Influences of different heating concepts for the energy demand of an airfield luggage tug

Kurzfassung

The advantages of battery electric vehicles (BEV) like good overall energy usage, no local emissions and reduced noise are well known. On the other side there are also disadvantages like a dramatic loss of range caused by thermal management of the driver cabin or long recharging times. In [1], the influence of different environmental conditions on the energy demand of a commercial electric car was disclosed. It was shown that the overall energy consumption was increased up to 50 % for winter conditions (heating), and 30 % for summer conditions (cooling). A combined range extender system based on a high temperature polymer electrolyte fuel cell was proposed in [2]. It allows both, to recharge the traction battery on board as well as optimized thermal management using waste heat for conditioning the driver cabin. Besides the raise of range, energy density and storage ability of hydrogen are decreasing the downtime of BEVs dramatically. Unfortunately, hydrogen filling stations are currently not widely available. The amount of 400 public refilling stations are planned up to 2023 in Germany. One way to hasten market penetration of fuel cell powered propulsion systems is to focus on local closed areas, e.g. airports. The advantages of being local emission free (e.g. driving in closed buildings, reducing air pollution, noise), the high amount of vehicles and a high operating time are predestined using fuel cell powered propulsion systems. In a project funded by the German government, DLR, Bosch and others are upgrading a BEV luggage tug (Figure 1) to a fuel cell vehicle (FCV) with a fuel cell based on board charging system. Figure 1: airfield luggage tug Mulag Comet 3E – BEV The electric airport luggage tug (BEV) weighs around 4000 kg and is powered by a 31 kWpeak electric engine. Energy is stored in a 48 kWh conventional lead acid battery working at 80 V. For cold environmental conditions and safety purposes, an electric 1.5 kW PTC-Heater is integrated in the luggage tug to heat the drivers cabin and avoid windshield fogging. In the upgrade, the BEV is rebuilt to a FCV with 8 kWh Li-Ion battery and 20 kW low temperature polymer electrolyte membrane fuel cell (PEM-FC). The aim is to study the energy saving potential of fuel cell thermal management using a virtual luggage tug model created in Dymola.