Estudo experimental de um concentrador solar de calha parabólica (PTC) com tubo evacuado

Abstract

Aiming at the partial or integral replacement of fossil fuels for power generation by renewable energy sources, solar energy proves to be a viable option due to its wide scope in residential, commercial and industrial applications. Based on the sustainable use of energy, a parabolic trough collector (PTC) was designed and built to use solar energy in water heating. The present proposal is the modification of the absorber tube, creating an evacuated glass envelope, in order to reduce heat losses and increase the thermal efficiency of the concentrator. The thermal efficiency of the concentrator after insertion of the evacuated tube will be compared with the results previously obtained for the nonevacuated absorber tube, in the conditions of tube with and without selective painting (NETZEL, 2019). The reduction in heat losses to the environment with the use of vacuum raised the thermal efficiency of the concentrator to 52,18%. The concentrator efficiency for the Unpainted configuration was 28.99% and for the Painted configuration was 36.69%, resulting in an increase of 79,99% and 42,22%, respectively. Thermal efficiency was directly proportional to incident solar radiation, while efficiency was inversely related to temperature levels and operating hours.