Turbomachinery

THE NEW JAGUAR

2009-06-06T19:15:00.003+08:00

Press Release

THE NEW JAGUAR XF DIESEL S
“The new XF V6 Diesel S – combining superb performance and excellent fuel economy – sets the pace with acceleration from 0-60mph in 5.9 seconds, a maximum speed of 155mph, yet delivers an average fuel consumption of 42mpg and CO2 emissions of 179g/km: Truly the best of both worlds!”
Mike O’Driscoll, Managing Director, Jaguar Cars

THE NEW XF DIESEL S – In Brief

* The most advanced, powerful and efficient Jaguar diesel ever
* New 275PS high-performance XF Diesel S featuring Jaguar’s new AJ-V6D Gen III S 3.0-litre diesel engine delivering a massive 600Nm of torque
* 0-60mph in just 5.9 seconds, 50-70mph in just 3.2 seconds and a maximum speed of 155mph, yet combined fuel economy of 42.0mpg – 12 percent better than the acclaimed 2.7-litre V6 diesel engine
* Emits just 179g/km – a 10 percent reduction in CO2. Conforms to EU5 emission regulations using conventional exhaust after-treatment
* 33 percent more powerful and 61 percent more torque from 1500rpm than the 2.7-litre V6 diesel

“With CO2 emissions of 179g/km, 42mpg average fuel economy and 0-60mph acceleration in 5.9 seconds, this is another great example of Jaguar delivering unrivalled performance while at the same time taking the level of refinement in diesel engines to a whole new level.”
Mick Mohan, Jaguar Programmes Director

When it was introduced last year, the XF was recognised as a dramatic expression of a bold new Jaguar design language. It also soon became apparent that here was a car where the driving experience exceeded the expectations created by the striking appearance. Now, the new XF Diesel S takes this driving experience to new levels, shifting the balance even further towards dynamic performance while still retaining the XF’s core values as a refined and luxurious sports saloon.

Distinguished by 19 inch wheels, an aerodynamic boot lid spoiler and discreet ‘S’ badging, the car that defines Jaguar sporting luxury is even better for the 2010 model year, with a stunning new high-performance diesel. Powered by a 275PS engine, the Diesel S gives the XF outstanding levels of performance, accelerating from 0-60mph in just 5.9 seconds, 1.8 seconds quicker than the excellent 2.7-litre model. In-gear acceleration is equally impressive, with a 50-70mph time of just 3.2 seconds. Maximum speed is electronically limited to 155mph.

Featuring parallel sequential turbochargers to help deliver the high levels of power and torque seamlessly and with effortless flexibility, this engine is perfectly matched to Jaguar’s sophisticated six-speed ZF 6HP28 automatic transmission.

“The new parallel sequential turbocharger system on our new V6 diesel delivers V8 levels of performance from very low revs. It’s a power unit that offers superb flexibility and remarkably low fuel consumption and emissions, while building on the refinement that has become a trademark of our Jaguar diesel engines.”
Ron Lee, Group Chief Engineer, Powertrain

There is an equally impressive 240PS version of the new 3.0-litre engine available too, which produces 16 percent more power and a 15 percent increase in torque over the 2.7-litre diesel, allowing the XF to reach 60mph in 6.7 seconds. Its 50-70mph time of just 3.7 seconds is only fractionally slower than the 275PS Diesel S model. Maximum speed is 149mph. And like the 275PS engine, these great performance leaps are achieved with combined average fuel consumption of 42.0mpg – an improvement on the 2.7-litre diesel of over 10 percent – and a CO2 emissions rating of only 179g/km.

There are also significant trim and specification changes – including many new features – and the introduction of a new luxurious Portfolio derivative as part of the core range. For Jaguar and the new 2010 model year XF, the high-performance diesel has truly arrived.

The acclaimed XF 2.7 Diesel has won several accolades, including in the UK What Car magazine’s ‘Diesel Car of the Year’ and ‘Car of the Year’, What Diesel magazine’s ‘Diesel Car of the Year’ and the Association of Scottish Motoring Writers’ Best Diesel of 2008.

The new AJ-V6D Gen III engine – In detail

Drawing on the experience gained in designing the original, acclaimed 2.7-litre engine, the new 3.0-litre AJ-V6D Gen III diesels demonstrate that it is possible to deliver improved performance, while reducing CO2 emissions and fuel economy. In the XF, the new engine produces 10 percent less CO2 than the 2.7-litre, while power has increased by 33 percent in Diesel S guise. As well as tackling CO2, the new 3.0-litre engines meet the forthcoming EU5 regulations, due to come into force at the start of 2011. And these great performance leaps are achieved with combined average fuel consumption in both models of 42.0mpg – an improvement on the 2.7-litre engine of 12 percent.

