gretchen/jason Posted May 18, 2007 Author Share Posted May 18, 2007 Ive yet to atempt a test i will try to see what happens this weekend with my bbq grill some pieces of aluminum and different paints and my laser thermometer . I apoligize for misspeled words . Jason Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 18, 2007 Share Posted May 18, 2007 Let me throw this out for comment. I'm pretty sure what I'm saying is correct, but if not, I would love to learn more! Note that the cheaper interferometers assume that the surface has an emissivity of about 0.95 or so. The ceramic/metallic coatings have emissivities of 0.15 to about 0.3, or there abouts. So if it is assuming 0.95, and doing the calculations from the incident IR energy entering the detector using the assumed 0.95 emissivity to get surface temperatures internally using 0.95 for the emissivity, the indicated surface temperature will be misleading. (see http://www.mikroninfrared.com/mikron_university/IR_Sensor_Construction.pdf) If the emissivity is substantially lower than 0.6, then the error will cause the indicated temperature to be lower than the actual surface temperature. And that's the beauty of the coatings, actually. The are less emissive, and radiate less than most materials. That property will also fool a single color interferometer. You really need a two color inferometer to know the true surface temperature for such materials. Quote Link to comment Share on other sites More sharing options...
SteelToad Posted May 18, 2007 Share Posted May 18, 2007 Paint is not the answer. The intake is still bolted to the engine, and these points would transfer more heat than you would reflect with white, pink or any other paint. Hmmmm... maybe nylon bolts, .. thats the ticket Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 18, 2007 Share Posted May 18, 2007 Steeltoad, I understand the line of thinking, but I'd like to see some data to back up the gut feel. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 21, 2007 Share Posted May 21, 2007 Let me throw this out for comment. I'm pretty sure what I'm saying is correct, but if not, I would love to learn more! Pete, you are absolutely 100% correct! I deal with using I-R thermometers on a daily basis, and anybody who has ever taken the time to actually read their instruction booklet will tell you that Stainless Steel is specifically called out in the I-R Thermometer instructions as a material with radically different emmisivity, causing terribly skewed (low) readings. In the Raytek Bulletins they recomend painting a circular spot on the surface of a stainless steel pipe to get the emissivity into a range where the I-R Thermometer can correctly read it. They also state sticking masking tape onto the surface will correct the reading substantially. Myself, I carry several cans of Flat-White High-Temp Engine Paint for shooting little circles so those that follow behind can correctly follow my temperature surveys of the system. You can see the difference immediately upon drying of the paint. On a discharge manifold pipe I can read 180F on the stainless steel pipe directly, and move a fraction of an inch over to the 'flat white dot' and the reading SOARS to 345F+! Operators, fellow Field Engineers, heck, just about everybody is amazed that the reading can be skewed as much as that, simply from surface emissivity. So yeah, when using I-R Temperature Sensing Technology, BE VERY CAREFUL on what you shoot. Some stuff can really give you bogus readings. The killer is when there are stainless fittings and a black rubber hose. Fitting elbow shows 180, rubber is over 300F! You would think rubber is 'an insulator'... Quote Link to comment Share on other sites More sharing options...
