Rankine Cycle Efficiency
Calculate the thermal efficiency of a Rankine cycle, η = (w_turbine − w_pump) ÷ q_boiler × 100%, dividing the net work (turbine work minus pump work) by the heat added in the boiler, all in kJ/kg. The Rankine cycle is the basis of steam power plants: water is pumped, heated and vaporized in the boiler, expands through the turbine producing work, then condenses. The result, in %, measures how much boiler heat becomes useful work; real cycles run 30–45%. Enter the turbine work, the pump work and the boiler heat.
Resultado
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Eficiência do ciclo Rankine
O ciclo Rankine é o ciclo termodinâmico das usinas termelétricas a vapor — a carvão, a óleo, a biomassa ou nucleares. Ele tem quatro etapas: a bomba pressuriza a água líquida; a caldeira aquece e vaporiza essa água a alta pressão; a turbina expande o vapor, produzindo trabalho; e o condensador resfria o vapor de volta a líquido. A eficiência térmica é a razão entre o que se ganha e o que se gasta: η = (w_turbina − w_bomba) ÷ q_caldeira × 100%. O numerador é o trabalho líquido — o trabalho bruto da turbina menos a parcela consumida pela bomba (que é pequena, pois bombear líquido custa pouco). O denominador é o calor fornecido na caldeira. O resultado diz quanto do calor investido virou trabalho aproveitável; o restante é rejeitado no condensador (imposição da segunda lei da termodinâmica). Ciclos reais ficam em 30–45%; superaquecimento, reaquecimento e regeneração elevam esse valor. Informe o trabalho da turbina, o da bomba e o calor da caldeira.
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Steam Turbine Power
Calculate the mechanical power generated by a steam turbine, P = ṁ × (h₁ − h₂), multiplying the steam mass flow (kg/s) by the enthalpy drop between turbine inlet and outlet (kJ/kg). The result, in kW, is the shaft power delivered to the generator, accounting for the expansion of high-pressure, high-temperature steam down to condenser pressure. It is the core calculation in sizing thermal power and cogeneration plants: the larger the enthalpy drop, the more power per kg of steam. Enter the steam flow and the inlet and outlet enthalpies.
Combined Cycle Efficiency
Calculate the efficiency of a gas-steam combined cycle, η_cc = η_gas + η_steam − (η_gas × η_steam ÷ 100), combining the gas turbine efficiency (Brayton, topping) with the steam cycle (Rankine, bottoming) that recovers heat from the exhaust gases. The result, in %, exceeds either cycle alone because the heat rejected by the gas turbine, instead of being wasted, raises steam for a second turbine. This is why modern combined-cycle plants top 60% efficiency, the highest in thermal generation. Enter the gas-cycle and steam-cycle efficiencies (in %).
Back Work Ratio (BWR)
Calculate the back work ratio (BWR) of a power cycle, BWR = w_compressor ÷ w_turbine, dividing the work consumed by the compressor (or pump) by the gross work produced by the turbine. The dimensionless result shows what fraction of turbine work is reinvested to compress the fluid. In gas turbines (Brayton cycle) the BWR is high (0.4–0.6), since compressing gas is costly; in steam Rankine cycles it is tiny (~0.01), since pumping liquid is cheap. A high BWR makes the cycle sensitive to component efficiencies. Enter the compressor work and the turbine work.
Heat Rate
Calculate the heat rate of a power plant, HR = 360000 ÷ η, dividing 360000 by the thermal efficiency in percent. The result, in kJ/kWh, is the fuel energy consumed to generate one kilowatt-hour of electricity — the inverse of efficiency expressed on an energy basis. It is the power-generation industry's standard metric: the lower the heat rate, the more efficient and economical the plant. A 40% efficiency equals 9000 kJ/kWh; modern combined-cycle plants reach ~6000 kJ/kWh. It lets you compare plants and estimate fuel use. Enter the thermal efficiency in percent.
Pump Work (Rankine)
Calculate the specific work consumed by the pump of a Rankine cycle, w_pump = v × (P₂ − P₁), multiplying the liquid specific volume (m³/kg, ~0.001 for water) by the pump pressure rise (kPa). The result, in kJ/kg, is the energy spent pressurizing the condensate before the boiler. Because the liquid is nearly incompressible, this work is tiny compared with the turbine's — which is why the Rankine cycle pumps a liquid (not a gas, as a gas Carnot cycle would), sharply reducing the back work. Enter the specific volume and the pump outlet and inlet pressures.
Specific Steam Consumption
Calculate the specific steam consumption (steam rate) of a turbine, SSC = 3600 ÷ Δh, dividing 3600 (s/h) by the available enthalpy drop in the turbine (kJ/kg). The result, in kg/kWh, gives how many kilograms of steam are needed to generate one kilowatt-hour. The lower the specific consumption, the more efficient the conversion: larger enthalpy drops (hotter steam and greater expansion) cut the steam needed per kWh. It is a practical indicator to compare turbines and estimate the steam flow required for a given power. Enter the available enthalpy drop.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.