| Summary: | 碩士 === 崑山科技大學 === 機械工程研究所 === 99 === Solar radiation is a huge source of energy striking the Earth’s surface every day, 48% of the energy is in the visible light spectrum which is desired for indoor illumination, 45.6% is in the infrared spectrum which is not desired to go indoors due to its heat gain effect; this is traduced to energy consumption by air conditioning. In order to reduce the solar heat gain in buildings and cars, a heat insulation film is attached to the glass; this material has the ability to absorb some part of the infrared spectrum due to nano-ceramic particles embedded within a thin PET layer.
This study deals with the comparison of experimental and numerical results, of three samples of different materials, to determinate their thermal insulation effect. The experimental results were obtained by use of a wood chamber with 2mm aluminum plate collector coated with carbon black and a 3mm regular glass exposed to a 250w infrared lamp during 4 hours, involving irradiance sensor and thermocouples mounted on several points. Optical transmittance test was performed with a spectrophotometer, for ultraviolet, visible and infrared spectrum. Numerical predictions were obtained with a mathematical model of the heat transfer in the chamber, simulated with Simulink Matlab software using the theoretical equations, with ideal insulated walls and neglecting the re-transmittance of the glass.
The comparison of experimental results showed that the best material is I999, in the thermal analysis on steady state showed an average temperature reduction of 21oC on the collector when using the thin film. The average transmittance is 57.6% for 400nm-700nm and 7.1% for 710nm-2500nm. The numerical simulation predicted the temperature tram with variances of 12.2% and 12.7% for collector plate and front air respectively. This thin film effectively reduces the temperature due to absorption of a selective band in the infrared spectrum; it is a high performance material to control the solar heat gain through windows.
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