Optical Performance and Optimization of Two Stationary Compound Parabolic Collectors (CPC)

Abstract

-Solar energy utilization is very important for our society in order to reduce the environmental problems. Solar collectors are the heat exchanger devices which capture the solar energy and produce useful heat from this. In this study, two stationar y compound parabolic collectors with tubular receivers are optimized and compared in order to determine the most suitable solution for yearly utilization. The fist cpc uses one reflector in order to concentrate the solar rays to the receiver and the other uses two reflectors in order to follow the solar position during the year. The shape of every reflector is parametrized with Bezier-Bernstein polynomials in order to optimize them. The reflectors are stationary without tracking in order to reduce the cost of them and to have a simple and lowcost technology. A typical day for every month is analyzed in order to cover all the year period and the total analysis is made with Solidworks flow simulations studio. The collectors are located in Athens with latitude 38 o and they are placed with zero azimuth angles in order to be turned in the south direction. The final results are evaluated yearly and monthly by comparing the energy that is delivered to the tubular receiver. The single reflector performs 3.2% better than the double, but the double gives a better distribution among the months. So the most suitable solution is the cpc with the double reflector in order to produce useful heat in all months with a similar way.

Efficiency Evaluation of Solar Concentrator without Tracking System Type of Compound Parabolic Concentrator (CPC)

“…Evangelos Bellos et.al. investigate the ability to improve and compare the twoStationary CPC, where they used one reflector and the other two inverters, and found that the performance of a single reflector better than double but double is better in producing heat for all months of the year [8]. Sainath A. Waghm is studies conducted on the effect of the difference in the solar acceptance angle and the shape of the absorbed part on the amount of concentration, where it is noticeable that the increase in the acceptance angle caused a decrease in focus, and led to a decrease in the efficiency of CPC [9].…”

Αξιοποίηση Και Βελτιστοποίση Της Χρήσης Ηλιακών Συστημάτων Στα Κτίρια

“…Η στρωτή ροή χαρακτηρίζεται από ήπια φαινόμενα και ομαλότητα στη ροή σε αντίθεση με την τυρβώδη ροή όπου υπάρχει αλλαγή «της υφής» της ροής και πιο έντονα φαινόμενα[3,3]. Στο στρωτό οριακό στρώμα η κλίση της ταχύτητας είναι γραμμική και το προφίλ της ταχύτητας είναι κοντά στη παραβολή, ενώ στην τυρβώδη ροή το προφίλ είναι πεπλατυσμένο στο κέντρο του αγωγού.…”