Optical study of twin-tanked ICS solar heaters combined with asymmetrical CPC-type reflectors

Abstract

Summary The distribution of solar irradiance on the absorbing surface of a typical integrated collector storage (ICS) system combined with reflector troughs is commonly studied by means of ray tracing techniques. A conceptually different alternative is offered by the method of the average number of reflections (ANR). In the present work, the latter is employed for the systematic optical study of realistic ICS models. In all cases, the solar devices consist of twin cylindrical storage tanks which are mounted on top of stationary asymmetrical CPC‐type reflectors. The emphasis of the current research is mainly placed on the evaluation of the ANR reliability for the calculation of the optical efficiency of the related twin‐tanked devices. Additionally, useful operational parameters, such as the optical performance of the proposed geometries, are also determined. The behavior of the tested ICS systems reveals that the optical efficiency may vary in the range of 0.75 to 0.91, exhibiting a strong dependence on the geometric parameters of the solar devices. The highest efficiency is achieved by the systems which combine large reflecting area and storage tanks in close proximity.

Dynamic testing of a new integrated collector storage solar water heater (ICSSWH) according to standard ISO 9459‐5: Use of a numerical approach for long‐term prediction in different climatic conditions

“…Souliotis et al 20 used ray tracing techniques to study the distribution of solar irradiance on the absorbing surface of an ICS system. Their results showed that the optical efficiency varied in the range of 0.75-0.91.…”

“…For the Integrated Collector Storage Solar Water Heater (ICSSWH), several studies 15–19 have been conducted to show its performances with respect of other existing and well marketed technologies. Souliotis et al 20 used ray tracing techniques to study the distribution of solar irradiance on the absorbing surface of an ICS system. Their results showed that the optical efficiency varied in the range of 0.75–0.91.…”

Simulation and experimental validation of solar radiation distribution on the absorber of a line-axis asymmetric compound parabolic concentrator

“…Many other scholars (Zacharopoulos et al, 2000;Zacharopoulos, 2001;Sarmah et al, 2011;Yurchenko et al, 2015;Ustaoglu et al, 2016;Paul, 2019) employed elaborate simulations that consider Fresnel formulas, optical properties of air, transparent media, and specular properties of reflector surfaces. Others (Rabl, 1976b;Souliotis and Tripanagnostopoulos, 2008;Souliotis et al, 2019) performed detailed optical assessments of CPCs through a theoretical evaluation of Average Number of Reflections (ANR) as an alternative to the ray tracing approach. Zacharopoulos et al (1996) performed optical analysis of four different absorber-envelope configurations in a CPC using a ray tracing model (RTM).…”