Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Pots!

[CronicHempHog]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Sweet Vid

 

[Graytail]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Say, Icemud ... you've done the research on retained heat in a sealed growing space ...

I was thinking about some ideas for fabric softpots for my room and wondering if white cloth would be better than black for general reflection. I painted my pots flat white like everything else in the room, and I never really thought much about it, assuming it didn't really make much of a difference in reflected light, etc., but ... what about heat absorption?

If everything in the room is white except the plants and the soil, then they'll absorb most of the photon heat, right? And they both use/consume that heat don't they? So would that be a significant difference in ambient temperature, do you suppose?

I'm still trying to reconcile the clear physics of LED vs HID lighting with my own experience. I'm running 1000 watts of mid-efficiency LEDs with about the same temperature rise as I had with a 600 watt hps. All gear is/was contained within the room in both cases with the same ventflow and ambient input temperature. The 1000 watts should run hotter and it doesn't.

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Say, Icemud ... you've done the research on retained heat in a sealed growing space ...

I was thinking about some ideas for fabric softpots for my room and wondering if white cloth would be better than black for general reflection. I painted my pots flat white like everything else in the room, and I never really thought much about it, assuming it didn't really make much of a difference in reflected light, etc., but ... what about heat absorption?

If everything in the room is white except the plants and the soil, then they'll absorb most of the photon heat, right? And they both use/consume that heat don't they? So would that be a significant difference in ambient temperature, do you suppose?

I'm still trying to reconcile the clear physics of LED vs HID lighting with my own experience. I'm running 1000 watts of mid-efficiency LEDs with about the same temperature rise as I had with a 600 watt hps. All gear is/was contained within the room in both cases with the same ventflow and ambient input temperature. The 1000 watts should run hotter and it doesn't.

Hey Graytail....

I will have to look into this more when I have the time to find out why you are seeing the differences. It takes so long to sort through all the physics information, laws, and resources that I almost fear reading more into this topic because it makes my brain hurt..LOL.

Here is a cool little experiment one of our 420 members did that shows equal wattage, equal heat.

LED vs CFL - My grade school level heat experiment

I actually see my LED setup at 750w running my tent much hotter than my 1000w HID setup ever got. I think its due to the ballasts of my HID grow being externally mounted, as well as having air cooled hoods to remove a lot of heat before it has a chance to enter the grow environment. I am not sure why you are seeing the opposite. Everything I have read shows that equal wattage in, equal heat load out.

As far as painting your pots, cool idea. I do think it would help reflect more light to the plants than a black pot would, and I think even though the difference would probably be slight, I do think you may even see a difference in soil temperature. Although I think the black may be better due to microbes being more apt to thrive in warmer soil than cold soil.

Very interesting questions and observations. I will get more in depth with it when my brain feels like cooperating me to inject into astrophysics lol

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

I found this video last night and thought it was excellent for anyone who is interested in plant light reactions. I have to give a lot of credit to Purdue University as they are really pushing the envelope on plant/light science and especially with LED..... They also are using the same LED's as used in the space station, made by Orbital Technologies Corp.
[video=youtube;Vt4hR_QVIyg]

[/video]

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Say, Icemud ... you've done the research on retained heat in a sealed growing space ...

I was thinking about some ideas for fabric softpots for my room and wondering if white cloth would be better than black for general reflection. I painted my pots flat white like everything else in the room, and I never really thought much about it, assuming it didn't really make much of a difference in reflected light, etc., but ... what about heat absorption?

If everything in the room is white except the plants and the soil, then they'll absorb most of the photon heat, right? And they both use/consume that heat don't they? So would that be a significant difference in ambient temperature, do you suppose?

I'm still trying to reconcile the clear physics of LED vs HID lighting with my own experience. I'm running 1000 watts of mid-efficiency LEDs with about the same temperature rise as I had with a 600 watt hps. All gear is/was contained within the room in both cases with the same ventflow and ambient input temperature. The 1000 watts should run hotter and it doesn't.

By the way....darn you! LOL You knew I would set off like the tazmanian devil tornadoing through research papers didn't you!! LOL just kidding buddy!


Well I am now far off in research land so I should be able to help "shine more light", no pun intended, on the subject. It really does puzzle me....

