Mister system

[windtrader]

I looked a fair bit for any real studies done on the additional cooling from a misting system added in front of a radiator. Could not find anything close.


It seems quite simple to obtain real measurements. Adding a water temp sensor on the input and output of the radiator would measure the cooling provided by the radiator. Run and measure with the mister on and off. Simple as pie.


The aux fans seem to make a difference on my bus but I've pondered doing this to take readings of the actual added cooling from the fans.


Any suggestions on placing a temp probe at those locations? It seems the most accurate placement is in the actual water flow. Second best would be attached to the hose strap on the exterior. Maybe either is sufficient for purposes of understanding just the difference in cooling.

[Iceni John]

I looked a fair bit for any real studies done on the additional cooling from a misting system added in front of a radiator. Could not find anything close.


It seems quite simple to obtain real measurements. Adding a water temp sensor on the input and output of the radiator would measure the cooling provided by the radiator. Run and measure with the mister on and off. Simple as pie.


The aux fans seem to make a difference on my bus but I've pondered doing this to take readings of the actual added cooling from the fans.


Any suggestions on placing a temp probe at those locations? It seems the most accurate placement is in the actual water flow. Second best would be attached to the hose strap on the exterior. Maybe either is sufficient for purposes of understanding just the difference in cooling.

I do actually have three additional temperature gauges back by the engine, one for each cylinder bank's coolant temperature at the thermostat housing, and a third for the coolant outflow temperature from the radiator, theoretically to see what's the temperature difference through the radiator.   It's not precise however, because A) the gauges are cheapo Chinese full-sweep Stewart Warner ones that all displayed slightly different temperatures when I tested them in boiling water before I used them, and B) the third gauge for outflow temperature is not in the actual return pipe to the water pump, but instead is in a T-fitting at the lower tank's drain valve, so it's not in actual flowing coolant.   I'm seeing about 20 to 25 degrees difference between the top and bottom of the radiator, ish, but I can't guarantee the accuracy of those numbers!   Unfortunately that doesn't seem to jive with the few degrees of temperature reduction I'm getting from the misters, so who knows?   I think at this stage it's a classic case of too much information but not enough knowledge!   Where are the experts here who can chime in and add some real knowledge to the subject?

John

[chessie4905]

Do you also use a water wetter?

[Jim Eh.]

Could you use one of those infared thermometers? The cheap ones probably don't show an accurate temperature but should at least accurately show temperature differential between locations. And seeing as it is a single instrument the differential should be more accurate.
You could even test between cylinders with a caveate of sorts in that all engines vary a bit between cylinder temps.

[lostagain]

All this discussion about cooling seems quite complex to me...

I think you mostly need to have the cooling system in good working order.

If my bus runs hot on a hot day, I just back off the accelerator, shift down a gear, and get over the hill a little slower...

JC

[Dave5Cs]

Agree with JC. And the higher you point the nose of the Bus in the air the hotter the mechanical s get if everything else remains the same.
Yes make sure your cooling system is clean and run test strips every so often to see if the correct balance is there. If not add what it needs and learn how to drive it up a hill slower and in a gear that won't make the engine work harder or lug down. Keep the rev's up.  I like to put it on auto pilot and go back and make a sandwich while waiting for the Bus to crest the hill...

[buswarrior]

Oh, I sure miss the automotive engineers that once frequented the conversion boards...

On misters, if my memory serves...

There are lots of big variablesn one mister system's success can be another's failure.

The actual coverage of water on the rad is problematic due to the wind patterns entering the rad cavity. At speed, some misters are not wetting anything except a thin strip behind them.

Condition of radiator is different, bus to bus. Both deterioration and construction.

Speed of air flow, current humidity levels, air temperature, temperature of water being misted, volume of misted water.

Small changes to some can have big effect on calculation.

What do the manufacturers do about cooling in hot regions...?

Neat science, better explained by the peeps who earn their living doing this stuff.

Moral of the story? Fix cooling system, size correctly, upgrade to dimples. Save water for drinking.

Happy coaching!
Buswarrior

[lvmci]

And On MCIs, seals around split radiators are not missing or cracked. Those huge squirrel cage fans will pull air thru the least obstructed area, so if the rubber seals are not sealing, air will be pulled from around the radiators, not thru them, lvmci....

