A solar collector design consists of several parallel tubes each enclosed concentrically in an outer tube which is transparent to solar radiation. The tubes are thin walled with diameter of the inner and outer cylinders of 0.10 and 0.15 m respectively. The annular space between the tubes is filled with air at atmospheric pressure. Under operating condition the inner and outer tube surface temperatures are 70?C and 30?C respectively.(a) What is the convective heat loss per meter of tube length?(b) If the emissivity of the outer surface of the inner tube is 0.2 and the outer cylinder behaves as though it were a black body, estimate the radiation loss.(c) Discuss design options for reducing the total heat loss.GIVENThin walled concentric tubes with air atmospheric pressure between themInner tube diameter (Di) = 0.1 mOuter tube diameter (Do) = 0.15 mInner tube temperature (Ti) = 70?C = 343 KOuter tube temperature (To) = 30?C = 303 KOuter surface emissivity of inner tube (ε) = 0.2ASSUMPTIONSSteady stateTubes arehorizontal

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Airbetween Tubes To = 30°C Do = 0.15 m D = 0.1 m T= 70°C