Impact Of Exhaust Gas Recirculation Research Articles

Impact of exhaust gas recirculation and nitric oxide on the autoignition of an oxygenated gasoline: Experiments and kinetic modelling

Exhaust gas recirculation (EGR) and NOx affect the autoignition of gasoline in internal combustion engines. In this work, ignition delay times of an oxygenated gasoline (Euro 6 E10) are investigated with EGR and NOx addition. The experimental data are of interest for gasoline surrogate modeling and for predicting fuel ignition behavior in various engine combustion modes. We studied Euro 6 E10 reactivity with EGR additions of 20 % and 40 % (by mass) doped, in select cases, with high levels of NOx (874, 1501, 3174, and 5568 ppm, by mol%). Experiments were performed in two high-pressure shock tubes (HPSTs) and two rapid compression machines (RCMs) over a wide range of temperature (658–1610 K), equivalence ratio (0.5, 1.0) and at pressures of 20 and 30 bar. Results show that EGR addition inhibits Euro 6 E10 gasoline reactivity in the intermediate- and low-temperature regimes, while it is minimally affected at high-temperatures. In contrast, a strong reactivity-promoting effect of NOx is observed at temperatures greater than 825 K for all equivalence ratios investigated, while an inhibiting effect is seen at lower temperatures with a high doping of NOx (1501 ppm). For fuel-lean cases, where Euro 6/EGR mixtures are sensitized with 3174 – 5568 ppm NOx, a significant reactivity-promoting effect is observed across the entire range of conditions investigated, except at temperatures below 830 K, where the NOx-inhibiting effect dominates. A gasoline surrogate model is developed by combining a detailed gasoline surrogate mechanism with appropriate sub-models and making minor updates. The proposed model captures well the influence of EGR and EGR/NOx on Euro 6 E10 autoignition over the wide range of conditions studied here. Finally, sensitivity analyses were conducted to identify key reactions contributing to the perturbative effects of EGR and EGR/NOx on oxygenated gasoline ignition.

Study on the Effects of the Hydrogen Substitution Rate on the Performance of a Hydrogen–Diesel Dual-Fuel Engine under Different Loads

Due to having zero carbon emissions and renewable advantages, hydrogen has great prospects as a renewable form of alternate energy. Engine load and hydrogen substitution rate have a considerable influence on a hydrogen–diesel dual-fuel engine’s efficiency. This experiment’s objective is to study the influence of hydrogen substitution rate on engine combustion and emission under different loads and to study the impact of exhaust gas recirculation (EGR) technology or main injection timing on the engine’s capability under high load and high hydrogen substitution rate. The range of the maximum hydrogen substitution rate was determined under different loads (30%~90%) at 1800 rpm and, then, the effects of the EGR rate (0%~15%) and main injection timing (−8 °CA ATDC~0 °CA ATDC) on the engine performance under 90% high load were studied. The research results show that the larger the load, the smaller the maximum hydrogen substitution rate that can be added to the dual-fuel engine. Under each load, with the increase of the hydrogen substitution rate, the cylinder pressure and the peak heat release rate (HRR) increase, the equivalent brake-specific fuel consumption (BSFCequ) decreases, the thermal efficiency increases, the maximum thermal efficiency is 43.1%, the carbon dioxide (CO2) emission is effectively reduced by 35.2%, and the nitrogen oxide (NOx) emission decreases at medium and low loads, and the maximum increase rate is 20.1% at 90% load. Under high load, with the increase of EGR rate or the delay of main injection timing, the problem of NOx emission increases after hydrogen doping can be effectively solved. As the EGR rate rises from 0% to 15%, the maximum reduction of NOx is 63.1% and, with the delay of main injection timing from −8 °CA ATDC to 0 °CA ATDC, the maximum reduction of NOx is 44.5%.

