Way Beyond the Volt

[dwightlooi]

Can GM leave the pulsatile engine behind?

Regardless of whether someone worships the Global Warming religion or think androgynous climate change is utter rubbish, regardless of whether that person cares a lot about fuel economy or not at all, anyone who has ever driven an electric car or a hybrid in purely electric mode will immediately appreciate the eerie absence of noise and vibration of an electric motor. Afterall, there are no contained explosions, no exhaust pulses and no vibrations from metal slugs going up & down. Put the smoothest V12 next to an electric motor and it suddenly sounds and feels crude. Selling "Green" only goes so far... selling ultimate refinement that just happens to be green goes a lot further.

But, the electric motor is not the only thing in the world with no reciprocating parts, no exhaust pulses and no vibrations. A gas turbine does exactly that. A Gas Turbine in industrial generation operates between 15~20 dB quieter than a diesel generator set of similar output. A turbine engine also have ony one or two moving parts and is traditionally a lot simpler to maintain than a reciprocating engine. In addition, it runs on fuel that weighs a heck of a lot less and takes up a lot less space than batteries big enough to power a fully electric vehicle with decent range.

Traditionally, gas turbines are not particularly suitable for automotive use. Fuel efficiency is worse than with the piston engine and especially so at lower rpms where the achieved compression is reduced. More importantly, turbines respond slowly to throttle inputs. It may be OK for a Boeing 737 to take 3 seconds reach full power after the pilot slams the throttle wide open. It is not OK by any measure to wait three seconds for power to build when you floor the gas pedal in city traffic and then wait another 3 seconds for power to fade after you lift off the gas. A car with this kind throttle behavior is beyond having bad case of turbolag, it is an accident waiting to happen. However, with electric motors driving the wheels and the engine operating only to generate electricity none of these concerns are valid. In fact, because the turbine's only job is to charge and sustain the batteries in can always operate at it's most efficient speed or not at all. Add to that the fact that we can get efficiency that matches and exceeds the best piston diesels by adding an intercooler and recuperator to the turbine system, and turbines become very attractive.

Here's an Idea:-

GM Advanced Propulsion Technology for high-end luxury vehicles

Power Source:

General Electric LV10 Gas turbine generator

Spools: Two

Compressor Stages: 2 x Centrifugal Compressor Stages

Turbine Stages: 1 x Axial, 1 x Centrifugal Turbine Stages

Intercooler: Air-to-water intercooler between compressor stages

Recuperator: Air-to-air recuperator between compressor output and combustor

Output: 100 kWe (134hp)

Thermal Efficiency: 34%

Propulsion Motors:

Front Axle: 1 x 149 hp Permanent Magnet Synchronous Motor w/open differential

Rear Axle: 1 x 149 hp Permanent Magent Synchronous Motorsw/open differential

Total Motor Output: 298 hp

Battery:

Plug-in version: 20 kWh Li-Ion Battery

Non Plug-in version: 4 kWh Li-Ion Battery

Edited October 16, 2010 by dwightlooi

[regfootball]

"you had me at hello"

"you lost with graphics and flow charts"

seriously though, in concept, why not try it?

i truly believe electric motors will ultimately be a major force BECAUSE they are so doggone simple.

[pow]

You lost me with "androgynous" climate change.

[hyperv6]

Someone would have to come up with a new cheaper type plant. What you are wanting to do is very similar to what the Goodyear Blimp used to use. they had a APU turbine they would mount under the Blimp car that would help generate power for the night sign when it still used bulbs. Goodyear has since gone to a LCD sign to not only have a better sign but to remove the APU turbine unit.

It is funny you brougth this up as I was just on board a old blimp car yesterday and was looking at the set up they used to use. This one had Turbine engines that ran the props and the electric both. Till it crashed a few years back. LOL!

The whole system on the older blimps were very similar to what Boeing used in a Airliner in the tail cone to generate power for the airplane.

I know they have since made these units smaller and more efficent for generators. I still wonder how the issue of cost is. These are still not a engine you see fo use in the low end market for Home systems from companies like Generac. They are using engines similat to a v twin Harley that don't leak oil.

These small Tubines are only uses with very expensive generators in industry that can afford them not mass market.

I think with work they could make something like this work but the cost would be much more than any 1.4 or even small deisel engine.

Other factors is repair how much to repair a system that failed do to the lack of care. The Turbines on the road would have to have a large filter system and how many people today check their filter like they should. Takes little dirt to damage the blades. A stationary engine has less issue with this.

[dwightlooi]

These small Tubines are only uses with very expensive generators in industry that can afford them not mass market.

I think with work they could make something like this work but the cost would be much more than any 1.4 or even small deisel engine.

Other factors is repair how much to repair a system that failed do to the lack of care. The Turbines on the road would have to have a large filter system and how many people today check their filter like they should. Takes little dirt to damage the blades. A stationary engine has less issue with this.

Turbines have no economies of scale today and are used only in niche applications outside of the aeronautical, marine and power generation industries. However, there is nothing in a turbine that is "expensive" by design or material. The compressor wheels and turbine wheels are no more complicated to make and require no more exotic materials than your typical turbocharger. In fact, they are a lot simpler than even the crudest 4-cylinder engine -- there only two moving parts compared to over 50. If you think the concentric shafts of a two spool design is a technical challenge, you can always use two parallel shafts -- it'll be like two turbos side-by-side, one driven by and feeding on the exhaust from the other. The reason you use two spools is because a single centrifugal compressor is only good for about 3~5:1 compression. You need two to get to the 10:1 ratio of a piston engine or the 20:1 ratio of a typical aviation turbine engine.

The efficiency enhancing attachments are also proven and commonplace tech. The intercooler is basically the same construct as you'll find in a turbocharged car. The recuperator is simply a heat exchanger between the exhaust and the compressed air. If you really want to go "crude" something similar to the heat exchanger found in those gas fired wall heaters an old home is basically the same concept.

Actually, it is a fallacy to assume that turbine systems have larger filters. They don't. The filters may be very big compared to the size of the turbine engine itself. But the filter is about the same size as you'll find in a piston engine of the same power output. This is because both burn fuel to make power, and both burn fuel at the same fuel-to-air ratio. For Gasoline, this is about 14.7 parts air to 1 part gasoline. Hence, a 100 hp engine must burn a given amount of fuel and ingest a given amount of air per minute. This is roughly the same whether regardless of the engine type. The only difference is that the Turbine is a lot smaller and moves the same amount of air by spinning a lot faster.