Right now I actually am reading into absorption vs emmissivity which also may explain the white paint/black paint effectiveness. Will write more later after I get a more solid grasp on the concepts. It seems that the ability to reflect light isn't quite the same as the ability to give off thermal radiation, hence absorbtion vs emmissivity. Very interesting stuff. I swear, by becoming a grower I also am inadvertently becoming a electrician, HVAC professional, physicist, carpenter...and what else... and the myths say marijuana makes people dumb...haha pssst to them! haha

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

While in the midst of researching, I figured I would post any "goodies" I find along the way, maybe collectively we can answer the question

From AHT Principles of Heat Transfer, Washington State University

Even More on Heat Transfer Properties of SurfacesReflectivity, emissivity, transmis-sivity and absorptivity are properties of a surface that affect radiation heat transfer. At any particular wavelength of radiation, these properties are all related to each other. How-ever, these relations do not generally hold when talking about radiation at different wavelengths; that is, a surface that is reflective to radiation in one part of the electromagnetic spectrum may not be reflective to a different part of the spec-trum. In fact, different behavior in different parts of the spec-trum can be very important in the effectiveness of a reflective product.

A useful relationship to under-stand is that the absorptivity and emissivity of a surface are approximately equal 1 (see Figure ). This means a surface that readily absorbs radiation just as readily reemits the energy it absorbs back to the environment. In other words, a dark surface absorbs heat easily, but also easily reemits energy (gets rid of its heat and cools down) when the surface is hot and the
surroundings are cooler. Another useful relationship when thinking about these properties is that for any particular wavelength of radiation, the sum of reflectivity and absorptivity must equal one for an opaque object (see Figure 2). That is, a surface that readily
reflects a particular wavelength of radiation does not absorb much of that radiation, and vice versa. For example, a surface
is shiny if it reflects much of the visible radiation (i.e., light) that falls on it or, equivalently, does not absorb much light. A surface may also be “shiny” (i.e., have high reflectivity and low absorptivity) to non-visible parts of the spectrum, such as UV radiation or infrared radiation. Remember we can think of emissivity and absorptivity as approximately equal, so low absorptivity also means low emissivity.
In evaluating sun-exposed building products or products used in solar applications, we are often particularly concerned with a surface’s “total solar reflectivity” and its “far-infrared emissivity” because both these properties affect radiation heat transfer of a sun-exposed surface. Total solar reflectivity is the surface’s reflectivity just to those wavelengths that compose solar radiation; i.e., it is the
fraction of solar radiation that is reflected by the surface and not absorbed by it. Far-infrared emissivity, usually referred to in
product data as simply infrared emissivity, is the surface’s ability to emit radiation in the far-infrared wavelengths, which we feel
as heat

Importantly, a surface absorbing solar radiation (of which only about half is infrared radiation) will reemit that radiation
at a longer wavelength (100% infrared radiation). For this reason, to keep roofs cool in sunny weather when the surface of the
roof gets hotter than its environment, it is desirable for the roof surface to have both high solar reflectivity and high infrared
emissivity. This way, the portion of solar energy that is absorbed by the surface is then readily reemitted back to the environment at the longer, infrared wavelengths. As an example, an unpainted aluminum or tin roof with 70% solar reflectivity and 4% far-infrared emissivity will be warmer on a sunny day than a white metal roof with 70% total solar reflectivity and 85% far-infrared emissivity (“cat
on a hot tin roof,” not “cat on a hot white roof”). If on the other hand, we want to enhance solar heating of a surface, a surface
with the opposite properties of a good “cool roof” is desired. That is, for a good solar absorber on, say, the tubes of a solar
water heater, we want low solar reflectivity as well as low far-infrared emissivity.
–––––––

Technically, this is true only at steady state but is a useful approximation for non-steady state. It is also true only
when speaking of total absorptivity (i.e., absorptivity over all wavelengths) and total emissivity. This relationship is derived
from an energy balance on the surface. If a body does not emit all the energy it absorbs, then its temperature will not
be constant and hence it will not be at steady state.

Solar radiation consists primarily of 6% visible, 9% near infrared, and % ultraviolet radiation. Other components,
such as far-infrared radiation, make up a tiny fraction.

Total solar reflectivity and far-infrared emissivity are not simply related and so must each be experimentally determined
independently of each other. Summed over the entire spectrum, reflectivity and emissivity must equal one. However, total
solar reflectivity and infrared emissivity do not generally equal one since they pertain to radiation of different wavelengths; that
is, they each pertain to different fractions of the spectrum of electro-magnetic radiation. Reflective paint additives, for
example, may increase the total solar reflectivity of the paint, but may or may not decrease the infrared emissivity, depending on the paint product

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

OK, I can't even begin to read that 'till later. Darn you Icemud! I was headed to the Callanetics mat when I fell through your door and got caught up in that video. I need to watch that again. There were a couple very interesting things buried in all that dry data.

Callanetics has to be my priority. That takes me two hours. Then I'm coming back to read more. Have fun.

 

[CronicHempHog]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

like I tell people and I been smoking cannabis for about 32 years
it aint the weed that makes you stupid
you was stupid before you even smoked it

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

While in the midst of researching, I figured I would post any "goodies" I find along the way, maybe collectively we can answer the question

From AHT Principles of Heat Transfer, Washington State University

Icemud, do you actually understand what this says? I catch parts of it but other parts just fly right over my head. Let me read it again.

