The Anonymous Widower

Looking At The Mathematics Of A Class 170 Train With An MTU Hybrid PowerPack

From various sources like the Wikipedia entry for the Class 170 train and various datasheets and other Internet sources, I will try to get the feel of Class 170 train, that has been fitted with two MTU Hybrid PowerPacks.

Assumptions And Source Data

For the purpose of this post, I shall make the following assumptions about the Class 170 train.

  • The train has two cars, each with their own engine.
  • The train has a capacity of 150 passengers.
  • The train weighs 90.41 tonnes.
  • The train has an operating speed of 100 mph.

After conversion each car will have MTU Hybrid PowerPack with a 6H 1800 engine.

The data sheet for the MTU Hybrid PowerPack with a 6H 1800 engine, indicates the following.

  • Up to four 30.6 kWh batteries can be added to each module.
  • Each battery weighs 350 Kg.
  • Various sizes of diesel engine can be specified.
  • The smallest is a 315kW unit, which is the same size as in a current Class 170 train.

If I assume that the two diesel engines weigh about the same, then any increase in train weight will be down to the batteries, the mounting, the traction motor and the control systems.

But the hydraulic system will be removed.

Calculation Of The Maximum Kinetic Energy

I will now calculate the maximum kinetic energy of a fully-loaded train, that is travelling at maximum speed.

  1. Assuming the average weight of each passenger is 90 Kg with baggage, bikes and buggies, the weight nof a full train becomes 103.91 tonnes
  2. The train is travelling at 100 mph.
  3. Using the Omni Kinetic Energy Calculator gives a kinetic energy of 28.84 kWh.

So even if only one battery is fitted to each engine, there will be 61.2 kWh of energy storage per train, which will probably be more than enough to handle the regenerative braking.

The hybrid PowerPack will probably add some extra weight to the train.

Even if I up the total train weight to 120 tonnes, the kinetic energy is still only 33.33 kWh.

So half this amount of energy can easily be stored in a 30.6 kWh battery in each car.

I would be very surprised, if this train needed a larger engine than the smallest 315 kW unit and more than one battery module in each car.

Does The MTU Hybrid PowerPack Work As A Series Hybrid?

In a series hybrid, the operation is as follows.

  • The diesel generator charges the battery.
  • The battery drives the train using the traction motor.
  • During braking, the electricity generated by the traction motor is returned to the battery.
  • If the battery is full, the regenerative braking energy is passed through resistors on the train roof to heat the sky.

There will also be a well-programmed computer to manage the train’s energy in the most efficient manner.

For a full explatation and how to increase the efficiency read the section on series hybrid, in Wikipedia.

I’m fairly certain that the MTU Hybrid PowerPack works as a series hybrid.

Will The Train Performance Be Increased?

I suspect the following improvements will be achieved.

  • Acceleration will be higher, as it seems to be in all battery road vehicles.
  • Braking will be smother and the rate of deceleration will probably be higher.
  • Station dwell times will be shorter.
  • Noise levels will be reduced.

This video explains the thinking.behind the MTU Hybrid PowerPack.

These trains will be liked by passengers, train operators and rail staff, especially if they enable faster services.

Will The MTU Hybrid PowerPacks Be Difficult To Install?

MTU built the original engines in the Class 170 trains and their must be well over two hundred installations in this class of train alone.

So in designing the PowerPack, it would be a very poor team of engineers, who didn’t design the PowerPack as almost a direct replacement for the existing engine,.

Fitting the new PowerPacks then becomes a question for the accountants, rather than the engineers.

As both a UK and a German project have been announced in the last few days, it looks likely that MTU have come up with a one PowerPack fits all their old engine installations solution.

Conclusion

This project could be a really successful one for MTU and their owner; Rolls-Royce.

 

September 20, 2018 - Posted by | Travel | , , , ,

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