What is constant in Rankine cycle?
The Rankine cycle is an idealized thermodynamic cycle of a constant pressure heat engine that converts part of heat into mechanical work. In this cycle, the heat is supplied externally to a closed loop, which usually uses water (in a liquid and vapor phase) as the working fluid.
What is the maximum temperature in Rankine cycle?
The Rankine cycle applied using a supercritical fluid combines the concepts of heat regeneration and supercritical Rankine cycle into a unified process called the regenerative supercritical cycle (RGSC). It is optimised for temperature sources 125–450 °C.
What is mean temperature in Rankine cycle?
In the Rankine cycle, the mean temperature at which heat is supplied is less than the maximum temperature, , so that the efficiency is less than that of a Carnot cycle working between the same maximum and minimum temperatures. The heat absorption takes place at constant pressure over , but only the part is isothermal.
What happens to the efficiency when temperature is increased in Rankine cycle?
Fig. 7: The ideal reheat Rankine cycle. The incorporation of the single reheat in a modern power plant improves the cycle efficiency by 4 to 5 percent by increasing the average temperature at which heat is transferred to the steam.
Is pressure constant in a Rankine cycle?
The Rankine cycle is an idealized thermodynamic cycle of a constant pressure heat engine that converts part of heat into mechanical work.
Which cycle of heat is added at constant pressure?
Explanation: Dual cycle: A dual cycle is a thermodynamic cycle that combines the Otto cycle and the Diesel cycle. In this cycle, the heat addition occurs partly at constant volume and partly at constant pressure.
How are the maximum temperature and minimum temperature in Rankine cycle is fixed?
1´- 2´- 3 – 4´- 1 is a Rankine cycle when the maximum steam temperature is fixed. As the maximum steam temperature is fixed because of the metallurgical condition and the boiler pressure is increased. The process 1 – 2 shifted to a process 1´ – 2´ and the boiler pressure changed from PB to P’B.
What is the effect of mean temperature on cycle efficiency?
Explanation: As there is an increase in superheat at constant pressure, the cycle efficiency increases & hence there is an increase in the mean temperature of heat addition.
How can you increase the thermal efficiency of a Rankine cycle?
There are three ways to increase the efficiency of the simple ideal Rankine cycle.
- Decreasing the condenser pressure. The effect of lowering the condenser pressure on the Rankine cycle efficiency is illustrated on a T-s diagram on the left.
- Superheating the steam to a high temperature.
- Increasing the boiler pressure.
How are the maximum temperature and maximum pressure in the Rankine cycle fixed?
Why pressure is constant in boiler?
The pressure is actually made constant. The boiler is designed to be isolated from the environment, but the superheated fluid is free to expand. Stress Engineering Services, Inc. When the boiler starts up from cold, adding heat increases the temperature and the pressure inside the boiler.
In which of the following cycle heat is added at constant volume process?
The Otto cycle consists of isentropic compression, heat addition at constant volume, isentropic expansion, and rejection of heat at constant volume.
Why there is constant pressure heat addition in Diesel cycle?
The reason, for constant pressure heat addition in a diesel cycle is that, when the fuel is injected into the compressed air inside the cylinder, question of maintaining a constant volume vanishes. We are adding more volume and igniting the mixture as heat addition. Hence, a constant volume is not possible.
How do you increase the thermal efficiency of a Rankine cycle?
How do you increase the mean temperature of heat addition in the Rankine cycle?
Increasing the operating pressure of the boiler, automatically raises the temperature at which boiling takes place. This raises the average temperature at which heat is added to the steam and thus raises the thermal efficiency of the cycle..
How do you keep pressure constant?
Another way to keep the pressure constant as the volume increases is to raise the average force that each particle exerts on the surface. This happens when the temperature is increased. So if the number of particles and the pressure are constant, temperature is proportional to the volume.
Which of the following cycles constant temperature heat addition takes place?
Important Points
| Otto Cycle | Constant volume heat addition. Constant volume heat rejection. |
|---|---|
| Carnot Cycle | Constant temperature heat addition Constant temperature heat rejection |
| Diesel Cycle | Constant pressure heat addition. Constant volume heat rejection. |
What is constant pressure heat addition?
When you add heat to a gas, it tries to expand due to increase in energy of the molecules and can be felt as increased pressure of the gas. In constant pressure heat addition process we adjust the volume of the gas in a way so that the pressure of the gas remains constant.
How the mean temperature of heat addition can be increased?
Mean temperature of heat addition can be increased by? Explanation: Increasing condensor pressure decreases turbine exit temperature which in turn increases mean temperature of heat addition.