Diesel v petrol fuel economy
11-09-2005 | 05:20 PM
#1
Guest
Posts: n/a
Diesel v petrol fuel economy
On the subject of fuel economy I wonder if anybody on the ng can answer this
question. Do diesels give more mpg because there's simply more energy per
unit volume in diesel fuel compared with petrol, or is a diesel engine
intrinsically more efficient at turning hydrocarbons into kinetic energy (or
perhaps I should phrase it "less inefficient")?
--
___________________
Homer: D'oh!
Bart: A deer!
Marge: A female deer!
question. Do diesels give more mpg because there's simply more energy per
unit volume in diesel fuel compared with petrol, or is a diesel engine
intrinsically more efficient at turning hydrocarbons into kinetic energy (or
perhaps I should phrase it "less inefficient")?
--
___________________
Homer: D'oh!
Bart: A deer!
Marge: A female deer!
11-10-2005 | 06:46 AM
#2
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
"Noisy bacon" <NeillYoung@crazyhorse.com> wrote in message
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
11-10-2005 | 06:46 AM
#3
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
"Noisy bacon" <NeillYoung@crazyhorse.com> wrote in message
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
11-10-2005 | 06:46 AM
#4
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
"Noisy bacon" <NeillYoung@crazyhorse.com> wrote in message
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
11-10-2005 | 06:46 AM
#5
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
"Noisy bacon" <NeillYoung@crazyhorse.com> wrote in message
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
news:XCucf.11849$f_5.5832@newsfe6-gui.ntli.net...
> On the subject of fuel economy I wonder if anybody on the ng can answer
this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> perhaps I should phrase it "less inefficient")?
In thermodynamic terms, they're totally different things. Best of all would
be the Carnot Cycle (I'm not even going to get started - just Google ;o)
Funnily enough, Diesel engines use the Compression Ignition Cycle, which
isn't quite as good as the Diesel Cycle. AFAIK, the "proper" Diesel engine
remains pretty much theoretical.
Depending upon how you look at it, Diesel was either a visionary or a bit of
an engineering idiot: he designed something to utilise waste coal and cotton
dust, but, given the state of materials technology at the time, the only
thing his engines powered were themselves - at high speed, and over an
expanding area of real estate. 400 bar and wrought iron just.. doesn't.
His design improved on steam engines of the day, in terms of fuel
efficiency, but lacked the power to weight ratio required for use in a car.
That took several decades' of development by slightly more switched-on
engineers.
--
Hairy One Kenobi
Disclaimer: the opinions expressed in this opinion do not necessarily
reflect the opinions of the highly-opinionated person expressing the opinion
in the first place. So there!
11-10-2005 | 04:33 PM
#6
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
Noisy bacon wrote:
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
11-10-2005 | 04:33 PM
#7
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
Noisy bacon wrote:
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
11-10-2005 | 04:33 PM
#8
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
Noisy bacon wrote:
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
11-10-2005 | 04:33 PM
#9
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
Noisy bacon wrote:
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
> On the subject of fuel economy I wonder if anybody on the ng can answer this
> question. Do diesels give more mpg because there's simply more energy per
> unit volume in diesel fuel compared with petrol, or is a diesel engine
> intrinsically more efficient at turning hydrocarbons into kinetic energy (or
> perhaps I should phrase it "less inefficient")?
>
Well, there was a rumour that at the time of it's launch, the VW-Audi PD
130 TDi was the most thermally efficient production car engine
available, if that's any help. I've read somewhere that it's acpable of
transferring 43% of the fuel energy into power, so "less inefficient"
may apply here, but that's much more efficient than, for example, an
ordinary lightbulb.
11-10-2005 | 07:27 PM
#10
Guest
Posts: n/a
Re: Diesel v petrol fuel economy
"Chris Bartram" <news@delete.me.piglet-net.net> wrote in message
news:81Pcf.5207$Lw5.4701@text.news.blueyonder.co.u k...
> Noisy bacon wrote:
> > On the subject of fuel economy I wonder if anybody on the ng can answer
this
> > question. Do diesels give more mpg because there's simply more energy
per
> > unit volume in diesel fuel compared with petrol, or is a diesel engine
> > intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> > perhaps I should phrase it "less inefficient")?
> >
> Well, there was a rumour that at the time of it's launch, the VW-Audi PD
> 130 TDi was the most thermally efficient production car engine
> available, if that's any help. I've read somewhere that it's acpable of
> transferring 43% of the fuel energy into power, so "less inefficient"
> may apply here, but that's much more efficient than, for example, an
> ordinary lightbulb.
Sounds like someone's dream - the mere age of the fuel would make several
percent difference in conversion efficiency, let alone the fact that they're
using the same thermodynamic cycle as everyone else!
It's been a couple of decades since College, but 43% sounds like the Carnot
Cycle (i.e. theoretically perfect), rather than something produced by a
typical petrol engine. The hs tables are undoubtedly in the loft, but, well,
um ;o)
Standing-by to be corrected...
H1K
news:81Pcf.5207$Lw5.4701@text.news.blueyonder.co.u k...
> Noisy bacon wrote:
> > On the subject of fuel economy I wonder if anybody on the ng can answer
this
> > question. Do diesels give more mpg because there's simply more energy
per
> > unit volume in diesel fuel compared with petrol, or is a diesel engine
> > intrinsically more efficient at turning hydrocarbons into kinetic energy
(or
> > perhaps I should phrase it "less inefficient")?
> >
> Well, there was a rumour that at the time of it's launch, the VW-Audi PD
> 130 TDi was the most thermally efficient production car engine
> available, if that's any help. I've read somewhere that it's acpable of
> transferring 43% of the fuel energy into power, so "less inefficient"
> may apply here, but that's much more efficient than, for example, an
> ordinary lightbulb.
Sounds like someone's dream - the mere age of the fuel would make several
percent difference in conversion efficiency, let alone the fact that they're
using the same thermodynamic cycle as everyone else!
It's been a couple of decades since College, but 43% sounds like the Carnot
Cycle (i.e. theoretically perfect), rather than something produced by a
typical petrol engine. The hs tables are undoubtedly in the loft, but, well,
um ;o)
Standing-by to be corrected...
H1K
