Papers by Keyword: Fresnel Lens

Abstract: Effects of shading and blocking of solar radiation intensity through Fresnel lens onto solar cell were investigated in this work. Fresnel lens was made of polyvinyl chloride to concentrate the solar radiation onto the polycrystalline silicon solar cell with the 0.767 m x 0.670 m in size and no cooling under the solar panels. The temperature and efficiency comparisons between solar module with and without Fresnel lens were observed. The performance of the two modules overtime is assessed by monitoring the characteristic I-V and P-V curves. The maximum efficiency of the solar panels with Fresnel lens and without Fresnel lens in each hour was approximately 5-6.7% and 8.8-11.5%, respectively. This lower efficiency of PV module with Fresnel lens was a result of unsuitable distance of Fresnel lens that operated with the PV module.

Abstract: A multi-curvature Fresnel concentrator is proposed in this study for a concentrated photovoltaic system (CPV) to suppress aberrations. Unlike a conventional Fresnel concentrator with a single curvature, the proposed one integrates several Fresnel concentrators with individual curvatures. An embodiment is designed for a PMMA concentrator comprising four curvatures. The simulated efficiency of the embodiment is 86.4%. The tolerance analyses and the fabrication considerations of the CPV are provided and discussed.

Abstract: Malaysia has great potential for biomass stock. The fact that oil palm fronds contain high moisture content makes it unsuitable to be used directly as a biomass fuel neither for direct combustion nor gasification. Conventional and costly drying methods make the fronds a non-attractive fuel especially in humid tropical countries, where sources of biomass is abundant. A new solar dryer design is proposed that utilizes concentrated solar thermal energy for drying oil palm fronds. A prototype for the dryer has been fabricated and tested. The system’s target is to maximize the thermal energy received by the system and to minimize energy loss out of the system. Experiments were performed on samples of oil palm fronds at a drying temperature not exceeding 110°C; in order not to affect the organic material of the biomass. Results were compared with another experiment performed at the same temperature. An electric oven was used for drying. The samples were completely dried using the proposed system for 6.5 hours, compared to 10.5 hours by using the electric oven. The proposed system achieved an average drying rate of 4.75 g/hr compared to an average drying rate of 2.83 g/hr using the electric oven. The efficiency of the dryer was calculated to be 55.4%, implying good potential of the proposed system.

Abstract: This paper analyzed the large diameter Fresnel lens mold machining mechanism based on modal test methods .The design and mold machining principle of Fresnel lens were introduced . Explored the cutting speed and feed on chip formation process. The results show that: the material strength and plastic brittle have significant impact on chip morphology in the H62 brass mold processing, an improvement of material strength with the increase of strain rate and the evolution process of the chip can be divided into: ribbon cuttings, serrated chips, cell chips.

Abstract: In this paper, the simple and effective experimental method is proposed for studying on the influence of tracing deviation on solar-pumped laser output performance. The threshold pumping power is obtained by the novelty method. The experimental setup of solar-pumped laser employed Fresnel lens of 1.4×1.05m² and diffuse reflective conical cavity focusing solar radiation on the size of 5mm×60mm Cr/Nd:YAG ceramic. The effective threshold pumping power calculated is 190W, which is about 30% lower than reported results.

Abstract: This paper presents a new kind of light emitting diode(LED) secondary light distribution lens which adopts the type of Fresnel lens surface. The research purpose of this paper is to improve the LED heat dissipation efficiency of the secondary light distribution lens and the light efficiency, so as to prolong the service life of the LED. In this paper, we use the numerical method for solving the partial differential equation to establish a freeform surface lens which could produce uniform illumination, then the innovative method of combine the Fresnel lens structure with freeform surface lens was proposed. The design of freeform surface Fresnel lens allows dramatically cut the thickness of the lens (as well as the weight and volume) , it can solve the problem of difficulty in heat dissipation. By comparing the ray tracing simulation results of original freeform surface lens and freeform surface Fresnel lens in optical simulation software, experiments show that the latter not only shows the same degree of illumination uniformity, but also greatly reduced the thickness of the lens.

Abstract: This paper describes the analysis of the chip formation mechanism in mold machining process of large diameter Fresnel lens based on the ABAQUS finite element simulation software and modal test methods. Combined with the material constitutive relation and material failure criteria etc, a two-dimensional orthogonal cutting model was established and the chip derived from the simulation was compared with the chip from modal test, with a consequent verification of the feasibility of simulation chip model. The simulation contributes to an investigation into the effects of the cutting speed on chip formation process. The results show that: the material strength and plastic brittle have significant impact on chip morphology in the H62 brass mold processing, and material strength will improve with the increase of strain rate, the evolution process of the chip of material plastic reduction can be divided into: ribbon cuttings, serrated chips, cell chips.

Abstract: When installing concentrator photovoltaic (CPV) systems in desert areas, we must consider the impact of sandstorms on the Fresnel lens in CPV modules. CPV systems are much more sensitive to sandstorms than flat-panel PV systems because they can only use the direct beam component of sunlight. In this study, the transmittance of a PMMA substrate after sandblasting was evaluated and the influence of sandblasting on the output of a CPV system was assessed. The transmittance of PMMA decreased with an increase in the momentum of blown sand. The conversion efficiency of a CPV module was determined by equivalent circuit calculation. The conversion efficiency decreased with increasing momentum. The coefficient of degradation was 0.17 point per unit momentum.

Abstract: If the optical collector surfaces in concentrator photovoltaic (CPV) systems are soiled, a significant proportion of sunlight is scattered and definitively lost because the scattered rays cannot be focused onto the solar cell. In this study, we studied the influence of soiling on poly-methyl methacrylate (PMMA) substrates with and without super-hydrophilicity anti-soiling layer. After 5 months, the reduction rate of transmittance for the sample without anti-soiling coat was 7.1%. In contrast, that for the sample with anti-soiling coat could be suppressed to 4.2%. Moreover, the relationship between wind speed and accumulation of dust was discussed.

Abstract: Shortly after the invention of the laser, researchers began to dream of converting sunlight into laser radiation directly. A direct conversion of concentrated solar light into a coherent laser beam improved the conversion efficiency because of the simple design of the structure, which is an innovation in the new field of solar energy utilization. We utilize the Fresnel lens of 1m2 to collect solar light, which is coupled into the conical chamber pumping Nd:YAG crystal, in 5mm-diameter 80mm-length rod. The pumping cavity is designed to combine end-pumping with side-pumping, in which the pumping light comes from many directions. It could compensate the drawbacks of single end-pumping or side-pumping. In the experiment, we obtain the maximum laser output power of 2.5 W, with a slope efficiency achieving 1.3%. By the Tracepro ray-tracing software, simulating the incoming energy distribution in the focus of the Fresnel lens, the concentration ratio of 104 is achieved.