On 21-Apr-17 8:51 AM, harry wrote:
On Thursday, 20 April 2017 16:39:29 UTC+1, Brian Reay wrote:
On 19/04/2017 19:47, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.


We looked at the Tesla and were told it didn't have a gear box.

We decided against all electric, we don't like the idea of being stuck
with a 'flat' battery on a journey. The idea of stopping for 'top ups'
on a long journey is fine until you consider the practical aspects.


The practical aspects are
1. The charge point(s) are in use.
2. The charge point has been vandalised.
3. Some idiot has parked an ICE car in the charge bay.

4 The council has removed the charge points from the car park, because
nobody has been using them, which is what has been happening around here.

--
--

Colin Bignell

On 21/04/2017 08:04, RJH wrote:
On 21/04/2017 00:04, wrote:
On 20/04/2017 17:23, Tim Streater wrote:
In article , Brian Reay wrote:

On 19/04/2017 19:47, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or does
the
motor just run faster the faster you go? I was told by the owner the
optimum
speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

We looked at the Tesla and were told it didn't have a gear box.

We decided against all electric, we don't like the idea of being stuck
with a 'flat' battery on a journey. The idea of stopping for 'top ups'
on a long journey is fine until you consider the practical aspects.

As a matter of interest, is anyone looking (as in considering making) a
hybrid electric? As in, rather than having a powerful petrol engine, a
less powerful electric motor, a normal size fuel tank and a smaller
battery (like my Toyota Auris), instead have a full-size electric
motor, larger battery, but with a small petrol engine and small fuel
tank?

That way one could stop anywhere to recharge or even do it on the go.

A few months ago I went through the EV search, I think the ones with
small ICEs are called Range Extenders. I decided on a plug-in hybrid and
am very pleased with it - 208HP ICE and 80HP electric motor driving a
seven speed auto box with some magic arrangement of clutches that allows
one or both to drive, or neither, or to use the motor for regen braking.
All very clever but probably a maintenance nightmare when it gets old.

BMW 3 series? A friend has one and likes it.

No, it's a M-B C350E estate.

On 20-Apr-17 11:41 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser that's
the problem.

With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range
and it could move off from cold in under 30 seconds.

http://www.popularmechanics.com/cars...le-steam-cars/


Presumably it needed fuel as well as water. What was that, and how much
was needed, and how was the boiler kept stoked etc.


According to the link I gave, they usually burned kerosene, but, being
an external combustion engine, almost anything would do. However, my
main point was that if they managed to get that range from one tank of
water in 1924, we should expect better today.

--
--

Colin Bignell

On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote:
On 21-Apr-17 8:47 AM, harry wrote:
On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser that's
the problem.


With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and
it could move off from cold in under 30 seconds.

Drivel.
Water is not fuel.

I was answering the point about the condenser. However, recent advances
in catalytic splitting of water could make it feasible to use water as
fuel, if you really wanted to.

Drivel.
Have you never heard of the Law of Conservation of Energy?

All steam engines and boilers are inherently inefficient.
They will never come anywhere near the ICE efficiency wise.

I spent forty years running them. And getting rid of them where possible.

On Friday, 21 April 2017 10:13:17 UTC+1, Nightjar wrote:
On 21-Apr-17 8:51 AM, harry wrote:
On Thursday, 20 April 2017 16:39:29 UTC+1, Brian Reay wrote:
On 19/04/2017 19:47, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.


We looked at the Tesla and were told it didn't have a gear box.

We decided against all electric, we don't like the idea of being stuck
with a 'flat' battery on a journey. The idea of stopping for 'top ups'
on a long journey is fine until you consider the practical aspects.


The practical aspects are
1. The charge point(s) are in use.
2. The charge point has been vandalised.
3. Some idiot has parked an ICE car in the charge bay.

4 The council has removed the charge points from the car park, because
nobody has been using them, which is what has been happening around here.

--
--

Colin Bignell

Very possible.The government has mishandled the whole business.
Most EV drivers charge their car at home far more cheaply.
I SummerI pay nothing mostly, due to PV panels.
99% of my journeys are in range.
The others, I use my other car.

"harry" wrote in message
...
Most EV drivers charge their car at home far more cheaply.
I Summer I pay nothing mostly, due to PV panels.
99% of my journeys are in range.
The others, I use my other car.

Is there enough time to charge the car, given that you will probably have it
away from home during most of the daylight hours and hence there are only a
few hours of light at the end of the day and the beginning of the day when
the car can charge off free electricity; during hours of darkness you'll
need to use electricity that you have to pay for, from the grid.

How much does gradient affect range? I imagine that a few 1:5 (or steeper)
hills on a journey would reduce the range quite significantly.

Do you keep your car outside or in a garage? If it's kept outside, how do
you protect against moisture (eg early morning dew) and someone maliciously
disconnecting the supply (either to use your electricity or just for the
hell of it)? How do car parks guard against malicious disconnections?

