CR4® - The Engineer's Place for News and Discussion®


Previous in Forum: Flattening Shrink Tube   Next in Forum: Ethical Standards on Mandatory Provisions of Manuals and Wiring Diagrams
Close
Close
Close
20 comments
Participant

Join Date: Dec 2017
Posts: 4

Infrared Heating

12/24/2017 2:10 PM

Hello ...Good day

It is posible to create a infrared heat through convection heating transfer ???

I am trying to get it done using a ceramic honeycomb plate (porous)

Thanks an advance

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru

Join Date: Oct 2008
Posts: 40722
Good Answers: 1606
#1

Re: Infrared Heating

12/24/2017 2:48 PM

No. Not in any significant amount. Convection heating does not create any heat. It just moves warm air.

Register to Reply
Guru

Join Date: Apr 2011
Posts: 6989
Good Answers: 241
#5
In reply to #1

Re: Infrared Heating

12/24/2017 8:34 PM

Hmmm. There would likely be a fair amount of infrared radiating from the exhaust in the picture below:

If the heat was not transfered to the pipes via convection, how do you suppose it got there?

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply
Guru
Engineering Fields - Electrical Engineering - Been there, done that, still doing it. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 12591
Good Answers: 788
#6
In reply to #5

Re: Infrared Heating

12/24/2017 10:57 PM

My understanding of convection heat transfer is that its actually a form of conductive heat transfer by a fluid where the motion of the fluid is due to density changes and gravity. I know a convection oven works by a fan moving the heated fluid (air), as does the exhaust gasses inside this header but this is not convection.

__________________
"Don't disturb my circles." translation of Archimedes last words
Register to Reply
Guru

Join Date: Oct 2008
Posts: 40722
Good Answers: 1606
#7
In reply to #6

Re: Infrared Heating

12/24/2017 11:32 PM

Good point.

I should have remembered that's why conduction and radiation are important to thermal control in satellite electronics.

Merry Christmas to you and yours.

Register to Reply
Guru

Join Date: Apr 2011
Posts: 6989
Good Answers: 241
#9
In reply to #7

Re: Infrared Heating

12/25/2017 12:06 AM

Now that is silly. As if heat pipes are not used in satellites. Yes, wicks or surface treatment is required for condensed liquid to return to the heat source, but guess what? Convection is still the MO....

....and it vastly outperforms conduction and radiation in heat transfer per cross section.

So, I have posed to you again a question of a technical nature related to the topic of the OP and your comment on such....and again, it appears you don't respond to questions like that.

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply
Guru

Join Date: Oct 2008
Posts: 40722
Good Answers: 1606
#11
In reply to #9

Re: Infrared Heating

12/25/2017 12:45 AM

So, enlighten the OP instead of bothering with me.

So far, you have not directed a single comment toward helping them. That speaks volumes about your true intentions.

Register to Reply
Guru

Join Date: Apr 2011
Posts: 6989
Good Answers: 241
#15
In reply to #11

Re: Infrared Heating

12/25/2017 1:56 PM

On the contrary, my comment disputing your outright dismissal of the possibility of anything resembling that which the OP inquired about, would definitely be helpful.

Moreover, your dismissal is worse than not helpful it is downright harmful.

Interesting that you see your own authoritative sounding yet factually vapid comment to be some form of 'help'.

Please note, you still have not offered some alternate explanation (or retracted your original flawed assertion) of by what heat transfer mode other than convection those exhaust headers might have been made hot enough to radiate visibly....

...I know, I know, it is my fault. Apparently I bother you too much when I point out the glaring problems with your flippant assertions.

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply Score 1 for Off Topic
Guru

Join Date: Apr 2011
Posts: 6989
Good Answers: 241
#8
In reply to #6

Re: Infrared Heating

12/24/2017 11:56 PM

You are mistaking phenomena of 'natural convection' which is driven by differences in density because of differences in temperature for the fundamenatal heat transfer mode of 'convection' which is heat transfer somewhat decoupled from the (heat) conductivity of the medium through which the heat is being transfered due to movement of the material in the direction of heat transfer.

There is definitely convection taking place in a convection oven, as well as in the motorcycle headers pictured.

Thermopedia defines convection as the transfer of thermal energy by the movement of fluid. While your definition is the first to come up in a general nontechnical search of the term, from an engineering perspective, 'natural convection' is a distict phenomena which does involve convection, it is not inclusive of the general term describing 'convection'.

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply
Guru

Join Date: Oct 2008
Posts: 40722
Good Answers: 1606
#10
In reply to #8

Re: Infrared Heating

12/25/2017 12:14 AM

Register to Reply
Guru
Engineering Fields - Electrical Engineering - Been there, done that, still doing it. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 12591
Good Answers: 788
#2

Re: Infrared Heating

12/24/2017 3:25 PM

I do not understand how a honeycomb plate can be used in either radiant or convective heating, please explain.

__________________
"Don't disturb my circles." translation of Archimedes last words
Register to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 20326
Good Answers: 1190
#3
In reply to #2

Re: Infrared Heating

12/24/2017 4:32 PM

Attach an electric element to the ceramic honeycomb disc and force the air through it...this would be a convection type heater...to make a radiant heater you need to heat the ceramic from the back, probably need gas, and the heat radiates from the ceramic as it glows red hot....

This would be called radiant infrared heater....blowing hot air would not reach the required temperature necessary...

..."High-Intensity Heaters; Highly Efficient Generators of Infrared Radiation by Heating a Ceramic Refractory Material to Incandescence; Infrared Radiation Heats People and Objects it Strikes and Not the Intervening Air"...

