scholarly journals Fuel reforming engine system using low concentration hydrous ethanol with improved thermal efficiency and low NOx emissions

2016 ◽  
Vol 82 (840) ◽  
pp. 15-00573-15-00573 ◽  
Author(s):  
Yuzo SHIRAKAWA ◽  
Atsushi SHIMADA ◽  
Takao ISHIKAWA
Keyword(s):  
Thermal Efficiency ◽  
Nox Emissions ◽  
Fuel Reforming ◽  
Low Concentration ◽  
Engine System ◽  
Hydrous Ethanol

Numerical Studies of Novel Aero Engine Secondary Combustors for Low-NOx Emissions

2020 ◽  
Author(s):  
Andrew Rolt ◽  
Victor Martínez Bueno ◽  
Mirko Romanelli ◽  
Xiaoxiao Sun ◽  
Pierre Gauthier ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Pressure Ratio ◽  
Flow Region ◽  
Nox Emissions ◽  
Low Oxygen ◽  
Engine Operation ◽  
Horizon 2020 ◽  
Novel Technologies ◽  
Numerical Studies ◽  
Aero Engine

Abstract Gas turbine thermal efficiency and fuel burn are very dependent on turbine entry temperature and overall pressure ratio (OPR). Unfortunately, increases in these two parameters compromise other key aspects of engine operation and tend to increase emissions of nitrogen oxides (NOx). The European Horizon 2020 ULTIMATE project researched advanced-cycle aero engines with synergistic combinations of novel technologies to increase thermal efficiency without increasing emissions. One candidate technology was the addition of secondary combustion to increase the mean temperature of heat addition to improve thermal efficiency while limiting the primary combustor flame temperatures and NOx formation. However, an overall reduction in NOx also requires the secondary combustor to be a low-NOx design. This paper describes numerical studies carried out on novel aero engine secondary combustor concepts developed in two MSc-thesis research projects. The studies have explored the potential of oxy-poor-flame combustion concepts. These annular combustor designs featured two distinct regions: (i) the vortex zone, which promotes recirculation of combustion products, a prerequisite for low-oxygen combustion, and (ii) a through-flow region where part of the incoming flow bypasses the vortex before the flows mix again. These studies have demonstrated the advantages and some limitations of the proposed designs and emissions assessments in comparison with previous secondary combustor studies. They suggest very low NOx is achievable with oxy-poor combustion, but will be more difficult if the incoming oxygen levels are above 10%. More-accurate assessments will require LES modelling and inclusion of the primary combustor in the simulations. However, if the low overall NOx emissions would include relatively higher levels of nitrous oxide (N2O) then this might raise concerns with respect to global warming.

Experimental Study on the Combustion Process and Performance of Diesel Engines Fueled by Emulsion Diesel With Novel Organic Additives

2013 ◽  
Author(s):  
Wenming Yang ◽  
Hui An ◽  
Jing Li ◽  
Amin Maghbouli ◽  
Kian Jon Chua
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Thermal Efficiency ◽  
Gasoline Engine ◽  
Combustion Process ◽  
Nox Emissions ◽  
Organic Additives ◽  
Oil Droplets ◽  
And Performance ◽  
One Year

Transportation is one of the major contributors to the world’s energy consumption and greenhouse gases emissions. The need for increased efficiency has placed diesel engine in the spotlight due to its superior thermal efficiency and fuel economy over gasoline engine. However, diesel engines also face the major disadvantage of increased NOx emissions. To address this issue, three types of emulsion fuels with different water concentrations (5%, 10% and 15% mass water) are produced and tested. Novel organic materials (glycerin and ployethoxy-ester) are added in the fuel to provide extra oxygen for improving combustion. NP-15 is added as surfactant which can help to reduce the oil and water surface tension, activates their surface, and maximizes their superficial contact areas, thereby forming a continuous and finely dispersed droplets phase. The stability of the emulsion fuels is tested under various environmental temperature for one year, and no significant separation is observed. It is better than normal emulsion fuel which can only maintain the state for up to three months. The combustion process and performance of the emulsion fuels are tested in a four-stroke, four cylinder diesel engine. The results indicate that the water droplets enclosed in the emulsion fuel explode at high temperature environment and help to break up the big oil droplets into smaller ones, thereby significantly increase the surface area of the oil droplets and enhance the heat transfer from hot gas to the fuel. As a result, the fuel evaporation is improved and the combustion process is accelerated, leading to an improved brake thermal efficiency (up to 14.2%). Meanwhile, the presence of the water causes the peak temperature of the flame to drop, thereby significantly bringing down the NOx emissions by more than 30%.

