Sixty-five years ago, the United States has begun trial operation of a truck tractor Kenworth 500 series. It was a gas turbine engine, and the tests took place in the framework of the joint project of Kenworth Trucks and Boeing. The engine is 175 HP, but weighed only 90 kg! The train made several commercial flights between Seattle and Los Angeles (≈1,850 km), but, alas (and other observations): extra urban fuel consumption reached to 240 l/100 km! However…
1. However, in September 2015 on US roads came the first turbo-electric trucks with engines of the company “Wrightspeed Powertrans” Ian Wright (Ian Wright), co-founder of Tesla Motors. One of them in the photo. Compared to diesel vehicles of the same weight here: fuel economy is more than 60% and emissions well below the most stringent standards, including California. Trucks are in trial operation, and mass production of power plants of a new type is expected in the near future… In the second picture: perspective of main tractor
2. Microturbines, by definition, is a compact gas turbine engines. They are well accustomed in the energy sector in the composition of microturbulence (hereafter MTG), which are used for Autonomous power supply of buildings and structures. Moreover, unlike internal combustion engines, virtually all the heat generated by the combustion of fuel, is concentrated in the exhaust system, therefore, for the engine cooling system is not needed, and energy learned to use it in the same hot water systems, therefore, the theoretical efficiency of MTG-installations up to 80 percent or more. Photo concept car microturbine with heat diagram
3. Microturbulent made in the form of construction with one moving part – a rotating shaft, which is coaxially arranged with the generator, compressor and turbine directly. The shaft rotates at up to 100,000 rpm under full load and is supported by air bearings that do not require liquid lubrication and periodic maintenance. In addition. In one small in size the unit has a compressor, combustion chamber, heat exchanger, directly to the turbine and permanent magnet generator. The latter is cooled by RAM air, which eliminates the need for the cooling system. In General, the unit operates without vibration and with low noise even without the use of special screens. By the way, on the last point. The estimated noise level for MTG – no more than 60 dB, for a turbo big diesel commercial trucks – at least 72-75 dB. For reference (sorry, Wikipedia): “60 dB is moderately loud, normal conversation, normal for offices”…
For understanding (photo): it looks like the microturbine from Wrightspeed is rated at 184 kW and a weight of 41 kg with generator. To remind you what it looks like (and how much weight) diesel engine of standard Euro-6 rated at 250 HP with a clutch and transmission?
4. Features for practical operation
– Simplicity of design. It is clear from the description above, for example, a schematic diagram of a microturbine Capstone C30: 1. The input air pipe; 2. Generator with air cooling; 3. The outlet for the exhaust gases; 4. Recuperator (heat exchanger); 5. Injector; 6. Combustion chamber; 7. Housing with thermal protection; 8. The impeller of the turbine; 9. Blade bearing; 10. The compressor wheel; 11. Shaft. It’s all…
– High theoretical reliability. Unlike internal combustion engines where it is necessary to convert the reciprocating motion of the piston into rotary crankshaft, there is only rotation of the shaft. Also in design there are no alternating loads, vibrations, a complex system of gas exchange and its drive (timing). Therefore, the resource of microturbines can reach 80-90 thousand hours, or about 8-9 years in operation 24х365.
– Low requirements to the lubrication system. The latest generation of micro-turbines, typically used petal gas bearings, in theory, do not require lubricating fluid: the working carrier gas (air) layer between the stationary housing and rotating shaft, and – not requiring insufflation (forcing of air into the working area). However the problem is that to “ascent” of the shaft on a cushion of air (the initial time) such a bearing operates in the mode of dry friction. This is solved by the use of antifriction materials or replaceable friction pads. But there remain problems with bearings operating in the hot zone of the turbines (including at Capstone Turbine Corporation)…
– The fuel. Without going into the details (and the example Capstone – since I started to mention), the MTG can operate on high sulfur fuel content of hydrogen sulfide (H2S) to 7%. So, are gas – compressed, liquefied gas and biogas; liquid: gasoline, diesel, kerosene, ethanol, methanol, butanol, dimethyl ether, biodiesel, sorry if forgot something…
5. The level of harmful emissions. To illustrate the table. However. The figures for the Capstone C30 received on the “open exhaust”: without the use of any technologies/systems of neutralization of exhaust gases
6. Not so simple… for Example, according to energy experts, using MTG, they need fairly regular maintenance. For example, every 8000 h should change all filters, candle, thermocouple every 20 000 h – injector, online batteries remains open. Necessary inspections or personnel of the manufacturer or its dealer 1 or 2 times a year. So, you will forever be tied to the official service with all its rates. Read more…
– The dust. It is believed that air flow at the gas turbine at least 2 times higher than that of diesel of the same power. However, MTG installed on the roofs of buildings or on the ground, but special closed boxes. And their producers are not limited in the layout diagram, therefore, the air purification system can be quite extensive. You can not say, for example, a passenger car, which moreover, moving along dusty roads. In other words, at least half will have to reduce the interval of air filter replacement.