Quantification of φ-operating range with impact of exhaust gas recirculation under low-temperature combustion mode with polyoxymethylene dimethyl ether: A perspective study

Low-Temperature Combustion (LTC) especially Homogeneous charge compression ignition (HCCI) mode of combustion is a capable substitute mode of combustion to conventional diesel combustion (CDC) to provide better soot-NOx trade-off and HC-CO trade-off characteristics. The current study mainly focuses on the Exhaust Gas Recirculation (EGR) effects and equivalence ratio optimization on W20P20 (64% diesel, 16% WCO biodiesel, and 20% PODE) fuel along with exergy analysis in the HCCI mode of operation. The reason for inculcating exergy analysis in this research is to depict that low-temperature combustion provides a better heat transfer rate inside the cylinder. EGR has been varied in terms of 10%, 20%, and 30% in volume proportions along with the inlet fuel-air mixtures since, the fuel was injected through a pilot fuel injector in the inlet manifold. A novel factor in this research is considering both soot-NOx and HC-CO trade-off characteristics in optimizing the equivalence ratio with the influence of EGR over W20P20 fuel. The performance parameters such as BTE and BSEC show a mere decrement of about 6.67% and 29% of maximum with the influence of EGR while better combustion was found in terms of avoiding misfiring at a low equivalence ratio of 0.29–0.35 and knocking at a high equivalence ratio of 0.61–0.71 for W20P20 fuel. The operating range extension of the equivalence ratio was found with W20P20 fuel which further increased again with the increase in EGR addition. The emission limits of soot, NOx, CO, and HC particles were analyzed, in which the highest NOx reduction of 53% was obtained with 30% EGR irrespective of the equivalence ratio. The highest soot reduction was 61.85% with 20% EGR at a higher equivalence ratio. The highest HC reduction was 18% with 20% EGR at a lower equivalence ratio. The CO emissions seemed to reduce by 12% at a lower equivalence ratio while they increased by 47% at a higher equivalence ratio. The comparative results were studied for EGR influence with W20P20 fuel in the HCCI mode of combustion.

An experimental study on biodiesel production and impact of EGR in a CRDI diesel engine propelled with leather industry waste fat biodiesel

The purpose of the predominant endeavor is the way of through an experiment aspect for the reticular effect of exhaust gas recirculation (EGR) on combustion, performance, emissions besides energy characteristic of common rail direct injection (CRDI) engine fuelled with leather industry waste fat biodiesel and diesel blends. Biodiesel was converted by the transesterification process from the raw fat oil extracted with leather waste fat feedstock. This work takes advantage of blends of both like B10, B20, B30 along with engines that were run with various EGR rates (5%, 10%, and 15%) to evaluate engine outcome parameters. The maximum in-cylinder pressure was examined with the blend B20 with EGR 5% rate about 6.65% higher than pure diesel fuel. The high heat release rate (HRR) was ascertained with the blend B30 with EGR 10% rate about 23.81% higher than neat diesel fuel. The brake thermal efficiency (BTE) for the blend B10 with EGR 5% rate is higher than other test conditions but 4.2% let down associated with simple diesel fuel. The nitrogen oxides (NOx) were lesser than the clean diesel fuel at all test fuels, the highest NOx emission reduction was achieved in blend B30 with EGR 15% rate of about 87.59% than neat diesel fuel operation. The smoke opacity increased by raising the EGR level, the combination B30 with EGR 5% rate displayed low smoke opacity about 64.5% lower than neat diesel fuel. The hydrocarbon (HC) emission was lower than neat diesel at a low EGR rate, the blend B10 with EGR 5% rate displayed the lowest HC emission about 85.71% decreased then neat diesel operation. The carbon monoxide (CO) emission displayed lower than neat diesel at low EGR rate, the blend B10 with EGR 5% rate displayed the lowest CO emission about 50% than neat diesel. As of energy analysis, it was noted that the heat equivalent to brake power and heat lost to engine cooling water is higher in diesel fuel than biodiesel blends and the heat lost to exhaust gases and heat unaccounted loss were lower in diesel than biodiesel blend. Finally, the TOPSIS optimization study was carried out for finding the optimum input conditions which could result in improved combustion, performance, and reduced emissions. The B30% blend with EGR 15% at full load achieved 1st rank with 0.849 relative closeness value. So, this operating condition was projected as the best prospect for the application of a CRDI diesel engine.

