engleski

APPLICATION OF RAY TRACING ANALYSIS IN THE DESIGN OF COMPLEX FLAT PLATE COLLECTORS

Flat plate solar thermal collectors are a widespread solar thermal technology, but they can experience overheating during periods of high insolation and low demand for hot water. This imposes considerable limitations on materials that can be used in their production. While in some commercially available collectors the overheating problem is mitigated by employing design features which reduce the stagnation temperature of the collector, there is currently no method that has gained wide use or provided an effective solution for the problem. Therefore, there is still a need for a cost effective and preferably passive method of limiting or preventing overheating, which leads to the development of increasingly complex designs. For solutions which employ complex geometries an analysis of the optical properties and thermal characteristics of the collector is required. While the use of ray tracing computational tools in designing and analyzing concentrating collectors is now commonplace, no evidence of its use in flat plate collector design has been found in the literature. This is despite the fact that some new flat plate collectors are now already of such complex design which requires ray tracing analysis to enable reliable modeling of the thermal performances in a CFD software. To address this issue, this paper analyzes the viability of using ray tracing analysis for complex designs of different types of flat plate collector and develops a simulation model which is compared with the measurements on a model collector. The results of these simulations are then used as input values for CFD modeling of the collector thermal characteristics. The overall simulation results proved that ray tracing analysis yields reliable input values for computing thermal performances of flat plate solar collectors of both simple and complex designs.

flat plate solar collector, overheating, ray tracing, thermal performances

nije evidentirano