On or around Fri, 18 Jul 2003 12:52:23 +0000 (UTC), "Tim.."
enlightened us thusly:


"Austin Shackles" wrote in message
.. .
On or around Thu, 17 Jul 2003 21:58:49 +0100, Peter Hill
enlightened us thusly:

hmmm. any idea which volvo? would be a good source of a second-hand
(i.e.
cheap) pump.

Yes, any of the 400 series turbo's, and on some of the carb equiped ones
too, to lessen fuel vapourization. Renault used one on the 21 turbo also.

Tim..

I'll bear it in mind. Found an old washing machine pump in the shed today,
which looks ideal - will impel water at a reasonable rate, must be able to
cope with hot water, and doesn't block the flow when stationary.

will play tomorrow, if it's fine.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Would to God that we might spend a single day really well!"
Thomas À Kempis (1380 - 1471) Imitation of Christ, I.xxiii.

On Tue, 15 Jul 2003 21:23:56 UTC, Austin Shackles
wrote:

: I should be able to get the cold to go into the
: heater element in the heater, there to exchange it with warmth from the
: atmosphere, making the air coming into the car cooler while at the same time
: supplying heat to the vapouriser. I guess it'll probably want a circulating
: pump to get the water to flow around the smaller circuit of heater element
: and vapouriser.
:
: The valve, of course, will be remotely operated, and can then be used to
: adjust the temperature. Provided the vapouriser is maintained above
: freezing point, I don't see it needs to be as hot as it normally runs.

Old Johnston's Prediction: it won't work.

You need about 3% of engine power to vapourize propane, so for most
cars you need around 2 - 3kW. The average car heater has an output of
about 1kW, and it needs a temperature difference between air and water
of around 60 degrees to do that. You'll have a temperature difference
of about 20 degrees to play with, so you'll be lucky to transfer 300W
- around a tenth of what you need.

You might manage something a with a second thermostat to bleed some
hot water into the system to keep it aboce zero, but water circulating
around vapourizer and heater will freexe in no time.

Prove me wrong!

Ian


--

"Ian Johnston" wrote in message
news:cCUlhtvFIYkV-pn2-i7QU2y0ldJBn@localhost...
On Tue, 15 Jul 2003 21:23:56 UTC, Austin Shackles
wrote:

You might manage something a with a second thermostat to bleed some
hot water into the system to keep it aboce zero, but water circulating
around vapourizer and heater will freexe in no time.

Prove me wrong!

Ian


As long as the coolent contains enough antifreeze, I can't see there being a
problem.

Dave

From a point at sea, to the circles of your mind, this is Austin
Shackles:


cooling the incoming air in the engine actually adds efficiency, hence
intercoolers on diesels.

Yes, you are right, though it is the larger volume of air that is
cooled rather than the lesser volume of fuel. I was also being vaguely
facetious.

But it has made me wonder further. The cooloing system of a car is
kept at a pretty constant temperature, and hence the energy supplied
to the vapouriser will be pretty constant under a given set of engine
conditions. The temperature of your air-sourced heater will fluctuate
as ambient conditions change, and will not be related to engine
conditions. I'm guessing again, but in an open loop system, the
varying density of the vapourised LPG may make a difference to engine
performance. Emissions for the MoT may be unpredictable.

On the pump issue that you raised elsewhere, what about an old fuel
pump? I think it would be a mistake to rely on convection - pumping
will allow you to transfer more energy in a given time. And I reckon
antifreeze may be advisable.


--

Stewart Hargrave

Faster than public transport


For email, replace 'SpamOnlyToHere' with my name

On Fri, 18 Jul 2003 23:09:38 UTC, "Dean Clayton"
wrote:

:
: "Ian Johnston" wrote in message
: news:cCUlhtvFIYkV-pn2-i7QU2y0ldJBn@localhost...
: On Tue, 15 Jul 2003 21:23:56 UTC, Austin Shackles
: wrote:
:
: You might manage something a with a second thermostat to bleed some
: hot water into the system to keep it aboce zero, but water circulating
: around vapourizer and heater will freexe in no time.

: As long as the coolent contains enough antifreeze, I can't see there being a
: problem.

The problem is that a simple vapouriser - heater circuit will take far
more heat out of the water in the vapouriser than it will replace in
the heater. The fluid in the circuit is irrelevant - 100% antifreeze
will just give a slightly extended time of operation before freezing.

Ian

Stewart wrote in
:

I'm guessing again, but in an open loop system, the
varying density of the vapourised LPG may make a difference to engine
performance. Emissions for the MoT may be unpredictable.


