Alabama Transportation Institute

Permanent URI for this community

https://ir.ua.edu/handle/123456789/8237

Browse

Browsing Alabama Transportation Institute by Author "Ran, Zhongnan"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Experimental study of lean spark ignition combustion using gasoline, ethanol, natural gas, and syngas
    (Elsevier, 2019) Ran, Zhongnan; Hariharan, Deivanayagam; Lawler, Benjamin; Mamalis, Sotirios; State University of New York (SUNY) System; State University of New York (SUNY) Stony Brook; University of Alabama Tuscaloosa
    In the development of internal combustion engines, engineers and researchers are facing the challenge of improving engine efficiency while reducing harmful exhaust emissions. Previous research has shown that lean combustion is one of the viable techniques that can improve engine efficiency while effectively reducing exhaust emissions. Lean burn engines operate at low burned gas temperatures and can achieve high thermal efficiency based on favorable mixture thermodynamic properties. However, under high dilution levels, a lean misfire limit is reached where the combustion process becomes unstable and incomplete combustion starts to occur. Instability significantly affects engine efficiency, driveability, and exhaust emissions, which limit the full potential of lean burn engines. The lean misfire limit is not only dependent on engine design but also on fuel properties. Therefore, fuels that are conducive to lean combustion can provide the opportunity for enhanced efficiency and reduced emissions. Spark ignited (SI) combustion with conventional gasoline has shown to have relatively narrow range of fuel-air equivalence ratio; therefore, it is desired to explore the lean limit of SI combustion by using alternative fuels, which can also contribute to the reduction of greenhouse gas emissions from transportation and power generation. Experiments were conducted on a Cooperative Fuel Research (CFR) engine with varying fuel-air equivalence ratio (phi) to assess the engine performance and emissions with three alternative fuels, natural gas, ethanol, and syngas, at compression ratio of 8:1 and engine speed of 1200 rev/min. Equivalence ratio was varied by decreasing the mass of fuel while keeping the mass of air the same. The lean misfire limit was defined as the equivalence ratio where the CoV of IMEP across multiple consecutive engine cycles was greater than 5%. It was found that syngas can maintain stable combustion at extremely lean conditions and has the lowest lean misfire limit. Natural gas combustion achieved a lower lean misfire limit than gasoline and ethanol. Gasoline and ethanol had similar lean misfire limits, but it was found that gasoline helped the engine to achieve higher load and fuel conversion efficiency compared to the three alternative fuels.
  • Thumbnail Image
    Item
    Experimental Study of Spark-Ignition Combustion using the Anode Off-Gas from a Solid Oxide Fuel Cell
    (2020) Ran, Zhongnan; Assanis, Dimitris; Hariharan, Deivanayagam; Mamalis, Sotirios; University of Alabama Tuscaloosa
    Hybridizing Solid Oxide Fuel Cells (SOFCs) with internal combustion engines is an attractive solution for power generation at high electrical conversion efficiency while emitting significantly reduced emissions than conventional fossil fueled plants. The gas that exits the anode of an SOFC operating on natural gas is a mixture of H2, CO, CO2, and H2O vapor, which are the products of the fuel reforming and the electrochemical process in the stack. In this study, experiments were conducted on a single-cylinder, spark-ignited Cooperative Fuel Research Engine using the anode off-gas as the fuel, at compression ratio of 11:1 and 13:1, engine speed of 1200 rev/min and intake pressure of 75 kPa, to investigate the combustion characteristics and emissions formation. A comparison was drawn with combustion with Compressed Natural Gas (CNG) at the same engine operating conditions. The experimental results revealed that the anode off-gas can be used as a potential alternative fuel for spark-ignition combustion, and an engine can be used to provide additional power to a hybrid SOFC-engine system. Combustion with the anode off-gas resulted in similar net indicated efficiency with CNG at CR of 13:1, but with negligible NOx emissions and zero total hydrocarbon emissions. However, combustion with the anode off-gas resulted in lower volumetric efficiency and lower load than CNG as a result of high levels of dilution in the off-gas, which greatly reduces the lower heating value of the fuel. This study demonstrated the feasibility of using the SOFC anode-off gas as a potential fuel for spark-ignition engines with good fuel conversion efficiency and minimal NOx and THC emissions.