A solar thermal central receiver generates heat by focusing sunlight with a field of mirrors on a bank of tubes through which a coolant flows. Solar energy absorbed by the tubes is transferred to the coolant which can then deliver useful heat to a load. Consider a receiver fabricated from multiple horizontal tubes in parallel. Each tube is 1 cm ID and 1 m long. The coolant is molten salt which enters the tubes at 370?C. Under start-up conditions, the salt flow is 10 gm/s in each tube and the net solar flux absorbed by the tubes is 104 W/m2. The tube wall material will tolerate temperatures up to 600?C. Will the tubes survive start-up? What is the salt outlet temperature?GIVENMolten salt flowing through a horizontal tube that is absorbing solar energyTube inside diameter (D) = 1 cm = 0.01 mTube length (L) = 1 mEntering salt temperature (Tb,in) = 370?CStart-up mass flow rate (m) = 10 gm/s = 0.01 kg/sNet solar energy absorbed by the tube (qs) = 104 W/m2Maximum tube wall temperature (Ts) =600?C

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Molten Salt ID=1 cm amex= 800° C To,out Tan -370° C m= 10 gm/s -? L=1M