Chapter 12, Problem 12.26P

A proposed method for generating electricity from solar irradiation is to concentrate the irradiation into a cavity that is placed within a large container of a salt with a high melting temperature. If all heat losses are neglected, part of the solar irradiation entering the cavity is used to melt the salt while the remainder is used to power a Rankine cycle. (The salt is melted during the day and is resolidified at night in order to generate electricity around the clock.)

Consider conditions for which the solar power entering the cavity is $q_{sol}=7.50MW$ and the time rate of change of energy stored in the salt is $E_{st}=3.45MW$ . For a cavity opening of diameter $D_s=1m$ , determine the heat transfer to the Rankine cycle, $q_r$ . The temperature of the salt is maintained at its melting point, $T_{salt}=T_m={1000}^{\circ }c$ . Neglect heat loss by convection and irradiation from the surroundings.