Advanced Combustion System Solutions for Increasing Thermal Efficiency in Natural Gas Engines While Meeting Future Demand for Low NOx Emissions

2007 ◽  
Author(s):  
Luigi Tozzi ◽  
Emmanuella Sotiropoulou ◽  
Paul Hicks
Keyword(s):  
Thermal Efficiency ◽  
Flow Fields ◽  
High Energy ◽  
High Flow ◽  
Electrode Erosion ◽  
Nox Emissions ◽  
Combustion System ◽  
Electrode Gap ◽  
Advanced Combustion ◽  
Spark Plug

Key requirements for state of the art industrial gas engines are high engine thermal efficiency, high engine brake mean effective pressure (BMEP), low NOx emissions, and acceptable spark plug life. Fundamentally, as engine thermal efficiency and power density increase, along with the requirement of reduced NOx emissions, the pressure at the time of ignition increases. This results in a higher spark breakdown voltage that negatively affects spark plug life. This problem is resolved with a smaller electrode gap and high spark energy to overcome quenching effects during ignition kernel development. High flow fields in the spark gap region are required to assure the spreading of the discharge, which reduces the rate of electrode erosion. In addition, these high flow fields overcome mixture inhomogeneities by developing large ignition kernels. These large ignition kernels, inside the prechamber spark plug, produce high velocity flame jets into the main chamber enhancing combustion, which results in thermal efficiency gains at lower NOx levels and higher BMEP. The advanced combustion system solution discussed in this paper is the combination of high-energy ignition and a prechamber spark plug with flow fields at the electrode gap. Future developments include improved ion signal quality detonation detection resulting in additional gains in thermal efficiency.

An Experimental Investigation of Reactivity-Controlled Compression Ignition Combustion in a Single-Cylinder Diesel Engine Using Hydrous Ethanol

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Wei Fang ◽  
Junhua Fang ◽  
David B. Kittelson ◽  
William F. Northrop
Keyword(s):  
Experimental Investigation ◽  
Diesel Engine ◽  
Thermal Efficiency ◽  
Alternative Fuels ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Single Cylinder ◽  
Diesel Injection ◽  
Soot Emissions ◽  
Hydrous Ethanol

Dual-fuel reactivity-controlled compression ignition (RCCI) combustion using port injection of a less reactive fuel and early-cycle direct injection (DI) of a more reactive fuel has been shown to yield both high thermal efficiency and low NOX and soot emissions over a wide engine operating range. Conventional and alternative fuels such as gasoline, natural gas, and E85 as the lower reactivity fuel in RCCI have been studied by many researchers; however, published experimental investigations of hydrous ethanol use in RCCI are scarce. Making greater use of hydrous ethanol in internal combustion engines has the potential to dramatically improve the economics and life cycle carbon dioxide emissions of using bioethanol. In this work, an experimental investigation was conducted using 150 proof hydrous ethanol as the low reactivity fuel and commercially available diesel as the high reactivity fuel in an RCCI combustion mode at various load conditions. A modified single-cylinder diesel engine was used for the experiments. Based on previous studies on RCCI combustion by other researchers, early-cycle split-injection strategy of diesel fuel was used to create an in-cylinder fuel reactivity distribution to maintain high thermal efficiency and low NOX and soot emissions. At each load condition, timing and mass fraction of the first diesel injection was held constant, while timing of the second diesel injection was swept over a range where stable combustion could be maintained. Since hydrous ethanol is highly resistant to auto-ignition and has large heat of vaporization, intake air heating was needed to obtain stable operations of the engine. The study shows that 150 proof hydrous ethanol can be used as the low reactivity fuel in RCCI through 8.6 bar indicated mean effective pressure (IMEP) and with ethanol energy fraction up to 75% while achieving simultaneously low levels of NOX and soot emissions. With increasing engine load, less intake heating is needed and exhaust gas recirculation (EGR) is required to maintain low NOX emissions.

