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Polygeneration in HCCI Engines: a kinetic and thermoeconomic analysis with focus on hydrogen production
Global greenhouse gas emissions should be reduced in the short term, and increasing efficiency in energy and material conversion is crucial for this. Therefore, novel conversion processes are required and polygeneration in engines poses a possible solution. However, these processes must also be competitive with the cost of conventional processes. The aim of this thesis is to evaluate the efficiency and costs of fuel-rich operated homogeneous charge compression ignition engines for a simultaneous provision of work, heat, and base chemicals. In literature fuel-rich operation of conventional spark-ignition engines have been proven. However, high fuel-air equivalence ratios are required for high yields of chemicals such as synthesis gas, but then spark-ignition causes misfires due to a reduced flame speed. In a few recent works, homogeneous charge compression igniting seemed promising for achieving high yields and high exergetic efficiencies. However, a comprehensive study of kinetically feasible and exergetically reasonable operating conditions in combination with an economic analysis has not yet been conducted. Consequently, this thesis draws the question what operating conditions are feasible and reasonable, considering methane containing fuels, and reactive additives like dimethyl ether and ozone to decrease the required intake temperature and to control ignition timing. Furthermore, the exergetic efficiencies at those conditions are evaluated and the product costs calculated and compared to conventional production processes. For this purpose, single-zone and multi-zone engine models have been developed in Python, as well as complete process concepts including hydrogen separation. It was found that ozone is the most suitable additive since if used in small amounts, it decreases the efficiency only slightly, and can be produced on-site. With reactive additives, the engine can be operated at fuel-rich conditions, up to fuel-air equivalence ratios of 2. The exergetic efficiency reaches up to 82 % for the engine ...
Polygeneration in HCCI Engines: a kinetic and thermoeconomic analysis with focus on hydrogen production
Global greenhouse gas emissions should be reduced in the short term, and increasing efficiency in energy and material conversion is crucial for this. Therefore, novel conversion processes are required and polygeneration in engines poses a possible solution. However, these processes must also be competitive with the cost of conventional processes. The aim of this thesis is to evaluate the efficiency and costs of fuel-rich operated homogeneous charge compression ignition engines for a simultaneous provision of work, heat, and base chemicals. In literature fuel-rich operation of conventional spark-ignition engines have been proven. However, high fuel-air equivalence ratios are required for high yields of chemicals such as synthesis gas, but then spark-ignition causes misfires due to a reduced flame speed. In a few recent works, homogeneous charge compression igniting seemed promising for achieving high yields and high exergetic efficiencies. However, a comprehensive study of kinetically feasible and exergetically reasonable operating conditions in combination with an economic analysis has not yet been conducted. Consequently, this thesis draws the question what operating conditions are feasible and reasonable, considering methane containing fuels, and reactive additives like dimethyl ether and ozone to decrease the required intake temperature and to control ignition timing. Furthermore, the exergetic efficiencies at those conditions are evaluated and the product costs calculated and compared to conventional production processes. For this purpose, single-zone and multi-zone engine models have been developed in Python, as well as complete process concepts including hydrogen separation. It was found that ozone is the most suitable additive since if used in small amounts, it decreases the efficiency only slightly, and can be produced on-site. With reactive additives, the engine can be operated at fuel-rich conditions, up to fuel-air equivalence ratios of 2. The exergetic efficiency reaches up to 82 % for the engine ...
Polygeneration in HCCI Engines: a kinetic and thermoeconomic analysis with focus on hydrogen production
Freund, Dominik (author) / Atakan, Burak
2023-07-06
Theses
Electronic Resource
English
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