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Instrument module cooling/demisting fans.

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rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Thu Apr 22, 2010 7:43 pm Post subject: Instrument module cooling/demisting fans.

I forget who asked me for information on my cooling/demisting fans.

Anyway near bottom of page are details:

http://www.europaowners.org/forums/gallery2.php?g2_itemId=27305



I went with four 30mm fans. Weight is under an oz. and a half. The fans I selected draw about half the amps, are quieter and flow about twice as much as other 30mm fans! By having 4 fans, true there is better spot cooling for radios and Dynon compared to 1 fan, but demisting covers about 18". Have high and low control and indicator. Boy does it sound great!

Ron Parigoris

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Apr 23, 2010 4:06 am Post subject: Re: Instrument module cooling/demisting fans.

Hi Ron,

Two notes of caution since your design probably won't be tested for several years to come.



1) Sucking air from a plenum is not as effective at cooling as a duct-

directed push of cooling air at the radios. This is what commercial

installations do.



2) The number of calories generated by your solid state radios, even if

optimally harvested and blown against the windscreen will have a 

marginal effect on condensation unless you concentrate the blast against a

small spot.  Your fan placement has the warm air widely separated and 

sourcing what is probably 4-5" from the plexi. With turbulent flow from the 

fans, I suspect you will not get much heat effect although you might

increase evaporation just by moving air.



Regards,

_________________
Ira N224XS

rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Fri Apr 23, 2010 8:39 am Post subject: Re: Instrument module cooling/demisting fans.

Hi Ira

Thx. for the reply.

 How are you cooling your radio, transponder and EFIS? 

I agree that a Cyclone style fan is more efficient at cooling a devise than removing the stratified/rarefied air that gets stuck at the top of instrument module (mine is flush to firewall). It is also more complicated and makes for more plumbing.

See:

http://www.europaowners.org/forums/gallery2.php?g2_itemId=78355

Quite a few folks that have computer fans at top of instrument module say that demisting is quite effective. I fooled with the fans I am using in my car, I chose a night where windscreen was fogging and put two fans about same spacing from window and width spacing as they will be in Europa. If I added defrost heat with car air conditioning blowing it clears up fog right away, but only  small fans even on low (series) did clear up enough to see through. 

I have 2 fans situated over com radio and transponder, and 2 fans over Dynon. I forget the temperature at which the Dynon quits, but figure best not have it happen in flight when you need it. 

It is not only radio, transponder and Dynon heat that needs to be dealt with, it is also heat that is given off from firewall/footwells. When testing fans I put a piece of clear plastic on firewall side of instrument module to replicate firewall and ducted convected heat from two 1500 watt electric/oil heaters (set on high) inside instrument module. After a few minutes could get inside temp to ~ 140F with fans not running (but there are gaps). Turning fans even on low reduced temps quickly. I have a temperature sender inside instrument module so I can monitor temps.

Ron Parigoris

DanBish

Joined: 24 May 2006
Posts: 29
Location: TUCSON, AZ

Posted: Fri Apr 23, 2010 10:20 am Post subject: Re: Instrument module cooling/demisting fans.

For what it's worth, those going with the new Dynon Skyview, there are two fans already built onto the back. Not sure how effective they'll be but should reduce the load of whatever cooling system is needed for the rest of the panel.

101120-000 - Rev C - SkyView 10 Inch Display Customer Drawing - Drawing.pdf

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rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Apr 23, 2010 12:42 pm Post subject: Re: Instrument module cooling/demisting fans.

Just like cooling inside the cowl, cooling of the instrument panel

can be non-or counter intuitive.



In some engine cowls, the air pressure gradients and consequent flow

can be stagnant or even flowing backward.



The same is true, no doubt for the instrument panel depending on a

myriad of custom factors like air flow up from the tunnel via the wiring to

the fuel pump and how closely seal the bottom of the panel is.



