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As an inexpensive and low carbon fuel, the combustion of natural gas reduces fuel cost and generates less carbon dioxide emissions than diesel and gasoline. Natural gas is also a clean fuel that generates less particulate matter emissions than diesel during combustion. Replacing diesel by natural gas in internal combustion engines is of great inter...
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... properties of the diesel fuel are listed in table 2. Natural gas used in the research was supplied by Enbridge Inc. The natural gas composition and lower heating value are listed in Table 3, which are the average values of one week. We noted that standard deviations of methane volume fraction and lower heating value (LHV) of natural gas during a one month period were 0.68% and 0.71%, respectively, suggesting that the variation in natural gas properties was small. ...
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Citations
... According to this, with the increased magnitude of PES, a gradual reduction in CO emission profile has been depicted corresponding to the diesel-hydrogen operation. This is attributed mainly to the increased fractions of premixed combustion due to higher proportions of pilot fuel in the mixture [74]. Thus, the present hydrogen-diesel operational strategy can significantly reduce CO emission footprints. ...
The present study highlights the comparative analysis of diesel-hydrogen and diesel- Liquefied-petroleum-gas bi-fuel operation. It investigates the ignition delay criterion and its effects on performance, emission, and stability characteristics under varying injection and reactivity phasings in an existing single-cylinder diesel engine. The experimental analysis-based statistical modelling approach for simultaneous identification of relative optimum parametric combination to improve the performance, emission, and stability has been incorporated in this study through response surface methodology. It is evident from the results that the different parametric combinations of input variables for both Liquefied-petroleum-gas and hydrogen-enriched diesel operation influenced the combustion parameter (ignition delay), performance, and emission significantly. Subsequently, the ignition delay corresponding to the maximum hydrogen enrichment scenario is 41.2% more than the corresponding Liquefied-petroleum-gas operational mode. Similarly, the exergetic efficiency attained with maximum hydrogen substitution is 9.54% higher than the exergetic efficiency of the corresponding Liquefied-petroleum-gas enriched operation. On the other hand, the minimum footprints of soot, total unburnt hydrocarbon, Carbon monoxide, and Carbon dioxide registered with hydrogen enrichment were 15.77%, 72.45%, 38.48%, and 2.37% lower than the corresponding Liquefied-petroleum-gas enriched operation. In contrast, the lowest recorded value of oxides of nitrogen with Liquefied-petroleum-gas enriched diesel operation was 77.93% lower than the corresponding hydrogen-enriched operation. Thus, the study presents itself as a first-of-a-kind strategy for the comparative analysis of the effect of ignition delay on the performance, emission, and stability matrices of existing infrastructure with diesel- Liquefied-petroleum-gas and diesel-hydrogen operation.
... According to this, with the increased magnitude of PES, a gradual reduction in CO emission profile has been depicted corresponding to the diesel-hydrogen operation. This is attributed mainly to the increased fractions of premixed combustion due to higher proportions of pilot fuel in the mixture [74]. Thus, the present hydrogen-diesel operational strategy can significantly reduce CO emission footprints. ...
To exploit the potential benefits of reactivity controlled combustion (RCCI) of methanol induced diesel dual fuel operation under split injection strategy, the present study has adopted data driven surrogate modelling technique in contrast to the computationally expensive computational fluid dynamics (CFD) platform. For the partial replacement of conventional diesel fuel, port premixed methanol has been introduced in this study as a renewable alternative energy resource considering its renewability and sustainability perspectives [E-fuel]. To explore the challenges and opportunities of RCCI operation the response parameters of nitrogen oxides (NOx), soot, unburned hydrocarbon (UHC), carbon-dioxide (CO2), exergy efficiency and co-efficient of variation of indicated mean effective pressure (COVIMEP) have been studied considering pilot (PIA) and main injection timings (MIA), overall reactivity (R0) and pilot injection mass percentage (PIM) of diesel fuel as the control parameters. A constrained optimization study has been carried out in this investigation based on the response surface methodology under the respective constraints of emission elements as per the EPA Tier-4 emission mandates and operational stability. The study also incorporated a novel customized design of experiment (DoE) for the multivariate exploration of design space followed by a thorough analysis of the robustness of design space, which has been characterized through the measures of fraction of design space (FDS) metric, D-optimality criteria, G-efficiency and condition number (CoN). Further, desirability based multi-criteria decision making approach has been undertaken wherein, the highest desirability was observed as 0.832. Subsequently the optimization results revealed that the footprints of NOx, soot, UHC, CO2 and COVIMEP were improved by 3.59%, 96.2%, 49.3%, 2.5% and 15.95% respectively compared to the experimental investigation. Besides, with respect to the limits for emission elements specified in the EPA Tier 4 norms, the study yielded 77 and 73.33% lower footprint of NHC and PM compared to the limits specified as constraints. The study further revealed that the CO2 emission is 42.3% less than the amount of CO2 consumed in the process of methanol production, which eventually displays the potential of such RCCI operational regime in addressing the carbon emissions crisis.
