Investigating anode off-gas under spark-ignition combustion for SOFC-ICE hybrid systems

Solid oxide fuel cell – internal combustion engine (SOFC-ICE) hybrid systems are an attractive solution for electricity generation. The system can achieve up to 70% theoretical electric power conversion efficiency through energy cascading enabled by utilizing the anode off-gas from the SOFC as the fuel source for the ICE. Experimental investigations were conducted with a single cylinder Cooperative Fuel Research (CFR) engine by altering fuel-air equivalence ratio (ϕ), and compression ratio (CR) to study the engine load, combustion characteristics, and emissions levels of dry SOFC anode off-gas consisting of 33.9% H2, 15.6% CO, and 50.5% CO2. The combustion efficiency of the anode off-gas was directly evaluated by measuring the engine-out CO emissions. The highest net-indicated fuel conversion efficiency of 31.3% occurred at ϕ = 0.90 and CR = 13:1. These results demonstrate that the anode off-gas can be successfully oxidized using a spark ignition combustion mode. The fuel conversion efficiency of the anode tail gas is expected to further increase in a more modern engine architecture that can achieve increased burn rates in comparison to the CFR engine. NOx emissions from the combustion of anode off-gas were minimal as the cylinder peak temperatures never exceeded 1800 K. This experimental study ultimately demonstrates the viability of an ICE to operate using an anode off-gas, thus creating a complementary role for an ICE to be paired with a SOFC in a hybrid power generation plant.

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Biodiesel Effects on Influencing Parameters of Brake Fuel Conversion Efficiency in a Medium Duty Diesel Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4001086 ◽

2010 ◽

Vol 132 (12) ◽

Cited By ~ 6

Author(s):

Joshua A. Bittle ◽

Jesse K. Younger ◽

Timothy J. Jacobs

Keyword(s):

Conversion Efficiency ◽

Energy Content ◽

Combustion Efficiency ◽

Operating Conditions ◽

Biodiesel Fuel ◽

Mass Energy ◽

Fuel Conversion ◽

Heating Value ◽

Lower Heating Value ◽

Lower Heating

Biodiesel remains an alternative fuel of interest for use in diesel engines. A common characteristic of biodiesel, relative to petroleum diesel, is a lowered heating value (or per mass energy content of the fuel). For same torque engine comparisons, the lower heating value translates into a higher brake specific fuel consumption (amount of fuel consumed per unit of power produced). The efficiency at which fuel energy converts into work energy, however, may remain unchanged. In this experimental study, evaluating nine unique engine operating conditions, the brake fuel conversion efficiency (an assessor of fuel energy to work energy efficiency) remains unchanged between 100% petroleum diesel fuel and 100% biodiesel fuel (palm olein) at all conditions, except for high load conditions. Several parameters may affect the brake fuel conversion efficiency, including heat loss, mixture properties, pumping work, friction, combustion efficiency, and combustion timing. This article describes a study that evaluates how the aforementioned parameters may change with the use of biodiesel and petroleum diesel, and how these parameters may result in differences in the brake fuel conversion efficiency.

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Performance and fuel conversion efficiency of a spark ignition engine fueled with iso-butanol

Applied Energy ◽

10.1016/j.apenergy.2012.03.012 ◽

2012 ◽

Vol 96 ◽

pp. 477-483 ◽

Cited By ~ 81

Author(s):

Adrian Irimescu

Keyword(s):

Conversion Efficiency ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Fuel Conversion

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Biodiesel Fuel’s Effects on Influencing Parameters of Brake Fuel Conversion Efficiency in a Medium Duty Diesel Engine

ASME 2009 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2009-76081 ◽

2009 ◽

Cited By ~ 7

Author(s):

Joshua A. Bittle ◽

Jesse K. Younger ◽

Timothy J. Jacobs

Keyword(s):

Conversion Efficiency ◽

Energy Content ◽

Combustion Efficiency ◽

Operating Conditions ◽

Biodiesel Fuel ◽

Mass Energy ◽

Fuel Conversion ◽

Heating Value ◽

Lower Heating Value ◽

Lower Heating

Biodiesel remains an alternative fuel of interest for use in diesel engines. A common characteristic of biodiesel, relative to petroleum diesel, is a lowered heating value (or per mass energy content of the fuel). For same-torque engine comparisons, the lower heating value translates into a higher brake specific fuel consumption (amount of fuel consumed per unit of power produced). The efficiency at which fuel energy converts into work energy, however, may remain unchanged. In this experimental study, evaluating nine unique engine operating conditions, brake fuel conversion efficiency (an assessor of fuel energy to work energy efficiency) remains unchanged between 100% petroleum diesel fuel and 100% biodiesel fuel (palm olein) at all conditions except for high load conditions. Several parameters may affect brake fuel conversion efficiency, including heat loss, mixture properties, pumping work, friction, combustion efficiency, and combustion timing. This article describes a study that evaluates how the aforementioned parameters may change with the use of biodiesel and petroleum diesel, and how these parameters may result in differences in brake fuel conversion efficiency.

