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B. Yang
to the parameters of equipment power, flow rate and head. After determining the type of
equipment, the structural parameters of pipeline and other components can be adjusted
according to the system structure and the size of different equipment, so as to obtain the
second loop system model.
3 Performance Analysis
For general PWR nuclear power systems, the total efficiency can be approximately
expressed as:
η pl = η b · η p · η t · η oi · η m · η g
(2)
η pl : Total thermal power plant;
η b : Equipment thermal power, generally 0.98–0.99;
η p : Pipeline thermal efficiency, generally 0.98–0.99;
η t : Theoretical Thermal Cycle Efficiency, generally 0.40–0.45;
η oi : Relative efficiency of steam turbine, generally 0.85–0.87;
η m : Mechanical efficiency of steam turbine units, generally 0.95–0.99;
η g : Generator efficiency, generally 0.98–0.99.
It can be seen that the methods to improve the thermal efficiency of PWR are mainly
from the above aspects. According to different efficiency values, it can be found that
improving the cycle efficiency of the second loop has the greatest potential to improve the
overall thermal efficiency. In large PWR nuclear power plants, there are no more space
and weight restrictions, the methods of increasing steam separation reheater, regenerative
heater, condenser performance and regenerative heat exchanger are often used to improve
the heat efficiency of nuclear power units. At the same time, the compactness and security
of equipment and system should be taken into account.
3.1 Simple Rankine Cycle Operating Characteristics
By using the design value of the two-loop system parameters for MATLAB modeling,
the efficiency of the Rankine cycle is 26.14. When any parameter is changed in a certain
range and the other parameters are kept in the design value, the simulation results are
shown in Fig. 1. The following rules can be obtained.
At the design value, the system cycle efficiency is 26.14%, and the cycle efficiency
fluctuates in the range of 21%–31% in the process of performance discussion. Considering the equipment bearing capacity, the space for improving the simple cycle efficiency
is not large; The smaller the condenser pressure, the higher the Rankine cycle efficiency
(Fig. 1(a)); Greater the steam generator pressure, the higher the Rankine cycle efficiency
(Fig. 1(b)); Higher equipment efficiency for pumps and steam turbines, higher Rankine
cycle efficiency (Fig. 1(c, d)); Steam generator outlet overheating can improve Rankine
cycle efficiency (Fig. 1 e).
Therefore, the effects of different parameter combinations on Rankine cycle efficiency are studied by changing the system parameters of the same properties at the same
B. Yang
to the parameters of equipment power, flow rate and head. After determining the type of
equipment, the structural parameters of pipeline and other components can be adjusted
according to the system structure and the size of different equipment, so as to obtain the
second loop system model.
3 Performance Analysis
For general PWR nuclear power systems, the total efficiency can be approximately
expressed as:
η pl = η b · η p · η t · η oi · η m · η g
(2)
η pl : Total thermal power plant;
η b : Equipment thermal power, generally 0.98–0.99;
η p : Pipeline thermal efficiency, generally 0.98–0.99;
η t : Theoretical Thermal Cycle Efficiency, generally 0.40–0.45;
η oi : Relative efficiency of steam turbine, generally 0.85–0.87;
η m : Mechanical efficiency of steam turbine units, generally 0.95–0.99;
η g : Generator efficiency, generally 0.98–0.99.
It can be seen that the methods to improve the thermal efficiency of PWR are mainly
from the above aspects. According to different efficiency values, it can be found that
improving the cycle efficiency of the second loop has the greatest potential to improve the
overall thermal efficiency. In large PWR nuclear power plants, there are no more space
and weight restrictions, the methods of increasing steam separation reheater, regenerative
heater, condenser performance and regenerative heat exchanger are often used to improve
the heat efficiency of nuclear power units. At the same time, the compactness and security
of equipment and system should be taken into account.
3.1 Simple Rankine Cycle Operating Characteristics
By using the design value of the two-loop system parameters for MATLAB modeling,
the efficiency of the Rankine cycle is 26.14. When any parameter is changed in a certain
range and the other parameters are kept in the design value, the simulation results are
shown in Fig. 1. The following rules can be obtained.
At the design value, the system cycle efficiency is 26.14%, and the cycle efficiency
fluctuates in the range of 21%–31% in the process of performance discussion. Considering the equipment bearing capacity, the space for improving the simple cycle efficiency
is not large; The smaller the condenser pressure, the higher the Rankine cycle efficiency
(Fig. 1(a)); Greater the steam generator pressure, the higher the Rankine cycle efficiency
(Fig. 1(b)); Higher equipment efficiency for pumps and steam turbines, higher Rankine
cycle efficiency (Fig. 1(c, d)); Steam generator outlet overheating can improve Rankine
cycle efficiency (Fig. 1 e).
Therefore, the effects of different parameter combinations on Rankine cycle efficiency are studied by changing the system parameters of the same properties at the same