China
Africa
Explore chapters and articles related to this topic
Energy, Environment, and Renewable Energy
Published in Radian Belu, Fundamentals and Source Characteristics of Renewable Energy Systems, 2019
Electromagnetic radiation is associated with the electromagnetic field under the form of waves, such as light. The electromagnetic radiation covers a very wide range of frequencies or wavelengths, X-rays, ultraviolet radiation, visible light, infrared radiation, radio waves, etc. Electromagnetic radiation for the Sun is our most important source of energy, being responsible for most other energy sources, such as fossil fuels, wind, solar energy, biomass, etc. Expressed in terms of photons or energy quanta electromagnetic energy is related to electromagnetic radiation frequency, f and Planck’s constant (h = 6.626 × 10−26 J∙s), through: () E=hf
Phosphors for Light-Emitting Diodes
Published in Vijay B. Pawade, Sanjay J. Dhoble, Phosphors for Energy Saving and Conversion Technology, 2018
Vijay B. Pawade, Sanjay J. Dhoble
Nowadays, LEDs are widely used in day-to-day life for general lighting and have nearly replaced incandescent bulbs and fluorescent lamps. These modern LEDs offer several benefits over conventional incandescent light. LEDs are much more efficient than incandescent bulbs in terms of converting electricity into visible light; they are compact and tiny; and most importantly, they have a lifespan of 100,000 hours, which is almost 100 times longer than the lifespan of incandescent bulbs [10, 11]. Furthermore, LEDs offer several other superior characteristics: they are monochromatic emitters of light, can produce bright light emission, and can produce any color. Due to these characteristics, LEDs are used in a number of applications in modern technology. LEDs are now being used in automotive taillights, turn signals, and side marker lights. The long lifespan of LEDs allows manufacturers to integrate the brake light into the vehicle design without the necessity of providing for frequent replacement, as is required when incandescent bulbs are used. Single color–emitting LEDs are also being used in runway lights at airports and as warning lights on radio and television transmission towers. Incandescent lights at traffic signals consume 50–150 Watts; compared with this, LEDs in traffic lights consume 10–25 Watts for a light of similar brightness.
Introduction
Published in Matt Fajkus, Dason Whitsett, Architectural Science and the Sun, 2018
In actuality, light can behave according to a particle theory and a wave theory simultaneously, depending on the context and dimension. Frequently, light acts as a wave, or electromagnetic wave due to being composed of both electric and magnetic fields. Light waves have two primary attributes—wavelength and frequency—both of which are quantitative and scalable dimensions, and theoretically go on for infinity. In essence, wave theory unites all forms of radiation and all kinds of matter and, as such, the universe can accurately be described as being composed of light.15 Light is therefore a component of the electromagnetic spectrum. The photoelectric effect is described as the phenomena in which atoms of a material or substance emit electrons when struck by light.
Optimization of microalgae growth for biofuel production using a new empirical dynamic model
Published in Biofuels, 2021
Ibifubara Humphrey, Michael A. C. Chendo, Abdulahi N. Njah, Dike I. Nwankwo
Visible light is a section of the electromagnetic radiation spectrum, sandwiched between ultraviolet and infrared radiation. Its wavelength ranges from 380 to 780 nm. The sunlight reaching the Earth’s atmosphere, which appears to us as white light, comprises seven colors – red, orange, yellow, green, blue, indigo and violet – which are scattered in all directions by the gases and particles in the air. The shorter the wavelength of light, the more it is scattered. Thus, magenta (indigo–violet) light is more scattered than blue light, which in turn is more scattered than red light. Also, under bright sunlight, it is difficult to achieve high photosynthetic efficiency, because cells absorb more light energy than can be converted to biochemical energy. Consequently, microalgae dissipate part of the absorbed light energy as heat, which inhibits the growth rate [31].
Factors Influencing the Temperature Distribution of 200 W Light Emitting Diode Module Used in the Spotlight
Published in Heat Transfer Engineering, 2018
Jicheng Zhou, Xing Chen, Zhuang Zhou, Yinqiao Peng, Yunyun Wang, Jinhui Huang
As a new energy-saving lamp, LED (light emitting diode) lamp has the advantages of high luminous efficiency, long service life and good stability compared with traditional incandescent lamp. It is a promising candidate for the next generation of general illumination applications and definitely the mainstream of lighting in the near future [1–4]. But the light extraction efficiency of the LED lamp is limited. With the increase of LED lamp power, the heat flux generated from LED chips is on the level of 300 W/cm2 or greater [5], which causes a fast rise of junction temperature, and too high temperature can limit the lifetime and luminous efficiency of LED greatly [6–9]. Therefore, the thermal management is essential to LED lamps with high power.
A Low-Cost, Wide-Range, CCT-Tunable, Variable-Illuminance LED Lighting System
Published in LEUKOS, 2020
Rajib Malik, Kalyankumar Ray, Saswati Mazumdar
For general lighting purposes, light emitting diodes (LEDs) have the notable advantages of high luminous efficiency and consequently reduced energy consumption, very low ultraviolet emission, high environmental friendliness, and longer operating lifetime over conventional incandescent and fluorescent lamps (Kim and Schubert 2008; Pinho et al. 2013; Protzman and Houser 2006). Researchers in the last two decades, in their pursuit of attaining high electrical energy efficiency, noted these advantages. Eventually, LEDs became very popular as alternative source of light (Kim and Schubert 2008; Protzman and Houser 2006).