 

[Graytail]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

By the way....darn you! LOL You knew I would set off like the tazmanian devil tornadoing through research papers didn't you!! LOL just kidding buddy!


Well I am now far off in research land so I should be able to help "shine more light", no pun intended, on the subject. It really does puzzle me....

Right now I actually am reading into absorption vs emmissivity which also may explain the white paint/black paint effectiveness. Will write more later after I get a more solid grasp on the concepts. It seems that the ability to reflect light isn't quite the same as the ability to give off thermal radiation, hence absorbtion vs emmissivity. Very interesting stuff. I swear, by becoming a grower I also am inadvertently becoming a electrician, HVAC professional, physicist, carpenter...and what else... and the myths say marijuana makes people dumb...haha pssst to them! haha

LOL, sorry for dangling the bright object.

I went on a little hunt myself, trying to find out how much heat plants consume, and that's a tough one to pin down. Yes, they do, in the process of evaporating water, most of which passes right through the plant, but I couldn't get anything very specific.

And I hadn't considered emissivity. I suppose that's why the outside of tents are always black? I'm still trying to figure out where the extra wattage goes. Photons bounce around until they transfer their energy to something else, and if the room is sealed, everything stays inside. As they bounce, they also drop into the infra-red frequencies. In a reflective room, the only things to absorb the heat are the plants themselves. I have an in-ground concrete-walled room. I wonder how much that contributes. I sure don't have any emission issues.

In your case, with the efficient vented hood and the ballast outside, I can understand why you're not getting my results. Right now, with an ambient temp of 73, I get a peak of 86 in the 4x4 room, with an exhaust of 50cfm, tops. I just went through several days of 77 degree ambient and the room peaked at 90 - pretty consistent. That's running 1000 watts, which is over twice the photon energy of a 600 watt hps.

Where does the LED heat go? They produce less infra-red, if that matters much ...

... sorry to get the whole puzzle started again ...

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

I always figured the black exterior of the tents was just a light-blocking function.

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

LOL, sorry for dangling the bright object.

I went on a little hunt myself, trying to find out how much heat plants consume, and that's a tough one to pin down. Yes, they do, in the process of evaporating water, most of which passes right through the plant, but I couldn't get anything very specific.

And I hadn't considered emissivity. I suppose that's why the outside of tents are always black? I'm still trying to figure out where the extra wattage goes. Photons bounce around until they transfer their energy to something else, and if the room is sealed, everything stays inside. As they bounce, they also drop into the infra-red frequencies. In a reflective room, the only things to absorb the heat are the plants themselves. I have an in-ground concrete-walled room. I wonder how much that contributes. I sure don't have any emission issues.

In your case, with the efficient vented hood and the ballast outside, I can understand why you're not getting my results. Right now, with an ambient temp of 73, I get a peak of 86 in the 4x4 room, with an exhaust of 50cfm, tops. I just went through several days of 77 degree ambient and the room peaked at 90 - pretty consistent. That's running 1000 watts, which is over twice the photon energy of a 600 watt hps.

Where does the LED heat go? They produce less infra-red, if that matters much ...

... sorry to get the whole puzzle started again ...

Its a very tricky question/area of discussion and this is why even though I love lighting, I almost fret from going in this direction because it probably requires a PHD at least..LOL But I love science and love a challenge so here we go...LOL Keep in mind this is all stuff I am learning currently, and even though I'm a damn good googler, I am not a scientist and I have a good understanding of this information, I may not be 100% correct so keep that in mind as we explore this I try

As far as everything you stated, is what I have gathered, as photons are eventually all absorbed and given off as thermal radiation (heat). Now what I think may be the difference of what you are seeing vs what I am seeing could be related to the actual surroundings we have, you have white paint and I have mylar. I think it may be a factor to look at.

When I started reading about emissivity, it struck me that you have concrete walls painted white and I have reflective mylar. Neither of us have Isolated environments which is where the conservation of energy says states that the total energy of an isolated system remains constant—it is said to be conserved over time. Energy can be neither created nor be destroyed, but it transforms from one form to another

Since on earth an Isolated system is physically impossible to create, and 100% of thermal radiation = reflection + absorbtion + transmission I think that even though equal wattage = equal heat load (in an isolated system) in our grow areas I believe that the materials our enclosures are built out of are causing this effect where you see LED being cooler and I see it being more hot... (I'm still trying to figure all this out so bare with me, and I may not be correct as I am learning this as I go)

Each type of material has a emissivity coefficient between 0 and 1. 1 would be a black body radiator, a material that has a 100% efficiency of emitting all of the IR radiation possible, where as 0 would be close to mylar (0.04) which hardly radiates any heat at all. (This is in terms of IR radiation, not visible light)

Mylar (0.04)
Concrete (0.95)
Flat white paint (0.97-0.99)

So what this means is that even though Flat white paint is roughly 80-90% reflective for visible light, it actually absorbs and radiates about 99% of the IR radiation.... Where as Mylar is roughly 90-95% reflective to visible light, it actually absorbs and radiates about .5% of the total IR radiation.

