Engineering Board Exam Reviewer · Thermodynamics · medium

A regenerator in a gas turbine plant is most effective when:

1. The pressure ratio is very high
2. The turbine exhaust temperature is higher than the compressor exit temperature
3. The compressor exit temperature exceeds the turbine exhaust temperature
4. The cycle has no intercooling

Answer

B. The turbine exhaust temperature is higher than the compressor exit temperature

Solution

Regeneration transfers heat from hot turbine exhaust to the cooler compressed air; it only helps when T4 > T2 (i.e., at lower pressure ratios).

More Thermodynamics questions

1. For an ideal Brayton cycle with minimum temperature 300 K and maximum temperature 1200 K, what pressure ratio gives the maximum net work?…
2. For an ideal Brayton cycle with compressor inlet at 300 K, pressure ratio 8, and turbine inlet at 1300 K, what is the back work ratio? (k…
3. An ideal Brayton cycle has a compressor inlet temperature of 300 K, a pressure ratio of 8, and a turbine inlet temperature of 1300 K. What…
4. An engine produces 1.2 kJ of net work per cycle with a displacement volume of 0.002 m3. What is the mean effective pressure?
5. In an air-standard Otto cycle, the temperature after compression is 700 K and after heat addition is 1800 K. What is the heat added per…
6. In an ideal Diesel cycle, the temperature at the start of heat addition is 900 K and at the end of heat addition is 1800 K. What is the…
7. An ideal Diesel cycle has a compression ratio of 18 and a cutoff ratio of 2. What is its thermal efficiency? (k = 1.4)
8. An ideal Otto cycle has an efficiency of 55%. What is its compression ratio? (k = 1.4)
9. What is the air-standard efficiency of an Otto cycle with a compression ratio of 10? (k = 1.4)
10. What is the thermal efficiency of an ideal Otto cycle with a compression ratio of 8? (k = 1.4)

All Thermodynamics Reviewer questions