In addition, the most important feature of the ships is that they have two low-power engines, twin propellers, and waste heat recovery systems.
此外，该船最重要的特点是拥有两台低功率发动机、双螺旋桨和废热回收系统。
英语百科
Waste heat recovery unit
A waste heat recovery unit (WHRU) is an energy recovery heat exchanger that recovers heat from hot streams with potential high energy content, such as hot flue gases from a diesel generator or steam from cooling towers or even waste water from different cooling processes such as in steel cooling.