Air mass 1.5 conditions

ISO 9845-1, Solar energy - Reference solar spectral irradiance at the ground at different receiving conditions - Part 1 Direct normal and hemispherical solar irradiance for air mass 1,5 (available in English only), 1992. 

The solar to electric power conversion efficiency of dye-sensitized solar cells of laboratory scale (0.158 cm2), validated by an accredited photovoltaic calibration laboratory, has reached 11.1% under standard reporting conditions, i.e., air mass 1.5 global sunlight at 1000 Wm-2 intensity and 298 K temperature, rendering it a credible alternative to conventional p-n junction photovoltaic devices [68]. Photovoltaic performance data obtained with a sandwich cell under illumination by simulated AM 1.5 solar light using complex 26 are shown in Fig. 16. At 1 sun the 26-sensitized solar cell exhibited 17.73 =b 0.5 mA current, 846 mV potential, and a fill factor of 0.75 yielding an overall conversion efficiency of 11.18%. 

Most often, AOD is referred to a specific wavelength, usually 500 nm, or occasionally 550 nm. An AOD of 0.01 at 500 nm represents very clean, pristine, clean atmosphere. Values of AOD at 500 nm of 0.1 to 0.2 are quite typical of average conditions. Values of 0.4 or greater represent a heavy aerosol load and very hazy skies. Figure 8 shows the clear sky direct beam spectral distribution at Air Mass 1.5 for a range of AOD from 0.05 to 0.40... 

Air mass 1.5 represents the condition where approximately 1/2 of the total available solar energy is available for air masses greater than and less than this condition, respectively. 

Specific solar radiation conditions are defined by the air mass (AM) value. The spectral distribution and total flux of radiation outside the Earth s atmosphere, similar to the radiation of a black body of 5,900 K, has been defined as AM-0. The AM-1 and AM-1.5 are defined as the path length of the solar light relative to a vertical position of the Sun above the terrestrial absorber, which is at the equator when the incidence of sunlight is vertical (90°) and 41.8°, respectively. The AM-1.5 conditions are achieved when the solar flux is 982 Wm2. However, for convenience purpose the flux of the standardized AM-1.5 spectrum has been corrected to 1,000 Wm2. 

PV devices are compared under standard conditions such as 100 mW cm (1 sun) solar radiation of (air mass) AMI.5 spectrum at 25 °C. The most common way devices are compared is by their current-voltage (J-V) characteristics (Figure 3.2). 

The air, in passing through the chamber at velocities in the range 1.5 to 3.5 m s" comes into intimate contact with the water, and depending on the conditions required, mass transfer of moisture into the airstream occurs. This transfer produces either addition or removal of moisture hot or chilled water is used in this process. 

Mass transfer may take place from a mixture of gases, such as the condensation of water from moist air. In this instance, the water vapour has to diffuse through the air, and the rate of mass transfer will depend also on the concentration of vapour in the air. In the air-water vapour mixture, the rate of mass transfer is roughly proportional to the rate of heat transfer at the interface and this simplifies predictions of the performance of air-conditioning coils [1,5, 9]. 

Example 28.1 All air A space is to he held at 21°C dry hulh and 50% saturation, and has an internal load of 14 kW sensible and 1.5 kW latent heat gain. The inlet grille system is suitable for an inlet air temperature of 12°C. What are the inlet air conditions and the mass air flow ... 

Considering the countercurrent flow of water and air in a tower of height z (Figure 13.15), the mass rate of flow of air per unit cross-section G is constant throughout the whole height of the tower and, because only a small proportion of the total supply of water is normally evaporated (1 -5 per cent), the liquid rate per unit area ll can be taken as constant. The temperature, enthalpy, and humidity will be denoted by the symbols 6, H, and Tf respectively, suffixes G, L, 1, 2, and / being used to denote conditions in the gas and liquid, at the bottom and top of the column, and of the air in contact with the water. 

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