TERS : Thermal Energy Recovery System

[wuzak]

Thank you Tommy. But the the energy production you mention here how is it done? I understand that it's the MGUK the one who runs then the wheels but how to get from the gas to the voltage.

the heat energy is really momentum energy from the hot exhaust gases. The inertia of the generator motor and turbine and the back EMF of the generator acts as a load for the hot gases. So as the gases expand through the turbine while pushing the turbine blades it looses momentum and thus temperature.
So it's not really transferring radiation energy to electrical energy. It's more mechanical energy from the hot gas.
It's similar to a hot air balloon that lifts the basket into the air. So its momentum from heat and pressure, to rotational to electrical.

Gas turbines, steam turbines and piston internal combustion engines are all heat engines. Why wouldn't a hot fluid expanding through a turbine to drive the MGUH be a heat process?

[ringo]

You are looking at it from the wording.
But a turbine blade design for example is really based of momentum and vector calculations.
The reaction force and impulse of the gas on the blade is what creates the motion.
Maybe Riffraff can elaborate with better wording than i can.

[gruntguru]

MGU-H = Motor-Generator-Unit-Heat recovery. The F1 rules committee didn't use the word "Heat" in naming the MGUH because they are stupid.

The turbine recovers waste heat from the exhaust. I have said this before - although the turbine is driven by momentum changes in the gas, the energy extracted from the exhaust is mostly in the form of heat energy. (internal energy or "U" in thermodynamics)

[ringo]

I don't remember there being any heat absorbing devices on a gas turbine...
Niether are there any heat exchangers.
There is no "heat extracted", unless i am misinterpreting your idea of what heat is.
The gases expand against the blades doing work by moving them and their inertial load (the generator) resulting in momentum change resulting in drop in pressure and temperature etc. etc.
Internal energy is a function of the kinetic energy of the particles of a gas as well. There's no fancy heat absorbtion going on as the name suggests.
I guess the FIA just wants it to look super fancy and hitech when they say MGUH. lol

[wuzak]

The expansion of the gases is driven by the heat content/temperature.

[gruntguru]

I don't remember there being any heat absorbing devices on a gas turbine...
Niether are there any heat exchangers.
There is no "heat extracted", unless i am misinterpreting your idea of what heat is.
The gases expand against the blades doing work by moving them and their inertial load (the generator) resulting in momentum change resulting in drop in pressure and temperature etc. etc.
Internal energy is a function of the kinetic energy of the particles of a gas as well. There's no fancy heat absorbtion going on as the name suggests.
I guess the FIA just wants it to look super fancy and hitech when they say MGUH. lol

I seem to recall you saying you were an engineer. Mechanical engineers are taught that heat is a form of energy - specifically the vibration of molecules in a substance - also known in thermodynamics as "internal energy". As you cool the substance the vibration reduces with temperature until at absolute zero, the vibration ceases and there is zero heat energy remaining.

If you examine the stream of exhaust gas coming from the ICE there are four types of energy embodied in it. In descending order of magnitude (for hot ICE exhaust gas) they are:
1. Internal energy. (heat)
2. Pressure-volume energy. (can "push" and release energy by expanding the gas)
3. Kinetic energy. (mass of gas times its velocity squared x 1/2)
4. Potential energy. (gravitational. i.e. mass of gas x height x g) Negligible for ICE exhaust.

When the exhaust gas exits the engine, the greatest of these is heat energy. After passing through the turbine the one that has reduced the most is also heat energy, so what has been extracted is primarily heat energy. The method of extracting this heat energy (expanding the gas in a nozzle to increase the kinetic energy then using the kinetic energy to push on the turbine blades) creates the illusion that the energy to drive the turbine is present as pressure or kinetic energy in the exhaust gas.

[Frank_]

I don't remember there being any heat absorbing devices on a gas turbine...
Niether are there any heat exchangers.
There is no "heat extracted", unless i am misinterpreting your idea of what heat is.
The gases expand against the blades doing work by moving them and their inertial load (the generator) resulting in momentum change resulting in drop in pressure and temperature etc. etc.
Internal energy is a function of the kinetic energy of the particles of a gas as well. There's no fancy heat absorbtion going on as the name suggests.
I guess the FIA just wants it to look super fancy and hitech when they say MGUH. lol

i too am mystified by the term "heat recovery", my understanding is that the turbine is powered by gasflow (albeit pulsed) and the vanes/blades of that turbine are shaped for that purpose, and that the exhaust gasses are channeled down to a fast flowing jet pre-turbine to enhance the effect.
the typical pressure inside a turbo exhaust manifold under duress is about 30 psi ?, and post turbine/exhaust system pressure is about 5 psi ?
so that 25 psi of spent pressure is the force that is powering the compressor surely ?
igniting some fuel inside an air compressor tank might be an analogy

[Tommy Cookers]

.......I guess the FIA just wants it to look super fancy and hitech when they say MGUH. lol

If you examine the stream of exhaust gas coming from the ICE there are four types of energy embodied in it. In descending order of magnitude (for hot ICE exhaust gas) they are:
1. Internal energy. (heat)
2. Pressure-volume energy. (can "push" and release energy by expanding the gas)
3. Kinetic energy. (mass of gas times its velocity squared x 1/2)
4. Potential energy. (gravitational. i.e. mass of gas x height x g) Negligible for ICE exhaust.