If you can manage to keep your journeys to within the daily range of the
car, you don't need to worry about recharge time because you've got loads of
"dead" time either when you are at work or else overnight. But you need a
second car (maybe not used normally, but still needing to be taxed and
insured) for holidays and other times when you will want to travel vastly in
excess of the electric car's range. It is the need for two cars, each suited
to a particular type of journey, where a single IC-engined car would
suffice, which is a big problem with EVs.

I don't see a way around the recharge time, unless cars use batteries that
are exchanged at fuel stops, because the rate at which energy is taken on
board with petrol or diesel is tremendous: within a couple of minutes I can
fill my 60-litre tank and have another 700 miles of range.

Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56
MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer
of

56*60/300 = 11 MW (!)

Try supplying electricity to a battery at that rate :-) Watch the lights go
dim in the neighbourhood while you are charging :-)

On 21/04/2017 08:55, harry wrote:
Wait until it breaks.
Then try and find someone to fix it.
The dealers lie BTW.

That's hardly unique to electric cars...

(Just found out the reason the mechanics have taken a week and not fixed
my IC car was they didn't have authorisation, and the **** paper pushers
hadn't asked me)

Andy

On 21/04/17 19:48, NY wrote:
Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 =
56 MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power
transfer of

56*60/300 = 11 MW (!)

Well diesels are at best 40% efficient and leccy motors at least 80%, so
halve that to 5.5MW.

Not that big a deal. similar to a train starting up I'd say. Its about
7000 bhp. So 10 formula one cars in qualifying trim...


So very doable at a custom built motorway service station, if not in yer
garage.

But thats where the car is kept and charged overnight innit?


--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly

"NY" wrote in message
o.uk...
"harry" wrote in message
...
Most EV drivers charge their car at home far more cheaply.
I Summer I pay nothing mostly, due to PV panels.
99% of my journeys are in range.
The others, I use my other car.

Is there enough time to charge the car, given that you will probably have
it away from home during most of the daylight hours

He's unemployed and is hardly ever out.

and hence there are only a few hours of light at the end of the day and
the beginning of the day when the car can charge off free electricity;
during hours of darkness you'll need to use electricity that you have to
pay for, from the grid.

How much does gradient affect range? I imagine that a few 1:5 (or steeper)
hills on a journey would reduce the range quite significantly.

Do you keep your car outside or in a garage? If it's kept outside, how do
you protect against moisture (eg early morning dew) and someone
maliciously disconnecting the supply (either to use your electricity or
just for the hell of it)? How do car parks guard against malicious
disconnections?

If you can manage to keep your journeys to within the daily range of the
car, you don't need to worry about recharge time because you've got loads
of "dead" time either when you are at work or else overnight. But you need
a second car (maybe not used normally, but still needing to be taxed and
insured) for holidays and other times when you will want to travel vastly
in excess of the electric car's range. It is the need for two cars, each
suited to a particular type of journey, where a single IC-engined car
would suffice, which is a big problem with EVs.

I don't see a way around the recharge time, unless cars use batteries that
are exchanged at fuel stops, because the rate at which energy is taken on
board with petrol or diesel is tremendous: within a couple of minutes I
can fill my 60-litre tank and have another 700 miles of range.

Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56
MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer
of

56*60/300 = 11 MW (!)

Try supplying electricity to a battery at that rate :-) Watch the lights
go dim in the neighbourhood while you are charging :-)

On 20/04/2017 19:24, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser that's
the problem.


With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and
it could move off from cold in under 30 seconds.

http://www.popularmechanics.com/cars...le-steam-cars/


Ta. And a video of it

https://www.youtube.com/watch?v=rUg_ukBwsyo



--
Adam

On Friday, 21 April 2017 21:50:10 UTC+1, Vir Campestris wrote:
On 21/04/2017 08:55, harry wrote:
Wait until it breaks.
Then try and find someone to fix it.
The dealers lie BTW.

That's hardly unique to electric cars...

(Just found out the reason the mechanics have taken a week and not fixed
my IC car was they didn't have authorisation, and the **** paper pushers
hadn't asked me)

Andy

Consider yourself lucky
It took them over three months to fix mine.
Under guarantee.

On Friday, 21 April 2017 19:48:45 UTC+1, NY wrote:
"harry" wrote in message
...
Most EV drivers charge their car at home far more cheaply.
I Summer I pay nothing mostly, due to PV panels.
99% of my journeys are in range.
The others, I use my other car.

Is there enough time to charge the car, given that you will probably have it
away from home during most of the daylight hours and hence there are only a
few hours of light at the end of the day and the beginning of the day when
the car can charge off free electricity; during hours of darkness you'll
need to use electricity that you have to pay for, from the grid.

How much does gradient affect range? I imagine that a few 1:5 (or steeper)
hills on a journey would reduce the range quite significantly.

