Prediction of Focal Image for Solar Parabolic Dish Concentrator With Square Facets – An Analytical Model

Solar parabolic dish concentrator is one of the high-temperature applications of more than 400 °C for thermal and electrical power generation. In the solar parabolic dish concentrator, the arrangement of reflectors over the surface area is the significant factor for effective concentration of solar radiation. Also, focal image is one of the most influencing parameters in the design of receiver. Among the various reflectors, the square shaped reflectors (facets) are comparatively effective in converging the incoming radiations to attain better focal image. In this regard, an attempt has been made to predict the focal image diameter of a solar parabolic dish concentrator with a square facet of different influencing parameters using a novel mathematical model. The influencing parameters considered for the study are aperture diameter, rim angle, and facet length of the dish concentrator. Based on the proposed model, the focal image dimension and aperture area of a solar parabolic dish concentrator with square facets can be predicted accurately for efficient design of a solar parabolic dish collector system. Finally, the proposed model is validated with the experimentally obtained focal image diameter and it is observed that the predicted result is in good agreement with the experimental one. Thus, the proposed model can be effectively used for the design of parabolic dish system for sustainable development.

Realization of a Solar Dryer Assisted by a Parabolic Dish Concentrator

Many studies have been conducted in the field of drying technology. The traditional dryingmethods are considered less effective and time consuming. The present study aims to develop the indirect solar dryer for agro-food products from El-Oued region (South-East of Algeria). The dryer is assisted by a parabolic dish concentrator to improve its performances through increasing its temperature and decreasing drying time. the realized solar dryer was tested on the red chilies during April 2018, the temperature in the drying chamber is reached intoxicating 55 °C with a drying time of 5 h.

Thermal performance analysis of a Solar parabolic dish concentrator system with modified cavity receiver

Purpose This paper aims to present the numerical models and experimental outcomes pertain to the performance of the parabolic dish concentrator system with a modified cavity-type receiver (hemispherical-shaped). Design/methodology/approach The numerical models were evolved based on two types of boundary conditions; isothermal receiver surface and non-isothermal receiver surface. For validation of the numerical models with experimental results, three statistical terms were used: mean of absolute deviation, R2 and root mean square error. Findings The thermal efficiency of the receiver values obtained using the numerical model with a non-isothermal receiver surface found agreeing well with experimental results. The numerical model with non-isothermal surface boundary condition exhibited more accurate results as compared to that with isothermal surface boundary condition. The receiver heat loss analysis based on the experimental outcomes is also carried out to estimate the contributions of various modes of heat transfer. The losses by radiation, convection and conduction contribute about 27.47%, 70.89% and 1.83%, in the total receiver loss, respectively. Practical implications An empirical correlation based on experimental data is also presented to anticipate the effect of studied parameters on the receiver collection efficiency. The anticipations may help to adopt the technology for practical use. Social implications The developed models would help to design and anticipating the performance of the dish concentrator system with a modified cavity receiver that may be used for applications e.g. power generation, water heating, air-conditioning, solar cooking, solar drying, energy storage, etc. Originality/value The originality of this manuscript comprising presenting a differential-mathematical analysis/modeling of hemispherical shaped modified cavity receiver with non-uniform surface temperature boundary condition. It can estimate the variation of temperature of heat transfer fluid (water) along with the receiver height, by taking into account the receiver cavity losses by means of radiation and convection modes. The model also considers the radiative heat exchange among the internal ring-surface elements of the cavity.