Adiabatic shaft-power estimate for a boil-off gas (BOG) compressor handling methane from atmospheric tank vapour to the DF-engine supply pressure.
Formula
$$ P_{shaft} = \frac{\dot m \cdot c_p \cdot T_1 \cdot \left[\left(\frac{p_2}{p_1}\right)^{\frac{k-1}{k}} - 1\right]}{\eta_{ad}} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\dot m$ | BOG mass flow | kg/s | tank BOR × volume × density |
| $c_p$ | Specific heat at constant pressure | kJ/kg·K | NIST REFPROP |
| $T_1$ | Suction temperature | K | suction RTD |
| $k$ | Isentropic exponent | - | NIST (methane) |
| $\eta_{ad}$ | Adiabatic efficiency | - | machine data sheet |
Sources
- GIIGNL Handbook - BOG Management.
- NIST Chemistry WebBook - methane.