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[IEEE 2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior) - Plovdiv, Bulgaria (2019.9.19-2019.9.21)] 2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior) - The effect of the continuous energy efficient upgrading of LED street lighting technology: The case study of Egnatia Odos
摘要： With the advent of LED technology, lighting studies have gained a great interest, especially street lighting. Nowadays, these studies demonstrate the great energy savings achieved by replacing high pressure sodium lamps with LED. As LED technology is continuously improving, energy savings are increased and thus the payback time of the investment is decreasing more and more. However, there are a lot of cases were the public constructions are delayed and the initial lighting design is getting obsolete, due to the energy efficient upgrade of the LEDs. In this research a newest version (2019) for the lighting design was performed using the latest technology of LED street lighting and compared with the one performed in 2017. Egnatia Odos EO, the largest national road in Greece, was selected as the case study for both studies (2017 and 2019). EO covers a distant of 670 km in northern Greece. Existing lighting infrastructure was designed and installed 17 years before, according to the previous version of EN12301 [1-3].
关键词： energy efficiency,upgraded LED,energy saving scenarios,Road lighting,adaptive lighting,European standards
更新于2025-09-12 10:27:22
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Influence of focal spot diameter and beam oscillation on the process efficiency of laser beam welding utilizing a direct diode laser
摘要： Costs of power consumption, efficiency improvement and a green image are increasing issues for automotive manufacturers. One possibility to reduce energy consumption is to increase process efficiency of the established laser beam welding. For this reason this contribution examines whether the laser output power of a direct diode laser can be reduced whilst keeping weld seam volumes constant. This is realized by a reduced spot diameter from initial 664 μm to 368 μm in combination with beam oscillation in order to generate blind seams in 22MnB5 and DC01 steel. It is shown that energy consumption can be reduced significantly.
关键词： Energy efficiency,Oscillation,Focal spot diameter,Direct-diode laser,Automotive
更新于2025-09-12 10:27:22
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A Heat Pipe Cooler for High Power LED’s Cooling in Harsh Conditions
摘要： The paper presents an innovative method for High Power LEDs cooling in harsh conditions. To take full advantage of the benefits of LEDs, proper thermal management must be realized. This paper describes the limits of the cooling solution based on heat pipe, to maintain the junction temperature close to the nominal value, to avoid the color shift, recoverable light output reduction, voltage decreases. The most important, the reliability of any LED is a direct function of junction temperature, knowing that the higher the junction temperature, the shorter the lifetime of the LED.
关键词： LED Cooling,Energy Efficiency.,Heat-Trap,Heat Pipe
更新于2025-09-12 10:27:22
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Investigation on Thermally Induced Efficiency Roll-Off: Toward Efficient and Ultrabright Quantum-Dot Light-Emitting Diodes
摘要： Quantum-dot light-emitting diodes (QLEDs) with high brightness have potential application in lighting and display. The high brightness is realized at high current density (J). However, at high J, the efficiency drops significantly, thereby limiting the achievable brightness. This notorious phenomenon has been known as efficiency roll-off, which is likely caused by the Auger- and/or thermal-induced emission quenching. In this work, we show that the Joule heat generated during device operation significantly affects the roll-off characteristics of QLEDs. To realize ultra-bright and efficient QLEDs, the thermal stability of QDs is improved by replacing the conventional oleic acid ligands with 1-dodecanethiol. By further using a substrate with high thermal conductivity, the Joule heat generated at high J is effectively dissipated. Because of the effective thermal management, thermal-induced emission quenching is significantly suppressed, and consequently, the QLEDs exhibit a high external quantum efficiency (EQE) of 16.6%, which is virtually droop-free over a wide range of brightness (e.g., EQE=16.1% @ 105 cd/m2 and 140 mA/cm2). Moreover, due to the reduced efficiency roll-off and enhanced heat dissipation, the demonstrated QLEDs can be operated at a very high J up to 3885 mA/cm2, thus enabling the devices to exhibit a record-high brightness of 1.6×106 cd/m2 and a lumen density of 500 lm/cm2. Our work demonstrates the significance of thermal management for the development of droop-free and ultra-bright QLED devices for a wide variety of applications including lighting, transparent display, projection display, outdoor digital signage, phototherapy and etc.
