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This study melted and mixed poly lactic acid and nano mica into a new nano composite material for injection molding. The injection parameters for the mixture included the melting time, screw speed, heating plate temperature, nano mica content, melting temperature, nozzle temperature, holding pressure, and injection speed. The quality considerations of the new nano composite material were ultraviolet (UV) absorption rate, far-infrared absorption rate, Rockwell hardness, and flame resistance. This study applied main effect analysis and variance analysis theory of the Taguchi method to analyze the single quality characteristic of the experimental results. The optimal factors and level combination was identified through multi-quality integration using the Analytic Hierarchy Process. After consistent examination and calculation of the total weighting of various parameter levels, as well as the ranking of the parameter levels, the optimal injection parameters were obtained. According to the confirmation experiment results, the Signal-to-Noise ratio of the four qualities for the new nano composite fell within the 95% confidence interval, indicating the experiment was reproducible and reliable. The results indicated that the best qualities for the new nano composite are UV absorption rate at 98.22%, far-infrared absorption rate at 90.53%, Rockwell hardness at 108.07, and the limiting oxygen index for fire resistance rating at 30.Poly lactic acid (PLA) is polymerized from lactic acid monomer. The lactic acid molecule has a hydroxyl group and two carboxyl functional groups of high activity. Under certain conditions, the lactic acid molecule can be easily dehydrated and condensed to PLA. Given this feature, there are two synthesis methods of PLA, the direct polycondensation method and the lactide ring-opening polymerization method, 1 as shown in Figures 1 and 2. Having a poor thermal stability along with the low glass transition temperature, the use of the PLA application is limited. When PLA and poly (methyl methacrylate) (PMMA) are compounded together to observe the glass transition temperature, the glass transition temperature increases with the proportion of added PMMA. 2 The addition of recycled newspaper fiber to PLA compared to pure PLA has significantly improved the tensile and flexural modulus. 3Mica is an aluminosilicate mineral with the sheet structure of potassium, magnesium, iron, and lithium. This aluminosilicate mineral can be completely dissociated and peeled into flexible sheets, and has physical properties of being bendable, soft, and transparent. A mica block is usually in the color of translucent gray, brown, light green, or maroon. The chemical composition of mica crystal is [KAl 2 (AlSi 3 )O 10 (OH) 2 ], which is an octahedral layer of an aluminum silicate mineral of

This study designed and optimized the system parameters for a photovoltaic thermal system (PV/thermal system) combined with reflectors. Moreover, it discussed the gain of electrical efficiency and thermal efficiency on the system after adding two reflectors on each of the south and north sides, and adjusting the water circulation system. As the rising angle and position of the sun varies each season, in order to make this study more rigorous, experiments were conducted in four seasons of a year. The Taguchi orthogonal array was used for experimental planning, and the optimal parameters were analyzed for electrical efficiency and thermal efficiency. The analysis of variance was conducted to examine the influential parameters, and principal component analysis was used to calculate the principal component point of each experiment. The results were employed to construct a response surface methodology model. Finally, the steepest descent method was applied to obtain the optimal parameters. The reflector theory was applied to calculate the gain of solar radiation amount after installing the reflector. Moreover, the gain was inputted into the simulation software TRNSYS to simulate the electrical power output and the water temperature in the water storage tank. The confirmatory experiments of the four seasons found that the electrical energy after installing the reflector increased by 0.117-0.183 kWh, and the thermal energy increased by 1.7-2.6 • C. The experiment confirmed that the prediction error was <4 %.Keywords Photovoltaic/thermal (PV/T) · Reflector · Taguchi method · Analysis of variance (ANOVA) · Principal component analysis (PCA) · Response surface methodology (RSM) · Steepest descent method (SDM) · Transient system simulation tool (TRNSYS) List of symbolsP Total generated electrical energy during the day (kWh) G Total solar radiation energy during the day (J/m 2 ) A Module dimension (m 2 ) V m PV voltage at maximum power point (V) I m PV current at maximum power point (A) Q Total generated thermal energy during the day (J) V Water mass flow rate (kg/s) C p Water specific heat (4.18 kJ/kg • C) T f Water final temperature ( • C) T i Water initial temperature ( • C) A r1_a Actual receivable area of upper reflector (m 2 ) W 1 Upper plate width (m) W 1 Upper plate reflect to module width (m) L 1 Upper plate reflect to module height (m) L 1 Upper plate height (m) A r1 Reflection area of upper reflector (m 2 ) 123 J Intell Manuf θ Included angle between reflector and azimuth ( • C) A r2_a Actual receivable area of lower reflector (m 2 ) W 2 Lower plate width (m) W 2 Lower plate reflect to module width (m) L 2 Lower plate height (m) L 2 Lower plate reflect to module height (m) A r 2Reflection area of lower reflector (m 2 ) G r1_c Reflection solar radiation of upper plate (J/m 2 ) G r1Receiving solar radiation of upper reflector (J/m 2 ) L 1Upper plate reflect to module lengthen width (m) G r2_c Reflection solar radiation of lower plate (J/m 2 ) G r2Receiving solar radiation of lower reflector (J/m 2 )