Heat balance

A heat balance accounts for where a marine engine’s fuel energy goes: roughly half is lost, split between exhaust gas, jacket and charge-air cooling, and radiation, with the remainder appearing as brake power. Drawn as a Sankey diagram, it identifies the recoverable streams (high-grade exhaust to an economizer, lower-grade jacket water to a fresh-water generator) that waste-heat recovery and combined plants exploit. It is the starting point for sizing recovery equipment.