关键词： high brightness,light-emitting diodes,quantum dot,thermal energy,efficiency roll-off
更新于2025-09-12 10:27:22
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Efficiency in Street Lighting Projects by Employing LED Luminaires and Mesopic Photometry
摘要： This paper discusses the importance of adapting conventional photometric quantities when lighting systems with low luminance levels are under analysis, as public lighting or external lighting in general. In this sense, it is presented an alternative methodology for lighting projects in street lighting, considering the mesopic photometry. The CIE recommendation 191:2010 proposes correction factors that convert conventional photometric quantities (photopic) into quantities adapted to the corresponding mesopic level. However, a necessary parameter to obtain these correction factors is the relationship between the scotopic and photopic light fluxes of a light source (S/P ratio), which requires special equipment that it is not easily available to engineers, technicians and lighting designers. Thus, this paper proposes a general equation that provides the S/P ratio as a function of the correlative color temperature and the color rendering index of the light source, which are information provided in the manufacturers’ catalogs or electric lamp packages. To illustrate the application of the experimentally derived relationship, a typical street lighting project is considered, specifically a retrofit from HPS lamps to modern LED luminaires. In this case, the conventional routine must be changed, allowing the adaptation of conventional quantities to mesopic quantities without need for specialized equipment. The case study evidences that the use of mesopic photometry in conjunction with more appropriate technologies, such as LED luminaires, lead to a higher energy efficiency of the system.
关键词： Scotopic/photopic ratio,Human visual system,Mesopic vision,CIE 191:2010 report,Street lighting,Photometry,outdoor lighting,energy efficiency
更新于2025-09-12 10:27:22
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A light salad [LED lighting applications in horticulture]
摘要： With their low energy usage, reduced heat output and the ability to control the light colour they emit, LEDs are poised to revolutionise the horticulture industry. This article explores the benefits of LED technology in vertical farming, including faster growth cycles, reduced water usage, and the elimination of pesticides. It also discusses the potential for custom-designed produce through controlled light exposure and the current economic challenges facing the adoption of LED technology in horticulture.
关键词： energy efficiency,LED,vertical farming,horticulture,controlled environment agriculture
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE Wireless Communications and Networking Conference (WCNC) - Marrakesh, Morocco (2019.4.15-2019.4.18)] 2019 IEEE Wireless Communications and Networking Conference (WCNC) - A Robust and Energy Efficient NOMA-Enabled Hybrid VLC/RF Wireless Network
摘要： The present work investigates the performance of non-orthogonal multiple access (NOMA) in a hybrid visible light communication (VLC)/radio frequency (RF) wireless network. In particular, we investigate the energy efficiency of the proposed architecture assuming imperfect channel state information (CSI), which is a realistic assumption that is encountered in practical indoor and outdoor wireless communication scenarios. We demonstrate that the performance of the proposed scheme in terms of energy efficiency outperforms by four-fold the corresponding performance of its orthogonal frequency division multiple access (OFDMA) counterpart. In addition, it is shown that the energy efficiency of the proposed scheme is more robust to CSI errors and line of sight (LOS) variations than the OFDMA-based scheme, which appears to be more susceptible to the CSI error and the LOS availability probability. Finally, our findings reveal that the performance gain of NOMA over OFDMA in the considered hybrid VLC/RF setup is directly proportional to the probability of LOS availability. These results are expected to be useful in the efficient design and efficient operation of hybrid VLC/RF wireless systems.
