ThermoFluidCalc Report

Organic Rankine Cycle โ€” 2026-09-29 07:21:34
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๐ŸŒฑ Organic Rankine Cycle (ORC)

Evaluate low-temperature heat recovery power plants using organic working fluids like R134a, R245fa.

โšก Fortran 90 Engine Double Precision (IEEE 754) โœ“ ISO / ASME Validated
Organic Rankine Cycle (ORC) Thermodynamics
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โšก Solves 88
๐Ÿ’พ Downloads 201 ๐Ÿ“ฆ Fortran Code 11.4 KB
๐Ÿ“… Released Jun 2026
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โšก TOOLS & REPORTS:
๐Ÿ’พ Download Fortran 90

๐Ÿ“ Configuration

๐Ÿงช Working Fluid
๐ŸŒก๏ธ Heat Source & Sink
150.0 ยฐC
30.0 ยฐC
โš™๏ธ Cycle Parameters
Key Equations:

ฮทth = Wnet/Qin
ฮทrelative = ฮทth/ฮทCarnot
hfg(T) = hfg(Tb)ยท((Tcโˆ’T)/(Tcโˆ’Tb))^0.38 (Watson)
BWR = Wpump/Wturbine
Dry fluid: superheated exit (no moisture)

๐Ÿ“Š Results

Configure inputs and click Analyze to view results.

๐Ÿ“˜ Methodology

Organic Rankine Cycles

ORCs use organic working fluids with low boiling points to convert low-temperature heat (80โ€“350ยฐC) into electricity. Applications include geothermal, solar thermal, waste heat recovery, and biomass. Typical efficiencies range from 5โ€“20%.

Dry vs Wet Fluids

Organic fluids like R245fa and pentane have positive-slope saturation curves (dry fluids), meaning turbine expansion ends in the superheated regionโ€”eliminating moisture erosion concerns. This is a key advantage over steam Rankine cycles at low temperatures.

Assumptions

  • Simplified constant cp model for liquid and vapor phases.
  • Watson correlation for latent heat variation with temperature.
  • Clausius-Clapeyron approximation for saturation pressures.
  • Steady-state, dry expansion assumed for all fluids.

๐Ÿ“˜ Calculation Methodology: Organic Rankine Cycle (ORC) Waste Heat Recovery

Mathematical Model & Theory

Organic Rankine Cycles utilize high-molecular-weight organic fluids (e.g. R245fa, n-pentane) with lower boiling points to recover low-temperature geothermal or industrial exhaust waste heat:

$$\eta_{th,ORC} = \frac{\dot{W}_{turb} - \dot{W}_{pump}}{\dot{Q}_{evap}} = \frac{(h_1 - h_2) - (h_4 - h_3)}{h_1 - h_4}$$
$$\text{Exergy Efficiency: } \eta_{II} = \frac{\dot{W}_{net}}{\dot{m}_{source}[(h_{in}-h_{out}) - T_0(s_{in}-s_{out})]}$$

Assumptions

  • Subcritical or supercritical dry/isentropic organic refrigerant.
  • Constant component isentropic efficiencies.

Academic References

  1. Colonna, P. et al.: Organic Rankine Cycle Technologies, J. Eng. Gas Turbines Power.
  2. Macchi, E., & Astolfi, M.: Organic Rankine Cycle (ORC) Power Systems, Woodhead.

Worked Engineering Example

Problem Statement:
An R245fa ORC absorbs $Q_{in} = 500\text{ kW}$ at $120^\circ\text{C}$ producing turbine power $W_t = 65\text{ kW}$ and pump power $W_p = 5\text{ kW}$. Calculate thermal efficiency.

Step-by-step Solution:
1. Net work output: $W_{net} = 65 - 5 = 60\text{ kW}$.
2. Thermal efficiency: $\eta = 60 / 500 = 0.120 = 12.0\%$.
Final Result:
ORC thermal efficiency is $\mathbf{12.0\%}$ (delivering 60 kW net electrical power).