Performance Improving of a Concentrating Photovoltaic System by Using a New Optical Adhesive

The objective of this present study is to manufacture a new silicone-based adhesive which is used for gluing and bonding the second optical elements (SOE) with Concentrating Photovoltaic solar cell (CPV) in order to guarantee a thickness that can provide a good silicone adherence to obtain long term stability and keeping a good solar transmittance performance, too. This new adhesive is made up of a mixture of silicone and transparent glass balls. The experimental part consists of the choice of the best size of glass balls with the suitable proportion of the glass balls weight in the mixture. For this purpose, ten samples were manufactured for every category of glass balls and weight ratio. Glass ball sizes between 100 and 1100 μm, and weight ratios between 1 and 10% were analyzed. For each category of glass balls, four proportions were mixed with the silicone. The thicknesses and transmittance of every sample were measured with appropriate instruments. The experimental results illustrate that the mixture containing balls with sizes inferior to 106 μm, is the best mixture which assures adhesive minimum thickness value necessary for an efficient mechanical bond and preserves also a good transmittance of solar irradiance.

Enhanced Heat Transfer of Carbon Nanotube Nanofluid Microchannels Applied on Cooling Gallium Arsenide Cell

Carbon nanotube nanofluids have wide application prospects due to their unique structure and excellent properties.In this study,the thermal conductivity properties of carbon nanotube nanofluids and SiO2/water nanofluids were compared and analyzed experimentally using different preparation methods.The physical properties of nanofluids were tested using a Malvern Zetasizer Nano Instrument and a Hot Disk Thermal Constant Analyzer.Combined with field synergy theory analysis of the heat transfer performance of nanofluids,results show that the thermal conductivity of carbon nanotube nanofluids is higher than that of SiO2/water nanofluids,and the thermal conductivity of nanofluid rises with the increase of mass fraction and temperature.Moreover,the synergistic performance of carbon nanotube nanofluids is also superior to that of SiO2/water nanofluids.When the mass fraction of the carbon nanotube nanofluids is 10%and the SiO2/water nanofluids is 8%,their field synergy numbers and heat transfer enhancement factors both reach maximum.From the perspective of the preparation method,the thermal conductivity of nanofluids dispersed by high shear microfluidizer is higher than that by ultrasonic dispersion.This result provides some reference for the selection and use of working substance in a microchannel cooling concentrated photovoltaic and thermal(CPV/T)system.