The work required for the compressor is given by W Pumps = H 2 – H 1. On the other hand, the entropy remains unchanged.
In this process, the surroundings work on the fluid, increasing its enthalpy (h = u+pv) and compressing it (increasing its pressure). The liquid condensate is pumped from the condenser into the higher pressure boiler. Isentropic compression (compression in centrifugal pumps) – The liquid condensate is compressed adiabatically from state 1 to state 2 by centrifugal pumps (usually by condensate pumps and then by feedwater pumps).
PROPERTY TABLE THERMODYNAMICS CALCULATOR SERIES
In an ideal Rankine cycle, the system executing the cycle undergoes a series of four processes: two isentropic (reversible adiabatic) processes alternated with two isobaric processes: These factors contribute to higher efficiency for the cycle. By condensing the working steam to a liquid (inside a condenser), the pressure at the turbine outlet is lowered, and the energy required by the feed pump consumes only 1% to 3% of the turbine output power. One of the major advantages of the Rankine cycle is that the compression process in the pump takes place on a liquid. Therefore all important parameters of water and steam are tabulated in so-called “ Steam Tables”. In the case of the Rankine cycle, the Ideal Gas Law almost cannot be used (steam does not follow pV=nRT). Moreover it has a very high heat of vaporization, making it an effective coolant and medium in thermal power plants and other energy industries. For example, water has the highest specific heat of any common substance – 4.19 kJ/kg K. While many substances could be used as the working fluid in the Rankine cycle (inorganic or even organic), water is usually the fluid of choice due to its favorable properties, such as its non-toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties. In contrast to the Brayton cycle, the working fluid in the Rankine cycle undergo the phase change from a liquid to vapor phase and vice versa. 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. The Rankine cycle is an idealized thermodynamic cycle of a constant pressure heat engine that converts part of heat into mechanical work. The Rankine cycle was named after him and describes the performance of steam turbine systems, though the theoretical principle also applies to reciprocating engines such as steam locomotives.
0 kommentar(er)