So lets look at the HPS (1000w) since it does emit radiant heat where LED's do not.

Based on Kirchoff's Law, absorption coefficient = emmissivity coefficient. Now based on the numbers above, the difference between my environment vs yours would be that the walls of my grow area hardly radiate and/or absorb any IR(heat) where as the white paint on your walls absorbs and radiates most of the IR. In other words your walls make very good radiators.



+++++My Hypothesis so far+++++++++
So lets say our grow areas were exactly the same size, but mine was lined with mylar, yours with white paint and we each had a 1000w HPS light. How would our temps differ?
I believe that your environment would have a higher ambient temperature based on the high emissivity coefficient for the IR region. More IR light would be captured by the walls and re introduced to the environment because your walls would act like radiators. Now one of the questions that led me to that I still have not answered yet is, what would happen in my environment to the IR, being that hardly any of it is absorbed by the mylar. My guess would be that it would be absorbed by the water vapor in the air, but that is just my guess because my research hasn't gone any further. And if that were true, would the rate of transfer of energy be the same between the water vapor and the white paint meaning would the environment heat up at the same rate? still to be answered.

So in the case that now we have the same environments, both same sized, one lined with mylar and the other with concrete and white paint. The only difference is we introduce 1000w of LED into the grow instead of HPS. Now being that LED hardly emits any radiant heat (IR) and instead dissipates the majority of the heat through conduction and convection I think it may change things slightly. I think that when compared the tents would have a much smaller margin of temperature difference because the percentages of visible light reflected are very similar, therefore they absorb roughly the same amount of visible light which means their radiant heat would also be virtually the same (in an environment with no IR).

So now lastly, you have the 2 same sized grow environments, both with white paint, but one has 1000w of HID and one has 1000w of LED. Since we are not in perfect isolated environments for conservation of energy to be 100% true I think that the grow area with the HID may get warmer than with the LED because even though the white painted walls are reflecting the LED light (very little to no radiant heat) when introduced to the HID light the white painted walls absorb and act like radiators to the abundant IR light from the HID. Now in a similar situation, but with mylar coated walls, I think that the variation in temperature would be much less, as the walls aren't capturing and radiating IR radiation which is why I may be seeing HPS run cooler because a large portion of heat is being extracted before influencing the environment however due to my mylar walls they are not acting like radiators under the HID heat.

Now again, this is my thoughts on everything that I have read so far, and it makes sense somewhat, but obviously there is still a lot to learn and this topic is very in depth. So please know this is my researched opinion on it, but may not be 100% factual.

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

My thoughts: Graytail's flat-white painted walls are concrete blocks of a root cellar. On the other side of those concrete blocks is a cooler Mother Earth, likely pulling some of that thermal energy through the walls and into the cooler ground.

Could that account for some of it?

Oh, Icemud - how impressed am I? Damn! Easy to follow too. How did I miss you for so long? Loving the passion sir.

 

[Graytail]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Its a very tricky question/area of discussion and this is why even though I love lighting, I almost fret from going in this direction because it probably requires a PHD at least..LOL But I love science and love a challenge so here we go...LOL Keep in mind this is all stuff I am learning currently, and even though I'm a damn good googler, I am not a scientist and I have a good understanding of this information, I may not be 100% correct so keep that in mind as we explore this I try

As far as everything you stated, is what I have gathered, as photons are eventually all absorbed and given off as thermal radiation (heat). Now what I think may be the difference of what you are seeing vs what I am seeing could be related to the actual surroundings we have, you have white paint and I have mylar. I think it may be a factor to look at.

When I started reading about emissivity, it struck me that you have concrete walls painted white and I have reflective mylar. Neither of us have Isolated environments which is where the conservation of energy says states that the total energy of an isolated system remains constant—it is said to be conserved over time. Energy can be neither created nor be destroyed, but it transforms from one form to another

Since on earth an Isolated system is physically impossible to create, and 100% of thermal radiation = reflection + absorbtion + transmission I think that even though equal wattage = equal heat load (in an isolated system) in our grow areas I believe that the materials our enclosures are built out of are causing this effect where you see LED being cooler and I see it being more hot... (I'm still trying to figure all this out so bare with me, and I may not be correct as I am learning this as I go)

Each type of material has a emissivity coefficient between 0 and 1. 1 would be a black body radiator, a material that has a 100% efficiency of emitting all of the IR radiation possible, where as 0 would be close to mylar (0.04) which hardly radiates any heat at all. (This is in terms of IR radiation, not visible light)

Mylar (0.04)
Concrete (0.95)
Flat white paint (0.97-0.99)

So what this means is that even though Flat white paint is roughly 80-90% reflective for visible light, it actually absorbs and radiates about 99% of the IR radiation.... Where as Mylar is roughly 90-95% reflective to visible light, it actually absorbs and radiates about .5% of the total IR radiation.