... Several strategies have been investigated to improve the thermal efficiency and unburned methane and GHG emissions of NDDF engines at low to medium load conditions. Advancing diesel injection timing [11,14,16,[18][19][20], increasing diesel injection rail pressure [21][22][23], using split diesel injection [15,[24][25][26][27], and stratification of natural gasair mixture [28][29][30][31] have been the most important strategies to achieve these goals. ...
Natural gas/diesel dual-fuel (NDDF) engine technology is an interesting concept for decreasing greenhouse gas (GHG) emissions of heavy-duty diesel engines. One of the main limitations of this concept is the emissions of unburned methane which is estimated to have a GHG potential factor of 25 – 34 over a 100-year period. Our previous study has shown that a NDDF engine using pre-main-post diesel injection strategy can reduce unburned methane emissions, but yields lower indicated thermal efficiency (ITE) and higher carbon dioxide (CO2) and nitrogen oxides (NOx) emissions compared to that using single diesel injection strategy under high engine load conditions due to the advanced combustion phasing. In this study, the combustion phasing of pre-main-post diesel injection strategy is further optimized with the goal to improve the ITE and reduce the GHG and NOx emissions without compromising the unburned methane emissions when compared to single injection strategy. The results reveal that changing pre diesel injection timing gives more controllability of the combustion phasing than changing the main and post diesel injection timing. A more homogenous premixed mixture of pre injected diesel – natural gas – air retards the combustion phasing which allowed further improvement of the ITE and GHG emissions of NDDF engines while maintaining the low unburned methane emissions feature of the pre-main-post injection strategy. It is found that the optimized pre-main-post diesel injection strategy is able to reduce unburned methane, GHG, and NOx emissions by 13.4%, 1.5%, and 42%, respectively, and increase ITE by 0.37% compared to single injection strategy.
... The drawback of diesel/natural gas dual-fuel engine technology resides in its poor thermal efficiency and HC and CO emissions at low load conditions [8,11,12]. Limitation of dual-fuel diesel/natural gas engines at low loads can be identified by the pattern of combustion phasing in the engine cylinder. There are several combustion stages under this load, including diesel ignition, diesel diffusion, and natural gas ignition [3]. ...
... Several diesel injection strategies have been examined and shown to improve thermal efficiency and reduce unburned hydrocarbons (UHC) and CO emissions of diesel/natural gas dual-fuel engine at low loads [2,5,9,15,16]. Advancing diesel injection timing [12], increasing diesel fuel injection pressure [17], and splitting diesel fuel injection [11] are some of these strategies. ...
The combination of diesel and natural gas fuels has superior performance in terms of nitrogen oxides (NOx) and particulate matter (PM) emissions when compared to conventional diesel engine. However, this advantage does not hold at low load operating conditions as indicated thermal efficiency (ITE), carbon monoxides (CO), and unburned hydrocarbon (HC) emissions deteriorate. Most published studies tried to resolve this drawback using diesel split injection. However, the present study evaluates natural gas split injection strategy as an alternative to improve the performance and emissions of diesel/natural gas dual-fuel engines at low load conditions. The results show that natural gas split injection with proportional split injection ratio (ISR) and small dwelling timing improves NOx, CO, and HC emissions. Moreover, split injection of natural gas with proportional ISR after intake valve closing (IVC) is found to improve SFC, ITE, and power. Conversely, natural gas split injection strategy with proportional ISR after intake valve opening (IVO) yields poor engine performance. Overall, split injection of natural gas with low ISR yields the greatest engine performance at long dwelling time, whereas it worsens emissions compared to single injection of natural gas at 560°CA ATDC, which serves as the baseline condition. However, very low CO and HC emissions of natural gas split injection is achieved at low ISR and short dwelling time. Finally, this study reveals also that stratification of air/natural gas mixture due to natural gas split injection strategy can significantly improve the performance and emissions of dual-fuel diesel/natural gas engine at low load conditions.
