Sterling Engine car - Page 1
Forum section: electronics / general

author: ADC-1995
author_rank: Regular Contributor
timestamp: June 25, 2016, 02:09:56 pm
content: The Sterling engine has been brought back from NASAs research and this tech claims to have it working. It the generator for an electric car system."MacDowell coupled the engine with existing hybrid technology, creating a system that will deliver 58 miles per gallon to a Ford F-150 and at least 100 miles per gallon in a smaller SUV."Another possible world changer. Claims less than 40 gallons to cross the united states. Lets wait and see....http://www.foxnews.com/leisure/2016/06/15/man-builds-100mpg-engine-using-200-year-old-technology/http://www.khou.com/features/san-antonino-man-has-engine-that-gets-100-mpg/24267392NASA's Sterling engineThis video has the classic narrator with shaky text overlay.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 25, 2016, 02:28:45 pm
content: Note the section on fox news - leisure. Definitely a hoax. If it isnt than where are the papers from the claimed university?

author: ADC-1995
author_rank: Regular Contributor
timestamp: June 25, 2016, 04:44:13 pm
content: I agree. I was reviewing the Texas A&M news and nothing mentions this revolutionary tech. I would think even a partnership they would put a plug in:http://research.tamu.edu/news/

author: apis
author_rank: Super Contributor
timestamp: June 25, 2016, 05:18:44 pm
content: Stirling engines have many desirable properties: main advantage is that they are efficient, silent and can run on different fuels. Their main disadvantages are that they have low power density and long start-up time. The disadvantages make them unsuited for use in cars but a hybrid electric system could in theory circumvent the disadvantages so it might not be such a bad idea. Making it work is one thing, being able to manufacture them in a cost efficient way is another. The internal combustion engine is a lot simpler to manufacture so will inevitably be cheaper I suspect.Stirling engines are perfect for submarines though:https://en.wikipedia.org/wiki/Gotland-class_submarineO0

author: rrinker
author_rank: Super Contributor
timestamp: June 27, 2016, 12:40:31 pm
content: I've long wondered why all these gas/electric hybrid cars use these complex transmissions to allow both the motor and gas engine to drive the wheels, when for nearly 100 years now we have been building railroad locomotives where the combustion engine drives only the generator and not the wheels. Tune a motor for maximum operating efficiency in a narrow operating range where, since it drives a generator (or more properly, an alternator these days), it can remain, regardless of the speed of the vehicle. Excess power can charge batteries for pure electric operation. The whole thing is more a matter of control system, the hardware for which is pretty well known by now, the rest is just software. The drive system would be extremely simply, same as in a straight electric car, and no complex mechanicals would be required because the engine would be hooked directly to the alternator and only the alternator. Accessories such as air conditioning could be engine driven, or electrically powered as in a pure electric car - either option is again common and a well known design, no challenges there.

author: Kevin93
author_rank: Newbie
timestamp: June 28, 2016, 03:09:09 am
content: The problem with doing it the simple way you suggest is that motor and generator losses will make the fuel consumption about 20% worse than need be.The Volt is basically done that way arranged as a "Series Hybrid". At high speeds the motor/generator inefficiency is unacceptable so a direct mechanical path is enabled by a clutch.The engine speed is not maintained constant but is varied depending upon the power required as that gives the optimum fuel consumption.The Prius is a organized a bit differently where a sun and planet gear allows most of power to be transferred mechanically at high-efficiency while cruising with the remainder going through the electrical path. This is a "Parallel Hybrid"At low speeds or when accelerating it is more like the Volt operating as a Series hybrid.Although you may describe it as complex in fact it is very simple with only the one moving part beyond the two motor generators. No clutches, brake bands, changing gears etc. As in the Volt the engine always operates at its optimum speed for the power required. At low speeds the power required is very low, below that at which the engine can operate efficiently so it will be stopped and the car operate from the hybrid battery until is discharged when the engine will be started to recharge the battery and drive the car.kevin

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 28, 2016, 03:20:17 am
content: Yeah, they can afford to do that on a train or cruise ship because they aren't particularly concerned about weight or size.For the cost, efficiency and power density, transmissions still win.Tim

author: Brumby
author_rank: Unknown
timestamp: June 28, 2016, 03:50:36 am
content: Big and heavy work for trains (for traction) and ships (for ballast).Efficiency in an automobile is a the forefront of everybody's thinking these days - and when you consider how many millions of them there are, it all adds up pretty quickly.

