Automated Stand for Measuring Thermal and Energy Characteristics of Solar Parabolic Trough Concentrators
Аннотация
This paper analyzes the optical, geometric, and thermal characteristics of a solar parabolic trough collector, which consists of an optical concentrator, cylindrical heat receiver, and Sun-tracking system. Optical-geometric and energy parameters such as geometric concentration, aperture width, coverage angle, receiver diameter, focal length, energy distribution, and energy concentration are considered. The analysis shows that the shape (angle of incidence) of solar radiation has a great influence on the optical-energy characteristics of the parabolic trough collector. An increase in the coverage angle increases the maximum geometric concentration and concentrator accuracy parameter, while a decrease in the receiver diameter increased the density of the reflected sunlight in the focal plane. Since a larger coverage angle usually indicates a larger span of the circumferential angle of the absorber, it is possible to obtain higher concentrated solar radiation from the reflector than the original low solar radiation directly from the Sun. On the basis of the analysis, an automated stand has been developed for measuring the thermal and energy characteristics of solar parabolic trough collectors. The experimental setup consists of a parabolic trough collector, a measuring tank, a converter, a meter, a level gauge, temperature sensors, and electric valves. Consumption (energy generated) is measured with a graduated water tank. By measuring the volume and temperature of the water passed through the solar collector, it is possible to estimate its efficiency. When the graduated tank is full, the discrete-output level gauge opens the electrical drain valve. The energy characteristics of the solar parabolic trough plant are determined on the basis of statistical processing of the experimental data.