Accurate Diesels Version of the FSD Cooler

[Wheat Whacker]

Anybody else notice that Accurate Diesel now has there own version of the FSD Cooler. It looks very simialar to the Beta version but with some differences that might make it a better product. Anybody have one or seen one up close? Hint Jim maybe this would be a good product to test. Accurate Diesel (http://www.accuratediesel.com)

[FinSub97]

If you have an object which is hotter than it's environment, it cools down to thermal equilibrium by three separate mechanisms.

1) Conduction
Metals in general have pretty good thermal conductivity. However, there are differences between metals as well. For instance, aluminium can conduct only approx. 60% of the heat carried by copper.

Conduction steps into play when you are designing a cooler and you need to define the material to be used. The better conduction, the more easily heat is transferred from hot to cooler areas. (There are other design parameters to be taken into account at this stage as well, like weight and stiffness.)

2)Convection
This mechanism carries heat away from the cooler. Air-cooler -interface is the bottleneck of this mechanism, since that interface has a poor heat transfer coefficient. This bottleneck tends to keep the heat inside the cooler instead of transferring it into surrounding medium.

The factors governing the performance of this cooling mechanism are the choice cooling medium (in practise water or air) and the mass flow of the chosen medium.

3) Radiation
The heat flux radiated depends on the surface temperatures of the surroundings, the object's surface temperature and the thermal emissivity of the object's surface. Net radiation (=in cooling process that's outflux-influx) drives the hotter surface to thermal equilibruim with the environment.

When designing a cooler, the only thing in radiation vise you can influence is the emissivity. It describes how the surface emits or absorbs heat to or from the enviroment. Since cooler is by definition always "cooling", you want to make emissivity as high as possible. That's easily accomplished by coloring the surface black. That's not the case when you want to shield you design from the heat coming from surroundings. Arabs use white clothes just because of this.

To give you an example how this works in practise: If you measure the surface temperature of bright, hot aluminium block straight from cast by infrared thermometer, you get absolutely incorrect results until you adjust the emissivity to a value 0.05 or so. This value means that aluminium prefers reflecting to absorbing or emitting by a ratio 0.05:1

If you now consider a cooler which is "bright" aluminium, you can easily see that radiation mechanism is overlooked. By making the surface black or otherwise enhance the emissivity you can improve this mechanism by a factor of 10-20!

Anodization makes a ceramic layer of aluminium oxide on the surface. Typically emissivity of black anodization can reach values of the order of 0.7-0.8 or in some extreme cases 0.94. Then there is an impact on heat conduction, since ceramic materials have distinctly poorer heat conduction properties. The thickness may vary but typically it is of the order of 1-10

[BETA]

Very Well doen Jari

[FinSub97]

A couple of small corrections and additions:
the ratio between relfection and absorbtion (or emission) for untreated aluminium is 0.95:0.05, not 1:0.05

And the other thing aside emissivity you can influence in radiation wise, is the total dissipating area seen from outside. Note, that fins "see" each other so that's not equal to wet area in general. The bigger radiation area, the bigger amount of heat dissipated through radiation.

The mass of the cooler can have an effect when transient processes are considered. That is, thermal inertia of the cooler can accumulate heat as long as the temperature of the cooler rises. That has no importance or relevance once the cooler reaches the steady-state temperature which is in thermal equilibrium with the surroundings. Larger thermal masses stay hot longer after the source of heat has disappeared.

One idea could be water cooling, but it snowballs easily out of budget. And location the cooler calls for additional considerations in terms of wiring, weather impact, etc. Since the engine block is a good source of external heat, the side of cooler facing hot surfaces of the engine block cannot dissipate any heat, but on the contrary, absorbs some more heat, provided that the surface temperature of the motor exceeds that of cooler.


Hope I made any sense,
jari

[kowsoc]

Good physics lesson!