author: IanB
author_rank: Super Contributor
timestamp: June 28, 2016, 04:08:50 am
content: Quote from: rrinker on June 27, 2016, 12:40:31 pmI believe that although this is a compelling engineering solution, the legislation in places such as California works against it. For instance, I think that such a vehicle would be considered a regular gasoline powered car and would not qualify for any of the incentives available to LEVs or ZEVs.As to the argument that weight or size would be a problem, I don't see it. You could have a small, highly tuned engine (think motorcycle) directly coupled to the generator that only runs when a recharge is needed. Engines in conventional cars have to be designed for flexibility at varying speeds and with adequate torque at low speeds to avoid stalling. This makes them larger and heavier than their maximum power output requires. A dedicated power plant running a generator has no such constraints. It can be small, light, and designed for maximum efficiency at one single speed.

author: Someone
author_rank: Super Contributor
timestamp: June 28, 2016, 04:43:29 am
content: Quote from: rrinker on June 27, 2016, 12:40:31 pmThat is close to how the Toyota Hybrid system works, read the phases of operation:https://en.wikipedia.org/wiki/Hybrid_Synergy_DriveThe additional losses in the electrical conversion processes are made up for by all the other energy saving characteristics of the car (the hybrid drive as a power source isn't actually leading in efficency) sizing the batteries is an interesting optimisation problem! The IC engine is still used over a 3:1 power ratio but its kept in an efficient operating regime where efficiency is above to 25%, while using only an IC without energy storage you drop back to only 10-15% efficiency at lower power.

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: June 28, 2016, 04:58:24 am
content: The reason you don't see them in hybrids is because thepracticalrealizable efficiency of a Stirling is nowhere near thetheoreticalmaximum. If you combust fuel at turbine temperatures (2000F) and can dump the heat at 100F, the theoretical efficiency is ~77% for a Stirling which sounds really good.... problem is the practical limit (so far) for an actually built Stirling is around 50% of the theoretical, or about 38.6% efficient in the former example. MOD II was (I believe) the most efficient car compatible Stirling made...actual efficiency was 38.5%...Then you get into manufacturing issues, long term high temp stability of materials, lightweight gas containment, and the fact that current hybrid cars require the engine to start/stop frequently...Modern gasoline engines in hybrids have high thermal efficiency (much higher than typical non-hybrid), the latest Prius engine has a peak thermal efficiency of 40%..... so you're really talking about ~40% vs ~40%....the benefit really isn't there unless someone makes a major advance in the practical thermal efficiency of a StirlingOne thing the Stirling maybe better at - emissions since the burner can be highly optimized...but have no idea what the practice difference is in that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 28, 2016, 06:29:24 am
content: Cheaper fuels would seem to be a trick, but there are two further drawbacks: 1. diesel isn't much cheaper, nor are most fuel oils (which don't need a cetane rating, but still need to burn completely, not leaving soot or ash); 2. diesel needs to be particularly clean (namely: low sulfur) to burn in domestic areas and on roads, and this won't change that at all.The really cheap stuff is bunker C and whatnot, which they can manage to burn in maritime diesels for shipping and whatnot. Lots of pollution, but it's the open seas so, until the consumption gets so huge that the whole hemisphere starts to sour -- it's not a big deal, at least for now. You can swing that in some places, like most of the US midwest, where density is low and airflow is good. Even so, big cities have emissions controls. Geographically unlucky places, like SF and LA, tend to trap smog and need more strict controls (and clean fuel requirements).So, I would imagine you could make a burner that doesn't need a cat, but as far as saving additional money, I don't think you'll find cheaper petroleum-as-in-liquid.Just having alternatives is probably the way to go. Natural gas is cheap right now, even though it's crappy to store on a mobile platform. You could even go as far as wood or coal fired, but setup and maintenance might be too poor for automated use (it's not as bad as it sounds -- wood pellet stoves work very well on their own). But for good performance, or operation at all in the case of pellet feeders -- you'll probably need a separate "stove" part, optimized for each kind of fuel, which means a lot of hardware and cost to change it out.Tim