– Heat. Exhaust gas temperature after recuperator (heat exchanger) can reach 300 °C. energy used in hot water systems or air conditioning systems (absorption refrigerating machine). You can probably allow something similar for a city bus, a vehicle with insulated body (though the refrigeration unit must be new, unknown type), but with difficulty – for a passenger car. Because the heat is too much. Emit 200-250 degrees? And fighters with global warming, what do you say?
– The fuel. Microturbines do mnogochislennye, but this cannot be said about the fuel system of the car. And if there are compressed gas cylinders, diesel fuel in them to fill, not to refill their liquefied gas. If we talk about liquid fuel, the turbine is still what will be the gasoline – 80th or 98th. But oil is clearly not all the same: they have invested money in upgrading refineries, and manufacturers of MTG tell them: “if you lost in the cards, we your super-gasoline is no longer needed
– Fuel consumption. Honestly if these data are not available, therefore we have. In the photo from the site fotobus.msk.ru. hybrid bus Trolza-5250 “Ekobus”, pilot operation, GUP “Mosgortrans” 24.12.2010-20.03.2011 Fuel – compressed gas. From the findings in the pilot operation: gas Flow bus Trolza-5250″ in the winter time exceeds the consumption of the bus LiAZ-52937 (Euro 4) for an average of 12-18 percent.” exhaust gas turbine in the roof and note the warning label: “Keep a distance of 60 meters. But here’s a touch: MTG with Capstone C65 turbine has an electrical capacity of 65 kW. Traction motor Trolza-5250 “Ekobus” – 120 kW. Consistent scheme of GSU involves charging the battery and from the power to the drive wheels. The lack of efficiency drives have led to the fact that in the process of recharging, MTG tried also to provide energy to the traction motor. Which led to increased fuel consumption.
Resource microturbines. All manufacturers mention the numbers from 60 to 100 thousand hours rated power. As a second measure for the calculation of the resource refers to the number of runs, but the numbers more than 5,000 is not met in any sources. In other words, a single run is equivalent to 12-20 hours, the MGT… Thus, if you start the engine 4 times a day, then it will have (not to repair), and change in 3.5 years instead of 8-9 years. And this is essentially…
7. A little bit exotic… the Concept car Jaguar C-X75 is equipped with a hybrid power plant with two Bladon Jets microturbines with a capacity of 70 kW at 80’000 rpm, each with a jet generator weighs in at 35 kg. Fuel: gasoline, diesel, biofuels, the variant with the gas. MTG can operate as series and parallel. Lubrication and cooling are missing. Battery weight – 185 lbs. an Autonomous Stock turn (only on battery) mode energy recovery up to 50 km. Four-wheel motor (wheel formula 4×4) with a weight of 50 kg ensure the power at the wheels to 780 HP at the moment of 1600 N•m acceleration Time to the speed of 100 mph (160 km/h is 5.5 s, with a maximum of 320 km/h (limited force)
8. If to speak about prospects, and the introduction of micro-turbines will affect the interests of many manufacturers of automotive components and consumables, let me remind “the accordionist” anecdote:
In Paris in the patent office refers people. Says that he invented a motor car that runs not on gasoline, but on water. Checked that it really works. Began to make an invention, they say to him:
In principle, two alternatives to offer or issue as one invention or as a two – motor on the water and water as fuel. You’re an expert on fuel?
Yes, I worked for many years with the oil in Saudi Arabia. There, by the way, and made his invention.
– And why you are there, your invention is not patented?
I tried. But when I described them to his invention, I also proposed two alternative options.
– What?
– Stoned or buried alive…
For understanding: electric cars THEY forgave from the current reserve and the price of them – they are not competitors of mass production the global automotive industry. But that’s another topic…
