There has been comment on this NG and in the press about air 
conditioning on trains failing to cope with the hot weather.

I've long noticed that the roofs of many coaches are BLACK, giving the 
greatest solar gain.
Some vehicles for use in the tropics have a 'tropical roof' which is 
simply a second skin open at all edges with an air gap of some 20mm.

Surely there would be sufficient clearance to add such a second skin to 
most of the roof area of many coaches? When in motion the air passing 
between the skins provides extra cooling, in addition to the reduced 
solar gain.

I know that this would increase the drag, but with trains using some 10% 
of power for 'hotel' services such as air-con. I think you might get 
significant 'net' gain in energy and capital cost, let alone passenger 
comfort!

Are such additions used in other hotter parts of the world, and has 
anybody quantified the benefits?

Jim Chisholm

J. Chisholm schrieb:

> There has been comment on this NG and in the press about air 
> conditioning on trains failing to cope with the hot weather.
> 
> I've long noticed that the roofs of many coaches are BLACK, giving the 
> greatest solar gain.
> Some vehicles for use in the tropics have a 'tropical roof' which is 
> simply a second skin open at all edges with an air gap of some 20mm.
> 
> Surely there would be sufficient clearance to add such a second skin to 
> most of the roof area of many coaches? When in motion the air passing 
> between the skins provides extra cooling, in addition to the reduced 
> solar gain.
> 
> I know that this would increase the drag, but with trains using some 10% 
> of power for 'hotel' services such as air-con. I think you might get 
> significant 'net' gain in energy and capital cost, let alone passenger 
> comfort!
> 
> Are such additions used in other hotter parts of the world, and has 
> anybody quantified the benefits?
> 
> Jim Chisholm



Hello,
I guess that the color of the roof plays no big role - insolation energy 
should be kept out by the insulation...

The other thing is the glazing and the air temperature.
I aggree that al engineers should try to add as much sunscreens as 
possible or special coatings and optimize the ventilation before 
investing in air condition.

My other idea is to use only the braking energy for cooling instead of 
burning it over the roof resistors. This of course mostly applies to 
older vehicles but it might be worth to think it over.


cheers

G.fried

J. Chisholm wrote:


> Are such additions used in other hotter parts of the world, and has
> anybody quantified the benefits?


Something similar used to be fitted to certain chemical tank-wagons,
notably those using the train ferry up to its demise.

"Chippy"  wrote:


>J. Chisholm wrote:
>
>> Are such additions used in other hotter parts of the world, and has
>> anybody quantified the benefits?
>
>Something similar used to be fitted to certain chemical tank-wagons,
>notably those using the train ferry up to its demise.



Also well known on the "Safari" Land Rovers up to Series III.

;-)

On Wednesday 20 July 2005 10:58 Tony Polson wrote:


> "Chippy"  wrote:
> 
>>J. Chisholm wrote:
>>
>>> Are such additions used in other hotter parts of the world, and has
>>> anybody quantified the benefits?
>>
>>Something similar used to be fitted to certain chemical tank-wagons,
>>notably those using the train ferry up to its demise.
> 
> 
> Also well known on the "Safari" Land Rovers up to Series III.
> 
> ;-)

Tony,
You beat me to it. Only I'd have called them Station Wagons.
I wonder what the extra drag costs in mpg.
Edgar

In article <dbl9hv$kvk$1@news5.svr.pol.co.uk>,
Edgar Iredale  <Please@no.spam.invalid> wrote:

>On Wednesday 20 July 2005 10:58 Tony Polson wrote:
>
>> "Chippy"  wrote:
>> 
>>>J. Chisholm wrote:
>>>
>>>> Are such additions used in other hotter parts of the world, and has
>>>> anybody quantified the benefits?
>>>
>>>Something similar used to be fitted to certain chemical tank-wagons,
>>>notably those using the train ferry up to its demise.
>> 
>> 
>> Also well known on the "Safari" Land Rovers up to Series III.


And beyond, I think. I'm sure I've seen 110s with the Safari roof.
May have been conversions or LRSV products, though...


>Tony,
>You beat me to it. Only I'd have called them Station Wagons.


As did LR: the plate on the back of my SIII said:

Land-/-Rover
Four wheel drive Station Wagon


>I wonder what the extra drag costs in mpg.