My panel is not currently cooled.  In six years of flying, I have seen the

need for cooling for a total of about 30 minutes of flying with my

UPS Stack and my Blue Mountain.  The BMA reports internal temp when

it exceeds 135F (Auto shutdown at 145 or 150F if I recall correctly)



Not a priority therefore, but somewhere on the to do list.

_________________
Ira N224XS

topglock(at)cox.net
Guest

Posted: Fri Apr 23, 2010 1:55 pm Post subject: Instrument module cooling/demisting fans.

Ira,



On my build site, you can see where I placed a computer case fan to 

evacuate the rear of the panel, should I encounter a situation where the 

equipment overheated.  My thoughts were that it would pull out warm air 

without really creating an air flow across the equipment.  To date, I've 

never had to use it.  Go figure...



Jeff - Baby Blue

500+ hours



On 4/23/2010 3:42 PM, rampil wrote:

 	  Quote: 	
		   



 Just like cooling inside the cowl, cooling of the instrument panel

 can be non-or counter intuitive.



 In some engine cowls, the air pressure gradients and consequent flow

 can be stagnant or even flowing backward.



 The same is true, no doubt for the instrument panel depending on a

 myriad of custom factors like air flow up from the tunnel via the wiring to

 the fuel pump and how closely seal the bottom of the panel is.



 My panel is not currently cooled.  In six years of flying, I have seen the

 need for cooling for a total of about 30 minutes of flying with my

 UPS Stack and my Blue Mountain.  The BMA reports internal temp when

 it exceeds 135F (Auto shutdown at 145 or 150F if I recall correctly)



 Not a priority therefore, but somewhere on the to do list.



 --------

 Ira N224XS





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=295451#295451







 Checked by AVG - www.avg.com

frans(at)privatepilots.nl
Guest

Posted: Fri Apr 23, 2010 3:08 pm Post subject: Instrument module cooling/demisting fans.

On 04/23/2010 06:39 PM, rparigoris wrote:



 	  Quote: 	
		   Hi Ira Thx. for the reply. How are you cooling your radio,

 transponder and EFIS?


	


Instrument cooling????

My Garmin SL-30 consumes less than 1 Amp max during receive. If it were

to convert this current totally into heat (efficiency zero), it could

only produce 14 Watts of heat.

My transponder consumes approximately 250mA. With this current it can

not produce more than 3 Watts of heat (again with a worst case

efficiency of 0). That's about the same as an annunciater light, and

that doesn't need cooling either.  I have no EFIS, but if such a beast

is not a powerhog, it can not produce much heat as well.

Modern avionics is very efficient and does't produce as much heat as the

older style equipment, and hence doesn't need cooling at all.

Have you actually tested how much "heat" your equipment produces?

If there is no heat production in the instrument module, there is no

need to remove it. 



Frans

rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Fri Apr 23, 2010 4:01 pm Post subject: Instrument module cooling/demisting fans.

Hi Ira"Just like cooling inside the cowl, cooling of the instrument panel can be non-or counter intuitive. In some engine cowls, the air pressure gradients and consequent flow  can be stagnant or even flowing backward."First off bottom line is figures don't lie, but liars sure do figure. When I am able to test I will post results of how my fans influence cooling.I don't think it is a fair comparison to compare dynamics of a Europa cowl with instrument module cooling. In cowl you are trying to force rarefied air down, it does not want to do that. As far as stalled or reversing air, you are taking accelerated air and trying to force it through a less than ideal duct in addition to forcing hot air down. The only means of propulsion is by pushing it.In my instrument module, dynamics are much more likely to be that of a base board radiator. If there is no heat and if it becomes stalled, not too much a problem. If it is hot inside, then through natural convection hot will go to top. I have a nice gap along bottom of module to allow cabin air to enter. Thus doing nothing natural convection "should" create a flow. Fans at top only enhance the natural convection.Comforting that not too many folks have had too much problems with overheating instruments or radios which I based my decision to help only a little with cooling and get a bit of demisting as well.FWIW I measured the pressure at the top of a hot air balloon with ambien 60F and  top of balloon inside 200F at sealevel, pressure was .008psi, at mouth of balloon .000psi, not too much pressure but amazing how much flow can be had.Ron Parigoris   [quote][b]

budyerly(at)msn.com
Guest

Posted: Fri Apr 23, 2010 5:09 pm Post subject: Instrument module cooling/demisting fans.

