Sputtering deposition of infra-red reflecting films on ellipsoidal bulbs of energy saving lamps

Omata, Y.; Hashimoto, Nozomu; Kawagoe, Satoshi; Suemitsu, Tetsuya; Yokoyama, Mika

doi:10.1191/1365782802li042oa

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…Ta 2 O 5 -SiO 2 multilayer films were found to offer the highest temperature stability and performance (luminous efficiency and CRI) for their application in ILBs. Several *aleroy@mit.edu; phone +1-617-715-4044; bulb or filter geometries such as cylindrical 5,[11][12][13]17,18,20 , spherical [6][7][8][9][10]19,21,22 , ellipsoidal 10,14,15 and planar 16 were also explored to maximize the amount of infrared radiation recycled back to the emitter, minimize hot-spots on the emitter and reduce fabrication complexity. Although extensive literature has been published on infrared recycling for ILBs, only limited energy savings (maximum experimentally demonstrated energy savings of 51% compared to traditional ILBs 7 ) has been achieved because of non-idealities in the filter, emitter and geometrical alignment.…”

Section: Introductionmentioning

confidence: 99%

High performance incandescent light bulb using a selective emitter and nanophotonic filters

Leroy

Bhatia

Wilke

et al. 2017

Thermal Radiation Management for Energy Applications

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Previous approaches for improving the efficiency of incandescent light bulbs (ILBs) have relied on tailoring the emitted spectrum using cold-side interference filters that reflect the infrared energy back to the emitter while transmitting the visible light. While this approach has, in theory, potential to surpass light-emitting diodes (LEDs) in terms of luminous efficiency while conserving the excellent color rendering index (CRI) inherent to ILBs, challenges such as low view factor between the emitter and filter, high emitter (>2800 K) and filter temperatures and emitter evaporation have significantly limited the maximum efficiency. In this work, we first analyze the effect of non-idealities in the cold-side filter, the emitter and the view factor on the luminous efficiency. Second, we theoretically and experimentally demonstrate that the loss in efficiency associated with low view factors can be minimized by using a selective emitter (e.g., high emissivity in the visible and low emissivity in the infrared) with a filter. Finally, we discuss the challenges in achieving a high performance and long-lasting incandescent light source including the emitter and filter thermal stability as well as emitter evaporation.

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Section: Introductionmentioning

confidence: 99%

High performance incandescent light bulb using a selective emitter and nanophotonic filters

Leroy

Bhatia

Wilke

et al. 2017

Thermal Radiation Management for Energy Applications

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show abstract

“…Ta 2 O 5 -SiO 2 multilayer films appeared to offer the best compromise between cost, optical properties, and thermal stability (up to 800 C 19,22,30 ). Concurrently, several bulb geometries (spherical, 10,11,16,28,29,31,32 cylindrical, 7,8,14,15,17,19,23,30 ellipsoidal, 18,22,29 and planar 21 ) were studied to reduce fabrication complexity and maximize the amount of recycled infrared radiation while minimizing hot spots on the filament which can reduce its lifetime. The emitter in all these past studies using selective filters was typically a tungsten filament, chosen due to its high temperature stability and low evaporation rate at incandescent temperatures.…”

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confidence: 99%

Combined selective emitter and filter for high performance incandescent lighting

Leroy

Bhatia

Wilke

et al. 2017

Applied Physics Letters

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The efficiency of incandescent light bulbs (ILBs) is inherently low due to the dominant emission at infrared wavelengths, diminishing its popularity today. ILBs with cold-side filters that transmit visible light but reflect infrared radiation back to the filament can surpass the efficiency of state-of-the-art light-emitting diodes (LEDs). However, practical challenges such as imperfect geometrical alignment (view factor) between the filament and cold-side filters can limit the maximum achievable efficiency and make the use of cold-side filters ineffective. In this work, we show that by combining a cold-side optical filter with a selective emitter, the effect of the imperfect view factor between the filament and filter on the system efficiency can be minimized. We experimentally and theoretically demonstrate energy savings of up to 67% compared to a bare tungsten emitter at 2000 K, representing a 34% improvement over a bare tungsten filament with a filter. Our work suggests that this approach can be competitive with LEDs in both luminous efficiency and color rendering index (CRI) when using selective emitters and filters already demonstrated in the literature, thus paving the way for next-generation high-efficiency ILBs.

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Specular side reflectors for high efficiency thermal-to-optical energy conversion

Leroy¹,

Bhatia²,

Zhao³

et al. 2018

Opt. Express

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The performance of incandescent light bulbs and thermophotovoltaic devices is fundamentally limited by our ability to tailor the emission spectrum of the thermal emitter. While much work has focused on improving the spectral selectivity of emitters and filters, relatively low view factors between the emitter and filter limit the efficiency of the systems. In this work, we investigate the use of specular side reflectors between the emitter and filter to increase the effective view factor and thus system efficiency. Using an analytical model and experiments, we demonstrate significant gains in efficiency (>10%) for systems converting broadband thermal radiation to a tailored spectrum using low-cost and easy-to-implement specular side reflectors.

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Sputtering deposition of infra-red reflecting films on ellipsoidal bulbs of energy saving lamps

Cited by 3 publications

References 6 publications

High performance incandescent light bulb using a selective emitter and nanophotonic filters

High performance incandescent light bulb using a selective emitter and nanophotonic filters

Combined selective emitter and filter for high performance incandescent lighting

Specular side reflectors for high efficiency thermal-to-optical energy conversion

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