Do you keep your car outside or in a garage? If it's kept outside, how do
you protect against moisture (eg early morning dew) and someone maliciously
disconnecting the supply (either to use your electricity or just for the
hell of it)? How do car parks guard against malicious disconnections?

If you can manage to keep your journeys to within the daily range of the
car, you don't need to worry about recharge time because you've got loads of
"dead" time either when you are at work or else overnight. But you need a
second car (maybe not used normally, but still needing to be taxed and
insured) for holidays and other times when you will want to travel vastly in
excess of the electric car's range. It is the need for two cars, each suited
to a particular type of journey, where a single IC-engined car would
suffice, which is a big problem with EVs.

I don't see a way around the recharge time, unless cars use batteries that
are exchanged at fuel stops, because the rate at which energy is taken on
board with petrol or diesel is tremendous: within a couple of minutes I can
fill my 60-litre tank and have another 700 miles of range.

Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56
MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer
of

56*60/300 = 11 MW (!)

Try supplying electricity to a battery at that rate :-) Watch the lights go
dim in the neighbourhood while you are charging :-)

I am retired so it can be charged through the day.
But even on mains electricity, the cost is negligable compared with petrol.
Often you can arrange to charge up at destination.
You get used to range estimations after a while.

Gradient has a big effect. But you get about half back descending the other side.

The heater has a big effect too.

My cars are indoors,
I also have an ICE car. But no tax and cheap to insure as it's a heritage vehicle.

On 21-Apr-17 6:46 PM, harry wrote:
On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote:
On 21-Apr-17 8:47 AM, harry wrote:
On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser that's
the problem.


With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and
it could move off from cold in under 30 seconds.

Drivel.
Water is not fuel.

I was answering the point about the condenser. However, recent advances
in catalytic splitting of water could make it feasible to use water as
fuel, if you really wanted to.

Drivel.
Have you never heard of the Law of Conservation of Energy?

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.

All steam engines and boilers are inherently inefficient.
They will never come anywhere near the ICE efficiency wise.

Petrol cars achieve a tank to wheel thermal efficiency of about 16%.
Non-condensing third generation steam locomotives achieve a drawbar
thermal efficiency of about 16%.

I spent forty years running them. And getting rid of them where possible.

I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium tube
flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics
allow engines to work at those temperatures and pressures and achieve
efficiencies not even dreamed of with conventional materials.


--
--

Colin Bignell

Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0

"Fabulous" seems like an apt description, stuff of fables.

Tim


--
Please don't feed the trolls

On 22/04/17 09:45, Nightjar wrote:
On 21-Apr-17 6:46 PM, harry wrote:
On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote:
On 21-Apr-17 8:47 AM, harry wrote:
On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the
owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser
that's
the problem.


With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range
and
it could move off from cold in under 30 seconds.

Drivel.
Water is not fuel.

I was answering the point about the condenser. However, recent advances
in catalytic splitting of water could make it feasible to use water as
fuel, if you really wanted to.

Drivel.
Have you never heard of the Law of Conservation of Energy?

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.

All steam engines and boilers are inherently inefficient.
They will never come anywhere near the ICE efficiency wise.

Typical modern steam power station 37%. More with supercritical steam
Typical diesel. 25%.



Petrol cars achieve a tank to wheel thermal efficiency of about 16%.
Non-condensing third generation steam locomotives achieve a drawbar
thermal efficiency of about 16%.

No use telling harry anything. The thermodynamics are all well
understood, but not by harry



I spent forty years running them. And getting rid of them where possible.

I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium tube
flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics
allow engines to work at those temperatures and pressures and achieve
efficiencies not even dreamed of with conventional materials.

Exatamondo. I cant remember what the law is called, but the hotter the
working fluid (steam in this case) is to start with, and the colder the
final exhaust, the more efficient is the engine.

Which is why a combined cycle gas turbine that starts with 1000C gases
in the jet engine, then heats a boler to get steam, and has a final
after condenser temp of around 50C, willnet you over 60% thermal efficiency.


Whether you call that an IC or a steam engine is up to you.





--
"Corbyn talks about equality, justice, opportunity, health care, peace,
community, compassion, investment, security, housing...."
"What kind of person is not interested in those things?"

"Jeremy Corbyn?"

On 22/04/17 10:36, Chris Hogg wrote:
On Sat, 22 Apr 2017 09:21:33 -0000 (UTC), Tim+
wrote:

Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0

"Fabulous" seems like an apt description, stuff of fables.

Tim

Sadly, the Green world is full of such nonsense. Anything is possible
if you know nothing.

Anything *seems* to be possible if you know nothing.

I have often said - and it bears repeating - that my education in hard
science and engineering doesn't tell me ultimately how to build stuff
that works, but it is incredibly effective at telling me what cannot
work, so I don't waste time trying.

This 'negative knowledge' is hugely useful.

