Page 134 - Handbook of Energy Engineering Calculations

1. Determine the cycle rate
Use Fig. 5, entering at the pressure ratio of 5 in Fig. 5c and projecting to the
1500°F (815.6°C) curve. At the left, read the cycle air rate as 52 lb/kWh
(23.6 kg/kWh).

2. Find the cycle thermal efficiency

Enter Fig. 5b at the pressure ratio of 5 and project vertically to the 1500°F
(815.6°C) curve. At left, read the cycle thermal efficiency as 35 percent. Note
that this point corresponds to the maximum efficiency obtainable from this
cycle.

3. Find the cycle work ratio
Enter Fig. 5d at the pressure ratio of 5 and project vertically to the 1500°F
(815.6°C) curve. At the left, read the work ratio as 44 percent.

4. Compute the turbine power output
For any gas turbine, the work ratio, percent = 100w /w , where w = work
c
c
c
input to the turbine, hp; w = work output of the turbine, hp. Substituting
t
gives 44 = 100(4400)/w ; w = 100(4400)/44 = 10,000 hp (7457.0 kW).
t
t
Related Calculations. Use this general procedure to analyze gas turbines for
power-plant, marine, and portable applications. Where the operating

conditions are different from those given here, use the manufacturer’s
engineering data for the turbine under consideration.
Figure 6 shows the effect of turbine-inlet temperature, regenerator
effectiveness, and compressor inlet-air temperature on the performance of a

modern gas turbine. Use these curves to analyze the cycles of gas turbines
being considered for a particular application if the operating conditions are
close to those plotted.