GB/T 4797.4-1989 Natural environmental conditions for electrical and electronic products Solar radiation and temperature GB/T4797.4-1989 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Natural environmental conditions for electric and electronic products
Solar radiation and temperature
Environmental conditions appearing innature for electric and electronic productsSolar radiation and temperatureSubject content and scope of application
This standard specifies the natural environmental conditions for electric and electronic products: solar radiation and temperature. GB4797.4---89
This standard applies to the selection of solar radiation and temperature levels for electric and electronic products in natural environmental conditions. This standard divides solar radiation into several main extreme severity levels according to regions, which serves as the basis for selecting the corresponding solar radiation severity for outdoor products. It is applicable to areas with an altitude of less than 5000m. When formulating environmental condition standards for transportation, storage and use of products, the levels of solar radiation must adopt the values ​​listed in GB·1796 "Classification of Environmental Parameters and Their Severity Classification". 2 Terminology
2.1 Solar radiation
Solar radiation is also called "sunlight", which usually refers to the electromagnetic wave energy radiated by the sun to the surrounding space. 2.2 Global radiation
The sum of direct solar radiation projected onto the horizontal ground surface and sky radiation. 2.3 Direct solar radiation Direct solar radiation, also known as direct solar radiation, is the part of solar radiation flux density received directly from the sun (excluding that scattered by the atmosphere) on a plane perpendicular to the direction of solar radiation. 2.4 Sky radiation Sky radiation, also known as sky scattered radiation, is the short-wave radiation flux from the hemispherical sky to the horizontal ground surface due to the scattering effect of the gas components of the atmosphere and impurities suspended in the atmosphere on solar radiation. 2.5 Total radiation radiation sum
The product of radiation intensity and exposure time, usually expressed in the basic unit of daily radiation total kW-h/(m·d). 2.6 Radiation intensity radiant intensity The radiation energy passing through a unit area per unit time, in units of W/m2 or cal/(cm2·min). 3 3.1 The severity of solar radiation depends on the intensity or total amount of radiation received by the product surface. 3.2 The maximum value of solar radiation occurs on a surface perpendicular to the direction of sunlight at noon on a cloudless day, that is, direct solar radiation perpendicular to the plane. Its maximum value depends on the content of suspended particles, ozone and water vapor in the air at that time. 3.3 When the maximum radiation intensity occurs, the temperature that occurs at the same time is not the highest, that is, the maximum temperature given in GB4797.1 for each corresponding area will not appear. t||GB4797.4—89
3.4The thermal effect of solar radiation is mainly caused by short-term high-intensity radiation, which is generally expressed by the maximum value of direct solar radiation. The following table lists the levels of solar radiation in my country.
Maximum value of direct solar radiation
1000(1.40)wwW.bzxz.Net
1120(1.60)
1180(1.70)
Scope of application
Subhumid and humid areas
Areas below 3000m above sea level
Areas between 3000 and 5000m above sea level
W/m\(cal/(cm2. min))
Excluding subhumid and humid areas, but including the mountains in these two areas
Including most areas of cold and temperate 1 and the western edge of warm temperature
Note: The climate zones in the table are divided according to the regional distribution map of GB4797.1, see the solar radiation intensity distribution map of China's six climate zones. 3.5 The light aging effect of solar radiation depends on the total daily radiation, which is generally expressed as the monthly average or annual average of the total daily radiation. Near the Antarctic, the highest monthly average of the total daily radiation is 10.8kW·h/(m2·d)(9288000cal/(m2.d)). In the subtropical desert area, the lowest monthly average of the total daily radiation is 8.5kW·h/(m2·d) (7300000cal/(m2.d)). In the subtropical desert area, the highest annual average of the total daily radiation is 7.0kW·h/(m2·d)(6027000cal/(m2.d)). Relationship between solar radiation and temperature
Relationship between solar radiation and temperature See Appendix A (Supplement) Chapter A2. 65
GB4797.4--89
A1 Physical process of solar radiation
GB4797.4---89
Appendix A
Overview of solar radiation and its relationship with temperature (Supplement)
Sunlight is emitted in the form of electromagnetic waves in a spherical shape from the radial direction to all directions through the universe to reach the earth. Most of the energy disks reaching the earth's surface have wavelengths within the range of 0.3~4um, including the three major spectral regions of ultraviolet, visible and infrared. Among them, 99% of solar energy is emitted with a wavelength below 1um. Most of the energy with a wavelength below 0.3um is absorbed by the atmosphere and therefore does not reach the earth's surface. The strongest radiation area appears in the visible light range of about 0.48um. The relative position of the sun to a certain point on the earth's surface varies between 0° and ~90°. At 0° (sunrise or sunset), the radiation is the weakest and approaches zero; at 90° (noon), the sun is directly shining and the radiation is the strongest. When the solar radiation is perpendicular to the ground, the solar energy (heat energy) received per unit area per unit time is the largest. If there is no atmosphere and the sun and the earth are at an average distance, this value is the solar constant, and its approximate value is 1.37kW! m (1.96cal/(cm2·min)). However, since the distance between the sun and the earth changes periodically during the year, the solar constant is different in different months, such as the approximate value of January is 1.41kw/m (2.02cal/(cm2·min)), and the approximate value of July is 1.32kw/m2 (1.89 cal/(cm2.min)).
