A detailed investigation of an evacuated flat plate solar collector

Abstract

The evacuated flat plate collector is a pioneering solar device for operation at medium temperatures (<200 °C) with high efficiency and without the need for tracking. The goal of this investigation lies in the detailed parametric analysis of an efficient evacuated flat plate collector and its daily performance for the city of Athens (Greece). The parametric analysis presents the instantaneous thermal and exergy performance of the collector for different inlet temperatures, solar irradiation levels, ambient temperatures, specific mass flow rates and the number of riser tubes. The daily analysis presents results for the thermal and exergy performance of the collector for different daily profiles of solar irradiation and ambient temperatures using real weather data. Also, the main innovation of this study lies in the development of a correlation of the daily useful output by taking into account the operating temperature level, the daily irradiation level and the mean ambient temperature. According to the yearly analysis, the optimum exergy efficiency is found at 13.33% for operation at 125 °C and the respective thermal efficiency is found at 47.24%. For this case, the levelized cost of energy and exergy were calculated at 0.0274 €/kWh and 0.1043 €/kWh respectively.