulse turbine, which offered many advantages in terms of cost, weight and size when compared to earlier concepts, and these are factors that are very beneficial when it comes to series production.

“We have made great progress toward achieving our original goal, which was to develop a system ready for series production within about ten years. When completed, this system will weigh only 10 kg to 15 kg and will be capable of supplying all of the electrical energy required by an automobile while cruising along the motorway or on country roads,” says Ringler. Under these conditions the developers are sure that the average driver will be able to reduce fuel consumption by up to 10 percent on long-distance journeys.

Initial integration of a mock-up system in the BMW 5 Saloon.

All of the system components developed on the test bench have been configured to form a module that can be integrated in vehicles. This has been done successfully by installing a mock-up system in the BMW 5 Saloon.

THERMOELECTRIC GENERATOR.

Considerable progress has also been made in the Thermoelectric Generator (TEG) Project that is also focused on series production of an energy-saving component. The two alternative systems developed to date differ in their positioning in the vehicle – one unit is designed for the exhaust system, while the other is intended for the exhaust gas recirculation system. The development phase focused on integrating units in the exhaust system has led to considerable component improvements, especially in terms of weight and size.

Electricity from waste heat – a space-age solution.

The thermoelectric generator converts heat directly into electricity. The engineers of the BMW Group basically refined a technology that has been used to power space probes for more than four decades by NASA, the aeronautics and space agency of the United States. The principle behind this technology is known as the Seebeck Effect, namely that an electrical voltage can be generated between two thermoelectric semiconducters if they have different temperatures. Since the percentage degree of efficiency of TEGs was rather low, this technology was considered unsuited for automotive applications. However, in recent years progress in the area of material research has led to discoveries that have improved the performance of TEG modules.

One principle – three generations.

The first step taken by engineers was to integrate a thermoelectric generator in the exhaust system to generate electrical current. The first such system was shown to the public in 2008 and delivered a maximum of 200 watts, which was relatively low in terms of power efficiency. But the use of new materials and improvements in the weight and size of the TEGs led to rapid new developments, so that the latest generation of TEGs installed in the exhaust are capable of generating 600 watts of electrical power, and it will not be long before the goal of 1,000 watts is reached as research progresses. The current prototype – a BMW X6 – was built as part of a development project funded by the US Department of Energy.

Then in 2009, the BMW Group unveiled an alternative development in this project. Rather than installing the TEG as a separate module in the exhaust system underneath the vehicle, engineers decided to integrate the TEG in the radiator of the exhaust gas recirculation system. In this configuration, customer testing has shown that 250 watts can be generated while CO2 emissions and fuel consumption are reduced by 2 percent at the same time.

What's more, this energy recovery system offers some interesting added benefits, such as supplying the engine or passenger compartment heating with additional warmth during cold starts. And the thermoelectric generator is the ideal counterpart for BMW EfficientDynamics Brake Energy Regeneration. While the brakes generate energy during deceleration and stopping, the TEG functions at its best when driving is really exciting – namely during acceleration. Researchers forecast that TEGs will lead to fuel consumption savings of up to 5 percent under real everyday driving conditions in the future.


The ideal combination: heat management and BMW EfficientDynamics

While some features of BMW EfficientDynamics, such as brake energy regeneration or the Auto Start Stop function help reduce consumption when decelerating or during idling periods, intelligent heat management can do the same when the vehicle is being accelerated and driven. In the future, even before starting the car, insulation and encapsulation of the engine compartment will ensure that the temperature of the drive train is stabilised by residual heat, thus shortening the cold start phase. An exhaust heat exchanger will also keep gearbox oil warm to reduce friction and fuel consumption as well. And a TEG or turbosteamer will supply the vehicle's electrical systems with ample power, delivering benefits when it makes the most sense – while enjoying sheer driving pleasure!

Depending on the vehicle environment and driving habits, heat management can deliver measurable benefits for specific driving scenarios. For both short and long-distance driving various features can reduce fuel consumption. Insulation of the engine compartment, gearbox oil heating with exhaust heat exchangers installed with petrol engines, or the heating function of the exhaust heat exchanger for diesel engines are features that are well-suited for vehicles that are predominately driven over short distances. During longer journeys the thermoelectric generator or turbosteamer add to that. And by utilising synergy effects, heat management will play a major role in reducing CO2 emissions in the future.

[bmwdinamo]

This is why BMW is number one. Always coming up with new technologies that progress the automotive industry into the future... then others follow.

[Kcc]

But there will be no exhaust system. Maybe axleback.

Kcc

[numba1guju]

nice concept...new to me...wonder if its a first?

[IancoleTX]

I think they should make an effort to simplify where possible.. Modern cars are incredibly complex as is, and the more systems you add, the more things will break and wear out.

Further, if the vehicle itself is designed as a disposable item with a shelf life of 10 years instead of 20 due to prohibitively expensive maintenance, what does that do for efficiency?