badjuju Posted May 21, 2007 Share Posted May 21, 2007 so... yeah i don't see how painting a manifold would keep it cool... anodized cpu heatsyncs don't work as well as plain ol aluminum and those don't work as well as copper... what we need is a copper manifold with fins all over it. or hell, a ceramic bottom manifold with a copper top and ceramic runners? Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 21, 2007 Share Posted May 21, 2007 so... yeah i don't see how painting a manifold would keep it cool... anodized cpu heatsyncs don't work as well as plain ol aluminum and those don't work as well as copper... what we need is a copper manifold with fins all over it. or hell, a ceramic bottom manifold with a copper top and ceramic runners? Actually, you need a Glasfibre Injection Moulded PLASTIC intake manifold which will insulate the HELL out of the incoming charge from any an all underhood heat. Ever take a gander at what many of the OEM's are doing? Injection moulded plastics can be put into very complex shapes, and do a dandy job of insulating heat and noise as well. Anybody remember the plastic L-Engine Turbo Valvecovers? JDM application. Kept underhood radiation of heat from the slung-off oil on the valve cover to nil, and quieted valve clatter quite a bit as well. Many Cedrics and Glorias had these valve covers. After a hard run, putting your bare hand straight on the valve cover was not a problem at all. The future: PLASTICS Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 21, 2007 Administrators Share Posted May 21, 2007 Excellent info Tony. Thank you for the schooling. I for one am definitely learning a lot from this thread. Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 21, 2007 Share Posted May 21, 2007 The future: PLASTICS As Sam Wainright said about plastics, ‘the biggest thing since radio.’ I agree - plastics can solve many problems a metal can't. I did my masters thesis on carbon reinforced epoxy "plastics" : http://ntrs.nasa.gov/search.jsp?R=741284&id=1&qs=Ntt%3Dparaska%257C19930015723%26Ntk%3DAuthorList%7CDocumentID%26Ntx%3Dmode%2520matchall%7Cmode%2520matchall%26N%3D4294967262%2B269%26Ns%3DHarvestDate%257C0 Fiber reinforced materials are great for a lot of things, especially when specific strength (strength per kg) or specific stiffness (stiffness per kg) is important. It can be a good thermal and electrical isolator too, relative to metals (well, carbon is not such a hot electrical insolator!!!). The intake manifold is a great application, as you can mold it to net shape and surface texture, and it is less thermally conductive compared to Aluminum. But I bet 1/100th of the carbon fiber used in the world is used for real functional purposes. It seems the bling masters think that CF parts need to be pimped onto their ride for them to have a "fast" car. I suppose being well versed in composite structures design makes me cringe to see it used as a "surface treatment" only. For example, CF hoods, CF interior parts, etc. when the reason the person bought it was only for the look, not the weight savings of strength/stiffness per kg attributes. It seems even a thermal barrier coated plastic intake would be a good idea. And coat the runners inside as well, to keep the temp of the material (although lower than an AL piece) from radiating into the flow stream. Probably a really small effect though. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 21, 2007 Administrators Share Posted May 21, 2007 It seems even a thermal barrier coated plastic intake would be a good idea. And coat the runners inside as well... For what its worth, Finish Line Coatings refuses to ceramic coat the interior of an intake manifold... ingestion risk should any of it 'depart', they claim. Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 21, 2007 Share Posted May 21, 2007 A damned good reason too! Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted May 31, 2010 Share Posted May 31, 2010 any relation as to why cooking pots and pans are coated/painted black?! Maybe the black radiates the heat more efficiently to transfer to the food or cooking material better then a different color?! Am I on the right track?! Quote Link to comment Share on other sites More sharing options...
19762802+2 Posted May 31, 2010 Share Posted May 31, 2010 I think you noticed that this thread is three years old, but I believe they paint them black because black absorbs heat better then lighter or different colors. When your cooking you want the pan to heat up as quick, and by painting a pan black it helps in that process. Like a black car and a white car, black car is hotter because it absorbs more heat while the white reflects it better (mythbusters). Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 31, 2010 Administrators Share Posted May 31, 2010 1) The laws of physics haven't changed much in the last three years... this thread is just as relevant today as it was then. 2) Conductive, convective, and radiant heating are not the same thing. Quote Link to comment Share on other sites More sharing options...
Xnke Posted June 1, 2010 Share Posted June 1, 2010 Ever wonder why black anodized heatsinks are the norm? Black objects pick up heat the fastest, by better absorbing IR radiation. They ALSO dissipate heat faster. Ever wear a black shirt on a sunny day? Got hot. Then you went inside, and were cooled of substantially faster than most other colors of shirt. White might reflect IR better, but it doesn't radiate IR as much. Stays cooler via reflection, but retains heat longer. Quote Link to comment Share on other sites More sharing options...
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