BMW to Enter Small Petrol Turbo Engine Fray, One or two turbos?

BMW brand will be turbocharging its smallest engines. We knew this of course, but this is the first confirmation by a BMW official of this fact. Jim O’Donnell, big boss of BMW in North America told Business Week that the engines will be 4-cylinder, turbocharged, offer stronger acceleration than the current 6-cylinder (NG6) and spew out better emission figures. Sounds impossible but Volkswagen and Mercedes-Benz have been doing it for years already. That Bavaria was going to join the party was not a matter of if, but when. Ok, we still don’t know when, but at least we know it’s no longer IF. We also don’t know if these engines will be just one engine size or different sizes, and if they will use single turbos or two. Lots of ifs still, but we can live with these. By twin-turbocharging their 2-litre diesel engine in the 123D, BMW signaled their intention for smaller petrol powerplants as well. Remember, they first used these new generation turbos in their oil-sippers, then petrol. O’Donnell also could not confirm if this Euro-bound engine will cross the Atlantic or not, only to say it depends on the new US Federal government and how they view America’s energy future. How sad is that?

Source: BusinessWeek

Combustor For Coal

At the University of Pennsylvania research is being made to develop a combustor for coal. This could solve the problems with carbon deposits forming in internal combustion turbine engines. This combustor for coal will be used in high powered internal combustion turbine engines commonly used in thermal power stations. The Star Rotor turbine under development at A&M University of Texas could also be used with the coal combustor. This engine could be used for road transportation. The positive displacement turbine of the star rotor allows to be delivered over a wide range of engine speeds. The engine will need a multi gear transmission.
As long as oil prices stay over $30.00 a barrel it will be cost effective to mass produce coal water fuel at $20.00 a barrel.
Coal-water fuel can be used in a rage of external combustion engines such as the Thermo-acoustic engine. This engine converts heat energy to low frequency sound waves that drives a linear alternator. These are high efficiency engines are equal or better than present diesel engines. The electricity generated recharges on board batteries turning electric motors that propel the vehicle. A wide range of hybrid vehicles can be used including hybrid municipal buses, hybrid taxis, hybrid trucks, and hybrid trains.
The performance of these hybrid vehicles can be vastly improved with ultra capacitors. These capacitors when used with batteries can rapidly absorb and discharge large amounts of electricity. The electricity stored in the capacitors can be used during accelerations and recovered during deceleration. This will greatly extend the energy stored in batteries and reduce the amount of energy used by the engine that recharges them. Capacitors are used today in electric drag racing cards.
Another engine that can be used in hybrid electric vehicles is the Proeschel modified Ericsson cycle engine. This external combustion piston engine could use the combustor technology from University of Pennsylvania burning coal-water fuel. This engine could drive an electric generator charging batteries which would drive electric motors in hybrid vehicles.
The hot exhaust from external combustion liquid coal fueled engines could be used to drive bottom-cycle engines which would add to the efficiency of the top side engine. There are two types of bottom cycle engines one type would be battery to thermo-acoustic engine and the other type would be the steam engine.
The thermo-acoustic engine converts the exhaust heat created by the top-cycle engine into sound waves and then into electricity. An additional electric motor would be added to the drive train increasing the efficiency. The efficiency of the external combustion turbine engine with combustion temperatures at 1400 degrees F would be 20% on coal-water fuel. The bottom cycle thermo acoustic engine could operate at 28% efficiency on the exhaust heat. Combined efficiency would be 48%.
An external combustion engine with combustion temperatures over 2000 degrees F operate at 30% efficiency would have enough exhaust heat to boil water and create steam for a conventional steam engine used as a bottom engine raising the total efficiency to over 44%. If a super critical steam engine was used the efficiency could be raised to 50%. Super critical steam engines can also be used as the main engine running on coal fuel in commercial on road and train applications.

Adapted from : BeyondFossilFuel.com

Difference between turbo charging and super charging

The differences between turbo and supercharging depend on the type of supercharger one compares it to.

If you were to compare a turbocharger to a centrifugal supercharger the differences would be small, after all a centrifugal supercharger is simply the compressor half of a turbocharger that is belt driven from the crank. The issue with these types of compressors is that they produce boost in a non-linear fashion, further compounding the issue that superchargers have with not being able to produce full boost until redline. This is because the supercharger is crank driven, so when the supercharger produces maximum boost must be directly synchronized with the engines redline, because if the supercharger were to produce full boost at half of the engines possible RPM, then in the other half of the engines RPM range the supercharger would choke and actually produce less CFM than before. When compared to a turbo, the turbo can build to its maximum potential very quickly in the RPM range and then be controlled by the wastegate to stay there.