Formula
- η_th = w_net / q_in
- w_t = η_t × (h₁ − h₂s)
- w_p = v_f × ΔP / η_p
- BWR = w_p / w_t × 100%
About this calculator
Part of our Thermal & Fluids Calculators collection. Heat transfer, pipe flow, Reynolds number, and thermodynamic cycles.
How it works
The calculator estimates state properties from your inlet and condenser conditions, then computes turbine work, pump work, heat input, and net work per kilogram. Thermal efficiency is net work divided by heat input. Back-work ratio shows how much pump work consumes turbine output.
Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.
Worked example
500°C turbine inlet, 3 MPa, condenser 10 kPa, η_t=85%, η_p=90%.
- Superheated steam enthalpy estimated from saturation table + Cp
- Isentropic expansion to condenser pressure
- Net work ≈ 944 kJ/kg, heat input ≈ 3153 kJ/kg
- η_th ≈ 29.9%
Result: Thermal efficiency ~30%, turbine exit quality ~0.85.
When to use
- Screening steam cycle efficiency for power plant studies
- Comparing turbine inlet temperature and pressure effects
- Estimating back-work ratio for pump sizing context
Limitations
- Simplified steam properties with interpolated saturation table
- Superheat enthalpy uses Cp ≈ 2.05 kJ/kg·K above saturation
- Not a full Mollier diagram cycle; reheat and regeneration not included
FAQ
- What is back-work ratio?
- Pump work divided by turbine work. Rankine cycles have low BWR (~1%) compared to gas turbines because liquid pumping is efficient.
- What is turbine exit quality?
- Wetness fraction at turbine exit after isentropic expansion. Values below 1 mean wet steam; erosion risk if too low.
Privacy and accuracy
Every calculation runs locally in your browser. Your design data never leaves your device. Results are intended for preliminary engineering work. Always verify critical designs with qualified review and applicable standards before production use.
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