Investigation of a hybrid solar collector/nocturnal radiator for water heating/cooling in selected Nigerian cities

The present investigation presents a finite element analysis of the dynamic performance of a hybrid flat-plate solar collector/nocturnal radiator (SCONOR) for water heating and cooling in five Nigerian cities. Riser tubes for water conduit were welded to the SCONOR underneath and model equations were developed for heat transfer processes around the SCONOR-bond-tube-water region during the heating, cool down and nocturnal phases. Also, appropriate climatic models were developed to capture absorptions and emissions of energy from the sun and the sky during periods of solar heating and night sky cooling respectively. Results obtained showed that the maximum temperatures attained by the water during diurnal heating were 84.6 degrees C, 75.61 degrees C, 86.4 degrees C, 88.33 degrees C, and 93.67 degrees C while during the nocturnal cooling period, the minimum temperatures of water were 20.21 degrees C, 20.12 degrees C, 21.9 degrees C, 20.95 degrees C and 22.01 degrees C for Owerri, Portharcourt, Ikeja, Maiduguri and Sokoto respectively. The optimum bond thickness for best performance is 3.0 x 10(-3) m at bond width of 0.26 m, tube spacing of 0.1 m and single polyethylene windscreen. For solar heating, Sokoto showed the best performance while for nocturnal cooling; Port Harcourt showed the best performance. Therefore, ambient energy possesses a great potential to ameliorate the energy security challenge and ensure a sustainably clean environment. (C) 2019 Elsevier Ltd. All rights reserved.