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Energy Balance and Power Loss Pathway Study of a 120 cc Four-Stroke Internal Combustion Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4038881 ◽

2018 ◽

Vol 140 (7) ◽

Author(s):

Jason R. Blantin ◽

Marc D. Polanka ◽

Joseph K. Ausserer ◽

Paul J. Litke ◽

Jacob A. Baranski

Keyword(s):

Internal Combustion Engine ◽

Conversion Efficiency ◽

Combustion Engine ◽

Internal Combustion ◽

Small Displacement ◽

Fuel Conversion ◽

Performance Improvements ◽

Group 2 ◽

Stroke Engine ◽

Energy Pathways

Efforts to improve the range and endurance of group 2 (10–25 kg), internal combustion engine (ICE) powered unmanned aerial vehicles (UAVs) have been underway for several years at Air Force Research Laboratory (AFRL). To obtain the desired performance improvements, research into improving the overall efficiency of the ICE powerplants is of great interest. The high specific energy of hydrocarbon fuels (13,000 W h/kg for gasoline), but low fuel conversion efficiency for small ICEs means that relatively minor improvements in the fuel conversion efficiency of the engines can yield large improvements in range and endurance. Little information is available however for the efficiency of ICEs in the size range of interest (10–200 cm3 displacement volume) for group 2 UAVs. Most of the currently available efficiency data for 10–200 cm3 ICEs is for two-stroke engines. The goal of this study was to provide an in-depth probe of the efficiency and energy losses of a small displacement four-stroke engine which could potentially be used to power a group 2 UAV. Energy balances were performed on a Honda GX120 four-stroke engine using empirical research methods. The engine was a 118 cm3 displacement, single cylinder ICE. Energy pathways were characterized as a percentage of the total chemical energy available in the fuel. Energy pathways were characterized into four categories: brake power, cooling load, exhaust sensible enthalpy and incomplete combustion. The effect of five operating parameters was examined in the study. Fuel conversion efficiency ranged from 22.2% to 25.8% as engine speed was swept from 2000 to 3600 RPM, from 20.8% to 27.3% as equivalence ratio was swept from 0.85 to 1.25, and from 15.7% to 24.9% as throttle was swept from 28.5% to 100%. Combustion phasing and cylinder head temperature sweeps showed only minor changes in fuel conversion efficiency.

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An experimental study on the fuel conversion efficiency and NOx emissions of a spark-ignition gas engine for power generation by fuel mixture of methane and model syngas (H2/CO)

Journal of Natural Gas Science and Engineering ◽

10.1016/j.jngse.2015.03.004 ◽

2015 ◽

Vol 23 ◽

pp. 517-523 ◽

Cited By ~ 10

Author(s):

Hyoseok Cha ◽

Taejun Eom ◽

Soonho Song ◽

Kwang Min Chun

Keyword(s):

Power Generation ◽

Experimental Study ◽

Conversion Efficiency ◽

Fuel Mixture ◽

Spark Ignition ◽

Nox Emissions ◽

Fuel Conversion ◽

Gas Engine

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Fuel conversion efficiency improvements in a highly boosted spark-ignition engine with ultra-expansion cycle

Energy Conversion and Management ◽

10.1016/j.enconman.2015.06.078 ◽

2015 ◽

Vol 103 ◽

pp. 448-458 ◽

Cited By ~ 13

Author(s):

Tie Li ◽

Bin Zheng ◽

Tao Yin

Keyword(s):

Conversion Efficiency ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Fuel Conversion

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Efficiency Considerations of Later-Phased Low Temperature Diesel Combustion

ASME 2010 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2010-35070 ◽

2010 ◽

Cited By ~ 5

Author(s):

Bryan M. Knight ◽

Joshua A. Bittle ◽

Timothy J. Jacobs

Keyword(s):

Heat Transfer ◽

Low Temperature ◽

Conversion Efficiency ◽

Combustion Efficiency ◽

Diesel Combustion ◽

Low Temperature Combustion ◽

Combustion Mode ◽

Fuel Conversion ◽

Particulate Matter Emissions ◽

Temperature Combustion

Low temperature diesel combustion offers an opportunity to simultaneously and substantially reduce exhaust nitrogen oxides and particulate matter emissions. One issue that remains an area of investigation is the improvement of engine efficiency (i.e., specific fuel consumption) for the novel mode of combustion. The objective of this article is to assess the several parameters (i.e., friction, pumping work, combustion phasing, heat transfer rate, and combustion efficiency) that affect the brake fuel conversion efficiencies of a medium-duty diesel engine as its combustion mode is transitioned from conventional to low temperature. The analysis reveals that, in this study’s development of low temperature combustion, late combustion phasing is the primary factor causing a decrease in brake fuel conversion efficiency. To enable low temperature combustion, combustion is retarded to a point where peak rate of heat release occurs at around 24° after top dead center. Such late combustion misses the opportunity to utilize the full expansion stroke of the piston. Although exhaust hydrocarbon and carbon monoxide concentrations increase as a result of the later-phased low temperature combustion mode, combustion efficiency only drops to around 90%. This decrease in combustion efficiency accounts for only about 18.7% of the corresponding decrease in brake fuel conversion efficiency (the balance decrease being caused by the later-phased combustion). Other factors that typically deteriorate brake fuel conversion efficiency (i.e., pumping work, friction, and rate of heat transfer) are all decreased with this study’s development of low temperature combustion. It is important to note that other implementations of low temperature combustion (e.g., advanced timing low temperature combustion) may not necessarily realize the same reductions in brake fuel conversion efficiency, or reductions may not necessarily be caused by the same dominant factors that are observed in this study’s later-phased low temperature combustion mode.

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