Cooling method for gas turbines. Refer to the Journal of Engineering for Gas Turbines and Power (January 2005) study of a high-pressure inlet fogging method for a gas turbine engine, Exercise 5.8 (p. 271). Consider a model for heat rate (kilojoules per kilowatt per hour) of a gas turbine as a function of cycle speed (revolutions per minute) and cycle pressure ratio. Recall that the data are saved in the GASTURBINE file. The GASTURBINE data are located from this link https://webpages.charlotte.edu/jbusitu/Exercise/stathw.html



(a) Write a complete second-order model for heat rate (y).

(b) Fit the model to the data and give the least squares prediction equation.

(c) Conduct a global F-test for overall model adequacy.

(d) Based on the prediction equation, graph the relationship between heat rate and cycle pressure ratio when cycle speed is held constant at 5,000 rpm.

(e) Repeat part d when cycle speed is held constant at 15,000 rpm.

(f) Compare the two graphs, parts d and e. What do you observe?