Greens call it 'being negative' :-)


--
"If you dont read the news paper, you are un-informed. If you read the
news paper, you are mis-informed."

Mark Twain

On 22/04/17 11:44, Chris Hogg wrote:
On Sat, 22 Apr 2017 10:48:32 +0100, The Natural Philosopher
wrote:

On 22/04/17 09:45, Nightjar wrote:
On 21-Apr-17 6:46 PM, harry wrote:
On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote:
On 21-Apr-17 8:47 AM, harry wrote:
On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the
owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser
that's
the problem.


With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range
and
it could move off from cold in under 30 seconds.

Drivel.
Water is not fuel.

I was answering the point about the condenser. However, recent advances
in catalytic splitting of water could make it feasible to use water as
fuel, if you really wanted to.

Drivel.
Have you never heard of the Law of Conservation of Energy?

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.

All steam engines and boilers are inherently inefficient.
They will never come anywhere near the ICE efficiency wise.

Typical modern steam power station 37%. More with supercritical steam
Typical diesel. 25%.



Petrol cars achieve a tank to wheel thermal efficiency of about 16%.
Non-condensing third generation steam locomotives achieve a drawbar
thermal efficiency of about 16%.

No use telling harry anything. The thermodynamics are all well
understood, but not by harry



I spent forty years running them. And getting rid of them where possible.

I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium tube
flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics
allow engines to work at those temperatures and pressures and achieve
efficiencies not even dreamed of with conventional materials.

Exatamondo. I cant remember what the law is called, but the hotter the
working fluid (steam in this case) is to start with, and the colder the
final exhaust, the more efficient is the engine.

Carnot cycle or Carnot's law.
https://en.wikipedia.org/wiki/Carnot_cycle
Not to be confused with Fred Karno, who had an 'army' IIRC!


That's the bugger!



Which is why a combined cycle gas turbine that starts with 1000C gases
in the jet engine, then heats a boler to get steam, and has a final
after condenser temp of around 50C, willnet you over 60% thermal efficiency.


Whether you call that an IC or a steam engine is up to you.






--
All political activity makes complete sense once the proposition that
all government is basically a self-legalising protection racket, is
fully understood.

In article ,
Nightjar wrote:
Petrol cars achieve a tank to wheel thermal efficiency of about 16%.
Non-condensing third generation steam locomotives achieve a drawbar
thermal efficiency of about 16%.

A steam locomotive generally operates under carefully controlled
conditions. Like all railways.

Cars don't.

--
*When a man opens a car door for his wife, it's either a new car or a new

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Tim Streater
wrote:
In article , The Natural Philosopher
wrote:

I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium
tube flash boiler can supply steam at up to 4,000 psi and 650C.
Ceramics allow engines to work at those temperatures and pressures and
achieve efficiencies not even dreamed of with conventional materials.

Exatamondo. I cant remember what the law is called, but the hotter the
working fluid (steam in this case) is to start with, and the colder the
final exhaust, the more efficient is the engine.

Which is why a combined cycle gas turbine that starts with 1000C gases
in the jet engine, then heats a boler to get steam, and has a final
after condenser temp of around 50C, willnet you over 60% thermal
efficiency.

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

--
from KT24 in Surrey, England

On 22-Apr-17 10:21 AM, Tim+ wrote:
Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0

"Fabulous" seems like an apt description, stuff of fables.

That looks like it. I only recall the publicity of its launch and didn't
follow up on what happened to it. However, MIT and Stanford University
have both demonstrated low energy water splitters that can run from low
voltage sources.

--
--

Colin Bignell

Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote:
Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0

"Fabulous" seems like an apt description, stuff of fables.

That looks like it. I only recall the publicity of its launch and didn't
follow up on what happened to it. However, MIT and Stanford University
have both demonstrated low energy water splitters that can run from low
voltage sources.


"Didn't follow up" is a lame excuse for believing in fairies! Do you
believe in other perpetual motion machines?

Tim

--
Please don't feed the trolls

On 22/04/2017 12:23, Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote:
Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0


"Fabulous" seems like an apt description, stuff of fables.

That looks like it. I only recall the publicity of its launch and didn't
follow up on what happened to it. However, MIT and Stanford University
have both demonstrated low energy water splitters that can run from low
voltage sources.


You can split water with an AAA battery, the voltage doesn't matter much
its how much energy it takes.

Rule one: you cannot get more energy out than you put in.

This means that all these split water put it through a fuel cell and
re-split it while taping off energy are scams, every one. There are no
exceptions no matter how many youtube likes they get.

I know its hard to understand but its the truth, in this reality anyway.

On 22/04/17 12:23, Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote:
Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0


"Fabulous" seems like an apt description, stuff of fables.