So lets look at the HPS (1000w) since it does emit radiant heat where LED's do not.

Based on Kirchoff's Law, absorption coefficient = emmissivity coefficient. Now based on the numbers above, the difference between my environment vs yours would be that the walls of my grow area hardly radiate and/or absorb any IR(heat) where as the white paint on your walls absorbs and radiates most of the IR. In other words your walls make very good radiators.



+++++My Hypothesis so far+++++++++
So lets say our grow areas were exactly the same size, but mine was lined with mylar, yours with white paint and we each had a 1000w HPS light. How would our temps differ?
I believe that your environment would have a higher ambient temperature based on the high emissivity coefficient for the IR region. More IR light would be captured by the walls and re introduced to the environment because your walls would act like radiators. Now one of the questions that led me to that I still have not answered yet is, what would happen in my environment to the IR, being that hardly any of it is absorbed by the mylar. My guess would be that it would be absorbed by the water vapor in the air, but that is just my guess because my research hasn't gone any further. And if that were true, would the rate of transfer of energy be the same between the water vapor and the white paint meaning would the environment heat up at the same rate? still to be answered.

So in the case that now we have the same environments, both same sized, one lined with mylar and the other with concrete and white paint. The only difference is we introduce 1000w of LED into the grow instead of HPS. Now being that LED hardly emits any radiant heat (IR) and instead dissipates the majority of the heat through conduction and convection I think it may change things slightly. I think that when compared the tents would have a much smaller margin of temperature difference because the percentages of visible light reflected are very similar, therefore they absorb roughly the same amount of visible light which means their radiant heat would also be virtually the same (in an environment with no IR).

So now lastly, you have the 2 same sized grow environments, both with white paint, but one has 1000w of HID and one has 1000w of LED. Since we are not in perfect isolated environments for conservation of energy to be 100% true I think that the grow area with the HID may get warmer than with the LED because even though the white painted walls are reflecting the LED light (very little to no radiant heat) when introduced to the HID light the white painted walls absorb and act like radiators to the abundant IR light from the HID. Now in a similar situation, but with mylar coated walls, I think that the variation in temperature would be much less, as the walls aren't capturing and radiating IR radiation which is why I may be seeing HPS run cooler because a large portion of heat is being extracted before influencing the environment however due to my mylar walls they are not acting like radiators under the HID heat.

Now again, this is my thoughts on everything that I have read so far, and it makes sense somewhat, but obviously there is still a lot to learn and this topic is very in depth. So please know this is my researched opinion on it, but may not be 100% factual.

In a delightful twist of synchronicity, I was watching the video you posted as I read this post. Some interesting things from the video:

1.) Night-interruption produces more compact growth than extended day period.
2.) Intensive red/blue at the end of bloom promotes color in the foliage.
3.) Higher DLI produces less foliage.

As far as our discussion, it seems we're on the same page. This year, I've noticed something significant about my room temp vs my ambient temp. I run my lights during the day, from 9AM to 8:30PM. The room is in the basement, which doesn't warm up much during the day and gets flushed with cooler air during the night. If outside temps stay in the high 60s/night and 90s/day the basement will warm to the high 70s, otherwise it stays in the low 70s. That's my intake air, ranging from 72-78, and that gets me a peak of 85-91 in the room during the day with this setup. What I've noticed is that the range has increased as the summer has progressed. I'm not certain but I'm pretty sure it was an 8 degree rise in June compared to 13 now. I also noticed a delayed need to add a heater last fall. My concrete walls, surrounded by soil, are a great big heat sink. The white paint has its own properties, but any heat it holds is passed to the concrete where it's trapped. On the other side is colder-than-air soil, which sucks it away. Even now, at the end of a heat wave, the soil is still near 60 degrees over most of the wall. So I have a room with some rather unique properties - it doesn't re-radiate IR into the room. Another significant point is that photons degrade as they bounce around, dropping into the infrared frequencies, and my room is better suited to removing IR. My white painted concrete sucks it up, while your mylar keeps it in the tent. Your photons eventually produce higher temps, while the energy from mine is lost heating the concrete and soil.