Twin-turbos – maximum efficiency, instant response

A key feature of the new engine is the unique, parallel sequential turbocharger system, the first of its type to be fitted to a V-engine anywhere in the world. Delivering high torque throughout the entire engine rev range, improved throttle response and low CO2 emissions, the twin-turbochargers work sequentially to deliver unrivalled response and best-in-class torque – an impressive 61 percent more than the 2.7-litre diesel from 1500rpm – while packing a huge punch at higher engine speeds.

For most day-to-day driving, including motorway cruising, a responsive, variable-geometry primary turbocharger does all the work, while the smaller, fixed-geometry, secondary turbo is dormant, saving energy and improving efficiency. When the engine revs climb above 2800rpm, the secondary turbo is brought on line within 300 milliseconds, smoothly and seamlessly boosting the engine output with no discernible turbo-lag or power-step.

Driving a turbocharger requires pressure from the exhaust, creating pumping losses in the engine and increasing fuel consumption. To alleviate this, valves under the control of the engine management system isolate the secondary turbocharger both from the exhaust stream and the engine inlet tract when it is not required.

Some twin-turbo systems rely on a smaller turbo for primary use, only using a larger turbo when higher power is required. Though effective, this has the disadvantage of raised exhaust pressure and increased pumping losses. The Jaguar system uses a larger, variable-geometry turbocharger more of the time, which not only reduces pumping losses, but also improves fuel consumption and CO2 emissions.

Jaguar engineers particularly focussed on the issue of turbocharger ‘lag’ at low engine speeds. The new AJ-V6D Gen III 3.0-litre diesels significantly out-perform their rivals by delivering 500Nm of torque in only 500 milliseconds from idle.

Third-generation commonrail

A new commonrail fuel-injection system delivers up to five injections on each cycle at a pressure of 2000bar. Each injector tip is perforated by seven holes through which finely atomised fuel is sprayed into the cylinders. The high-pressure injection increases power, improves economy and reduces both CO2 and particulate emissions. New, third-generation high-speed piezo injectors allow up to five precise injection events during each combustion cycle, minimising engine combustion noise.

Piezo crystal ‘packs’ operate each injector by expanding when an electric current is passed through them. They react virtually instantaneously but can make a distinctive click when fired, which can add to diesel engine noise at idle. The crystals in Jaguar’s new injectors are fitted nearer the tip, meaning they are mounted deeper inside the engine providing better sound insulation and quieter operation.

Another new feature of the third-generation fuel-injection system is the metering mode. Traditional diesel commonrail fuel pumps oversupply the injectors, with the surplus being returned to the fuel tank. During this process, fuel temperature increases and cooling it again consumes considerable amounts of energy. In metering mode, the pump delivers fuel to the injectors only at the rate required. Consequentially, there is no rise in fuel temperature and no wasted energy.

Compact, light and clean

The two cylinder heads, with four valves per cylinder, are made from aluminium and the cylinder block is made from compact graphite iron (CGI). The higher tensile strength of CGI makes it possible to cast a smaller block; some 80mm shorter than a conventional ‘grey’ cast iron equivalent.

The new, water-cooled, exhaust gas recirculation system (EGR), important for reducing pumping losses and emissions of NOx in a diesel engine, is more efficient and consumes less power than the 2.7-litre unit. The valves that allow exhaust gas into the system are located on the ‘hot side’ of the engine nearest the exhaust manifolds; these valves never cool while the engine is running, so there is no condensation of combustion deposits which occurs on engines fitted with ‘cold side’ valves, hence the EGR system always works at maximum efficiency. Since the EGR cooling is so effective, exhaust gasses can bypass the system and return to the exhaust pipes, allowing faster engine warm-up from start-up and reducing emissions still further.

EU5 emissions regulations have been achieved ahead of the 2011 legislative timetable using conventional diesel oxidation catalysts and diesel particulate filters (DPFs). NOx levels are reduced at source through the combustion system design, the addition of the new commonrail injection system and the new EGR system with by-pass. As a result, specialised NOx exhaust after-treatment is unnecessary, avoiding a potential cost and the need to use additional precious metals in the exhaust system.

Remarkably quiet for a diesel

The CGI cylinder block and new piezo injectors reduce combustion noise in the engine. Multiple, precise injections of fuel on the combustion stroke also reduce combustion noise and all engine covers including camshaft covers, front covers and the sump have been optimised to subdue radiated noise. Engine enclosures have been ribbed to minimise radiated noise and the sump pan is manufactured from sound deadening steel (SDS), comprising a polymer layer sandwiched between two layers of steel.

Internal friction, a major contributor to unnecessary fuel consumption, has been addressed by careful optimisation of the crankshaft, valves and pistons. All these features combine to make the new Jaguar AJ-V6D Gen III engines amongst the quietest premium diesels on the market.