However, the location of the cooler is very important as a heatsink will "grab" heat very quickly in a hot surrounding. I think past discussions have concluded that the intake is not a good place to try to keep a FSD cool. The key is to mount the unit away from underhood heat. I have mine inside the airbox, which I also insulated (to reduce heatsoak of the FSD at shutdown) and there is no lack of airflow over the sink. I've been running 2 years and 100,000 km's with no problems. I am planning to put a temperature sensor on the FSD just to know what is going on.

[pannhead]

i have a water-cooled thermo-electric FSD cooler (home-made)that is mounted next to the brake pedal..it keeps the FSD more than 30 degrees below ambient at idle and about 10 degrees below ambient while driving agressive..the cool and hot plates are 1/4" copper and utilizes 1 50mm peltier and 4 40mm peltiers (without engine on the cool plate temp is close to freezing)..the hot plate is cooled by water circulated from the intercooler system...if your theory is correct that it is JUST HEAT that kills the POS fsd, then my FSD should last forever (we'll see :confused: )...i saw your other post about FSD and only problem i see is that there is no ABSOLUTE test for a FSD...i posted about my FSD cooler a while back and it didnt generate any interest so i just installed without pics..if i have it out again i will take pic if anyone is intereted......i have a question/thoery :rolleyes: : i ran my truck stock for years without a fsd failure,then when i installed all the performance stuff i have had 2 fsd failures...could the higher expectation of the engine be "stressing" out the FSD ?...it sure is too bad we cant get these POS apart to establish the exact failure (i and many others :( )...without knowing the exact cause we'll never be able to have an exact solution

[FinSub97]

your water-cooled peltier system sounds a most effective way to handle the overheated POS. I don't know how difficult it is/was to build such a system, but without any other info but your statement on those temperatures, I think your system would be closest to my heart. Not quite sure about next to brake pedal though ;)

and then again, I have no real concrete knowledge of the true origin of the problems. I just suppose it is the excessive heat...

jari

[pannhead]

3 primary reasons for the brake pedal location is that i have to run the fsd harness,water lines,and (most important) i want it away from engine bay...as for the temps (although primitive),i used a cheap digital temp gauge that has a 6' wired probe and stuck it on the cool plate right next to the FSD,the best place would be between the plates measuring the underside of the cool plate but the probe is too thick to be sandwhich between the plates...hence the qualifier of "although primitive".....time will tell if it is just a heat issue or not

[FinSub97]

Tell me pannhead, when did you install your cooler? You mentioned that you have had 2 FSD failures, were they before peltier time?

[pannhead]

1st failure was while mounted on IP, 2nd failure was on fsd cooler mounted to intake manifold...from my experience i believe the engine bay is a BAD place for cooling especially after engine shutdown followed by heatsoak...others on the DP have taken actual temp readings after shutdown and the temps are high enough to cook your breakfast on :eek:

[pannhead]

oops..forgot your main question: the new cooler has only been in service about a month although the FSD is about a year old

[FinSub97]

If it is purely heat related, your solution can be the answer. Send some pics sometimes, I am interested.

how many miles ago you changed this 3rd one and how much did it cost?

[MTTwister]

Panhead - maybe even post some pics here - this would be interesting - even if out of the reach of some of us to duplicate. Thanks

[pannhead]

its location makes pics impossible..when i have it out again i will snap a pic....someone before this post wanted pics of my intercooler but i dont know how to "link" or know how to "link" from :confused: i only know how to thru e-mail...do i need a website or something?

[MTTwister]

I'm not sure about this site - on the Moparts.com threads - you can post a link from a picture hosting site - I use PhotoIsland.com free for the first - ?10 megs?.

Once you have a pic to show - you have a menu option to post a link for an 'auction', copy the complicated give link into this sites ubb code ( such as ..... ) to post the link into the thread.

Others seem to have set up 'home pages' dunno - maybe a free Yahoo home page would work.

Let a local chime in on the 'right' way here.