__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Register to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 20326
Good Answers: 1190
#4
In reply to #3

Re: Infrared Heating

12/24/2017 4:48 PM

..."Ceramic elements operate in the temperature of 300 to 700 °C (570 to 1,290 °F) "...

https://en.wikipedia.org/wiki/Infrared_heater

http://www.promolife.com/home-office/heaters/large-area-ceramic/

__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Register to Reply
Participant

Join Date: Dec 2017
Posts: 4
#12

Re: Infrared Heating

12/25/2017 11:46 AM

Hello...Merry Christmas

Just "going to the base" of the knowledge...Am I rigth if I understand that (regarding the sketch):

1.- Gas and air (by Ventuy principal) is entering the machine.

2.- There is a plenum where gas and air are mix & distribuited

3.- Ceramic honeycomb porous plate

4.- Ther is a "iniciator" (spark) to get the ceramic be on fire

All the combustion will be "at the ceramic plate location". After this the ceramic with high temperature will provoke radiation.

Am I rigth in this criteria ??

Thank you guys.... again

Hello Lyn

Register to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 20326
Good Answers: 1190
#13
In reply to #12

Re: Infrared Heating

12/25/2017 12:36 PM

http://www.induceramic.com/industrial-ceramics-application/machinery-and-industrial-equipment/coating-equipment/infrared-honeycomb-ceramic-burner-plate

..."The fuel and oxidizing gas are combined catalytically and burn without flame formation at the surface of a non-combustible unitary ceramic skeletal block with gas flow channels."...

https://www.google.com/patents/US3441359

It takes a while for the catalytic heater to get up to operating temperature...

__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Register to Reply
Participant

Join Date: Dec 2017
Posts: 4
#16
In reply to #13

Re: Infrared Heating

12/27/2017 11:12 AM

Hello…Good day.

After your discussion and explanations….May I think that the way I understand the radiant heat production is bassically correct ?

Because the next question here will be the use of natural gas….which by the way, I understand natural gas can not be storage ?

Thanks an advance

Register to Reply
Guru

Join Date: Oct 2014
Location: Hemet, Land of milk and honey.
Posts: 1632
Good Answers: 26
#14

Re: Infrared Heating

12/25/2017 1:01 PM

I thought that using a ceramic honey comb plate was to prevent the transfer of radiant heat through convection.

I have a portable propane heater that uses a ceramic honey comb plate, when it's operating, the side where the gas is combusting is hot and is radiating heat. On the other side of the honey comb plate it is cool to the touch, so no convection is taking place.

It seems that if the ceramic honey comb plate were to convect, the ceramic would need to get very hot.

I can't really answer what temperature that would require. I'm not as brainy as these guys.

Merry Christmas.

Register to Reply
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 19798
Good Answers: 358
#17

Re: Infrared Heating

12/27/2017 11:57 AM

They use Infrared heating on some paint curing tunnels, So I believe the process may be similar.

I can understand the issue you may have with insulated boundary layers on your honeycombs.

For convection heating, You would need to get a air flow going to break up these boundary layers... one can use fans.... The issue you may have is contamination these fans may stir up... but all you need is to break up the insulating boundary layers.

Types of fans I have used in the past, I had ordered from McMaster.com. You drives would need to go through the insulated wall to be powered by a drive belt on the out side.

I don't recall, but I believe it would be similar to these (E) on this page.

Have them on the top and bottom (if you can)

__________________
phoenix911
Register to Reply
Guru
Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3105
Good Answers: 429
#18

Re: Infrared Heating

12/30/2017 1:47 AM

As long as the process conditions provide a working fluid of high enough temperature to cause the target material's surface to get hotter than the surrounding material, radiant heat energy will be transferred to a cooler surface. Problem is that at lower temperatures, it is a very inefficient process. Put your hand near (not on!) your front brake disks after a rapid 60 to 0 quick stop, you'll feel the heat. And let's not forget the InfraRed noncontact thermometer you can buy at Harbor Freight for 20 bucks. Google on "black body radiation" for more info.

Now you've added the fact that you want to burn a fuel gas to heat your ceramic element, which makes me wonder why you're looking at convection at all. Please explain...

__________________
“Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
Register to Reply
Participant

Join Date: Dec 2017
Posts: 4
#19
In reply to #18

Re: Infrared Heating

01/01/2018 2:26 PM

Hello...Happy New Year

I understand that in order to heat the ceramic element and this provoke a radiant heat, the source of heat is gas + air (which I think is convection).

Please take a look of this..

https://www.youtube.com/watch?v=-xlHhIt7RPQ

https://www.youtube.com/watch?v=8EfRobemfBM

this gentlement in some part say "turn off the fan"...and he said also "turn off the gas !!!"

I am trying to soft and melt some material very very similar to asphalt layer.

Because it's cheap, I would like to use Natural gas as energetic source

With all due respect

Register to Reply
Guru
Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3105
Good Answers: 429
#20
In reply to #19

Re: Infrared Heating

01/01/2018 5:19 PM

When you mix gas(fuel) with air (oxygen) and burn them together, it is known as combustion.

__________________
“Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
Register to Reply
Register to Reply 20 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Copy to Clipboard

Users who posted comments:

lyn (4); phoenix911 (1); RAMConsult (2); redfred (2); SolarEagle (3); sqyuma (3); tonyhemet (1); truth is not a compromise (4)

Previous in Forum: Flattening Shrink Tube   Next in Forum: Ethical Standards on Mandatory Provisions of Manuals and Wiring Diagrams

Advertisement