A major step forward

With its parallel sequential turbocharger system, third-generation commonrail fuel injection system and fully optimised EGR system, the new 3.0-litre AJ-V6D Gen III diesel sets new class standards when it comes to power, response and refinement in the premium diesel segment.

“The new XF challenges the rules and redefines Jaguar sporting luxury. Our designers and engineers have worked together to develop elegant, inspired solutions to complex technical challenges. It’s a simple but very effective philosophy and the result is great new products like the new 3.0-litre diesel XF.”
Mike O’Driscoll, Managing Director, Jaguar Cars.

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

2008-09-21T18:26:00.003+08:00

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

2008-03-31T19:43:00.002+08:00

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

2008-03-19T00:05:00.000+08:00

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.

Reaction Turbine and Impulse Turbine

2006-11-30T16:30:00.000+08:00

The reaction turbine is quite different from the impulse turbine.

In the reaction turbine a portion of the energy of the fluid is converted into energy by the fluid’s passing through adjustable gates before entering the runner, and the remainder of the conversion takes place through the runner.

Two types of the reaction turbines:
-Radial flow, e.g Francis turbine
-Axial flow, e.g Kaplan turbine

In the impulse turbine all the mechanical energy of the liquid is converted into kinetic energy by a nozzle that forms a free jet. The energy is then taken from the jet by suitable flow through moving vanes.The vanes are partly filled with the jet open to the atmosphere throughout its travel through the runner.

Type of the impulse turbine, e.g Pelton Wheel

Pump Losses

2006-11-30T16:24:00.000+08:00

The shaft power or energy that is supplied to the pump by the prime mover is not the same as the energy received by the liquid, some energy is dissipated as the liquid passes through the machine.

The mechanism of the loss in a pump:

Mechanical friction power loss due to friction between the fixed and rotating parts in the bearing and boxes
Leakage and circulating power loss due to a loss of liquid from the pump or circulation of the liquid in the impeller
Disc friction power loss due to friction between the rotating faces of the impeller and the liquid.
Casing power loss

CAVITATION IN PUMPS

2006-11-29T16:46:00.000+08:00

When the liquid flows through a centrifugal or axial flow pump, the static pressure (suction pressure) at the eye of the impeller is reduced and the velocity increases. There is therefore a danger that cavitation bubbles may form at the inlet to the impeller.

- Local pitting of the impeller can result when the bubbles collapse on a metallic surface
- Noise is generated in the form of sharp cracking when cavitation takes place.

Cavitation will not occur if critical cavitation number is greater than cavitation available. Every pump has a critical cavitation number which can only be determined by testing to find the minimum value of NPSH before cavitation occurs.

STEPS TO SELECT A CENTRIFUGAL PUMP

2006-11-19T19:31:00.000+08:00

STEPS TO SELECT A CENTRIFUGAL PUMP
Centrifugal pump selection is the process of choosing the most suitable centrifugal pump for your needs.

1. Several factors must be considered when selecting the configuration and size of the pump necessary for your system. Factors that include location, available space, maintenance requirements, reliability, are all factors in the selection process.

2. The performance requirements of your system must be specified and the pump type must be selected.

3. Alternate pumps that meet the requirements of the application also should be specified. Normally, the most suitable pump is chosen from these pumps considering economic factors.

Five steps to select a pump are:
1. Determine flow rate
2. Determine static head
3. Determine friction head
4. Calculate total head
5. Select the pump (you can use manufacturer’s catalogue)

WHAT IS TURBOMACHINE?

2006-11-13T19:34:00.000+08:00

WHAT IS TURBOMACHINE?
Any devices that extracts energy from or imparts energy to a continuously moving stream of fluid (liquid or gas) can be called a turbomachine. The Examples of turbomachine: windmills, waterwheels, ship propeller, hydraulic and gas turbines, pump and compressor.

The work principle of turbomachine: the energy transfer being carried out by the action of one or more rotating blade rows. The dynamic action of rotating blades sets up forces between the blades and fluid while the components of these forces in the direction of blade motion give rise to the energy transfer between the blades and fluid.

The type of turbomachines fall into 2 categories depending on:

whether work is done by the fluid on the rotating member
or
whether work is done by the rotating member on the fluid

Work is done by fluid, examples:
Axial flow hydraulic turbine
Radial flow hydraulic turbine
Mixed flow hydraulic turbine
Axial flow gas turbine
Pelton wheel hydraulic turbine

Work is done on fluid, examples:
Axial flow pump
Centrifugal pump
Axial flow compressor
Centrifugal compressor
Radial flow fan

The type of turbomachines can also be defined as
the manner of fluid movement through the rotating member
If the flow is essentially axial with no radial movement of the streamlines then the machine is called an axial flow machine.
If the flow is radial, the machine is classed as a radial flow centrifugal machine