关键词： Non-orthogonal multiple access (NOMA),Energy efficiency,Channel state information (CSI),Radio frequency (RF),Visible light communication (VLC),Hybrid wireless network
更新于2025-09-12 10:27:22
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Performance study on a photovoltaic thermal (PV/T) stepped solar still with a bottom channel
摘要： This study presents a novel type of stepped PV/T solar still in which a bottom channel is designed under the base of the still, aiming to enhance heat transfer. In order to assess the performance of the desalination system, a theoretical model is established, and validated by the existing experimental data, thus can be used for energy and exergy analysis. The effects of bottom channel structure on thermal performance (temperatures of components, heat transfer coefficients, thermal efficiency), exergy performance (total exergy loss of each component, exergy efficiency) and freshwater productivity are investigated. The comparative results show that, when the depth of bottom channel H is 0.01 m, the average heat transfer rate from absorber plate to saline water is improved by 44%, thereby the average temperature of saline water is raised by 16.4% and the daily freshwater productivity is improved by 51.7%. Moreover, the average thermal efficiency and exergy efficiency are increased by 17% and 3% respectively. However, the freshwater productivity could be decreased due to the increase of H. Compared with H = 0.01 m, the daily fresh water production is decreased by 17% when H = 0.03 m. The results of the exergy analysis indicate that the optimum depth of bottom channel is around 0.01 m.
关键词： Bottom channel,Exergy efficiency,PV/T system,Energy efficiency,Stepped solar still
更新于2025-09-11 14:15:04
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A Simulated Study of Building Integrated Photovoltaics (BIPV) as an Approach for Energy Retrofit in Buildings
摘要： Building envelopes can play a significant role in controlling energy consumption, especially in hot regions because of the wide variety of envelope materials and technologies that have been developed. Currently, because of the high rise in energy prices, especially with the high demand of fossil energy in the building sector worldwide, using curtain walls for maintaining adequate lighting in public buildings could lead to higher energy consumption because of the continuous exposure to the sun in hot regions. For this reason, studying the use of renewable or smart alternatives in the building sector to ensure a cleaner, greener environment by deploying sustainable technology in order to reduce energy demand and support economic long-term solutions would be important for solving such a problem. This paper aims at studying the use of renewable energy technologies and alternatives; represented in new building integrated photovoltaics (BIPVs) technology that could be integrated within building skin to reduce energy demand. The methodology follows a quantitative comparative approach, using an energy simulation software to study two different types of BIPV technology (BISOL Premium BXO 365 Wp monocrystalline and BXU 330 Wp, polycrystalline) on an existing building by retrofitting a part of its curtain wall. This is to conclude the energy saving percentage and feasibility of both alternatives.
关键词： building envelopes,energy efficiency,BIPVs technology,BIPVs feasibility,energy simulation
更新于2025-09-11 14:15:04
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Evaluation of Energy and Daylight Performance of Old Office Buildings in South Korea with Curtain Walls Remodeled Using Polymer Dispersed Liquid Crystal (PDLC) Films
摘要： Globally, energy standards for new buildings are being reinforced to improve energy efficiency, and remodeling policies are being promoted for old buildings. The South Korean Government is promoting green remodeling projects, and focusing on research and product development to improve the performance of old windows and curtain walls. In line with this, the present study proposes two remodeling methods using polymer dispersed liquid crystal (PDLC) films, which can adjust solar radiation for old office buildings. In addition, energy efficiency improvement and daylight performance according to remodeling were analyzed. Attaching PDLC films to the glass of old curtain walls was analyzed; this can reduce heating and cooling energy, reduce the annual discomfort glare occurrence rate, and increase the annual indoor appropriate illuminance ratio. Furthermore, producing a window by laminating a PDLC film between two sheets of glass and putting it over the existing curtain wall was also analyzed; this can reduce annual building energy consumption and the annual discomfort glare occurrence rate, and improve the annual indoor appropriate illuminance ratio. Therefore, PDLC film is expected to be applicable as a next-generation green remodeling material because using it in remodeling can improve energy efficiency of old office buildings and indoor daylight performance.
关键词： EnergyPlus,polymer dispersed liquid crystal,green remodeling,building energy efficiency
更新于2025-09-11 14:15:04