A Highly Efficient Small-Displacement Marine Two-Stroke H2DI Engine With Low Emissions

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
David Oh ◽  
Jean-Sébastien Plante
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Cost Effective ◽  
Current Status ◽  
Small Displacement ◽  
Injection Timing ◽  
Nox Emissions ◽  
Indicated Mean Effective Pressure ◽  
Fuel Delivery ◽  
Gas Measurements

A hydrogen-fueled two-stroke prototype demonstrator based on a 9.9 hp (7.4 kW) production gasoline marine outboard engine is presented, which, while matching the original engine's rated power output on hydrogen, achieves a best-point gross indicated thermal efficiency (ITE) of 42.4% at the ICOMIA mode 4 operating point, corresponding to 80% and 71.6% of the rated engine speed and torque, respectively. The brake thermal efficiency (BTE) at the rated power is 32.3%. Preliminary exhaust gas measurements suggest that the engine could also meet the most stringent CARB 5-Star marine spark-ignition emission standards limiting HC + NOx emissions to 2.5 g/kWh without any after-treatment. These are realized in a cost-effective concept around a proven two-stroke base engine and a low-pressure direct-injected gaseous hydrogen (LPDI GH2) system, which employs no additional fuel pump and is uniquely adapted from volume production components. Later fuel injection is found to improve thermal efficiency at the expense of increased NOx emissions and, at the extreme, increased cyclic variation. These observations are hypothesized and supported by phenomenological inferences of the observed trends of combustion duration, NOx concentration, and indicated mean effective pressure (IMEP) variance to be due to increasing charge stratification with the later timings. This work outlines the pathway—including investigations of several fuel delivery strategies with limited success—leading to the current status, including design, modeling with GT-POWER, delivery of lube oil, lubrication issues using hydrogen, and calibration sweeps. The experimental results comprising steady-state dynamometer performance, cylinder pressure traces, NOx emission measurements, along with heat release analyses, support the reported numbers and the key finding that late fuel injection timing and charge stratification drive the high efficiencies and the NOx trade-off; this is discussed and forms the basis for future work.

scholarly journals Evaluation Dual Fuel Engine Fuelled With Hydrogen and Biogas as Secondary Fuel

2019 ◽  
Vol 8 (2) ◽  
pp. 1902-1905
Keyword(s):  
Diesel Engine ◽  
Thermal Efficiency ◽  
Dominant Role ◽  
Single Mode ◽  
Dual Fuel ◽  
Nox Emissions ◽  
Brake Thermal Efficiency ◽  
Pilot Fuel ◽  
Present Context ◽  
Inlet Manifold

The present energy scenario hydrogen fuel plays a dominant role in the power generation. Due to its unique characteristics of an extensive range of flammability, high flame speed, and diffusivity. In this present investigation, the diesel engine is converted into dual-fuel mode devoid of major conversions of the engine. The tests are performed on a dual-fuel mode and investigated the efficiency, emissions, and combustion features of the diesel engine. In the present context, hydrogen and biogas are injected from the inlet manifold as subsidiary fuel and diesel are injected as pilot fuel. The gaseous fuel injected in two different flow rates they are, 3 litres per minute (lpm), and 4lpm. The results from the experimentation revealed that the diesel with 4 lpm of hydrogen shows the 31.11 % enhancement of brake thermal efficiency but it shows 4.14% higher NOX emissions when compared with the pure diesel. But it shows. At the same time diesel with 4 lpm of Biogas exhibits 15.90% enhancement of brake thermal efficiency and 8.96% decrease in the NOX emissions in contrast to that of the single-mode of fuel with diesel.

