Previsioning solar collector thermal efficiency from design parameters: a numerical model achieved from test results


Solar thermal energy has an important role in the current world energetic transition from fossil fuels to renewable energy sources. Solar thermal market enlargement, however, hinges on the enhancement of solar collector thermal efficiency, which, in its turn, strongly depends on collector design parameters such as geometric features, construction quality and design specifications. In this context, the present work aims to obtain a numerical model correlating some collector design parameters to its thermal efficiency for different climatic conditions. The model comprise a set of linear equations, each one for an specific operation and climate condition, using as inputs the absorber plate thickness, number of riser tubes, plate and tube contact type and absorber painting type and providing the thermal efficiency as output for the selected climate and operating condition. For this, a set of 49 thermal efficiency tests results performed on different types of flat plate solar collectors from Brazilian industry was analyzed and correlated with equipment design specifications. The model was validated by submitting an additional collector to experimental test and comparing the experimental result with the predicted one. Validation procedure led to an error lower than 2%. Additionally, using the obtained model, the above mentioned design parameters were ranked according to their influence on thermal efficiency. Results showed that the rank depends on the climate and operation situation. For cold and less sunny operating conditions, painting and tubes are the most important design parameters and for hot and sunny climates, plate thickness and type of contact between plate and tube are more critical. In any case, the efficiency increases as thickness and quantity of tubes increase. Likewise efficiency increases as welding is used instead of fit contact and as selective painting is used instead of standard black painting.

ARA, Paulo Jose Schiavon; SOWMY, Daniel Setrak; PRADO, Racine T.A. Previsioning solar collector thermal efficiency from design parameters: a numerical model achieved from test results. In: CONFERÊNCIA INTERNACIONAL SOBRE AQUECIMENTO SOLAR E RESFRIAMENTO PARA EDIFÍCIOS E INDÚSTRIA, 2019, Santiago. Proceedings… 9p.

Access to the article on the event website:

SUBSCRIBE to our newsletter

Receive our news in your email.

INSCREVA-se em nossa newsletter

Receba nossas novidades em seu e-mail.