I think this innovation is excellent and commendable.. it just seems like things are getting so very complex.

[Tag]

Originally Posted by bmwdinamo

This is why BMW is number one. Always coming up with new technologies that progress the automotive industry into the future... then others follow.

lol, I think they have a lot of catching up to do with MB who has come out with way more innovative stuff than all car companies to date combined.

[HermanL]

TEG is just simply not ready yet, all known thermoelectric materials have really low efficiency.

[han405]

Originally Posted by bmwdinamo

This is why BMW is number one. Always coming up with new technologies that progress the automotive industry into the future... then others follow.

unless it is hydrogen..

[SoCali E36]

Back to basics. This came into mind lol

[Fellfromdsky]

very cool!

[BMWPower06]

This is nothing new...I remember a professor of mine teaching us about this over a year ago in an engineering class. Still very cool nonetheless

[Quasimodem]

Harness the steam so we can make espresso and chicks can save money on facials and BMW will actually have gone the extra distance here.

[CarolinaBlue]

Originally Posted by tag824

lol, I think they have a lot of catching up to do with MB who has come out with way more innovative stuff than all car companies to date combined.

Oh really, would you like to back up that bold statement with some facts?

Morgan Stanley thinks BMW has a $2 Billion R

[marcel b]

Originally Posted by tag824

lol, I think they have a lot of catching up to do with MB who has come out with way more innovative stuff than all car companies to date combined.

lol. MB is for sure innovative in safety equipment, but regarding CO2 reduction / fuel economy improvement BMW is leading.... by a mile

[JoeyFiasco]

Originally Posted by BMWPower06

This is nothing new...I remember a professor of mine teaching us about this over a year ago in an engineering class. Still very cool nonetheless

In my first engineering class over ten years ago my professor was predicting the future of solid state electric components and how they will have completely over taken the light bulb industry for example. It's yet to happen all of this will take time to develop and become profitable enough. BMW is not just going to attach a new innovation to a vehicle if the price diff will be too obvious to the consumer. Unless they make it an option.

[mapezzul]

Originally Posted by numba1guju

nice concept...new to me...wonder if its a first?

BMW has been working on these for sometime- the turbo steamer was unveiled back in 2005, and the TEG in 2008. These are nothing "new" just updating about the technology and where it is in development which usually means that we will be seeing a concept in the not so distant future.... because they are giving us back story.

[conradb]

Originally Posted by SoCali E90

Back to basics. This came into mind lol

Sterling engines are pretty cool, I will admit.

[GT1281]

Is this some sort of KERS?

[Diver]

Not KERS, thermal recovery. This stuff is pretty exotic and the efficiency boost is not that great. I think the solution will be light hybrid KERS similar to that used in F1 cars. The ZF 8 speed is designed to allow substitution of an electric motor for the torque converter. That eliminates the starter/alternator used for start stop as well. Coupled with a smallish L-ion battery capable of storing the energy from a 50 mph to 0 stop and there should be a 30% increase in efficiency for the cost of the battery, plus a kick in the pants from a 47 Kw electric motor with full torque at 0 rpm.

[E60orBust]

Originally Posted by Kcc

But there will be no exhaust system. Maybe axleback.

Kcc

That is the first place my mind went too. Depending on whether or not this is standard, I can see it birthing a new class of exhausts; TEG-back systems

Or future aftermarket exhausts will either get a lot more expensive or take a lot more to install like cutting out the 2.3" pipes before and after the TEG and sleeving on the 2.5"+ aftermarket pipes.

[Tag]

Originally Posted by CarolinaBlue

Oh really, would you like to back up that bold statement with some facts?

Morgan Stanley thinks BMW has a $2 Billion R

Mercedes-Benz has 90% of all patents held globally for motor vehicles. But many of those patents are used by all manufacturers for safety purposes, like crumple zone, airbags, anti-lock brakes and more, all Mercedes inventions but now relatively commonplace...

http://www2.mercedes-benz.co.uk/cont...nventions.html

[muskamatt]

Originally Posted by IancoleTX

I think they should make an effort to simplify where possible.. Modern cars are incredibly complex as is, and the more systems you add, the more things will break and wear out.

Further, if the vehicle itself is designed as a disposable item with a shelf life of 10 years instead of 20 due to prohibitively expensive maintenance, what does that do for efficiency?

I think this innovation is excellent and commendable.. it just seems like things are getting so very complex.

+1 It is a nightmare to buy these things out of warranty and it seems like it is just getting worse. Think about this; I can get an e60 with under 75k miles for under $16,000. Now let's say this car only comes with one key and I lost it or I just really need 2 keys for my car...BMW-"that will be $750 sir". Really?

They make these things pretty much impossible to afford 2nd handed. Or even if it is possible to afford, many aren't willing to take the risk on something that can practically bankrupt them at any given time.