[windtrader]

Given the age and state of these old coaches, it makes sense to really inspect and repair the airflow path ensuring everything is fully sealed and unobstructed as delivered.


The engineering and science involved to make informed mods is galaxies beyond me and probably most of us here. Those working on the original design had a variety of variables to balance including raw material costs, production costs, complexity of design, maintainability, etc. So far more than simply optimizing cooling under conditions experienced a small percentage of time. Side note is the obvious second roof skin like Dave has on his bus; those destined to operate in 100+ days nearly everyday.


The temp probes need to display while underway. The IR units is a good idea but only work while the bus is stopped so it can capture temp only at a single moment. Far more insight would be derived while underway and receiving dynamic updates show response to varying conditions.


There are thermistors which are very small to capture temp. I used them in an electronic project a few moons ago. they are dirt cheap and really small. I'd bet you can slip one into the flow by simply sandwiching the thin wire between the hose and the radiator connector and clamp it up. The wire can be very thin gauge so sealing shouldn't be an issue.

[lostagain]

Back a few decades ago, buses were designed with the skills of the drivers as an integral part of its operation. Such as, for example, the cooling system not being perfect, the drivers were trained, and expected to make up for the shortcomings by watching the temperature gauge, backing off the pedal, and downshifting as necessary, on a hot day.

Modern vehicles now have taken the driver out of the equation with technology. All a driver has to do now is steer, the machine does pretty well everything else on it's own. And soon not even a driver will be needed...

JC

[Iceni John]

Agree with JC. And the higher you point the nose of the Bus in the air the hotter the mechanical s get if everything else remains the same.
Yes make sure your cooling system is clean and run test strips every so often to see if the correct balance is there. If not add what it needs and learn how to drive it up a hill slower and in a gear that won't make the engine work harder or lug down. Keep the rev's up.  I like to put it on auto pilot and go back and make a sandwich while waiting for the Bus to crest the hill...

I agree 100%.   One thing I added that makes it easier to control temperature when climbing long grades is my turbo boost gauge.   It tells me exactly how hard the engine is working, i.e. how much fuel it's burning and therefore how much heat it's producing.   I know now that I can climb a steady 6% grade in all but the very hottest weather without overheating if I keep boost to no more than 18 PSI, on a 3/4 throttle in 3rd gear at about 1900 to 2000 RPM.   The moment boost exceeds 20 PSI I see an instant rise in temperature.   And if it's still getting hotter, then I drop to 2nd.   The mister system is for those rare occasions when sensible and focused driving isn't quite enough to control heat, and I don't intend to use it unless absolutely necessary.   It's just another tool in the toolbox.

John

[lvmci]

I Agree JC,  I shot the 1st ever driverless 18 wheeler demonstration at Hoover Dam a couple years ago, for Damler Freightliner Detroit Diesel, Nevada gave the first license to a driverless trucks, the pitch from the prez of Mercedes Benz was the driver was now a load coordinator, setting up delivery times and getting next loads, all thru the satellite dish on the truck,the funny part was the Interior Dept. wouldn't let the truck drive itself across the Dam! It was also the largest, longest throw, projection image, with using the Dam as the screen. for me the best part was getting to work with my son for the first time on a shoot, lvmci...

[luvrbus]

You guys do know that Hayden makes a mister in a kit the truckers use dosen't look like it the tank hold much water to me but has a high pressure pump so maybe it doesn't need that much water 

[Iceni John]

You guys do know that Hayden makes a mister in a kit the truckers use dosen't look like it the tank hold much water to me but has a high pressure pump so maybe it doesn't need that much water

Yup, but Hayden's kit is so naff.   Alliance Bus Lines in Ontario CA had a Super II like mine, and they tried the Hayden mister in it.   Apparently it did tiddly-squat.   That's why my mister is (I hope) better than the Hayden one.   At least mine does something!

John

[luvrbus]

All the home grown systems use to much water,LVMCI has a nice system he installed but he left it on for a few mintues in the shop and there was water everywhere on the floor.To me it seems like a system like that would be worthless like a Evap cooler in a high humidity area.I am missing something I thought the whole idea is to cool the air before it reaches the radiator,the fan sucking water in acts like a sand blaster I have seen it on to many radiators