Simulation dataset for the thermodynamic optimization of a triple combined cycle power plant with a bottoming Organic Rankine Cycle
Description
This dataset contains the complete set of steady-state thermodynamic simulations supporting the optimization of a 500 MWe natural-gas combined cycle power plant retrofitted with a bottoming subcritical Organic Rankine Cycle, forming a triple combined cycle. All simulations were carried out in EBSILON Professional. The dataset has two parts. The first is a full factorial sweep of the topping Brayton–Rankine plant over 125 combinations of compressor pressure ratio (5–25), gas turbine exhaust temperature (400–600 °C) and HRSG live-steam pressure (60–140 bar), reporting net thermal efficiency and net electrical output for each case. The second is a set of 28 converged design points of the bottoming ORC, covering six dry hydrocarbon working fluids (n-butane, n-pentane, , cyclopentane, n-hexane and cyclohexane) at evaporation temperatures between 90 and 150 °C. Every design point satisfies an explicitly enforced 10 K pinch-point temperature difference in the evaporator, obtained by adjusting the organic mass flow rate. For each point the dataset reports the imposed boundary conditions, the raw EBSILON outputs (power, stack temperature, pinch point, evaporator conductance, condenser duty, turbine enthalpies and volume flow rates) and a set of derived quantities: isentropic enthalpy drop, turbine size parameter, volume flow ratio, exergy recovered from the flue gas and second-law efficiency of the bottoming cycle. A Python script is included that recomputes all derived quantities from the raw EBSILON outputs and reproduces the corresponding figures of the associated article, so that every derived value can be independently verified. The data support the finding that, once a realistic pinch-point constraint is enforced, the thermodynamic performance of the six candidate fluids is almost indistinguishable above a stack temperature of about 100 °C, and that the selection of the working fluid is instead governed by the achievable stack temperature, the size of the expander and the required evaporator surface.
Files
Steps to reproduce
All results were generated with EBSILON Professional. Water and steam properties follow IAPWS-IF97; organic fluid properties were taken from the REFPROP-based property tables supplied with the software. 1. Topping plant. Build the 500 MWe single-pressure combined cycle described in the associated article, with the boundary conditions of its Table 1. Use two mass-flow controllers: one regulating the fuel flow to meet the prescribed gas turbine exhaust temperature, the other regulating the air flow to meet the 500 MWe net output at the imposed pressure ratio. Sweep the three design variables over the grid given in file 01. 2. Bottoming cycle. Couple an ORC to the flue gas leaving the HRSG at 175.0 °C and 672.82 kg/s. Set the condenser to the saturation pressure of the working fluid at 35 °C. Component efficiencies: turbine isentropic 0.91, feed pump 0.74, generator 0.98; mechanical losses are included in the generator efficiency. 3. Evaporator specification. Set the design specification method to "both cold and one hot stream temperatures given", imposing the organic outlet temperature at the saturation temperature corresponding to the pump discharge pressure plus 5 K of superheat. The evaporator cold-side pressure drop is 0.05 bar. 4. Pinch-point convergence. For each combination of fluid and evaporation temperature, adjust the organic mass flow rate until the pinch-point temperature difference reaches 10 K. Because the pinch occurs at the onset of evaporation, it is a linear function of the organic mass flow rate at fixed evaporation temperature, so two simulations are sufficient to locate the admissible flow exactly. The values reported here converged to between 9.70 and 10.22 K; the residual spread reflects the temperature dependence of the flue-gas specific heat capacity. 5. Derived quantities. Run `03_derive_quantities.py` to recompute the isentropic enthalpy drop, the size parameter, the volume flow ratio, the recovered exergy (dead state 15 °C) and the second-law efficiency from the raw EBSILON outputs, and to regenerate the figures.
Institutions
- Universidad Rey Juan CarlosMadrid, Madrid