Reconsider Prob. 6–128. Using EES (or other) software, investigate the effects of the heat engine source temperature, the environment temperature, and the cooled space temperature on the required heat supply to the heat engine and the total rate of heat rejection to the environment. Let the source temperature vary from 500 to 1000 K, the environment temperature vary from 275 to 325 K, and the cooled space temperature vary from -20 to 0°C. Plot the required heat supply against the source temperature for the cooled space temperature of 15°C and environment temperatures of 275, 300, and 325 K, and discuss the results.