... HC and CO emissions tend to be significantly higher [15,16,19,20,22,25,26], and a worsening is often observed also in terms of NO x and BTE [15,20,21,24,26]. In practice, the goal of a clean and efficient DF NG-Diesel combustion can be achieved only with the support of a modern Diesel injection system and a full electronic control [12,21,22,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41]. ...
... However, most of the experimental investigations are conducted on single-cylinder research engines [12,17,18,24,19,20,21,25,26,27,28,31,32,33,44], completely different from modern light-duty Diesel units. In other cases, HD engines are considered [13,22,29,34,35,36,38]. In the few cases where a modern automotive light-duty engine equipped with Common Rail is investigated [37,39], the experimental campaign is carried out only at low loads (BMEP < 4 bar); in other publications [14,45,46,47,41], the experimental measures are taken only to calibrate a 3D CFD model, which is then used as the main investigation tool. ...
... Methane emissions can therefore offset the advantage of lower CO 2 emissions of the dual-fuel engines, especially at low load conditions. Advanced combustion strategies have been proposed that can minimize the methane emissions at low loads (Srinivasan et al., 2006;Guo et al., 2017;Yousefi et al., 2018). At medium to high load conditions, owing to the high fueling rate and higher temperatures which result in higher flame propagation speed, methane emissions are much lower than that at low load conditions, but they may still be greater than those of diesel engines (Papagiannakis and Hountalas, 2003). ...
... There are many examples in literature that have summarized the fundamental performance of such dualfuel engines (Karim, 1980;Wagemakers and Leermakers, 2012;Wei and Geng, 2016). There have also been researches on the effect of the injection parameters of NG and diesel of dual-fuel engines with the aim to improve engine efficiency and reduce methane emissions (Figer et al., 2014;Yang et al., 2015;Guo et al., 2017). Increasing the NG fraction in the total fuel energy input, especially at low and intermediate loads, can cause the brake thermal efficiency (BTE) to decrease and the carbon monoxide and methane emissions to increase (Papagiannakis et al., 2010;Imran et al., 2014). ...
... The authors' laboratory has previously studied pollutant emissions from dual-fuel engines including the pollutant formation mechanisms (Guo et al., 2017;Li et al., 2018). The present work builds on the previous research by studying the effect of increasing NG fraction and DI timing (of diesel) on engine performance and exhaust emissions at high load-low speed operating conditions. ...
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 (CO 2 ), nitrogen oxides (NOx), and particulate matter (PM) emissions. One solution to reduce the CO 2 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 CO 2 emissions (cumulative greenhouse gas effect of CO 2 and CH 4 ) 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 CO 2 -equivalent emissions.
... A single cylinder, four stroke Caterpillar 3401 heavy-duty engine coupled with an eddy-current dynamometer was used to investigate the impact of single and split diesel injection strategies on knocking intensity, combustion performance, and unburned methane, GHG and NO x emissions of NDDF engine technology. The characteristics of the engine used in this study have been described elsewhere [39], and thus only a brief summary is given in this paper. Fig. 1 shows a schematic of the engine setup and Tables 1 and 2 provide the engine specifications and fuel properties. ...
Advancing the start of diesel injection timing is an effective way to enhance thermal efficiency and reduce greenhouse gas (GHG) emissions of natural gas/diesel dual-fuel (NDDF) engine. However, severe thermodynamic conditions under high engine load conditions may increase the propensity for engine knocking when advancing the start of diesel injection (SODI). In this study, the strategy of split diesel injection (two-pulse injection) is used and its feasibility as a method to reduce knocking intensity and improve thermal efficiency of NDDF engine is investigated. The results reveal that advancing single diesel injection timing significantly increases knocking intensity, whereas split diesel injection strategy decreases knocking intensity. The results also show that, when using split diesel injection, the flame kernels do not propagate as fast and deep as in the case of single diesel injection. This slows down the pressure and temperature rise rate in the unburned end-gas region and thus reduces knocking tendency. Moreover, the early partially burning of the premixed natural gas – air mixture in the squish region dilutes the unburned end-gas and consequently makes it resistant to auto-ignition. NDDF engine with split diesel injection can reach a maximum thermal efficiency that is comparable to that observed under knocking conditions of single diesel injection. Using either, single or split,
diesel injection strategy reduces GHG emissions of NDDF engine (up to 12%) compared to its counterpart diesel engine. However, the lowest GHG emissions of NDDF engine with single diesel injection strategy is recorded under knocking conditions.