I still don't run across an explanation for the law of thermodynamics. I think the venting difference explains a lot in your situation, but in most cases, LEDs run much cooler. Even in my veg room, I can tell that 180 watts of low-power blue LEDs run much cooler than a 250 watt MH - not just a third cooler - more than half, easily. 200 watts of CFLs are almost as hot.

It has to have something to do with photon degradation, I think. They're trapped in there, they have to eventually produce heat, where does that heat go? Hps directly produces a lot of IR, where LED doesn't. So maybe the plants use the LED photons before they degrade to IR?

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

That's an interesting supposition Graytail. How on earth do we prove it?

Icemud, I can almost feel the air around you crackle when you get into research mode.

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

In a delightful twist of synchronicity, I was watching the video you posted as I read this post. Some interesting things from the video:

1.) Night-interruption produces more compact growth than extended day period.
2.) Intensive red/blue at the end of bloom promotes color in the foliage.
3.) Higher DLI produces less foliage.

As far as our discussion, it seems we're on the same page. This year, I've noticed something significant about my room temp vs my ambient temp. I run my lights during the day, from 9AM to 8:30PM. The room is in the basement, which doesn't warm up much during the day and gets flushed with cooler air during the night. If outside temps stay in the high 60s/night and 90s/day the basement will warm to the high 70s, otherwise it stays in the low 70s. That's my intake air, ranging from 72-78, and that gets me a peak of 85-91 in the room during the day with this setup. What I've noticed is that the range has increased as the summer has progressed. I'm not certain but I'm pretty sure it was an 8 degree rise in June compared to 13 now. I also noticed a delayed need to add a heater last fall. My concrete walls, surrounded by soil, are a great big heat sink. The white paint has its own properties, but any heat it holds is passed to the concrete where it's trapped. On the other side is colder-than-air soil, which sucks it away. Even now, at the end of a heat wave, the soil is still near 60 degrees over most of the wall. So I have a room with some rather unique properties - it doesn't re-radiate IR into the room. Another significant point is that photons degrade as they bounce around, dropping into the infrared frequencies, and my room is better suited to removing IR. My white painted concrete sucks it up, while your mylar keeps it in the tent. Your photons eventually produce higher temps, while the energy from mine is lost heating the concrete and soil.

I still don't run across an explanation for the law of thermodynamics. I think the venting difference explains a lot in your situation, but in most cases, LEDs run much cooler. Even in my veg room, I can tell that 180 watts of low-power blue LEDs run much cooler than a 250 watt MH - not just a third cooler - more than half, easily. 200 watts of CFLs are almost as hot.

It has to have something to do with photon degradation, I think. They're trapped in there, they have to eventually produce heat, where does that heat go? Hps directly produces a lot of IR, where LED doesn't. So maybe the plants use the LED photons before they degrade to IR?

Glad you picked up a few neat factoids from the video. I thought it was very interesting as well and a few things I found to counter my previous research, however it seems with plants, each species, phenotype and so on all react differently to light, even as their studies showed. The more I read about plant lighting, the more I see that we still have a ton of work to do to understand them

Since last post I made I haven't had as much time to look into the heating topic much but did spend a few hours last night searching for more information and there is so many variables involved its really quite confusing.

Here is the law of thermodynamics, and as you can see, equal "work" or energy introduced to a system, equal heat. This is why I am pretty firm on my belief that lights of equal wattage produce equal heat, and the differences seen by all of us is results of the surrounding environment.

BASIC HEAT TRANSFER AND SOME APPLICATIONS IN POLYMER
PROCESSING
(A version of this was published as a book chapter in Plastics Technician’s Toolbox,
Volume 2, Pages 21-33, SPE 2002)
John Vlachopoulos and David Strutt

Heat transfer is a branch of engineering science which seeks to determine the rate of energy transfer between bodies as a result of temperature differences. The concept of rate is the basic difference between heat transfer and thermodynamics. Thermodynamics deals with systems in equilibrium and is concerned with the amount of heat required to change a system from one state to another. Thermodynamics does not answer the question of “how fast” a change is accomplished. It is the science of heat transfer that deals with this question.

BASIC CONCEPTS
The terms temperature and heat are understood intuitively. Temperature is the physical property that describes whether a body is “hot or cold”. If we touch a hot metal at 120°F (49°C) heat flows from the metal to our hand. If we touch a cold block of ice heat will flow from our hand to the ice. So, the intuitive concept of temperature is really defined by the heat exchange from one body to another. Heat is a form of energy that flows from one body to another as a result of a temperature difference.

