Thermodynamic and Economic Analysis of an Integrated Solar Combined Cycle System
Integrating solar thermal energy into the conventional Combined Cycle Power Plant (CCPP) has been proved to be an efficient way to use solar energy and improve the generation efficiency of CCPP. In this paper, the energy, exergy, and economic (3E) methods were applied to the models of the Integrated Solar Combined Cycle System (ISCCS). The performances of the proposed system were not only assessed by energy and exergy efficiency, as well as exergy destruction, but also through varied thermodynamic parameters such as DNI and Ta. Besides, to better understand the real potentials for improving the components, exergy destruction was split into endogenous/exogenous and avoidable/unavoidable parts. Results indicate that the combustion chamber of the gas turbine has the largest endogenous and unavoidable exergy destruction values of 202.23 MW and 197.63 MW, and the values of the parabolic trough solar collector are 51.77 MW and 50.01 MW. For the overall power plant, the exogenous and avoidable exergy destruction rates resulted in 17.61% and 17.78%, respectively. In addition, the proposed system can save a fuel cost of 1.86 $/MW·h per year accompanied by reducing CO2 emissions of about 88.40 kg/MW·h, further highlighting the great potential of ISCCS.
Optimisation of displacement selections and structures for the Geothermal Aided Power Generation plant

 Geothermal Aided Power Generation (GAPG) technology is a method of integrating geothermal energy into a regenerative Rankine cycle (RRC) power plant. In such a power system, the geothermal energy is used to preheat the feedwater to boiler of the power plant. Therefore, the extraction steam of RRC power plant is displaced by the geothermal energy. Then, the displaced extraction steam is expended further in steam turbine to produce power. In a GAPG plant, a heat exchanger system is used to facilitate the heat exchange between the geothermal fluid and the feedwater. As power from geothermal energy comes from displaced extraction steam, different displacement selections for extraction steam would lead to different technical performance of the GAPG plant. When the geothermal fluid flows up from the geothermal well and quench to a lower temperature in the heat exchanger system, the silica scaling occurs in the heat exchanger system. As silica scaling can be controlled by adjusting geothermal fluid temperature, different displacement selections would have different influences on the silica scaling process in the heat exchanger system. There are two kinds of structures for the heat exchanger system of the GAPG plant, which are series structure and parallel structure. The different structures also lead to different performance of the GAPG plant. In present paper, a 300 MW GAPG plant is used as a case study to optimise displacement selections and structures of the GAPG plant. The results show that there is no silica scaling in the heat exchanger system for the displacement selection of geothermal energy to displace extraction to all high-pressure feedwater heaters. For this displacement selection, the power output of the Parallel GAPG plant is higher than the Series GAPG plant.
Slotted Waveguide Antenna With Two Radiation Nulls
A design of a linear array antenna having two radiation nulls and otherwise omnidirectional radiation pattern is reported. A new configuration of a waveguide broad wall longitudinal slot doublet with positive and negative offsets with respect to the waveguide center line is used to design the array. This type of doublet produces two radiation nulls. Each of the null directions can be shifted at least up to plusmn25deg by proper choice of slot offset. Resonance and radiation characteristics of the proposed doublet are also presented. Finally, one linear array antenna consisting of seven doublets has been fabricated. Measurements show that the 15 dB null widths are 14.2deg and the null depths are at least 24.8 dB. Maximum gain ripple in the omnidirectional region is 1.75 dB.