| General > General Technical Chat |
| The Dubai Lamp |
| << < (10/13) > >> |
| james_s:
--- Quote from: MK14 on April 12, 2022, 07:16:41 am --- --- Quote from: james_s on April 11, 2022, 06:51:19 pm ---A 120V 60W incandescent lamp produces about 800 lumens for example, while the 240V version is only about 700 lumens. You can see the same effect by looking at the lumens per watt of different wattages of lamps. --- End quote --- TL;DR Just to be clear. I somewhat agree with you, and your explanation as to why the 120V 60W lamps, are more efficient than the 240V versions. It's deceptively difficult to properly/accurately interpret the situation. Because, changes to the filament design parameters, have to take place to restore the 1,000 hour life, between the 120V and 240V versions. Also, the exact definition/quality of the 1,000 hours burn life, might vary between the US and Europe/UK. Which could also confuse/complicate the issue. Because any genuine increase in burn life, the Europe/UK versions gain. Would be expected to respectively reduce the efficiency, between the 120V/240V lamp types. I wonder if there is much difference between 120V and 240V LED bulb, efficiencies and burn life expectancy. It can be tricky when trying to directly compare things between the US and Europe/UK, because standards, laws, and other things are different. E.g. Even the size of Gallons is in disagreement between the US and UK, and measurements are not necessarily done in the same way. E.g. Is a 1,000 hour burn life or 800 Lumens, truly identical between the US and UK ? Anyway, it does make a fair bit of sense. That a 120V lamp filament would be thicker, and hence take longer to thin out, intuitively speaking. --- End quote --- Yes, the life is the same. You can see further examples of this, look at long filament decorative lamps like the sort used to light sheet music and paintings and such, they are even lower efficiency than standard lamps because the filament is stretched out so long. The thing I think you and some on those other threads are overlooking is that light output is not dependent on filament heat output, but on filament *temperature*. A standard lamp filament runs at 2700K and the hotter it is, the more the output shifts toward visible light and the more efficient it is but the more rapidly it burns out. Anything that draws heat away from the filament will require more energy input to maintain the same temperature, and if you can keep the heat in the filament then it will require less input energy for the same light output. Indeed there are high efficiency incandescent lamps which employ an IR reflective coating on the inside of the capsule to direct heat back at a precisely positioned filament and those lamps managed about 800 lumens output from only 40W electrical input. A similar thing applies with your house, the better insulated it is, the less energy you will have to consume to maintain the temperature. If you could completely eliminate heat losses from convection, radiation, and conduction through the lead in wires and supports, an incandescent lamp could be 100% efficient but in the real world of course this is impossible. You cannot reflect anywhere near 100% of the IR back at the filament nor can you have a filament that is not connected to metal wires or supported by something. Most lamps are filled with an inert gas rather than a vacuum. The increased pressure inside a gas filled lamp reduces the rate of tungsten evaporation of the filament but increases convective losses. Below about 40 watts or so the convective losses start to get too significant so vacuum fill is used instead in order to keep the efficiency reasonable. For LED lamps the input voltage makes no real difference, a buck converter can be made to operate efficiently at any line voltage. |
| MK14:
--- Quote from: james_s on April 12, 2022, 06:44:01 pm ---Yes, the life is the same. You can see further examples of this, look at long filament decorative lamps like the sort used to light sheet music and paintings and such, they are even lower efficiency than standard lamps because the filament is stretched out so long. The thing I think you and some on those other threads are overlooking is that light output is not dependent on filament heat output, but on filament *temperature*. A standard lamp filament runs at 2700K and the hotter it is, the more the output shifts toward visible light and the more efficient it is but the more rapidly it burns out. Anything that draws heat away from the filament will require more energy input to maintain the same temperature, and if you can keep the heat in the filament then it will require less input energy for the same light output. Indeed there are high efficiency incandescent lamps which employ an IR reflective coating on the inside of the capsule to direct heat back at a precisely positioned filament and those lamps managed about 800 lumens output from only 40W electrical input. A similar thing applies with your house, the better insulated it is, the less energy you will have to consume to maintain the temperature. If you could completely eliminate heat losses from convection, radiation, and conduction through the lead in wires and supports, an incandescent lamp could be 