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The paper describes the methods used to select appropriate engines for renewing an existing fleet of fork lift truck models with new Diesel and LPG engines. The target was to achieve a better performance with the new engines and to find a better cost / benefit ratio for the customer. The aid of a simulation was used to fulfill this task. Selecting suitable engines from a variety of industrial and mass production passenger car engines which fulfill above requirements seems to be an easy task on first sight, but looking at the details the matter becomes more complex. Of particular interest were the effects of replacing naturally aspirated (NA) engines by smaller swept volume turbocharged (TC) engines. A power train simulation model including the hydraulic lift part was developed and used for Diesel and LPG engines. For several different operating situations and load profiles a set of simulations was performed for different engines.

The well-to-wheel CO2 emissions and energy use of internal combustion engines (diesel and gasoline) are compared to fuel cell automotive propulsion systems. The fuel cell technologies investigated are polymer electrolyte fuel cell (PEFC), alkaline fuel cell (AFC) and solid oxide fuel cell (SOFC). The fuels are assumed to be produced from either crude oil or natural gas. The comparison is based on driving cycle simulations of a mid-class passenger car with an inertia test weight of 1350 kg. The study shows that the optimized diesel drive train (downsized mated to an integrated starter generator) achieves the best overall energy efficiency. The lowest CO2 emissions are produced by compressed natural gas (CNG) vehicles. Fuel cell propulsion systems achieve similar or even better CO2 emission values under hot start conditions but suffer from high energy input required during warm-up.