A Rankine Bottoming Cycle System for Heavy-Duty Applications

Fuel costs represent a major portion of the total operating expense of a heavy-duty engine in continuous service. Many new technologies are being developed to lower engine fuel consumption, but a 10–15 percent reduction in fuel costs is now achievable using Rankine Bottoming Cycle (RBC) technology. System economics require integration of state-of-the-art technology in the turbine, heat exchangers, and automatic controls. This paper describes the design and initial test results of a project to demonstrate a diesel engine-RBC power plant. The system was constructed for a Caterpillar 3500 series 16-cylinder (3516) engine with a combined output of 1415 kW. Initial test results have demonstrated a 10.4 percent fuel savings at a thermal efficiency of 44.5 percent. The RBC module is a steam-based, stand-alone unit featuring unattended operation through the use of on-board water treatment, a once-through boiler, automatic control system, and a unique design three-stage-dual pressure steam turbine. The modular concept allows the system to be adapted to other engines and alternative heat sources.