The two temperature scales used for measurement purposes are the Fahrenheit (°F) and Celsius(°C) scales. These scales were established by specifying the number of increments between the freezing (32°F, 0°C) and boiling point (212°F, 100°C) of water at standard atmospheric pressure. The absolute Celsius scale is called the Kelvin (K) and the absolute Fahrenheit scale is termed
Rankine (R). In other words, 0 degrees R = -459.69°F and 0 degrees K = -273.16°C (absolute zero). Temperature is measured by observing its effect on some easily observable property of a measuring device e.g. expansion of mercury in a glass thermometer.

Heat, or energy in general, is usually measured in Btu, cal, kcal and Joule (J). 1 Btu will raise1 lbm of water 1°F at 68°F, 1 cal will raise 1 g of water 1°C at 20°C, 1 kcal will raise 1 kg of water 1°C at 20°C. The definition of Joule (J) comes from the definition of work done by a force on an object: (Newton * meter = N * m = J)

Work W = F * S

where F is the force and S the distance traveled. Power is the work done per second and J/s is called Watt (W)

Power= F* (S/T)= F*V

where t is time and V the velocity of travel. If we multiply Watts by time, the result is workdone. The work done by electricity is usually expressed as kilowatt hours, 1000 Watts times 3600 seconds, or 3.6  106 Joules.

The following conversion relations apply:
1 Btu = 1055 J
1 kcal = 4182 J
1 Btu = 252 cal

1W= 1* (J/S) = 3.413 Btu/hr

The human metabolism requires about 2500 kcal per day (roughly 400 Btu per hour) according to frequently quoted guidelines for daily food consumption.

FUNDAMENTAL THERMODYNAMIC LAWS
The First Law of Thermodynamics is the principle of conservation of energy, which states that energy cannot be created nor destroyed.

A more technical definition is:
The increase of internal energy (E) of a given system is equal to heat (Q) absorbed from the surroundings plus the mechanical work
(W) added.

Q + W = E

If no heat enters or leaves the system the process is referred to as adiabatic thus
E = W

So what I think to be theoretically true as equal wattage = equal temp in a isolated and sealed off environment, may not be "reality" in terms of heat load in our semi sealed environments because of all the different factors at play such as grow space volume, humidity, leaks/extraction and external influence, materials surrounding the grow environment, plants introduced... and so on... So I think with all these factors at play is why not only we are seeing the differences in results, but how the actual grow environment can be influential to the heat of the garden... (very interesting stuff the more I read into thermal barriers).

What I find very interesting is how much emmissivity has to do with the heat we feel. Lets look at black asphalt and concrete on a summer day. Now which would you rather walk on in bare feet? Obviously the concrete will feel cooler to our feet. Now even more interesting is people related IR to Heat but somehow dis-associate visible light with heat. Now looking at the emissivity of the asphalt is typcially .90-1.00 being very good at absorbing IR light. Now Concrete has a emmissivity in the thermal region of around .95 which means it also absorbs almost all the IR radiation... So why the difference in temperature we feel? The asphalt is also absorbing virtually all the visible light, converting it to heat, where as the concrete is reflecting a good percentage of visible light. Concrete reflectance for visible light is between 40-70% depending on age (sidewalk concrete) where asphalt only reflects 5%-10% visible light. (both absorb roughly the same in the IR region).Where does the extra heat come from...? The aborption of visible light Kind of fun thought to ponder

So while I was searching yesterday and the day before for information, I was looking to find out what actually happens to the IR in my grow area with the metallic silver foil, which is also a IR barrier. Obviously it has to at some point absorb due to the nature of things moving toward thermal equillibrium, but I can't find any information of what actually happens and how it would contribute to heat load. If the grow tent was just empty, with only the light in it, then the only point of absorbtion would be the light itself, and a very very small percentage into the silver lining. Also since the air typically is made of around 80% oxygen and nitrogen which are not subject to the heating effects of IR, only the 20% of remaining gasses would absorb the IR as well as water vapor. CO2 is the gas which absorbs a good amount of IR which is interesting because elevated CO2 levels could also influence the heat rise in a garden.

The other thing I am having a hard time finding info on is how the photons would hit your wall and react. Since the wall is white, most visible light is going to be reflected, but almost all the IR will be absorbed. Now when radiant energy is absorbed, it also releases the heat, in 2 ways, radiating back into the grow area, and transmitting the heat to the brick/concrete/and to the ground/. What I can't find is the percentages of what is transmitted vs radiated. Since heat energy flows from hot to cold until thermal equillibrium is reached, I am curious on how the heat would transfer in your room.

I did find a formula which does go over the heat transfer through a solid wall, but the formula lacks for the addition of paint, as well as it looked like cinderblock walls on part of your grow area which have air spaces, and air spaces help reject conductive heat transfer.

