scholarly journals Assessment of solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers in Malaysian tropical latitude

Author(s):  
Khai Ng ◽  
Nor Adam ◽  
Othman Inayatullah ◽  
Mohd Zainal Abidin Kadir
PEDIATRICS ◽  
1990 ◽  
Vol 85 (4) ◽  
pp. 626-627
Author(s):  
KARL F. WEYRAUCH ◽  
PATRICIA E. BOIKO

To the Editor.— Weinstock et al1 observed "a significant association of melanoma with latitude of residence during the teenage years," thereby implying a direct relationship between solar radiation intensity and increasing tropical latitude. However, for specific locations, this relationship may not be true. For example, average daily solar radiation in Spokane, WA (latitude 47 degrees, 40 minutes, elevation 2400 feet), was 1314 BTU during July, compared to 862 BTU in Charleston, SC (latitude 32 degrees, 53 minutes, elevation sea level).2


Author(s):  
Lijuan Mu ◽  
Qunzhi Zhu ◽  
Leilei Si

Solar energy utilization is very important in the background of global warming and reduction of carbon dioxide emission. Solar air/water collectors are convenient to convert solar energy into heat. Compared with regular solar collectors, direct absorption solar absorbers are not common. However, nanofluids can be used in direct solar absorbers to improve their performances. The objective of this paper is to evaluate the potential of application of nanofluids in direct solar absorbers. Spectral transmittances of nanofluids within the solar spectrum have been measured by a customized spectrophotometer. A direct solar absorber has been built to use nanofluids as the working fluid and its performance has been experimentally investigated. It is found that the radiative properties of nanofluids deviate significantly from that of the base fluid. A remarkable amount of visible light can pass through the SiO2 nanofluid while solar radiation can hardly transmit through the TiO2 nanofluid and ZrC nanofluid. The ZrC nanofluid shows the highest solar absorbance among the studied nanofluids. The temperature increase rate of the nanofluid is faster than that of water when the liquid stagnant in the absorber is illuminated by solar radiation. Furthermore, the temperature differences between the inlet and outlet of the TiO2 nanofluid and ZrC nanofluid are higher than that of the SiO2 nanofluid at the same flow rate. This work is beneficial for the exploration of nanofluids in direct solar absorbers.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1013
Author(s):  
M. Alejandra Mazo ◽  
Isabel Padilla ◽  
Aurora López-Delgado ◽  
Aitana Tamayo ◽  
Juan Rubio

The potential application of silicon oxycarbonitride (SiOCN), silicon oxycarbide (SiOC) and silicon oxycarbide–SiC (SiOC–SiC) for photothermal devices such as volumetric solar absorbers has been studied evaluating the response to thermal shock from a Fresnel lens. The accelerated ageing test comprises fast heating (32 °C min−1) and cooling rates (27 °C min−1) from 100 to 1000 °C and dwelling times of 10 min. Porous materials (SiOCNp and SiOCp) failed the thermal shock tests; they were massively degraded by the formation of a large depression in the focus of solar radiation. Dense materials (SiOCd and SiOC–SiCd) withstood 100 cycles of thermal shock ageing tests due to the formation of a protective silica layer. The absorptance values for dense materials remained fairly constant before and after thermal shock tests: from 94.5 to 94.3% for SiOCd and from 93.3 to 93.3% for SiOC–SiCd. These preliminary studies indicate their potential for high-temperature solar receiver applications.


Space Weather ◽  
2006 ◽  
Vol 4 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Tracy Staedter
Keyword(s):  

2003 ◽  
Vol 107 ◽  
pp. 743-747
Author(s):  
D. R.S. Lean ◽  
SD. Siciliano
Keyword(s):  

2019 ◽  
pp. 53-65
Author(s):  
Renata Domingos ◽  
Emeli Guarda ◽  
Elaise Gabriel ◽  
João Sanches

In the last decades, many studies have shown ample evidence that the existence of trees and vegetation around buildings can contribute to reduce the demand for energy by cooling and heating. The use of green areas in the urban environment as an effective strategy in reducing the cooling load of buildings has attracted much attention, though there is a lack of quantitative actions to apply the general idea to a specific building or location. Due to the large-scale construction of high buildings, large amounts of solar radiation are reflected and stored in the canyons of the streets. This causes higher air temperature and surface temperature in city areas compared to the rural environment and, consequently, deteriorates the urban heat island effect. The constant high temperatures lead to more air conditioning demand time, which results in a significant increase in building energy consumption. In general, the shade of the trees reduces the building energy demand for air conditioning, reducing solar radiation on the walls and roofs. The increase of urban green spaces has been extensively accepted as effective in mitigating the effects of heat island and reducing energy use in buildings. However, by influencing temperatures, especially extreme, it is likely that trees also affect human health, an important economic variable of interest. Since human behavior has a major influence on maintaining environmental quality, today's urban problems such as air and water pollution, floods, excessive noise, cause serious damage to the physical and mental health of the population. By minimizing these problems, vegetation (especially trees) is generally known to provide a range of ecosystem services such as rainwater reduction, air pollution mitigation, noise reduction, etc. This study focuses on the functions of temperature regulation, improvement of external thermal comfort and cooling energy reduction, so it aims to evaluate the influence of trees on the energy consumption of a house in the mid-western Brazil, located at latitude 15 ° S, in the center of South America. The methodology adopted was computer simulation, analyzing two scenarios that deal with issues such as the influence of vegetation and tree shade on the energy consumption of a building. In this way, the methodological procedures were divided into three stages: climatic contextualization of the study region; definition of a basic dwelling, of the thermophysical properties; computational simulation for quantification of energy consumption for the four facade orientations. The results show that the façades orientated to north, east and south, without the insertion of arboreal shading, obtained higher values of annual energy consumption. With the adoption of shading, the facades obtained a consumption reduction of around 7,4%. It is concluded that shading vegetation can bring significant climatic contribution to the interior of built environments and, consequently, reduction in energy consumption, promoting improvements in the thermal comfort conditions of users.


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