100% efficient but in the real world of course this is impossible. You cannot reflect anywhere near 100% of the IR back at the filament nor can you have a filament that is not connected to metal wires or supported by something. Most lamps are filled with an inert gas rather than a vacuum. The increased pressure inside a gas filled lamp reduces the rate of tungsten evaporation of the filament but increases convective losses. Below about 40 watts or so the convective losses start to get too significant so vacuum fill is used instead in order to keep the efficiency reasonable. For LED lamps the input voltage makes no real difference, a buck converter can be made to operate efficiently at any line voltage. --- End quote --- Thanks, that is a very nice answer. :) I see. There use to be a lot of those 'novelty', long tube/filament bulbs, in the UK. In places like shaving/mirror lights, picture frame lights and other similar uses. It had never dawned on me, that there was a reasonable quantity of electricity (watts, not huge, maybe 15W, but big, compared to the relatively small light output), going into it, and yet very little actual useful light coming out. But now you mention it, that makes lots of sense. It reminds me a lot about soldering irons, especially from quite a while back (before temperature control was common place). The actual wattage, didn't necessarily tell you its temperature, because if it was an old style, massive type, hence with huge heat losses, it still didn't get that hot, but enough to melt solder. Where as, a tiny, low mass, fine tipped, hence little heat losses, relatively low wattage soldering iron, perhaps 15 watts, can get quite usefully hot. So of course (completely obvious, now you have persistently mentioned it, i.e. hindsight). Any bulb, which instead of having an optimally small compact filament, that simply turns the (perhaps 60 watts, like we mentioned earlier), because of it being 120V AC mains supply in that country, can have the best/maximum efficiency level. I.e. biggest lumens per watt, just like you have been, repeatedly saying. But, anything that worsens that scenario, such as 240V AC mains countries (as you said, it needs a thinner and longer filament, to cope with the higher voltage), big long decorative filaments, poorly designed light bulbs, long life ones, etc. Need much more heat, just to make a much lower amount of actual usable light output. Hence the lumens per watt (efficiency), is significantly worse. Pity they couldn't have invented some kind of thermos flask like glass tube, that goes round the filament, which both highly insulates the filament, and reflects the non-visible IR (heat) radiation, back onto the filament, to make it considerably more efficient. Which is what (or similar to), what you mentioned in the quote above, but with a possibly different design. I suppose, even the LEDs may one day become obsolete. Replaced by who knows what. Maybe some kind of semi-conductor material, which with almost 100% efficiency, converts all electrical power, into light, within the visible ranges that are desired (100% CRI, or whatever the terminology is). Or perhaps, almost 100% efficient LEDs, will become that technology. Hopefully one day, fusion (power, or whatever is needed) will be invented, practicable, economically viable, and then made available, to help keep planet Earth going, without it getting into difficulties, such as very bad weather, and other effects of climate change. EDIT: Made this post a little more accurate/better, slightly/moderately. But basically as it was. |
| james_s:
--- Quote from: MK14 on April 12, 2022, 07:04:23 pm ---Pity they couldn't have invented some kind of thermos flask like glass tube, that goes round the filament, which both highly insulates the filament, and reflects the non-visible IR (heat) radiation, back onto the filament, to make it considerably more efficient. Which is what (or similar to), what you mentioned in the quote above, but with a possibly different design. I suppose, even the LEDs may one day become obsolete. Replaced by who knows what. Maybe some kind of semi-conductor material, which with almost 100% efficiency, converts all electrical power, into light, within the visible ranges that are desired (100% CRI, or whatever the terminology is). Or perhaps, almost 100% efficient LEDs, will become that technology. --- End quote --- Well they have tried something a bit like that, one example is this http://lamptech.co.uk/Spec%20Sheets/IN%20WC%20DuroTest%20120-65G30IRC-E26.htm where the entire bulb had a reflective coating. In the early 2000's Philips refined this concept using a small spherical quartz capsule with an IR reflective coating within an outer bulb. There is a cost to this though, any IR reflective coating is going to reflect and absorb some amount of visible light as well, and even just a layer of plain glass reflects a significant amount of light which then bounces around inside the bulb and turns into heat. The filament loses heat in three different ways, radiation, convection and conduction. The IR coating attempts to deal with the radiated losses but then if you have a gas fill that results in convection losses, and the lead wires and filament supports result in conductive losses. Ultimately there is only so much you can do to optimize this, and for better or worse technology has marched on and all development of incandescent lamps has stopped, we've passed the pinnacle there and all attention is on other technologies now. I'm pretty confident that LED of one sort or another is the future of lighting, mass produced LED lamps such as the Dubai lamp that started this thread have already reached 200 lm/W which is a substantial fraction of the theoretical maximum of around 600 lm/W representing 100% efficiency. LEDs continue to improve steadily. |