When solar radiation passes through the atmosphere, it will encounter various particles (such as water vapor, clouds, raindrops, dust) and gases (oxygen, carbon dioxide, ozone, etc.), and the radiation will be further absorbed and scattered. The shorter wavelength part of the radiation will be scattered by air molecules and dust floating in the atmosphere. As a result of scattering, part of the energy received by a certain place on the earth comes from direct radiation, and the other part is scattered radiation. The sum of the two is called total radiation. The maximum value of solar radiation occurs in the direction perpendicular to the earth's surface on a cloudless day. When the water content in the air is nearly 1cm, the ozone content is 2mm, and the air turbidity coefficient is 0.05 suspended particles, the maximum value of direct solar radiation will reach 1.12kW/m2 (1.60cal/(cm2·min)). When the incident angle of the sun to the ground is greater than 60°, this value is representative for cities without industrial pollution.
The intensity of direct solar radiation decreases with the increase of air turbidity. Subtropical climate has higher turbidity than temperate and cold climate. The turbidity over cities is higher than over rural areas. At the same location, the turbidity is higher in summer than in winter. Therefore, the maximum solar radiation intensity does not occur when the temperature is highest.
After the ground becomes hot due to solar energy, it also radiates to the atmosphere, which is called ground radiation. Because ground radiation is long-wave radiation, it is quickly absorbed by water vapor, clouds and carbon dioxide in the atmosphere. When the atmosphere is heated by absorbing ground radiation, it also radiates long-wave radiation outward. The downward radiation is called back radiation because it is in the opposite direction of ground radiation. At night, the heat loss caused by ground radiation always exceeds the absorption of back radiation, so the temperature decreases at night due to radiation cooling. A2 Impact of solar radiation on products
The impact of solar radiation on products can be divided into the following two aspects. A2.1 Temperature rise caused by product heating After outdoor products are exposed to solar radiation, the temperature t reached can be defined as the temperature of a certain surface of an object when the actual surrounding air temperature and the solar radiation E are combined to reach a stable state. In addition, it is also related to the absorption coefficient of the object surface to sunlight and the surface heat conduction coefficient. The approximate value can be obtained from formula (Al): &E
Where: α—depends on the color of the object surface, generally 0.7; y-heat conductivity of the surface, including heat radiation to the surrounding environment, heat conduction and heat convection caused by wind, W/(m2.), 67
GB4797.4-89
-generally 20w/(m.℃);
E----the representative value for sunny days is 1000W/m2. Calculated according to formula (A1). The "temperature rise" (not included) caused by solar radiation is about 35℃. It can be seen that when estimating the intensity of solar radiation, the corresponding temperature will be less than 5℃ due to a 10% error. Therefore, it is not necessary to classify the solar radiation level very accurately. A2.2 The service life of the product is affected by light aging. The ultraviolet rays in the sun have a light aging effect on most organic materials, which reduces the transparency of optical glass, fades the paint, gradually loses the elasticity of rubber products, and deforms and cracks plastic products. Therefore, attention must be paid to the design and material selection of the product shell and its auxiliary parts.
Additional Notes:
This standard was proposed by the National Technical Committee for Standardization of Environmental Conditions and Environmental Tests for Electrical and Electronic Products. This standard is under the jurisdiction of the Guangzhou Electrical Science Research Institute. This standard was drafted by the Solar Radiation and Temperature Working Group of the Environmental Standardization Committee. The main drafters of this standard are Zhao Peiyu, Huang Wenzhong, Huang Yuzhou, Huang Wenlin, and Zhu Yaochang.
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