scholarly journals A Study on the High Load Operation of a Natural Gas-Diesel Dual-Fuel Engine

2020 ◽  
Vol 6 ◽  
Author(s):  
Shouvik Dev ◽  
Hongsheng Guo ◽  
Brian Liko
Keyword(s):  
Particulate Matter ◽  
Natural Gas ◽  
Diesel Engines ◽  
Thermal Efficiency ◽  
Direct Injection ◽  
High Load ◽  
Dual Fuel ◽  
Nox Emissions ◽  
Brake Thermal Efficiency ◽  
Dual Fuel Engines

Diesel fueled compression ignition engines are widely used in power generation and freight transport owing to their high fuel conversion efficiency and ability to operate reliably for long periods of time at high loads. However, such engines generate significant amounts of carbon dioxide (CO2), nitrogen oxides (NOx), and particulate matter (PM) emissions. One solution to reduce the CO2 and particulate matter emissions of diesel engines while maintaining their efficiency and reliability is natural gas (NG)-diesel dual-fuel combustion. In addition to methane emissions, the temperatures of the diesel injector tip and exhaust gas can also be concerns for dual-fuel engines at medium and high load operating conditions. In this study, a single cylinder NG-diesel dual-fuel research engine is operated at two high load conditions (75% and 100% load). NG fraction and diesel direct injection (DI) timing are two of the simplest control parameters for optimization of diesel engines converted to dual-fuel engines. In addition to studying the combined impact of these parameters on combustion and emissions performance, another unique aspect of this research is the measurement of the diesel injector tip temperature which can predict potential coking issues in dual-fuel engines. Results show that increasing NG fraction and advancing diesel direct injection timing can increase the injector tip temperature. With increasing NG fraction, while the methane emissions increase, the equivalent CO2 emissions (cumulative greenhouse gas effect of CO2 and CH4) of the engine decrease. Increasing NG fraction also improves the brake thermal efficiency of the engine though NOx emissions increase. By optimizing the combustion phasing through control of the DI timing, brake thermal efficiencies of the order of ∼42% can be achieved. At high loads, advanced diesel DI timings typically correspond to the higher maximum cylinder pressure, maximum pressure rise rate, brake thermal efficiency and NOx emissions, and lower soot, CO, and CO2-equivalent emissions.

Stoichiometric Operation of a Gas Engine Utilizing Synthesis Gas and EGR for NOx Control

2000 ◽  
Vol 122 (4) ◽  
pp. 617-623 ◽  
Author(s):  
Jack A. Smith ◽  
Gordon J. J. Bartley
Keyword(s):  
Natural Gas ◽  
Synthesis Gas ◽  
Engine Performance ◽  
Constant Load ◽  
Nox Emissions ◽  
Fuel Reforming ◽  
Southwest Research Institute ◽  
Performance And Emissions ◽  
Nox Control ◽  
Engine Performance And Emissions

This paper presents the results from an internal research study conducted at the Southwest Research Institute (SwRI) on the effects of stoichiometric mixtures of natural gas and synthesis gas with exhaust gas recirculation (EGR) on engine performance and exhaust emissions. Constant load performance and emissions tests were conducted on a modified, single-cylinder, Caterpillar 1Y540 research engine at 11.0 bar (160 psi) bmep. Engine performance and emissions comparisons between natural gas with EGR, and natural gas with syngas and EGR are presented. In addition, the performance characteristics of the fuel reforming catalyst are presented. Results show that thermal efficiency increases with increasing EGR for both natural gas operation and natural gas with syngas operation at constant load. The use of syngas with natural gas extended the EGR tolerance by 44.4 percent on a mass basis compared to natural gas only, leading to a 77 percent reduction in raw NOx emissions over the lowest natural gas with EGR NOx emissions. [S0742-4795(00)00504-4]

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