6. Refrigerant 134a is the working fluid in a solar power plant operating on a Rankine cycle. Saturated vapor at 52C enters the turbine, and the condenser operates at a pressure of 5 bar. The rate of energy input to the collectors from solar radiation is 0.4 kW per m of collector surface area. Determine the minimum possible solar collector surface area, in m, per kW of power developed by the plant.