The model was used in the modeling section of the Chalmers University of Technology TME-180 Automotive Engineering Project to analyze the operation of a fuel cell excavator at different altitudes. The model was developed by Zikun Wang, Jinge Gao, Emil Alexsson, Shamith Satish and Pontus Rhedin (in no particular order).
To try this model, you need to run CNV.m first to set up parameters, then use the slx file to start Simulink model.
Excavators and other heavy equipment have a long history of utilizing a conventional internal combustion engine powertrain layout. With the escalating global climate crisis, the urgency to reduce greenhouse gas emissions from excavators has increased which requires research on sustainable energy sources for these applications. Since excavators may operate in tough terrain with long distances to infrastructure, a fuel cell hybrid electric (FCEV) powertrain could potentially have benefits over a battery electric powertrain because of hydrogen's power density and portability. However, the performance of FCEV powertrains are, unlike batteries, dependent on air pressure since the fuel cell stack is fed ambient air that is pressurized by an air compressor. Since excavators might operate in mines at high altitudes, this could potentially mean that the overall efficiency of a FCEV excavator is reduced at these sites. The research question for this project is therefore to evaluate how large impact altitude has on the efficiency of a FCEV excavator. The project covers the theory and development of a fuel cell stack model using experimental data from a 5 kW stack which is scaled to 180 kW, a "balance of plant" (BOP) model with auxiliary components to operate the stack and a powertrain model in MatLab Simulink for a 26 tonne 180 kW excavator. The BOP includes all components to pressurize, circulate and control the flows to the fuel cell stack as well as a model for the cooling system. With these components modelled, the pressure and temperature of the ambient air are affecting the parasitic losses to the fuel cell system. The powertrain model includes simplified models of an electric machine, inverter, DC/DC converters and battery in which a driving cycle is implemented to approximate efficiencies. The resulting efficiencies at 0, 3000 and 5091 meters above sea level are found. The ambient temperatures are 25, 12 and -4 degrees Celsius respectively. The drop in BOP efficiency is 3-7% which is a result of lower intake air pressure which require more compressor work, but the BOP efficiency is compensated by the lower temperatures which reduces the radiator fan power.The results may be affected by the fact that some of the parameters of the model built are idealized or simplified.