Vapour Power Cycle full chapter .
INTRODUCTION .
A thermo dynamic process with in dentical end state is called thermo dynamic cycle .
The thermo dynamic cycle are two types
(1) Power cycle
(2) Refrigeration cycle
The thermo dynamic cycle are two types
(1) Power cycle
(2) Refrigeration cycle
Power cycle
Power Cycle are that thermodynamic cycle which can generate net power output
Refrigeration
Refrigeration cycle is that type of thermodynamic cycle which can produce a cooling effect .
Power cycle are two types .
(1) Vapour power cycle .
(2) Gas power cycle .
∆. Vapour Power cycle uses high pressure vapour to produce mechanical work . It is used to in steam power plant
∆. Gas power cycle utilises high pressure gas to convert highest in to mechanical work . It is used in aeroplane .
STEAM POWER PLANT CYCLE .
In this cycle water is the working fluid . It under goes a change of phase during cycle . Heat is produce by burning the Cole in side the burner which produces heat . Heat is utilises to convert water in to steam in side the boiler . This steam then passes through the super heater to the turbine . High pressure high temperature steam expand in side the turbine to produce mechanical work . Exhaust steam from the turbine enter in to the condenser . Where it is cooled by the cooling water and converted into water . The feed water again enter in to the boiler through the feed pump and economiser . In this cycle heat energy of the coal is converted in to mechanical energy .
Power cycle are two types .
(1) Vapour power cycle .
(2) Gas power cycle .
∆. Vapour Power cycle uses high pressure vapour to produce mechanical work . It is used to in steam power plant
∆. Gas power cycle utilises high pressure gas to convert highest in to mechanical work . It is used in aeroplane .
STEAM POWER PLANT CYCLE .
In this cycle water is the working fluid . It under goes a change of phase during cycle . Heat is produce by burning the Cole in side the burner which produces heat . Heat is utilises to convert water in to steam in side the boiler . This steam then passes through the super heater to the turbine . High pressure high temperature steam expand in side the turbine to produce mechanical work . Exhaust steam from the turbine enter in to the condenser . Where it is cooled by the cooling water and converted into water . The feed water again enter in to the boiler through the feed pump and economiser . In this cycle heat energy of the coal is converted in to mechanical energy .
STEAM POWER PLANT CAN BE RUN IN THE FLOWING CYCLE .
(1) Carnot cycle .
(2) Rankine cycle .
(3) Reheat cycle .
(4) Regenerative Cycle .
(5) Reheat regenerative cycle .
(6) Binery Vapour cycle .
CARNOT CYCLE :
The Carnot cycle is a theoretical ideal thermodynamic cycle proposed by French physicist Sadi Carnot at in 1824 and expanded upon by others in the 1830s and 1840s. It provides an upper limit on the efficiency that any classical thermodynamic engine can achieve during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference by the application of work to the system. It is not an actual thermodynamic cycle but is a theoretical construct. practically not possible .
Steam power plant Carnot cycle consist of
(1) Two isothermal process
(2) Two adiabatic process
Carnot limitations
∆ It Is extremely difficult to operate in practice becubec of following reasons :-
(1) It is difficult to comparess a wet Vapour isentropically to the saturated state as required by process 3-4
(2) It is difficult to control the quality of condensate coming out of the condenser so that state 3 is exactly obtained .
(3) The size of the pump has to be large to handle the condensate steam vapour minture corresponding to state 3 .
(4) The compression work is large resulting in a low cycle efficiency .
(5) The steam at the turbine in let is just dry saturated during its expansion over the turbine blades . It's be coming progressively wetter causing erosion damage of the turbine blades .
(2) It is difficult to control the quality of condensate coming out of the condenser so that state 3 is exactly obtained .
(3) The size of the pump has to be large to handle the condensate steam vapour minture corresponding to state 3 .
(4) The compression work is large resulting in a low cycle efficiency .
(5) The steam at the turbine in let is just dry saturated during its expansion over the turbine blades . It's be coming progressively wetter causing erosion damage of the turbine blades .
RANKINE VAPOUR CYCLE
The Rankine cycle is a model used to predict the performance of steam turbine systems. It was also used to study the performance of reciprocating steam engines. The Rankine cycle is an idealized thermodynamic cycle of a heat engine that converts heat into mechanical work while undergoing phase change. It is an idealized cycle in which friction losses in each of the four components are neglected. The heat is supplied externally to a closed loop, which usually uses water as the working fluid. It is named after William John Macquorn Rankine, a Scottish polymathand Glasgow University professor.
Rankine cycle consist of following processes
Process (1-2) :- Isentropic expansion inside
the turbine .
Process (2-3) :- Constant pressure heat
resection inside.
Process (3-4) :- Isentropic compression inside
the pump.
Process (4-1) :- constant pressure heat a adelition inside the boiler.
REGENERATIVE CYCLE
Regeneration in thermodynamics process refers to a method where the certain quantity of heat abstracted from the steam is utilized to heat the water. The regeneration process occurs between the stages of turbine and pump respectively. Using regeneration, the efficiencies of thermodynamic cycles can be improved.
The overall efficiency of both the Rankine cycle and the Carnot cycle will be identical, when there is a complete accomplishment of heat regeneration.With the steam regeneration, the efficiency of Rankine cycle can be improved more equivalent to that of Carnot cycle when both the cycles are operated between the same intervals of time.
BINARY VAPOUR CYCLE.
A binary vapour cycle comprises two different cycle working with two different fluid so that the condenser one cycle becomes boiler of another cycle .
This cycle is used to increase the overall efficiency of the plant.
The must important binary comprise of the mercury cycle and steam cycle .
This cycle is used to increase the overall efficiency of the plant.
The must important binary comprise of the mercury cycle and steam cycle .
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