I don't think this will matter as the bulk of the fuel/air mixture is the
incoming air at about ambient temperature.

If the low temperature difference between the heater matrix and the
vapuriser is a problem then a peltier solid state heat pump would boost the
difference at the expence of amps from the battery.

Terry

On or around Sat, 19 Jul 2003 01:17:54 +0100, Stewart
enlightened us thusly:

From a point at sea, to the circles of your mind, this is Austin
Shackles:


cooling the incoming air in the engine actually adds efficiency, hence
intercoolers on diesels.

Yes, you are right, though it is the larger volume of air that is
cooled rather than the lesser volume of fuel. I was also being vaguely
facetious.

The thought had crossed my mind.

But it has made me wonder further. The cooloing system of a car is
kept at a pretty constant temperature, and hence the energy supplied
to the vapouriser will be pretty constant under a given set of engine
conditions. The temperature of your air-sourced heater will fluctuate
as ambient conditions change, and will not be related to engine
conditions. I'm guessing again, but in an open loop system, the
varying density of the vapourised LPG may make a difference to engine
performance. Emissions for the MoT may be unpredictable.

maybe, dunno. can always turn it back to "hot" for the MOT.

On the pump issue that you raised elsewhere, what about an old fuel
pump? I think it would be a mistake to rely on convection - pumping
will allow you to transfer more energy in a given time. And I reckon
antifreeze may be advisable.

I've found an old washing machine pump which looks a good possibility. It
has the advantage of being made to work in hot water. not sure how well
sealed they are mind, not much pressure in yer average washing machine
outlet.

have to work out which is the supply to the heater, so the 2 pumps don't
manage to work against eachother. I tend to assume that the engine water
pump pumps "upwards", i.e. towards the top of the rad and away from the
bottom of the rad, so the heater pipe that goes into the pipe from the
bottom of the rad should be the outlet side, in theory.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"My centre is giving way, my right is in retreat; situation excellent.
I shall attack. - Marshal Foch (1851 - 1929)

On or around 18 Jul 2003 22:33:21 GMT, "Ian Johnston"
enlightened us thusly:

You need about 3% of engine power to vapourize propane, so for most
cars you need around 2 - 3kW. The average car heater has an output of
about 1kW, and it needs a temperature difference between air and water
of around 60 degrees to do that. You'll have a temperature difference
of about 20 degrees to play with, so you'll be lucky to transfer 300W
- around a tenth of what you need.

You might manage something a with a second thermostat to bleed some
hot water into the system to keep it aboce zero, but water circulating
around vapourizer and heater will freexe in no time.

I'll have a water control valve on the "hot" pipe from the engine. This
will serve to regulate the heater output and the vapouriser thing as well -
the idea being that if it tries to freeze, it just needs a small amount of
hot supplied to keep the vapouriser above freezing point. I see no reason
why the vapouriser needn't run fairly cold, and the water system always has
antifreeze in it anyway.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"My centre is giving way, my right is in retreat; situation excellent.
I shall attack. - Marshal Foch (1851 - 1929)

On Sat, 19 Jul 2003 08:50:29 UTC, Austin Shackles
wrote:

: I'll have a water control valve on the "hot" pipe from the engine. This
: will serve to regulate the heater output and the vapouriser thing as well -
: the idea being that if it tries to freeze, it just needs a small amount of
: hot supplied to keep the vapouriser above freezing point. I see no reason
: why the vapouriser needn't run fairly cold, and the water system always has
: antifreeze in it anyway.

Should work, as long as you get the control system OK - but I still
don't think you'll get more than 200 - 300W of cooling power, which
ain't much at all.

Ian


--

On or around 19 Jul 2003 09:14:11 GMT, "Ian Johnston"
enlightened us thusly:

On Sat, 19 Jul 2003 08:50:29 UTC, Austin Shackles
wrote:

: I'll have a water control valve on the "hot" pipe from the engine. This
: will serve to regulate the heater output and the vapouriser thing as well -
: the idea being that if it tries to freeze, it just needs a small amount of
: hot supplied to keep the vapouriser above freezing point. I see no reason
: why the vapouriser needn't run fairly cold, and the water system always has
: antifreeze in it anyway.

Should work, as long as you get the control system OK - but I still
don't think you'll get more than 200 - 300W of cooling power, which
ain't much at all.

better than nothing, and better than the current situation, where the heater
can't effectively be turned off, though.

might require an additional radiator, but that makes it more complicated
again.



--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Blue: The sky is blue for a reason. Blue light is a source of strength
and harmony in the cosmos. Create a blue light in your life by
telephoning the police
from the Little Book of Complete B***ocks by Alistair Beaton.