RESUMEN
An integrated solar combined cycle (ISCC) with a low temperature waste heat recovery system is proposed in this paper. The combined system consists of a conventional natural gas combined cycle, organic Rankine cycle and solar fields. The performance of an organic Rankine cycle subsystem as well as the overall proposed ISCC system are analyzed using organic working fluids. Besides, parameters including the pump discharge pressure, exhaust gas temperature, thermal and exergy efficiencies, unit cost of exergy for product and annual CO2-savings were considered. Results indicate that Rc318 contributes the highest exhaust gas temperature of 71.2â, while R113 showed the lowest exhaust gas temperature of 65.89 at 800 W/m2, in the proposed ISCC system. The overall plant thermal efficiency increases rapidly with solar radiation, while the exergy efficiency appears to have a downward trend. R227ea had both the largest thermal efficiency of 58.33% and exergy efficiency of 48.09% at 800W/m2. In addition, for the organic Rankine cycle, the exergy destructions of the evaporator, turbine and condenser decreased with increasing solar radiation. The evaporator contributed the largest exergy destruction followed by the turbine, condenser and pump. Besides, according to the economic analysis, R227ea had the lowest production cost of 19.3 $/GJ.
RESUMEN
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.
RESUMEN
The energy use analysis of coal-fired power plant units is of significance for energy conservation and consumption reduction. One of the most serious problems attributed to Chinese coal-fired power plants is coal waste. Several units in one plant may experience a practical rated output situation at the same time, which may increase the coal consumption of the power plant. Here, we propose a new hybrid methodology for plant-level load optimization to minimize coal consumption for coal-fired power plants. The proposed methodology includes two parts. One part determines the reference value of the controllable operating parameters of net coal consumption under typical load conditions, based on an improved K-means algorithm and the Hadoop platform. The other part utilizes a support vector machine to determine the sensitivity coefficients of various operating parameters for the net coal consumption under different load conditions. Additionally, the fuzzy rough set attribute reduction method was employed to obtain the minimalist properties reduction method parameters to reduce the complexity of the dataset. This work is based on continuously-measured information system data from a 600 MW coal-fired power plant in China. The results show that the proposed strategy achieves high energy conservation performance. Taking the 600 MW load optimization value as an example, the optimized power supply coal consumption is 307.95 g/(kW·h) compared to the actual operating value of 313.45 g/(kW·h). It is important for coal-fired power plants to reduce their coal consumption.
RESUMEN
The C1ε = 1.6 standard k - ε equation combined with the steady flamelet model was applied to a methane/dimethyl ether swirl combustion field, and the effects of the dimethyl ether (DME) blending ratio and operating pressure on the flame behavior, including species variation, reaction zone behavior, and flame entrainment, were investigated. The results demonstrated that selected models could better reproduce the trends of the experimental measurements. The downstream reaction zone achieved better calculation accuracy than the outer shear layer of the first recirculation zone. The addition of DME accelerated the accumulation process of H2, O, H, and OH radicals. The intermediate radical CH2O was rapidly developed by the influence of the H extraction rate under a constant fuel volume flow rate. The reaction zone dimensions were approximately linearly and positively correlated with the DME blending ratio, whereas flame entrainment expressed a lower DME concentration dependence in the high-DME mass-dominated system. The operating pressure significantly impacted the distribution of reactive radicals in the turbulent flame; meanwhile, the flame and reaction zone length showed nonlinear inverse behavior with pressure variation, while the thickness of the reaction zone was always linearly and negatively correlated with pressure. Moreover, the peak flame entrainment rate also experienced a nonlinear decline with pressure elevation; however, the peak positions were not sensitive to pressure fluctuation. Concurrently, the response surface functions for the reaction zone dimensions were established covering the range of 0-1 for the DME blending ratio and 1-5 atm operating pressure, which could provide assistance for combustion condition optimization and combustion chamber design.