A porous shield of porosity P, surface area A and thickness L is heated with flux ???? '' . Coolant at a reservoir temperature To is used to protect the heated surface. Determine the coolant flow rate...

A porous shield of porosity P, surface area A and thickness L is heated with flux ???? '' . Coolant at a reservoir temperature To is used to protect the heated surface. Determine the coolant flow rate ??? needed to maintain the heated surface at design temperature Td .