Cooling questions

[AdeV73]

Hi chaps,

Now that my racing car has packed up again I'm back on the other love of my life (no, not her...)  .

A plumber mate of mine recently dropped off an indirect hot water cylinder & central heating pump; and I've picked up a couple of new threaded flanges & various bits of copper from various places; the end result is I think - bar some flexible pipe - have enough bits to complete my cooling system.

The plan is similar to "Eadie McCreadie"'s from a while back: Circulate engine coolant in the heat transfer coil, to heat up the tank of clean water for - well, whatever. Experimental purposes at the moment, but eventually I'd hope to use it to supply the house.

Q1: The heat transfer coil is 22mm diameter. I've got expansion joints to 28mm for all the external pipework, which terminates in a 28mm-1"BSP fitting in the side of the engine. Is the engine likely to thermocycle effectively with this diameter and shape of pipe? Plumber reckons yes, I'm not so sure... I'll fit the CH pump in somewhere along the line, but if I'm lucky I won't have to use it.

Q2: I fancy using a regular car expansion bottle to allow the system to pressurise slightly, as well as to contain any excess coolant. Is this likely to be a problem? I suspect not, as I can't see the pressure being that high, but if anyone's already been running a pressurised circuit successfully, that'd be really nice to know.

Q3: I'd like to fit a temperature gauge, probably from the same car I get the expansion bottle from. Obviously, the best place for it would be right at the head. My new water flanges are significantly thinner than the original articles; but I have 2 originals (which are a good inch thick). With suitable replacement studs, I could sandwich an old flange between the engine & new flange; this I could then drill & tap to accept a standard temperature probe. However, the probe would take quite a lot of room up in the pipe, would it leave enough space for thermosyphoning to work? Again, I can pump it if I have to, but I'd like to avoid that if possible.

Q4: I was planning on using silicone hoses to provide the flexible element between engine & tank; but they're pretty expensive. Does anyone know off-hand of any model of car which uses 28mm ID rubber pipework in its cooling system?

Any thoughts most gratefully received. I'll stick a couple of pictures up tomorrow as well, so you can see what I'm talking about.

[ronmar]

How long is that heat transfer coil pipe, or more specifically how much heat transfer surface area do you have inside the water tank.  What is the heat transfer material, copper?  What size/type engine are we talking about here?  This info is needed before I could even take a guess at how well this will work.

Some basic things to consider are:
1. Thermosiphon is powered by gravity and the density changes caused by heating and cooling.  If you are not removing enough heat, you could run into problems with slow flow. 
2. Heat transfer is dependent on temperature difference between the two fluids, the thermal conductiviy of the material separating the fluids, and the time the fluids are allowed to transfer the heat.  Also the agitation or turbulence of the two fluids has a HUGE effect on heat transfer.  A lack of turbulence will allow thermal layers to form which slow overall heat transfer.  With the heat coil inside the hot water tank, as the tank warms, less heat will be removed from the coil.  The flow in the tank will be dependent on convection of the fluid, which might be slow, allowing the water immediatly around the coil to form a warm blanket, like water in a scuba divers wetsuit, slowing heat transfer.
3. Since the change in density of the fluid is small,  there is not a lot of energy involved in thermosiphon.  If the coil does not have much volume, the ammount of fluid in the cylinder and head can outweigh the smaller ammount of fluid in the coil, even if it has good cooling.  I ran into this problem with my heatexchanger.  the heatex had such a low volume, it would not thermosiphon very well untill I raised it several more feet.  This gave enough cooled fluid in the pipe comming down from the heatex to power the thermosiphon flow.  Once I figured this out, it thermosiphones very well.  If there is not much mass in the coil, you will need the pump to maintain adequate flow. 

[mike90045]

Q2: I fancy using a regular car expansion bottle to allow the system to pressurise slightly, as well as to contain any excess coolant. Is this likely to be a problem? I suspect not, as I can't see the pressure being that high, but if anyone's already been running a pressurised circuit successfully, that'd be really nice to know.

I don't think the O ring is good for more than a couple PSI, and I would NOT seal it.  (or else I missed what engine you are talking about).

 A small expansion tank would not be a bad idea.

[oliver90owner]

AdeV

Unless you are changing the head gasket to a different type, you may well quickly run into water leakage across the gasket.  The originals were not designed for pressurised systems.

Regards, RAB

[AdeV73]

Thanks for the answers so far...

The bits I missed out:

• The engine is a 6/1 original Lister.
• I'm not sure what the heat transfer area is (it may say on the tank label, I will check & amend accordingly).
• Everything's copper, so excellent thermal conductivity there.

ronmar - interesting thoughts about turbulence and heat layers; I don't mind agitating the water in the tank, either by pumping it around, or by installing a home-made stirrer in the immersion heater port... probably the former if I'm honest.