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Frans, Ira and others...

 As a weight and power Zealot I see your points, however the fastest way to  kill electronics is heat.

  

 My panel only draws a few amps, and the manufacturers do not require  cooling fans, but without the fan cooling, the slow steady increase in heat  makes the inside of my vented panel rise to over 100 degrees even on a cloudy  day.  The Europa panel is made for ease of installation and removal for  maintenance.  However, the novice does not notice that the panel can be  built almost air tight.  Many put extensions and iso mounts to allow air  flow, but still it is a hot box.

  

  In winter I wanted some warmth and vented my panel from the passenger side  footwell ( a fan blowing up on my radios over to the pilot side footwell which  has a tube sucking air from the top of the Blue Mountain Lite down and out the  left rear of the panel), my thinking was that it would keep my  feet warm.  I am here to tell you, it got hot.  The steady stream of  90 F air on my feet became annoying.  I will vent back to a vent in the top  of the panel onto the windscreen very soon.

  



 Our experience at Custom Flight has seen the Dynon Flight Deck 180 or  D100s go blank on a 90 F summer day.  The Dynon is  working but the screen video goes near blank.  The panel interior  temperature was about 100 on the outside but the local component  inside was hotter causing the blanking.  As far as the newer  avionics we all can't live without, if you hold your hand to the back of  the new Garmin G3X (2.75amps -35to +70C), or Dynon Skyview (3.5 amps -40 to  +60C), the case is actually very warm (hot), and although neither needs direct  fan cooling, the manufacturers require space and air movement, which to me  means, I need a fan.  Grand Rapids Sport is a very low power system however  they warn: 

  

 "The GRT Horizon EFIS does not require external cooling. However, as with  all

electronic equipment, lower operating temperatures extend equipment life.  Units

in an avionics stack heat each other through radiation, convection  and

sometimes by direct conduction. Even a stand- alone unit operates at a  higher

temperature in still air than in moving air. Fans or some other means  of moving

air around electronic equipment are usually worthwhile. Be certain  that cooling

air does not contain water – a problem often encountered when  using external

forced air cooling air.

The Horizon HX contains in internal  cooling fan. Be sure that there is adequate

air available so that it can cool  the display unit.  Although the microprocessors 

 don't use much power, they do need heat dissapation."  

  

 As for venting the windshield, I couldn't agree more, that a pleasant 85  degree Zephyr bathing the windscreen should work on a coolish day and  modest humidity, but on those rainy days such as when we left Sunday after Sun  'n Fun, the only way to keep the windscreen clear was a rag, a Zephyr doesn't  hack it.  Like the car, the windscreen needs a pretty stout blast of very  warm air if it is to clear effectively in high humidity conditions and those  high speed descents from 10 grand back into the hot sticky airports of  Florida.   

  

 The open panel metal airplanes get enough air to get by because of their  hangy downey wires from their open panels and drafty metal construction.   We have a neat and tidy panel package that alas, can cook our  avionics.  Bottom line is, fans or outside ducted air are a good thing for  the life of avionics.

  

 Just my opinion,

 Bud Yerly

  

 [quote]   ---

rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Sat Apr 24, 2010 11:36 am Post subject: Re: Instrument module cooling/demisting fans.

Figure if anyone is interested in installing cooling fans, might as well keep in archives a slick way to give you high and low speeds (you need an even number of fans). The LED either gets full voltage or half.

http://www.europaowners.org/forums/gallery2.php?g2_itemId=79799

Ron Parigoris

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