Impact of exhaust gas recirculation and split injection strategy combustion behavior on premixed charge compression ignition engine fuelled with moringa oleifera methyl ester

Influence of split injection strategy of moringa oleifera methyl ester and its blends with exhaust gas recirculation on diesel engine combustion, performance and emission characteristics using common rail direct injection (CRDI) system were investigated in this work. In split injection strategy, the pilot (PIT) and main injection timings (MIT) were fixed between 35 °CA – 40 °CA bTDC and 15 °CA –25 °CA bTDC, respectively. The minimum and maximum nozzle opening pressure were fixed as 300 and 600 bar with an interval of 100 bar. In addition, 10% to 30% of EGR flow rate was introduced with an interval of 5%. Experimental results reveal that B100-10%-90% has achieved maximum brake thermal efficiency of 35% at PIT of 35 °CA bTDC, MIT of 25 °CA and NOP of 300 bar. Usage of pure moringa oleifera biodiesel in diesel engine under split injection strategy results in better combustion characteristics due to premixed and diffused heat release rate phasing with lower peak cylinder pressure. In addition, B100-10%-90% emits maximum nitric oxide emission of 1520 ppm, and least unburned hydrocarbon and carbon monoxide emission of 4 ppm and 0.01% vol respectively at 600 bar NOP with PIT of 35 °CA and MIT of 25 °CA. Moreover, Nitric oxide emission is reduced as the EGR rate gradually increases from 10% to 30%; on the other side, brake specific fuel consumption, carbon monoxide, and unburned hydrocarbon emissions are marginally increased. This research depicts that split injection strategy and EGR technique have simultaneously lowered the nitric oxide and smoke emissions while improving engine performance.

Three-Dimensional Simulation Analysis of the Effect of Hydrous Ethanol and Exhaust Gas Recirculation on Gasoline Direct Injection Engine Combustion and Emissions

Abstract To analyze the influence of hydrous ethanol on the performance of the direct-injection engine, the three-dimensional simulation is carried out by using converge software coupled with the combustion mechanism of hydrous ethanol gasoline and the soot model. The combustion and soot generation characteristics of a direct-injection gasoline engine burning hydrous ethanol gasoline using exhaust gas recirculation (EGR) technology are investigated. It is found that the increase of the blending ratio of the hydrous ethanol can accelerate the flame propagation speed, shorten the combustion duration, and improve the combustion isovolumetric. The nucleation and growth of soot are jointly controlled by polycyclic aromatic hydrocarbons (PAHs) and the small molecular components such as C2H2. The oxygen content properties and high reactive OH of the hydrous ethanol-containing gasoline inhibit soot formation. Compared with pure gasoline, the carbon soot precursor mass is reduced by 60%, 54.5%, 73.3%, and 52.4% for 20% anhydrous ethanol blended with gasoline, A1, A2, A3, and A4, respectively, and the carbon soot mass is reduced by 63.6% and the carbon soot volume density is reduced by 40%. The introduction of EGR exhaust reduces the burning rate and leads to an increase in the production of carbon monoxide, hydrocarbon, and soot. However, the combination of EGR with hydrous ethanol gasoline can significantly improve the engine combustion environment and significantly reduce soot and PAHs concentrations. The impact of EGR also includes the ability to reduce combustion chamber temperatures and reduce NOx emissions from hydrous ethanol gasoline by 75%.

Impact of Exhaust Gas Recirculation (EGR) on the Emission of the Dual-Fuel Diesel Engine with Hydrogen as a Secondary Fuel

Impact of Exhaust Gas Recirculation (EGR) on the Emission of the Dual-Fuel Diesel Engine with Hydrogen as a Secondary Fuel

A comprehensive study on the effects of multiple injection strategies and exhaust gas recirculation on diesel engine characteristics that utilize waste high density polyethylene oil