When the exhaust gas exits the engine, the greatest of these is heat energy. After passing through the turbine the one that has reduced the most is also heat energy, so what has been extracted is primarily heat energy. The method of extracting this heat energy (expanding the gas in a nozzle to increase the kinetic energy then using the kinetic energy to push on the turbine blades) creates the illusion that the energy to drive the turbine is present as pressure or kinetic energy in the exhaust gas.

@gg .... if the exhaust is very hot but only at ambient pressure it cannot drive a turbine ??

presumably then expansion across the turbine means a drop in pressure
ie a mean exhaust pressure above the turbine significantly above ambient ie a raised mean pressure
recovery does not need a raised mean exhaust pressure eg the 14000 Wright Turbocompounds had blowdown turbines
Wright showed that mean exhaust pressure was not raised
(btw Wright stated that 35% of the exhaust energy was of a form potentially useable by the turbines)

@ gg ..... is the pressure energy less than the heat energy at the start of exhaust valve opening ????

'steady-stateist ' visions of a 'stream of exhaust coming from the ICE' as above ignores the basic nature of the piston engine
ie intermittent release by the exhaust valve from a high pressure around 8 bar above ambient
much of that intermittent (pulse) pressure energy is lost as increased heat (the gas flow goes supersonic)
a way to conserve pressure energy is to raise mean exhaust pressure even to true back pressure (ie greater then induction pressure)
presumably the greater downstream gas density and inertia limits acceleration and more of the flow will remain subsonic
the NACA proved this in WW2
that true backpressure gave very high recovery and the best BTE (but only when exhaust valve closure was suitable)

this all suggests that preserving pressure energy 'pulses' works well without any raising of mean exhaust pressure
.... or with raising it to extremes ....... and at positions in between

Mercedes has designed its exhaust system to destroy pressure pulses
this surely raising mean exhaust pressure 'at source' (with their good conservation of heat)
in addition to any other raising they may have chosen from their turbine and its loading

[gruntguru]

It is not necessary to complicate the discussion by differentiating steady flow versus pulsating flow and blowdown energy. Thermodynamically the process is the same. In the blowdown case, heat and pressure energy in the cylinder is converted to kinetic energy as the gas is expanded through the exhaust valve. If a small diameter pipe is provided all the way to the turbine, this kinetic energy can be applied directly to the turbine blades.

Mercedes have not deliberately designed their exhaust to destroy pressure pulses, in fact it is almost certain that their system is still capturing some blowdown energy. There is no other point in keeping 3 cylinders seperate to the other 3 all the way to the turbine wheel as their divided housing does. All the teams will be utilising both blowdown and pressure recovery in their turbines - under cruise conditions the Wright TC does not even capture enough blowdown energy to drive the supercharger.

[gruntguru]

@gg .... if the exhaust is very hot but only at ambient pressure it cannot drive a turbine ??

True.
OTOH a turbine (80% efficiency) operating between 3 bar and 1 bar with a mass flow of 0.5 kg/s will produce:
- 122 kW if the engine exhaust temperature is 850*C
- 32 kW if the exhaust temperature is 20*C

[ringo]

I don't remember there being any heat absorbing devices on a gas turbine...
Niether are there any heat exchangers.
There is no "heat extracted", unless i am misinterpreting your idea of what heat is.
The gases expand against the blades doing work by moving them and their inertial load (the generator) resulting in momentum change resulting in drop in pressure and temperature etc. etc.
Internal energy is a function of the kinetic energy of the particles of a gas as well. There's no fancy heat absorbtion going on as the name suggests.
I guess the FIA just wants it to look super fancy and hitech when they say MGUH. lol

i too am mystified by the term "heat recovery", my understanding is that the turbine is powered by gasflow (albeit pulsed) and the vanes/blades of that turbine are shaped for that purpose, and that the exhaust gasses are channeled down to a fast flowing jet pre-turbine to enhance the effect.
the typical pressure inside a turbo exhaust manifold under duress is about 30 psi ?, and post turbine/exhaust system pressure is about 5 psi ?
so that 25 psi of spent pressure is the force that is powering the compressor surely ?
igniting some fuel inside an air compressor tank might be an analogy

Yes,
The heat energy that we are talking about is converted within the gas as the energy of the particles change. There is no "extraction" so to speak. The physical turbine housing and blades don't absorb heat energy and somehow put that energy into the generator.

[gruntguru]

Agreed.

[Brian Coat]

The turbine efficiency looks like a fertile area for optimisation.

One percent more would make a difference.

Hard to get 1 pct more than all the other (aerodynamically clever) teams though ...

Is active clearance control permitted within the rules?

[wuzak]

Is active clearance control permitted within the rules?

No. It has to be fixed geometry.

[gruntguru]

The turbine efficiency looks like a fertile area for optimisation.

One percent more would make a difference.

Hard to get 1 pct more than all the other (aerodynamically clever) teams though ...

Absolutely. Brings to mind the Mercedes "log" manifolds - hard to imagine they are not capturing blowdown energy. That would be like throwing away several percent turbine efficiency.

I would guess the "logs" are designed to still capture blowdown energy - at least in the critical engine speed range around 11,000 rpm.