On a series Landy? Marginal, I'd suspect. The beasts aren't
that aerodynamically efficient (!!). Less effect than the
forests of snorts, high-level exhausts, lights, chequer
-plate and roof-racks that many of 'em sprout, though.
Suspect its effect of drag lies slightly above the moss
growing in the window slides...

-- 
Andy Breen ~ 	Interplanetary Scintillation Research Group
		http://users.aber.ac.uk/azb/
		"Who dies with the most toys wins" (Gary Barnes)

On Wednesday 20 July 2005 11:53 Andrew Robert Breen wrote:


> In article <dbl9hv$kvk$1@news5.svr.pol.co.uk>,
> Edgar Iredale  <Please@no.spam.invalid> wrote:
>>On Wednesday 20 July 2005 10:58 Tony Polson wrote:
>>
>>> "Chippy"  wrote:
>>> 
>>>>J. Chisholm wrote:
>>>>
>>>>> Are such additions used in other hotter parts of the world, and has
>>>>> anybody quantified the benefits?
>>>>
>>>>Something similar used to be fitted to certain chemical tank-wagons,
>>>>notably those using the train ferry up to its demise.
>>> 
>>> 
>>> Also well known on the "Safari" Land Rovers up to Series III.
> 
> And beyond, I think. I'm sure I've seen 110s with the Safari roof.
> May have been conversions or LRSV products, though...
> 
>>Tony,
>>You beat me to it. Only I'd have called them Station Wagons.
> 
> As did LR: the plate on the back of my SIII said:
> 
> Land-/-Rover
> Four wheel drive Station Wagon
> 
>>I wonder what the extra drag costs in mpg.
> 
> On a series Landy? Marginal, I'd suspect. The beasts aren't
> that aerodynamically efficient (!!). Less effect than the
> forests of snorts, high-level exhausts, lights, chequer
> -plate and roof-racks that many of 'em sprout, though.
> Suspect its effect of drag lies slightly above the moss
> growing in the window slides...
> 

Tongue was in cheek about mpg. I have a series 1(not Station Wagon).

Back to trains though - I doubt there'd be much value from a tropical roof
as I assume railway carriages have insulated roofs in this country (Land
Rovers used the tropical roof instead of insulation or trim or anything). 
Edgar

In article <dblcri$49t$1@newsg3.svr.pol.co.uk>,
Edgar Iredale  <Please@no.spam.invalid> wrote:

>On Wednesday 20 July 2005 11:53 Andrew Robert Breen wrote:


/safari roofs/


>> -plate and roof-racks that many of 'em sprout, though.
>> Suspect its effect of drag lies slightly above the moss
>> growing in the window slides...
>> 
>Tongue was in cheek about mpg. I have a series 1(not Station Wagon).
>
>Back to trains though - I doubt there'd be much value from a tropical roof
>as I assume railway carriages have insulated roofs in this country (Land
>Rovers used the tropical roof instead of insulation or trim or anything). 
>Edgar


I'd be inclined to agree - though double roofs have been used on railways
in the past (and maybe still today) - certainly 19th and early 20th
century carriages in .au, .za and .in had double roofs. Given modern
train speeds air-con is almost certain to be a more energy-efficient
alternative (and air-con //does// work on stopping trains and
metro-type trains, or at least it does in the much more onerous
environment of .jp)

-- 
Andy Breen ~ 	Interplanetary Scintillation Research Group
		http://users.aber.ac.uk/azb/
		"Time has stopped, says the Black Lion clock
  		 and eternity has begun" (Dylan Thomas)

"Andrew Robert Breen"  wrote in message
news:dbledj$4l7$1@central.aber.ac.uk...

> Given modern
> train speeds air-con is almost certain to be a more energy-efficient
> alternative (and air-con //does// work on stopping trains and
> metro-type trains, or at least it does in the much more onerous
> environment of .jp)


Have to say that despite my scepticism about aircon on trains, it's always a
pleasure to enter the temperate-to-cool environment of a 333, especially on
a baking hot day. Now if only it worked that well on all classes and types
of train...

> "Chippy"  wrote:
> 
> > Are such additions used in other hotter parts of the world, and has
> > anybody quantified the benefits?
> 
> Something similar used to be fitted to certain chemical tank-wagons,
> notably those using the train ferry up to its demise.
> 


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