| MK14:
--- Quote from: james_s on April 13, 2022, 07:00:22 pm ---Well they have tried something a bit like that, one example is this http://lamptech.co.uk/Spec%20Sheets/IN%20WC%20DuroTest%20120-65G30IRC-E26.htm where the entire bulb had a reflective coating. In the early 2000's Philips refined this concept using a small spherical quartz capsule with an IR reflective coating within an outer bulb. There is a cost to this though, any IR reflective coating is going to reflect and absorb some amount of visible light as well, and even just a layer of plain glass reflects a significant amount of light which then bounces around inside the bulb and turns into heat. The filament loses heat in three different ways, radiation, convection and conduction. The IR coating attempts to deal with the radiated losses but then if you have a gas fill that results in convection losses, and the lead wires and filament supports result in conductive losses. Ultimately there is only so much you can do to optimize this, and for better or worse technology has marched on and all development of incandescent lamps has stopped, we've passed the pinnacle there and all attention is on other technologies now. I'm pretty confident that LED of one sort or another is the future of lighting, mass produced LED lamps such as the Dubai lamp that started this thread have already reached 200 lm/W which is a substantial fraction of the theoretical maximum of around 600 lm/W representing 100% efficiency. LEDs continue to improve steadily. --- End quote --- Thanks for the link, it made an interesting read. Ignoring that (to me, at least), it looks a bit like an ugly-duckling (sorry!), it's a clever attempt, at making more efficient, lamps. I presume what happened, is long ago, they went through various possibilities, and were not especially successful, with most of the (tungsten filament) ideas. Except perhaps, the Halogen (and similar gases) types. But they did develop, other solutions. Such as fluorescent tubes and Sodium lamps. Which did work out, and enabled much more efficient lamps, in previous decades. I think the compact florescent lights (CFLs), were potentially good and promising, in the past. But, there seemed to be a number of them, which had cut too many corners (in my opinion), in its construction and component quality/specifications. Resulting in sub-par optical quality, efficiency and burn-life. Possibly even a fire risk, in some cases and/or undesirable feature of sometimes having the base of the units, over-heat and make a bad smell. Which happened to me, occasionally, when CFL lamps were somewhat common place, and usually with very cheap CFLs. I prefer quality CFLs, but did sometimes try the very cheap ones, in case, they were any good. It was usually those, that tended to fail early (or even almost immediately), sometimes filling a room with a rather bad burning electronics smell. Which I hope was not poisonous/harmful to peoples health. I rather like Neon, and similar lamps. Apart from the tiny (NE-2 and similar), ones, many people are familiar with. They did make some amazingly big (think piggy bulb sized and maybe bigger), which I found seemed rather cute. With my expectation, of them being very economical with electricity and very long lasting. But, unfortunately, they seemed to have come from an era, of a VERY long time ago. They were perhaps originally manufactured in the 1940s and 1950s (years, complete guesses on my part). So, it has been rare to see them (age dependent). So, it is a pity, they couldn't invent some kind of similar bulb, with just gases inside it (ideally NOT using any toxic metals), which uses very little power, is very efficient, and produces lots of, hopefully mainly white light. I suppose, LEDs, are the modern way, of achieving, a somewhat ideal light bulb. Very high efficiency, low waste heat generation, somewhat ideal light colour, instant on, very long burn life expectancy (50,000+ hours is achievable), affordable cost and no bigger than standard tungsten filament lamps, of the past. Also, minimal consumption of any rare (and especially toxic) materials, and finally minimization of harm to the planet. |
| MK14:
--- Quote from: MK14 on April 10, 2022, 08:01:31 pm ---I'm hoping to buy a limited quantity (maybe 2 of them) of those bulbs, in around a weeks time, if things go to plan. If I do, I'll try and remember to report back on that arabic text and what I think of them. --- End quote --- I haven't bought those lamps yet, my plans changed, maybe another time. But, fortunately, BigClive has produced a suitable video on those bulbs, today. Here it is: |
| Navigation |
| Message Index |
| Next page |
| Previous page |