10. (15 %) Sketch schematic diagrams and accompanying T-s diagrams of a two-stage cascade refrigeration. What are the advantages of a cascade system over a single stage system?

5. (6%) Consider a thermal energy reservoir at 1227*C that can supply heat at a rate of 150,000 kJ/h to an engine. Determine the maximum output power (in kW unit) of the engine, assuming an ambient temperature of 25C. Will higher temperature of heat source increase the maximum power?