[compig]

Regarding hose , just find a local industrial hose stockist (not Hydraulic) and ask for Radiator hose. It's available in incremental sizes in 1 mtr lengths and 28 mm i.d. is fairly standard. Keeping things simple , I doubt there is enough fluid volume in that circuit for good thermosyphon and as the water in the tank heats up the coil will be at more or less the same temp at both ends. Think your going to need that pump !! To install your temp gauge use an inline aluminium gauge adaptor , very popular with the car tuning scene.

[AdeV73]

Thanks compig - I'll try our local motor factor. 15 quid for silicone hoses was a bit much, especially as they don't do them in mid-Brunswick Green

Some pix of my developing layout (click the pictures for the big version):

	New (from stationaryengineparts.com) 3/4" flange with 1" to 28mm adapter (B&Q)
	Original 1" wide Lister fitting
	Cooling tank next to engine, showing off its coil fittings
	Grump, I'd cleaned all that bit up. Luckily, I have some new gaskets.

[compig]

Actually , Gates do a silicone hose in a sort of green colour , but if you thought £15 was expensive ??!!  I could have silcone hose made in a green close to Lister , but you would have to want it real bad to pay the price !!  The chicks would fall at your feet though !! LOL !!
BTW , whats up with the race car ?
 

[AdeV73]

Actually , Gates do a silicone hose in a sort of green colour , but if you thought £15 was expensive ??!!

£15 is expensive for a bit of flexi hose.... when the equivalent scavenged off a car in a scrapyard would be pennies...

I could have silcone hose made in a green close to Lister , but you would have to want it real bad to pay the price !!  The chicks would fall at your feet though !! LOL !!

Indeed... Demon Tweeks do silicone hose in British Racing Green, which would be fairly close to Lister green, I should imagine. But that's around £25+vat+delivery for 1m... crazy money! 

BTW , whats up with the race car ?

OK, long story short:

• 2 yrs ago, I broke the crankshaft. Engine survived, went for rebuild.
• 18 months later, I start chasing the builder, as I want to go racing. Repeated promises "it'll be ready next week"... Requires new block, I supply 4, one of which is chosen.
• Finally get the engine back at end of last year. Manifold gasket had blown on dyno, so engine is full of mayonnaise.
• Set about flushing with cheap oil when it develops a misfire; loose rockers diagnosed, back to engine builder because if the rockers are loose, what else is wrong with it?
• Returned & refitted earlier this year, take it to Cadwell for test day + race. Drops core plug & all its water 5 mins into 1st test session. Replace original core plug ('cos I couldn't find a new one) which repeats its falling out trick. Replace with new core plug for race, only to have ignition switch short out in assembly area, no race.
• Engine back to fitter with instructions to "bloody well get it right this time"...
• Engine on dyno Monday, massively down on power, sounds awful.
• Dissasembled Tuesday, gudgeon pin has fallen out of one of the pistons & destroyed the block. Miss another test day + race (this Saturday).

[compig]

Good grief !!  This guy calls himself an engine builder ??!!  If you want it doing properly get it down to me and we'll sort it !! I can have everything needed done. Block prep , balancing , blueprinting , you name it.

Actually , I could make your eyes water with hose and fittings prices ! Average spend for a fully stainless braided fuel , oil & turbo install on a highly tuned Jap performance car is about £800 !!  One fitting can be £50 !! Silicone hose is very costly to manufacture hence the price , but for what you get it's cheap. Cosmetics are a pleasant side issue but the reliability and durability are very worthwhile when the life of an expensive engine is at risk. Commercial vehicles now use nothing else on OEM.  On a Lister it's not viable unless it's the aesthetics that are desired. Good quality , epdm radiator hose is fine for at least 5 years life.   

[GuyFawkes]

Hi chaps,

Now that my racing car has packed up again I'm back on the other love of my life (no, not her...)  .

A plumber mate of mine recently dropped off an indirect hot water cylinder & central heating pump; and I've picked up a couple of new threaded flanges & various bits of copper from various places; the end result is I think - bar some flexible pipe - have enough bits to complete my cooling system.

The plan is similar to "Eadie McCreadie"'s from a while back: Circulate engine coolant in the heat transfer coil, to heat up the tank of clean water for - well, whatever. Experimental purposes at the moment, but eventually I'd hope to use it to supply the house.

