Papers by Keyword: Solar Concentrator

Abstract: The solar parabolic trough collector technology is one of the most reliable technologies in the field of solar thermal. This is due to the fact that temperatures as high as 300-400°C can be achieved using this technology. This technology is used for hot water production, process steam requirement, power generation and many more. In the present work a thermal study on a parabolic trough collector is performed to observe the range of steam temperatures to be useful for small scale industry applications. The paper presents the steam temperatures, temperature profiles for the solar collector components and the solar radiation variation over the day. On the basis of several experiments it was found that in the parabolic trough collector the maximum pressure of 221 bar and the maximum steam temperature of around 374°C is achieved. From the experimental data obtained, the variation in temperatures with solar radiation on clear and intermittent cloud cover is discussed. From the results it can be concluded that this system may be used successfully for production of hot water and steam for use in many different industries such as dairy, textile, paper, timber, bricks, chemicals, plastics etc. Hot water and steam from solar system can be used in small scale industries for rose water making, cooking, drying, sterilization, food processing etc. In this paper a design for rose water making process through parabolic trough collector has been proposed. Keywords: Solar concentrator, parabolic trough, cylindrical parabolic collector, steam, temperature profile, industry applications.

Abstract: In this paper the problem of guiding a parabolic trough solar concentrator through a system based on a water displacement mechanism is addressed. The actuator mechanism consists of a set of four on/off electrovalves in ”H-bridge” configuration, a small water pump, a sun sensor and two containers half-filled with water, installed on the side ends of the concentrator. To guide and balance the concentrator, a sliding mode controller (SMC) to enable / disable the opening and closing of the valves that control the direction and flow of water between the two containers is proposed. The validity of the implementation of the proposed law of control applied to the actuator mechanism is verified with stability analysis and simulation results.

Abstract: In this article, we have designed and fabricated the gamma-type Stirling engine based on the compression ratio technique. This engine is attached on a parabolic dish of a solar collector. The engine shows a good performance in terms of compression ratio, external work, total pressure, and engine’s speed. Our engine offers the thermal efficiency of 30.59 % so that it can reach the output mechanical power of 0.934. The temperature difference of 137 K can maintain very well for the heat collection of the solar collector even when the weather conditions are poor. Furthermore, our materials are environmentally friendly and this design is expected to be in the applications of the solar tracker in the future.

Abstract: It has been proved that creation of vacuum between the absorber and the cover of a solar collector is resulting in a substantial improvement in the collector efficiency due to reduction in the heat loss through convection ad conduction. In this work, the performance of evacuated tube collectors is investigated using TRNSYS simulation model. Different levels of concentrations have been considered in the simulation to predict the power generation. The simulation results showed that the thermal performance of evacuated tube collectors with high concentration ratio can provide a good improvement to the receiver output.

Abstract: This paper mainly aims at the special requirement of the solar energys application in tunnel direct lighting engineering, where the light receiver is fixed. Therefore, it has given a new automatic tracking method of polar axis type, which can effectively make the concentrator to realize the function of tracking the sun automatically with high precision and fixed-point output. Based on expounding the working principle of the automatic tracker with polar axis, meanwhile combining with the obliquely installed concentrator load, it talks about the detailed design and explanation of mechanical structure, characteristics and implementation of the suns hour angle and declination angle tracking mechanism.

Abstract: The use of solar divergence collimators is the key for reliable optical tests that reproduce the on-field collector operating conditions. Aiming to test small (<80 mm diameter/diagonal) and large concentrators (80-240 mm diameter/diagonal range), the collimator geometry should be evaluated because of some optical errors introduced by the need of bending the optical axis. This paper discusses the optical characteristics of the beams obtained with straight and bent collimators with solar divergence. The collimated beams are examined by ray tracing simulations, studying the aberrations as a function of bend angle, and measured in laboratory. Finally characterisation tests for sunlight concentrators of various shapes, dimensions and collection features are presented describing instrumentation, optical set-up and methodology to determine collection efficiency, image plane analysis and spot size.