Electrical output from an exhaust-gas WHR system and the auxiliary fuel it displaces. Feeds the EEDI Category-B innovative-technology credit.
Formula
$$ P_\text{WHR} \approx P_\text{ME} \cdot \frac{f_\text{exh}}{1 - f_\text{exh}} \cdot \eta_\text{WHR} $$$$ F_\text{saved} = \frac{P_\text{WHR} \cdot h \cdot \text{SFOC}_\text{AE}}{10^6} $$Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $P_\text{WHR}$ | Electrical power produced by the WHR system | kW | result |
| $P_\text{ME}$ | Brake power of the main engine at reference load | kW | NOx Technical File |
| $f_\text{exh}$ | Share of fuel energy leaving through the exhaust (≈ 0.45 for modern two-strokes) | - | MAN / WinGD technical data |
| $\eta_\text{WHR}$ | Overall heat-to-shaft WHR efficiency - single-pressure 6–8 %, dual-pressure + power turbine 10–12 % | - | WHR-maker data |
| $F_\text{saved}$ | Auxiliary fuel displaced by WHR electricity | t | result |
| $h$ | Running hours at reference load | h | operating profile |
| $\text{SFOC}_\text{AE}$ | SFOC of the displaced aux engine | g / kWh | NOx Technical File |
Per MEPC.1/Circ.815 (Category B), the WHR credit is subtracted directly from the EEDI numerator, so a 10 % WHR cuts the Attained EEDI by close to the same fraction for a typical container-ship.
Sources
- IMO MEPC.1/Circ.815 - innovative energy-efficient technologies.
- MAN Energy Solutions - Waste Heat Recovery System.