Performance evaluation of solar aided feedwater heating of coal-fired power generation (SAFHCPG) system under different operating conditions

• The performance of a SAFHCPG system at design point is analyzed.
• The solar radiation intensity and the electrical load demand on the grid side are considered in the annual performance analysis.
• The optimum aperture area of the solar field has been discussed based on the annual performance.

Integrating solar energy with a coal-fired power plant or other power systems has been proved to be an efficient way to utilize solar energy for power generation. Solar aided feedwater heating of a coal-fired power generation (SAFHCPG) system, which is mainly discussed in this paper, is chosen as an option for its easy operation and flexible control nature.The performance of a SAFHCPG system at design point is analyzed under various load conditions in the paper. As the results show in Table 4, the lower load of coal-fired unit that solar aid, the lower solar-to-electric efficiency will be. For a SAFHCPG system, its performance is influenced by the solar radiation intensity and the electrical load demand on the grid side. The correlation between the annual performance of a SAFHCPG plant and the two key factors is discussed and then the optimal aperture area of solar field is derived. The result shows that, for the case studied the optimal aperture area of solar field and the lowest LEC (Levelized Electricity Costs) are: 115395 m2 and 0.472 ¥/kW h in a typical year; 138945 m2 and 1.010 ¥/kW h in an extremely low radiation year; 91845 m2 and 0.426 ¥/kW h in an extremely high radiation year respectively.