Chapter 3 - Solar Energy Collectors

Abstract

Chapter 3 gives a review of solar collectors which are the main components of any solar system. The review includes various types of stationary and sun-tracking collectors. The stationary collectors include flat-plate collectors (FPCs), under which glazing materials, collector absorbing plates, and collector construction are presented; compound parabolic collectors (CPCs) and evacuated tube collectors (ETCs). The sun-tracking concentrating collectors section cover parabolic trough collectors (PTCs), which include parabola construction and tracking mechanisms; Fresnel collectors; parabolic dish reflector and heliostat field collector. This review is followed by the optical and thermal analysis of both FPCs and concentrating collectors. The analysis for FPCs includes both water and air type systems whereas the analysis for concentrating collectors includes the CPC and the PTC. The analysis of flat-plate water collectors starts with an analysis of the absorbed solar radiation followed by collector energy losses, temperature distribution between the tubes, collector efficiency factor, heat removal factor, flow factor, and thermal efficiency. This is followed by practical considerations concerning FPCs. Subsequently, concentrating collectors are considered which include optical and thermal analysis of a CPC and optical and thermal analysis of PTCs. The chapter includes also the second law analysis of solar thermal systems and includes minimum entropy generation rate, optimum collector temperature, and non-isothermal collector analysis.