Solar Tank
- Thread starter pixelpixi
- Start date
pixelpixi
Guest
[quote author=Gomer link=topic=4256.msg51231#msg51231 date=1218059464]
what would be nice to have would be a 1000nm cutoff filter. Time to look into that!
edit: thor has it...now to find out if it is just a coating...
[/quote]
Yeah, it looks like you'd need a good bit of water to filter out the 1000 to 1500nm range. I wish rosco had a spectrum chart on their "super heat shield." I wonder how it does in that range.
what would be nice to have would be a 1000nm cutoff filter. Time to look into that!
edit: thor has it...now to find out if it is just a coating...
[/quote]
Yeah, it looks like you'd need a good bit of water to filter out the 1000 to 1500nm range. I wish rosco had a spectrum chart on their "super heat shield." I wonder how it does in that range.
sfsuphysics
Supporting Member
[quote author=pixelpixi link=topic=4256.msg51210#msg51210 date=1218054063]
In theory, temperature should be easier to keep down with with sunlight than with electrical lighting, since with a lamp, 70% of the energy is going directly to heat.
[/quote]
Yeah but having the bulb be hot vs light going into the tank are two separate deals, Light energy heats the tank, "heat" (temp of the bulb) gives off some IR radiation but most likely is transferring energy via convective means not so much radiation. So you're trading off relatively low intensity radiative energy transfer (metal halides) with high convective energy transfer vs high intensity radiative energy transfer (sun light) with zero convective energy transfer (save the air around it the tank which doesn't count since its the same in both cases). Not to mention you can always turn your lights off if it gets too hot, unless you had some sort of automatic shade can't exactly do that with sunlight.
In theory, temperature should be easier to keep down with with sunlight than with electrical lighting, since with a lamp, 70% of the energy is going directly to heat.
[/quote]
Yeah but having the bulb be hot vs light going into the tank are two separate deals, Light energy heats the tank, "heat" (temp of the bulb) gives off some IR radiation but most likely is transferring energy via convective means not so much radiation. So you're trading off relatively low intensity radiative energy transfer (metal halides) with high convective energy transfer vs high intensity radiative energy transfer (sun light) with zero convective energy transfer (save the air around it the tank which doesn't count since its the same in both cases). Not to mention you can always turn your lights off if it gets too hot, unless you had some sort of automatic shade can't exactly do that with sunlight.
pixelpixi
Guest
[quote author=sfsuphysics link=topic=4256.msg51254#msg51254 date=1218064544]
[quote author=pixelpixi link=topic=4256.msg51210#msg51210 date=1218054063]
In theory, temperature should be easier to keep down with with sunlight than with electrical lighting, since with a lamp, 70% of the energy is going directly to heat.
[/quote]
Yeah but having the bulb be hot vs light going into the tank are two separate deals, Light energy heats the tank, "heat" (temp of the bulb) gives off some IR radiation but most likely is transferring energy via convective means not so much radiation.
[/quote]
Really? Certainly an incandescent bulb produces heat almost exclusively as IR, since it produces light via black body radiation. (some IR energy is absorbed by the glass and transferred by convection to the air, but I doubt it's a high percentage.)
I assumed that MH bulbs would also produce more heat via radiation, but maybe not? I don't know much about how they work. Since most of the sun's energy is visible light, I'm skeptical that a given amount of sunlight would heat a tank more than the same amount of MH light.
Regardless, an IR filter seems like a good idea. :->
Also, solatube does have a little baffle thing that lets you turn the light "on and off".
[quote author=pixelpixi link=topic=4256.msg51210#msg51210 date=1218054063]
In theory, temperature should be easier to keep down with with sunlight than with electrical lighting, since with a lamp, 70% of the energy is going directly to heat.
[/quote]
Yeah but having the bulb be hot vs light going into the tank are two separate deals, Light energy heats the tank, "heat" (temp of the bulb) gives off some IR radiation but most likely is transferring energy via convective means not so much radiation.
[/quote]
Really? Certainly an incandescent bulb produces heat almost exclusively as IR, since it produces light via black body radiation. (some IR energy is absorbed by the glass and transferred by convection to the air, but I doubt it's a high percentage.)
I assumed that MH bulbs would also produce more heat via radiation, but maybe not? I don't know much about how they work. Since most of the sun's energy is visible light, I'm skeptical that a given amount of sunlight would heat a tank more than the same amount of MH light.
Regardless, an IR filter seems like a good idea. :->
Also, solatube does have a little baffle thing that lets you turn the light "on and off".
corals b 4 bills
Guest
I love all the high tech talk here-I read every word, but god damm if we we stranded on Gilligans Island I would be the one building the huts ;D
BTW - Mike I want to come by your..Crib and check out your tank.........What up G.
BTW - Mike I want to come by your..Crib and check out your tank.........What up G.
pixelpixi
Guest
[quote author=Gomer link=topic=4256.msg51224#msg51224 date=1218057628]
it is more than just exponential.
Here is a chart for you to look at. bulk water at different thicknesses vs the solar spectrum at noon at the equator.
gas phase water filters out a chunk already, but bulk will filter out more.
[/quote]
That's a really interesting graph. Thanks!
By exponential, though, I meant the transmission as function of water thickness, not as a function of wavelength. It must be something like exp(-x)
it is more than just exponential.
Here is a chart for you to look at. bulk water at different thicknesses vs the solar spectrum at noon at the equator.
gas phase water filters out a chunk already, but bulk will filter out more.
[/quote]
That's a really interesting graph. Thanks!
By exponential, though, I meant the transmission as function of water thickness, not as a function of wavelength. It must be something like exp(-x)