That looks like it. I only recall the publicity of its launch and didn't
follow up on what happened to it. However, MIT and Stanford University
have both demonstrated low energy water splitters that can run from low
voltage sources.

well I am sorry, but unless the laws of physics have changed the energy
required to split a molecule of water into hydrogen and oxygen is the
same whatever method you use, and about three times what you are likely
to get back recombining them to make mechanical or electrical power.


--
If I had all the money I've spent on drink...
...I'd spend it on drink.

Sir Henry (at Rawlinson's End)

On 22/04/17 12:13, charles wrote:
In article , Tim Streater
wrote:
In article , The Natural Philosopher
wrote:

I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium
tube flash boiler can supply steam at up to 4,000 psi and 650C.
Ceramics allow engines to work at those temperatures and pressures and
achieve efficiencies not even dreamed of with conventional materials.

Exatamondo. I cant remember what the law is called, but the hotter the
working fluid (steam in this case) is to start with, and the colder the
final exhaust, the more efficient is the engine.

Which is why a combined cycle gas turbine that starts with 1000C gases
in the jet engine, then heats a boler to get steam, and has a final
after condenser temp of around 50C, willnet you over 60% thermal
efficiency.

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

Well its not actually the temperature difference, its the *ratio* of the
temperatures.

The total input energy in heat is proportional to the absolute temperature.

The lost output energy as heat is proportional to the output temperature
in absolute degrees.

Theres a bit of a fudge in that you start with ambient to do your
heating of course.



--
If I had all the money I've spent on drink...
...I'd spend it on drink.

Sir Henry (at Rawlinson's End)

In article ,
Chris Hogg wrote:
t always sup rises me that seemingly intelligent people who claim to
have invented the perpetual motion machines that they proudly display
on Youtube, aren't multi-millionaires, having solved the world's
energy and AGW problems at a stroke with their carbon-free,
non-nuclear methods of electricity generation, such as cars that run
on water or spinning magnet arrangements to make electricity.

The fact that they aren't multi-millionaires says it all.

Rather like someone trying to sell you a money making scheme. If it were
good, they'd keep it to themselves, and make all the money they want.

--
*I'm reading a book about anti-gravity. I just can't put it down.*

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:

In article , Tim Streater
wrote:
In article , The Natural Philosopher
wrote:

I suspect that the boilers and engines you are familiar with are
more nineteenth century technology than twenty-first century. A
titanium tube flash boiler can supply steam at up to 4,000 psi and
650C. Ceramics allow engines to work at those temperatures and
pressures and achieve efficiencies not even dreamed of with
conventional materials.

Exatamondo. I cant remember what the law is called, but the hotter the
working fluid (steam in this case) is to start with, and the colder
the final exhaust, the more efficient is the engine.

Which is why a combined cycle gas turbine that starts with 1000C gases
in the jet engine, then heats a boler to get steam, and has a final
after condenser temp of around 50C, willnet you over 60% thermal
efficiency.

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

The main benefit of using deg K instead of Deg C is the complete and
utter absence of negative numbers by which to confuse the mathematics. :-)

It's true enough that as far as steam engines are concerned, this is
unlikely to effect calculations involving deg C, but there are other heat
engines designs based on fluids with much lower freezing and boiling
points than zero deg C (the triple point of water to within an accuracy
of one decimal place).

--
Johnny B Good

On Saturday, 22 April 2017 09:45:40 UTC+1, Nightjar wrote:
On 21-Apr-17 6:46 PM, harry wrote:
On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote:
On 21-Apr-17 8:47 AM, harry wrote:
On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote:
In article , Nightjar
wrote:

On 20-Apr-17 8:18 AM, harry wrote:
On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote:
I've just been for a ride in someone's Nissan Leaf - it was
impressive, so
quiet and amazing acceleration.

Do electric cars have a gearbox (an automatic one I presume)? Or
does the
motor just run faster the faster you go? I was told by the owner the
optimum speed for economy of battery usage is about 55mph.

It doesn't sound like it's changing gear.

Internal combustion engines are inherently unsuitable for traction,
hence
the need for gearboxes/clutches etc.
Electric motors can be designed to be ideal for traction.
Max torque at zero rpm.

I could get that with a steam engine.

And a small one at that for a car. But AIUI, it's the condenser that's
the problem.


With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and
it could move off from cold in under 30 seconds.

Drivel.
Water is not fuel.

I was answering the point about the condenser. However, recent advances
in catalytic splitting of water could make it feasible to use water as
fuel, if you really wanted to.

Drivel.
Have you never heard of the Law of Conservation of Energy?

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.

All steam engines and boilers are inherently inefficient.
They will never come anywhere near the ICE efficiency wise.

Petrol cars achieve a tank to wheel thermal efficiency of about 16%.
Non-condensing third generation steam locomotives achieve a drawbar
thermal efficiency of about 16%.

I spent forty years running them. And getting rid of them where possible.

I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium tube
flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics
allow engines to work at those temperatures and pressures and achieve
efficiencies not even dreamed of with conventional materials.

