Photothermal performance of selective black nickel coatings

Selective black nickel coatings with solar absorptance (αs = 0·94) and thermal emittance (ε = 0.08) at 100°C have been developed on galvanized steel using electroplating and chemical conversion techniques. Thermal performance tests have been conducted on selective and non‐selective collectors with single glass cover. A suitable collector test assembly has been constructed for thermal performance study. Measurements have been made under clear sky conditions over a wide range of inlet temperatures. For comparison, measurements have been carried out on an identical collector painted black. Thermal efficiencies of about 28 per cent at an operating water temperature =100°C ambient temperature =35°C and incident insolation =1000 W/m2 have been obtained.