Investigation of Concentrating Parabolic Collectors Integrated with Hot Water Cylinder for Solar Water and Space Heating Applications

Flat plate collectors are the most common type of collectors used in residential applications. However, efficiency of these collectors decrease in situations when the available beam radiation is limited. This study aims to investigate the potential of Compound Parabolic Collectors (CPC) for being utilized in residential solar water heating systems, instead of conventional flat plate collectors. To do so, several related parameters like useful solar heat gains, auxiliary power requirements and efficiencies of both collector types under same operating conditions are examined and compared. Within the study, a solar water heating system consisting of a solar collector, a storage tank and a circulating pump was simulated in TRNSYS. The simulations were carried out in the first week of January for two different cities, Nicosia with abundant and London with limited solar radiations. Water circulates between the collector and the tank to generate solar sourced heat and to store it for later use. Tank temperature is maintained at 60oC thought the simulation. An electric heater is considered as auxiliary heating device to boost the water temperature to the set point when there is not sufficient solar radiation available. The results show that in both considered locations (Nicosia and London) CPC provides higher outlet temperatures compared to flat plate collector. The gap is more meaningful particularly in days with low beam radiation. According to the results, weekly efficiency of CPC and flat plate collector are 34% and 21% for Nicosia and 30% and 15% for London, respectively. In addition, useful solar energy gain of CPC is 61% and 97% more than that of the flat plate collector in Nicosia and London, respectively. As a result, auxiliary power requirements are 11% and 6% less for CPC, respectively. Also, CPC provides a higher yearly performance in both cities.