Total drivel.
Steam locomotive efficiency, typically 5%.

The most efficient power stations use rejected heat for district heating. But that only applies in Winter. In Summer the heat is dumped.
And it only works if the heat is needed nearby.
Higher steam temperatures results in less efficient boilers because the exiting combustion gases can be at no lower temperature than the stem.

If you look at the picture, there are cooling towers. What do you suppose they are for? (Clue,dumping excess heat)
http://cornerstonemag.net/setting-th...-power-plants/

The problem of what to do with rejected low grade heat has proved insurmountable.

Flash steam boilers are suited for rapid start up, cheapness and low weight. But are notoriously inefficient, high maintenance and short life.
Yes,I have run these too.

On Saturday, 22 April 2017 12:23:33 UTC+1, Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote:
Nightjar wrote:

The principle has been demonstrated. A few years ago the Japanese
demonstrated a fuel cell car that ran entirely on water.


Eh? Now who's talking drivel?

A fuel cell that magically splits water or in some other way converts
*only* water into electrical energy? This greatest, most fabulous
discovery was made a few years ago and nobody has heard of it?

This one perhaps?
https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0

"Fabulous" seems like an apt description, stuff of fables.

That looks like it. I only recall the publicity of its launch and didn't
follow up on what happened to it. However, MIT and Stanford University
have both demonstrated low energy water splitters that can run from low
voltage sources.

--
--

Colin Bignell
You don't get anything for nothing.
In theory it take the same amount of energy to split hydrogen and oxygen as you get burning the hydrogen.
In practice, splitting the hydrogen is very inefficient.
So the whole concept is/was doomed.

On 22-Apr-17 12:47 PM, Chris Hogg wrote:
....
Splitting water only requires 1.23v in theory. If it's low energy, as
opposed to low voltage, you only get low amounts of H2 and O2. And
with the usual systematic energy losses, you'll get even lower amounts
of energy back when you recombine them. The idea that you can split
water, recombine the products, and get more energy out than you put
in, is pure fantasy, like the thinking on any other perpetual motion
machine.


As they are working on ways of reducing the cost of producing hydrogen,
they have been working on getting the same amount while using less
energy. Both claim to have made breakthroughs in doing that. As these
are processes with commercial applications, no details have been given,
but I assume that the use of catalysts implies that there is some
chemical reaction involved as well as pure electrolysis.

--
--

Colin Bignell

On 23/04/17 09:19, Nightjar wrote:
On 22-Apr-17 12:47 PM, Chris Hogg wrote:
....
Splitting water only requires 1.23v in theory. If it's low energy, as
opposed to low voltage, you only get low amounts of H2 and O2. And
with the usual systematic energy losses, you'll get even lower amounts
of energy back when you recombine them. The idea that you can split
water, recombine the products, and get more energy out than you put
in, is pure fantasy, like the thinking on any other perpetual motion
machine.


As they are working on ways of reducing the cost of producing hydrogen,
they have been working on getting the same amount while using less
energy. Both claim to have made breakthroughs in doing that. As these
are processes with commercial applications, no details have been given,
but I assume that the use of catalysts implies that there is some
chemical reaction involved as well as pure electrolysis.

You can assume what you like mate, but the fact remains that the binding
energy has to be overcome, and that sets a limit on the process. You
cant magically create energy out of nothing. The energy you get be
recombining hydrogen and oxygen will never exceed what you put in to
split them in the first place.

And in fact is usually a whole lot less.

Using electricity to make hydrogen and then burning that to create
electricity is a round trip efficiency of probably less than 30% as
batteries go, that's crap.

If basic physics wer mandatory like English is supposed to be there
wouldn't be as single renewable/alternative energy company in operation.

They all survive because of grants granted by the technically illiterate.

--
Karl Marx said religion is the opium of the people.
But Marxism is the crack cocaine.

On 23-Apr-17 8:13 AM, harry wrote:
....
I suspect that the boilers and engines you are familiar with are more
nineteenth century technology than twenty-first century. A titanium tube
flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics
allow engines to work at those temperatures and pressures and achieve
efficiencies not even dreamed of with conventional materials.

Total drivel.
Steam locomotive efficiency, typically 5%....

Third generation steam locomotives are not typical. They have been
specifically designed to use modern technology. The 5AT project failed
to get the target funding, but the calculation of drawbar efficiency is
given he

http://5at.co.uk/index.php/definitio...fficiency.html

Flash steam boilers are suited for rapid start up, cheapness and low weight. But are notoriously inefficient, high maintenance and short life.
Yes,I have run these too.

Using 21st century or 19th century materials?

