Engineering Board Exam Reviewer · Thermodynamics · medium
Which of the following increases the thermal efficiency of a Rankine cycle?
- Raising the condenser pressure
- Lowering the boiler pressure
- Lowering the condenser pressure
- Lowering the superheat temperature
Answer
C. Lowering the condenser pressure
Solution
Lower condenser pressure lowers the average heat-rejection temperature; higher boiler pressure and superheat raise the average heat-addition temperature.
More Thermodynamics questions
- Air enters a compressor at 300 K and is compressed with a pressure ratio of 8. The actual exit temperature is 590 K. What is the…
- A steam power plant has a net work of 992 kJ per kg of steam. What is its steam rate?
- In an ideal Rankine cycle, the turbine inlet enthalpy is 3200 kJ/kg, turbine exit enthalpy is 2200 kJ/kg, the pump inlet enthalpy is 192…
- A regenerator in a gas turbine plant is most effective when:
- For an ideal Brayton cycle with minimum temperature 300 K and maximum temperature 1200 K, what pressure ratio gives the maximum net work?…
- 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…
- 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…
- 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?
- 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…
- 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…