Assessment of waste heat recovery for heavy-duty vehicles during on-road operation

Waste Heat Recovery (WHR) by means of an Organic Rankine Cycle is a technology often proposed to reduce the fuel consumption and CO2 emissions of heavy-duty vehicles. A Class 5 Heavy Lorry (tractor) with a WHR system was measured over various driving cycles on the chassis dyno and under realistic conditions on the road, performing each test-cycle with WHR enabled and disabled. The use of WHR lead to reductions in fuel consumption of 3.1% over the World Harmonized Vehicle Cycle, 2.5% over the Regional Delivery Cycle (RDC) and 1.9% over the on-road trips. The WHR system was able to produce more power output during the RDC on the chassis dyno compared to the on-road trips, as more exhaust energy was available during the RDC, resulting in a more considerable reduction of the fuel consumption. No statistically significant reduction of the pollutant emissions was observed. On-road trips were simulated with the Vehicle Energy Consumption calculation Tool, (VECTO), and the fuel consumption was predicted with an error of less than 1.5% for the individual trips and less than 0.5% when averaged over the different repetitions. These findings demonstrate the capability of VECTO to accurately simulate vehicles with Waste Heat Recovery under realistic conditions on the road.

Automated summary

Experiment results show that heavy-duty vehicles equipped with waste heat recovery systems can indeed reduce fuel consumption in different driving cycles, but do not significantly reduce pollutant emissions. The Vehicle Energy Consumption calculation Tool (VECTO) used for simulating on-road trips can accurately predict fuel consumption.