Whatever you want to think, an R&D subsidiary of IAV Gmbh developed a
small, lightweight steam engine, using modern technology throughout,
that could be fitted into motor vehicles, although they see the initial
application as being in auxiliary power units, particularly in third
world countries. They claim fuel efficiency as being similar to a diesel
engine. It uses catalytic heating to avoid flames, which keeps emissions
down to very low levels, and can burn a very wide range of fuels. Steam
is viable, even if that does not sit well with your world view.



--
--

Colin Bignell

On 23/04/17 09:49, Nightjar wrote:
Steam is viable, even if that does not sit well with your world view.
Technically perhaps ...but economically?

IC engines are good because you don't have to lug the fuel oxidant or
the working fluid around. Its in huge supply as atmospheric oxygen and
gases respectively.

Once you are building a static installation though, steam predominates
and is more efficient, because you can run huge condensers on the back end.

And you have a variety of thermal sources that you can hook up - coal,
oil gas, nuclear.


--
The New Left are the people they warned you about.

On Fri, 21 Apr 2017 10:08:00 +0100, Muddymike
wrote:

On 21/04/2017 10:01, Tim Streater wrote:
In article ,
Muddymike wrote:

Or like my Peugeot ICE drives front wheels, Electric motor drives rear
wheels. So I have 4WD when I need it, and silent running when in town
just to scare the natives:-)

Can you put the ICE in reverse while the electric is going forwards?

To get a stretched limo?

Wouldn't it get you a city car? ;-)

Cheers, T i m

On 22/04/2017 22:43, Johnny B Good wrote:
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:
In article , Tim Streater
wrote:

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

The main benefit of using deg K instead of Deg C is the complete and
utter absence of negative numbers by which to confuse the mathematics. :-)

It's true enough that as far as steam engines are concerned, this is
unlikely to effect calculations involving deg C, but there are other heat
engines designs based on fluids with much lower freezing and boiling
points than zero deg C (the triple point of water to within an accuracy
of one decimal place).

Freezing points are irrelevant. So are boiling points. It's just gases
and absolute temperatures.

--
Max Demian

On 23-Apr-17 10:10 AM, Tim Streater wrote:
In article , Nightjar
wrote:
.....
Whatever you want to think, an R&D subsidiary of IAV Gmbh developed a
small, lightweight steam engine, using modern technology throughout,
that could be fitted into motor vehicles, although they see the
initial application as being in auxiliary power units, particularly in
third world countries. They claim fuel efficiency as being similar to
a diesel engine. It uses catalytic heating to avoid flames, which
keeps emissions down to very low levels, and can burn a very wide
range of fuels. Steam is viable, even if that does not sit well with
your world view.

As I hinted at before, where is the condenser and how big does it have
to be?


You would have to ask the developers that. However, they have said that
the engine could be fitted into a car, so they obviously don't think it
is a serious problem.

--
--

Colin Bignell

On 23/04/17 16:39, Chris Hogg wrote:
On Sat, 22 Apr 2017 22:46:33 +0100, Tim Streater
wrote:

In article , Johnny B Good
wrote:

On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:

In article , Tim Streater
wrote:
In article , The Natural Philosopher
wrote:

I suspect that the boilers and engines you are familiar with are
more nineteenth century technology than twenty-first century. A
titanium tube flash boiler can supply steam at up to 4,000 psi and
650C. Ceramics allow engines to work at those temperatures and
pressures and achieve efficiencies not even dreamed of with
conventional materials.

Exatamondo. I cant remember what the law is called, but the hotter the
working fluid (steam in this case) is to start with, and the colder
the final exhaust, the more efficient is the engine.

Which is why a combined cycle gas turbine that starts with 1000C gases
in the jet engine, then heats a boler to get steam, and has a final
after condenser temp of around 50C, willnet you over 60% thermal
efficiency.

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

The main benefit of using deg K instead of Deg C is the complete and
utter absence of negative numbers by which to confuse the mathematics. :-)

It's true enough that as far as steam engines are concerned, this is
unlikely to effect calculations involving deg C, but there are other heat
engines designs based on fluids with much lower freezing and boiling
points than zero deg C (the triple point of water to within an accuracy
of one decimal place).

The formula for efficiency *requires* K.


+1

From the wiki entry for the Carnot cycle I posted elsewhere in this
thread, the theoretical maximum efficiency of a heat engine is given
as 1 - Tc/Th, where Tc is the lower temperature and Th is the higher
temperature, both in kelvins http://tinyurl.com/alle4tg (Equation 3).
For a heat engine where the operating temperature is say 600°C (873K)
and exhausting into ambient of say 20°C (293K), you get very different
results if you attempt the calculation in °C compared to calculating
in kelvins, 0.97 for the former, 0.66 for the latter. It is the latter
which is correct.

A quote from that article:

"Carnot realized that in reality it is not possible to build a
thermodynamically reversible engine, so real heat engines are even
less efficient than indicated by Equation 3. In addition, real engines
that operate along this cycle are rare. Nevertheless, Equation 3 is
extremely useful for determining the maximum efficiency that could
ever be expected for a given set of thermal reservoirs".