Here is the formula:
The conductivity of concrete: Thermal conductivity (cal/sec)/(cm2 C/cm) 0.002, Thermal conductivity (W/m K)*0.8

CONDUCTION
Consider the solid wall shown in Fig. 1. Temperature T1 is higher than temperature T2. Heat flows from the high temperature to the low temperature. If A is the area normal to the direction of heat flow, Fourier’s Law states that the amount of heat flow is proportional to the area A, the temperature difference T1 – T2 and inversely proportional to the thickness of the wall.

Q= K*(A/B)T1-T2

Q= Heat
K=thermal conductivity measured in W/m °C or Btu/hr ft °F
A=Area Normal to direction of heat flow (I'm assuming they are referring the the wall area)
B=Wall Thickness
T1=Higher Temp
T2=Lower Temp

The proportionality constant k is the thermal conductivity measured in W/m °C or Btu/hr ft °F
(see Table 1).

I think by understanding this, it not only would explain the differences in our results we are seeing, but also would really help us as growers narrow down the correct materials to use in grow areas... Just as houses in different regions are built with different types of insulation and such, our grow areas could even be catered more to our needs, such as if I want to trap the heat then use XX, but if I want to rid the heat then I use YY material.

Very very interesting stuff, and puts my brain on overload after a couple hours of readings..... my brain is taking these informational photons and absorbing them, giving off heat LOL

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

That's an interesting supposition Graytail. How on earth do we prove it?

Icemud, I can almost feel the air around you crackle when you get into research mode.

I say we raid a discussion hall at MIT and snatch up some men with funky hair, white coats and all have the last name PhD.. LOL

I found a few formula's in my last post to figure out how much heat is transferred through a solid wall so it may help. I guess what is important to take from all of this is if its not broken, don't fix it, and if you need to fix it... kidnap scientists lol

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Well, that was like attending a mini seminar Icemud. Lots of useful information to digest there. Thanks for the time and effort to get this far. I like your point about more careful consideration to the construction of a grow space given the laws of thermodynamics and these fancy lights we all play with.

The LED companies are really using us as the lab rats. I don't know if they expected some of us to be more insatiably curious than others. It should be easier to find the research materials the industry pulls from. Of course, none of us is professionally trained in the field are we? We first have to figure out which direction to look.

You do a bang-up job of this. No wonder he lit that fire under you.

 

[SweetSue]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

i say we raid a discussion hall at mit and snatch up some men with funky hair, white coats and all have the last name phd.. Lol

i found a few formula's in my last post to figure out how much heat is transferred through a solid wall so it may help. I guess what is important to take from all of this is if its not broken, don't fix it, and if you need to fix it... Kidnap scientists lol

we have a plan!!!

 

[Icemud]

Re: Icemud's Advanced LED XTE Grow - Harlequin - Ogiesel - Black Cherry Cola - Big Po

Well, that was like attending a mini seminar Icemud. Lots of useful information to digest there. Thanks for the time and effort to get this far. I like your point about more careful consideration to the construction of a grow space given the laws of thermodynamics and these fancy lights we all play with.

The LED companies are really using us as the lab rats. I don't know if they expected some of us to be more insatiably curious than others. It should be easier to find the research materials the industry pulls from. Of course, none of us is professionally trained in the field are we? We first have to figure out which direction to look.

You do a bang-up job of this. No wonder he lit that fire under you.

Thanks SweetSue... I probably put in a good 8-12 hours of reading between my 2 posts, with lots of breaks in-between. Each couple hours I read, I would have to let the information settle and makes sense to me before moving on but what I am finding information wise is way beyond the research in this area I did before. I'm glad that Graytail and I are discussion as I have learned a lot and gained some clarity on to how an environment can drastically effect heat load.

I definitely can agree that we are labrats for these LED companies...(I don't mind testing LED's, but wont share any profitable ideas). I actually find it quite sad that you have companies that just regurgitate bad information to unknowning growers who believe it, and yet they fail to actually research lighting and help people make the right decisions... There are a few companies that do go into detail, but they are few and far between.

In reality I would estimate that 80% of the LED's on the market are just re-branded products, with cosmetic changes and slight spectral changes (basically switch a few diodes and call it proprietary). I do like that there are a few companies that are a few grassroots companies building with extremely quality parts (unfortunately cant name them due to 420 Mags policies) but I think as time comes more and more domestic companies may start popping up. I just hope that when they do they are run by actual growers and not just investors looking to get rich which also seems to be the majority in the industry currently.

I try to contribute to discussions on LED but also hold back a ton of information because I don't want to be these companies resource to innovate new ideas and get rich on my times expense. However in the same I do try to contribute as much as I can that helps growers make the right decisions and help clarify this fog we are all subject to. I keep my design ideas, spectrum research under lock and key

Thanks for the compliments Sweetsue, I just really take an interest in really anything science related and lighting really intrigues me, especially when related to our favorite plant