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Modellering av autotermisk reformering i hjälpkraftaggregat

Diarienummer
SM07-0018
Start- och slutdatum
080301-100930
Beviljat belopp
1 142 442 kr
Förvaltande organisation
Chalmers University of Technology
Forskningsområde
Övrigt

Summary

Much of the current research today in the vehicle manufacturing industry is dedicated towards products that can improve the sustainability of the transport sector. Two important efforts are the adoption of renewable fuels and development of technology to improve vehicle fuel efficiency. Dimethyl ether (DME) is a potentially sustainable alternative for diesel fuel, with lower pollutant emissions. The development of auxiliary power units (APUs) is aimed at eliminating inefficient truck idling, for on board generation of heat and electricity for the vehicle. Idling accounts for a significant part of the greenhouse gas and other pollutant emissions from heavy-duty trucks. The objective of this project is to carry out modelling studies to aid the development of an autothermal DME reformer, a key component within a heavy-duty truck APU system. The research will involve a study of the kinetics of the reactions, and potentially limiting transport processes that occur within the reactor. Further goals for the research project are for example to investigate the optimal operating conditions for these reactors for efficient and stable operation, determine if alternative structured designs can improve their performance, and examine the integration of the reactor within an APU system. The study will be carried out in close conjunction with experimental studies and also aid in the evaluation of the effect of catalyst material properties on reactor performance.

Populärvetenskaplig beskrivning

Air pollution from emissions of nitric oxides (NOx) and particulates in addition to the threat of climate change due to increasing concentrations of carbon dioxide (CO2) in the atmosphere has made the adoption of renewable fuels and efforts to increase energy efficiency a high priority in the transport sector. An attractive alternative to fossil diesel fuel is dimethyl ether (DME). Since DME can be produced from renewable biomass resources, its use would reduce the accumulation of CO2 in the atmosphere. In addition the exhaust from DME fuelled engines have lower concentrations of air pollutants. It has been estimated that idling accounts for between 20 to 40% of the operating time of heavy-duty truck engines. Truck engines idle to produce electricity for driver comfort or cargo refrigeration needs. The energy efficiency of a truck engine during idling is only about 2%. This means that idling accounts for a significant part of the negative environmental impact of trucks. Efforts are underway to develop on board auxiliary power units (APU) to eliminate the need for idling. An APU that produces electricity from a fuel cell powered by the steam reforming of DME could have an efficiency of 40%. Such an APU could drastically reduce fuel consumption and in turn emissions of CO2 and other air pollutants. Fuel cells, powered by hydrogen, which on board a vehicle can be produced from the fuel, by steam reforming reactions in a specialized reformer reactor in the APU. During steam reforming, steam reacts with DME to produce hydrogen as will as carbon oxides. Steam reforming reactions are catalyzed by various metals including nickel and palladium supported on high surface area materials such as aluminium oxide. The steam reforming reactions are also endothermic which means that they must be supplied with heat, otherwise they self-extinguish. Heat would be produced in the reactor by also feeding it with some air, so that oxygen will also react with some DME to produce heat by oxidation reactions such as combustion. In the proposed project modelling studies will be carried out with the aim to gain a better understanding of the chemical reactions and the transport of heat and mass in the reactor. The project could also encompass work aimed at examining the optimal operating conditions, exploring alternative improved designs, investigating integration of the reactor with the other equipment in an APU system, and evaluation of alternative catalyst formulations.