Note that the basis for the formula depends on a relationship between
energy and temperature that is not necessarily obeyed if you go through
a phase change.


--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

On 23/04/2017 08:13, harry wrote:
Higher steam temperatures results in less efficient boilers because the exiting combustion gases can be at no lower temperature than the stem.

This turns out not to be the case.

You can, for example, use the warm exhaust to preheat the incoming air &
fuel.

Andy

On 22/04/2017 22:43, Johnny B Good wrote:
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:

In article , Tim Streater
wrote:

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

The main benefit of using deg K instead of Deg C is the complete and
utter absence of negative numbers by which to confuse the mathematics. :-)

It's true enough that as far as steam engines are concerned, this is
unlikely to effect calculations involving deg C, but there are other heat
engines designs based on fluids with much lower freezing and boiling
points than zero deg C (the triple point of water to within an accuracy
of one decimal place).

FFS Kelvins aren't degrees.

And it must be absolute temperature for the equations to work.

Just consider what the results would look like for Tin-Tout/Tout if Tout
was negative.

Andy

On Sun, 23 Apr 2017 21:42:59 +0100, Vir Campestris wrote:

On 22/04/2017 22:43, Johnny B Good wrote:
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:

In article , Tim Streater
wrote:

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

The main benefit of using deg K instead of Deg C is the complete and
utter absence of negative numbers by which to confuse the mathematics.
:-)

It's true enough that as far as steam engines are concerned, this is
unlikely to effect calculations involving deg C, but there are other
heat engines designs based on fluids with much lower freezing and
boiling points than zero deg C (the triple point of water to within an
accuracy of one decimal place).

FFS Kelvins aren't degrees.

Well, assuming by "Kelvins" you meant Degrees Kelvin and by "degrees"
you meant degrees Celcius, they are! If the standard atmospheric pressure
had been a higher value than it's currently assumed, those degrees Celcius
would simply have been a larger sized increment across the arbitrary 100
degrees Mr Celcius had chosen to span the freezing and boiling points of
pure water and a smaller starting volume of gas than the 273cc's worth at
zero degrees Celcius would have been determined as the basis for
establishing where absolute zero would be in the (now) larger scale units
of degrees Celcius.

Anyhow, putting that aside, degrees Kelvin are directly based on degrees
Celcius no matter that there is an element of arbitrariness in the Celcius
scale. The difference is merely in where the zero point is set on the
scales. In the case of degrees Kelvin, this was based on an Absolute Zero
derived from the behaviour of gases which all exhibited the same
expansion coefficient throughout their gas phase, allowing the Absolute
Zero point to be extrapolated beyond the limits set by each particular
gas's liquifaction points at NTP.


And it must be absolute temperature for the equations to work.

My bad, I just assumed that mere temperature differences would
suffice. :-(


Just consider what the results would look like for Tin-Tout/Tout if Tout
was negative.

Obviously, I *didn't* consider negative temperatures, just temperature
differences. :-(

--
Johnny B Good

On Sun, 23 Apr 2017 21:37:06 +0100, Vir Campestris wrote:

On 23/04/2017 08:13, harry wrote:
Higher steam temperatures results in less efficient boilers because the
exiting combustion gases can be at no lower temperature than the stem.

This turns out not to be the case.

You can, for example, use the warm exhaust to preheat the incoming air &
fuel.


Mother nature has beaten us to this 'trick' as can be seen in the
anatomy of penguins' feet where the veins and arteries in their legs run
side by side so as to allow the veins to recover heat from the arteries
before it gets lost by contact with the ice upon which they roost or
walk. The feet themselves are little more than bones, ligaments and
tendons acting as remote controlled low temperature tolerant appendages.

In the case of the flash boiler, the hot combustion products are routed
in a contra-flow to the direction of the feed water flow from the
condenser and the boiler unit itself is extremely well insulated to
minimise unproductive heat loss through the casing.

Getting back to the original question, most electric vehicle designs
eliminate the mechanical variable ratio gearbox, electing instead to use
high power handling switching converters to control the motor speed
instead. Even when a design uses a fixed gear ratio box to better match
the loading on the drive motor, electronic drive voltage control is still
the method by which modern electric road vehicles are speed regulated.

In an ideal setup, you would have hub motors in each wheel which could
be arranged as a series wired pair on each axle to provide a built in
differential and halving of the current required to drive each axle's
worth of hub motors.

However, in order to maximise efficiency and power to weight performance
of electric traction motors, you get the best performance using a high rpm
motor[1] which basically precludes direct drive hub motor designs unless
you're prepared to sacrifice top end performance for improved battery
economy at more modest urban traffic speeds (you replace mechanical
transmission losses with much lower electric cabling losses).

[1] High rpm on account it uses less turns of heavier gauge copper in its
windings, meaning reduced I squared R losses.

--
Johnny B Good