... Among the strategies that have been carried out, the split injection strategy for diesel fuel is a strategy that is widely used today to improve exhaust emissions and combustion quality, especially at low loads on dual-fuel engines. Guo et al. [6] identified the impact of the split pilot diesel strategy on dual-fuel engines on performance and exhaust emissions, especially under low load conditions. HC emissions can be reduced by advancing the diesel injection timing. ...
... Many studies have been conducted for various issues of dual fuel engines [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Our previous studies investigated the combustion and emission performance of a dual fuel engine at low and medium loads using conventional diesel injection strategies [8], effect of split diesel injection on engine performance at low load condition [23], unburned hydrocarbon emissions [6], and injection tip temperature performance of dual fuel engines [24]. We also conducted numerical studies to understand the fundamental mechanisms of CH4 and NO2 emissions [25][26][27][28] in dual fuel engines. ...
... The original engine was modified to suit for dual fuel combustion. More details of the engine can be found elsewhere [6,8,23,24]. Fig. 1 Schematic of experimental setup. ...
... They are three typical modes in AVL 8model heavy duty test cycle. The load of 4.05 bar BMEP is a typical low load condition and has been investigated in our previous studies [6,23], but is still included in this paper for the sake of comparison. The other two conditions are two typical high load conditions with low and high speeds, respectively. ...
The Paris agreement is exerting pressure on industries that generate significant greenhouse gas (GHG) emissions, such as transportation. Electrification can help reduce GHG emissions from light duty vehicles, but it is unfeasible for heavy duty vehicles that are predominately powered by diesel engines. Fuel switching from diesel to low carbon fuels is a more practical way helping reduce GHG emissions from heavy duty vehicles. Natural gas and renewable natural gas are low carbon or renewable fuels that generate much less carbon dioxide (CO2) emissions than diesel during combustion. Natural gas/renewable natural gas – diesel dual fuel combustion is an efficient way to replace diesel by natural gas/renewable natural gas in heavy duty diesel engines.
This paper reports an experimental investigation on combustion and GHG emissions of a heavy duty natural gas – diesel dual fuel engine at different load/speed conditions. The variation in the effect of natural gas fraction on engine performance with changing engine load was compared and analyzed. Nitrous oxide (N2O), nitrogen oxides (NOx), methane (CH4) and CO2 emissions were experimentally investigated and analyzed. The results revealed that the effect of natural gas fraction on engine performance changed with varying engine load and speed condition. N2O emissions from a dual fuel engine changed with increasing natural gas fraction, but the effect of N2O emissions on overall GHG emissions was not significant. However, CH4 emissions contributed significantly to the overall GHG emissions in a dual fuel engine, especially at low load conditions.
... Therefore, NOx increased by 74% due to the faster combustion process. In this method, earlier injection timing is necessary to increase the peak pressure rise rate [47]. When tested numerically by Wu, et al. [48] against two combustion chamber models, in the form of stock and bathtub, there are fewer significant differences. ...
Ship main engine exhaust gas emissions are a worldwide concern. Dual fuel diesel engines are a type of ship main engine that complies with MARPOL Annex VI. Low exhaust emissions and operational cost are the main advantages of using natural gas as fuel. Moreover, the use of natural gas improves lean combustion process; it results in fewer exhaust emissions and improves performance. Some technical adjustments are required to achieve maximum efficiency. This paper has reviewed various technical approaches to understand the combustion phenomenon of natural gas dual fuel engine diesel with experimental and numerical studies. Gaseous fuel/air mixture phenomena, pilot-fuel injection, and flame propagation processes that occur in the cylinder chamber are reviewed. Some improvements to the variation of test parameters of dual fuel diesel engines are highlighted to determine the characteristics. Additionally, the impact of natural gas-diesel dual fuel engines for performance and emissions is accurately described.
