Kum ile radyatif soğutma

Passive radiative cooling is one of the upcoming technologies likely to help decrease the negative impacts of climate crises and reduce energy consumption in buildings. The principle of radiative cooling involves radiating heat from the surface of a building into space, thus reducing the reliance on air conditioning systems. Understanding the fundamentals of passive radiative cooling is important for thermal management related to buildings and industrial applications. The principle of radiative cooling in buildings involves selectively reflecting incident radiating heat from the surroundings and selectively emitting energy from a surface to the surroundings to achieve minimum heat load on the system. In the case of buildings, solar radiation incident on roofs can be reflected or absorbed. The absorbed heat is either transferred to the surrounding air by convection or it will be emitted back to the sky. If a surface is desired to be radiatively cooled it must have a large reflection of solar energy at the visible wavelength range and the highest radiation emission at the atmospheric window range (8-13 µm wavelength range) as discussed in detail in the thesis. This technique can significantly help reduce greenhouse gas emissions as it will help decrease air-conditioner use in warm climates during the summer months. Recently, the use of nanoparticles and different structures has been considered for passive radiative cooling applications. In this study, we investigate the radiative cooling properties of sand particles experimentally and compare their performance with other materials including silicon dioxide, titanium dioxide, and zinc oxide. Scanning electron microscopy (SEM) is used to analyze the morphology of the surface of sand the particles, and the other materials used in the study for comparison. Fourier transform infrared spectroscopy (FT-IR) experiments were conducted in order to measure the absorbance and transmittance percentage of the samples. In addition, the absorption coefficient was calculated from the FT-IR measurements. The absorption coefficient of the sand samples showed a high ratio (in the units of 1/m which was approximately between 0.4⨯10^4 and 0.8⨯10^4 for all the pellet samples at the atmospheric window range. Also, the behavior of the absorption profiles of the sand sample and ZnO were very similar in their ratios, especially in the atmospheric window range. Also, we observed that the emission shows the highest peaks at 6.78 µm, 9.24 µm, 11.69 µm, and 14.05 µm for all sand pellet samples. Thus, the properties of sand samples experimentally studied in this work show that they can be used for radiative cooling due to their abundance and thermal properties with better performance.