6. (8 %) What is heat engine? Please explain its purpose, efficiency and give a sketch to show its operating character.

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?