Comparative assessment of high efficiency flat solar thermal collectors’ performances

Abstract

Abstract The study investigates the performances of high efficiency flat solar thermal collectors, under the climatic conditions of Galați, Romania. The same mathematical model was used to evaluate the stationary and the transitory thermal behavior of 12 high effic iency collectors, with reduced heat losses. The thermal characteristics of the collectors were extracted from the technical reports of two European independent testing laboratories. The annual specific energy production was found to vary in a large domain between 415.9 kWh/m2 and 947.9 kWh/m2, the maxim value representing more than the double of the minimum one. It was highlighted that both the optical efficiency and the heat losses contribute to the global efficiency of the flat solar thermal collectors, and the most efficient one is the flat evacuated one.