Q1: The heat transfer coil is 22mm diameter. I've got expansion joints to 28mm for all the external pipework, which terminates in a 28mm-1"BSP fitting in the side of the engine. Is the engine likely to thermocycle effectively with this diameter and shape of pipe? Plumber reckons yes, I'm not so sure... I'll fit the CH pump in somewhere along the line, but if I'm lucky I won't have to use it.

An elbow = 3' of pipe, rule of thumb, two bends = 1 elbow, rule of thumb
If the engine coolant consists solely of the coil you absolutely require a circulation pump.

reverse it and add a second tank, engine coolant thermosiphons to first tank, second tank is higher and thermosiphons from coil in top 18" of first tank, it will work sand circulation pump.

Q2: I fancy using a regular car expansion bottle to allow the system to pressurise slightly, as well as to contain any excess coolant. Is this likely to be a problem? I suspect not, as I can't see the pressure being that high, but if anyone's already been running a pressurised circuit successfully, that'd be really nice to know.

open to atmosphere, no problem, capped in any way, problem.

open != pinhole either

Q3: I'd like to fit a temperature gauge, probably from the same car I get the expansion bottle from. Obviously, the best place for it would be right at the head. My new water flanges are significantly thinner than the original articles; but I have 2 originals (which are a good inch thick). With suitable replacement studs, I could sandwich an old flange between the engine & new flange; this I could then drill & tap to accept a standard temperature probe. However, the probe would take quite a lot of room up in the pipe, would it leave enough space for thermosyphoning to work? Again, I can pump it if I have to, but I'd like to avoid that if possible.

best place for it is at the head, assuming the head never can get dry, eg boil dry or coolant leak

Q4: I was planning on using silicone hoses to provide the flexible element between engine & tank; but they're pretty expensive. Does anyone know off-hand of any model of car which uses 28mm ID rubber pipework in its cooling system?

ANy decent motor factor has generic rad hose in lengths , cheap.

any marine supplier has wire wound generic hose, which won't collapse or kink

don't dismiss the green spiral plastic stuff used on boats, if she boils it gets as soft as butter, quite useful. make sure you use bolt type clamps, not cheap ass clone jubilee clips.

[Stan]

So who sells the genuine brass bolt type hose clamps?   I need 1 for my original Lister to keep them all consistent.
Stan

[compig]

So who sells the genuine brass bolt type hose clamps? I need 1 for my original Lister to keep them all consistent.
Stan

It would lucky to find those !  Classic car parts suppliers or ebay would be your best bet I reckon.

 make sure you use bolt type clamps, not cheap ass clone jubilee clips.

Depends on the type of worm drive you use. Best type in my experience are stainless steel by ABA , never had one fail or strip it's threads. Actual Jubilee are not that good. The problem with bolt type is their limited size range in each nominal size. 

[AdeV73]

GuyFawkes,

Thanks for that, an interesting set of answers:

An elbow = 3' of pipe, rule of thumb, two bends = 1 elbow, rule of thumb
If the engine coolant consists solely of the coil you absolutely require a circulation pump.

reverse it and add a second tank, engine coolant thermosiphons to first tank, second tank is higher and thermosiphons from coil in top 18" of first tank, it will work sand circulation pump.

Initially, I only plan to use the heat transfer coil & whatever copper is between engine & tank. I'll plumb the CH pump in, then. 2nd tank sounds like a project for a future date... CH pump is also a temporary thing, I will use a 12v or 24v water pump in the fullness of time.

open to atmosphere, no problem, capped in any way, problem.

open != pinhole either

OK; cap off then. I must admit, I was lairy of pressurising it anyway.

best place for it is at the head, assuming the head never can get dry, eg boil dry or coolant leak

There's never a guarantee that it won't boil off or leak dry. For the moment, this is just an experimental lash-up, so it won't be leaking or boiling without my noticing something being amiss. I could automate a shutdown using a simple level switch in the expansion bottle; that will empty in the event of a leak prior to the temp sender becoming uncovered.

ANy decent motor factor has generic rad hose in lengths , cheap.

any marine supplier has wire wound generic hose, which won't collapse or kink

don't dismiss the green spiral plastic stuff used on boats, if she boils it gets as soft as butter, quite useful. make sure you use bolt type clamps, not cheap ass clone jubilee clips.

Cheap rad hose for now. I'll use something better [read: nicer cosmetically] later. Again, for now, cheapo jubilees will do ('cos I'll be watching it whenever it's running).

[Stan]

Here's a pic of the hose clamps I am trying to find.  Even if I can get them in steel, that would be a start.

[/img]

As you can see I have had a problem with this one.  It is unfixable.  I have tried soldering, brazing, epoxying etc. etc...  Too much time spent, now looking to purcha$e.

Stan