ABSTRACT The present study utilized the catalytic pyrolysis method for extracting oil from waste high-density polyethylene (WHDPE) plastics. Experiments were carried out with D70H30 (diesel-70%, WHDPE oil-30%) blend under the influence of three start of pilot injection (SoPI) timings [45° before top dead center (bTDC), 50°bTDC, and 55°bTDC] and three pilot fuel injection quantity (PFIQ) (10%, 20%, and 30%) at the engine’s rated power output. Later, the impact of exhaust gas recirculation (EGR) (0%, 10%, and 20%) was studied with the optimum SoPI and PFIQ. Experimental results indicated that at SoPI timing of 55°bTDC and at PFIQ of 30%, the brake thermal efficiency (BTE) increased by 8.5%, nitrogen oxides (NOx) increased by 19.25%, while smoke, hydrocarbons (HC), and CO emission got lowered with baseline operation of the blend and found to be best among other modifications. In the next phase of the work, exhaust gas is recirculated at 10% and 20%. The results portray that inclusion of 10% EGR in the intake at SoPI 55°bTDC and at PFIQ 30% has shown 1.7% higher BTE, with 3.7% and 28.9% lower NOx and smoke emission compared to the single main injection of the blend. It is concluded that pilot injection strategy with 30% PFIQ and SoPI timing of 55°bTDC at 10% EGR rate can be adopted to utilize WHDPE oil/diesel in diesel engines effectively.

Impact of Exhaust Gas Recirculation on Gaseous Emissions of Turbocharged Spark-Ignition Engines

Exhaust gas recirculation is one of the technologies that can be used to improve the efficiency of spark-ignition engines. However, apart from fuel consumption reduction, this technology has a significant impact on exhaust gaseous emissions, inducing a significant reduction in nitrogen oxides and an increase in unburned hydrocarbons and carbon monoxide, which can affect operation of the aftertreatment system. In order to evaluate these effects, data extracted from design of experiments done on a multi-cylinder 1.3 L turbocharged spark-ignition engine with variable valve timing and low-pressure exhaust gas recirculation (EGR) are used. The test campaign covers the area of interest for the engine to be used in new-generation hybrid electric platforms. In general, external EGR provides an approximately linear decrease of nitrogen oxides and deterioration of unburned hydrocarbon emissions due to thermal and flame quenching effects. At low load, the impact on emissions is directly linked to actuation of the variable valve timing system due to the interaction of EGR with internal residuals. For the same external EGR rate, running with high valve overlap increases the amount of internal residuals trapped inside the cylinder, slowing down combustion and increasing Unburnt hydrocarbon (HC) emissions. However, low valve overlap (i.e., low internal residuals) operation implies a decrease in oxygen concentration in the exhaust line for the same air–fuel ratio inside the cylinders. At high load, interaction with the variable valve timing system is reduced, and general trends of HC increase and of oxygen and carbon monoxide decrease appear as EGR is introduced. Finally, a simple stoichiometric model evaluates the potential performance of a catalyst targeted for EGR operation. The results highlight that the decrease of nitrogen oxides and oxygen availability together with the increase of unburned hydrocarbons results in a huge reduction of the margin in oxygen availability to achieve a complete oxidation from a theoretical perspective. This implies the need to rely on the oxygen storage capability of the catalyst or the possibility to control at slightly lean conditions, taking advantage of the nitrogen oxide reduction at engine-out with EGR.

Impact of Exhaust Gas Recirculation in VCR Engine Fuelled with Pongamia - Biodiesel

Biodiesel is one of the alternatives which are being widely studied and production of biodiesel is limited by crop land displacement, the Trial examinations are carried on a four stroke Diesel Engine (DE) to inspect the solidness. Exhaust gas recirculation (EGR) is used for control the emission reduction such as NOx, HC & CO. The pongamia oil blended with B20, B40 and B50 of them biodiesel. The biodiesel oils performance are assessed. The performance parameters such as Specific Fuel Consumption (SFC) and Brake Thermal Efficiency (BTE) are calculated. The exhaust emissions such as unburned Hydro-Carbon (HC), oxides of nitrogen (NOx), carbon monoxide (CO), carbon dioxide (co2) and combustion and smoke parameters is discussed in this paper.

Experimental investigation of combustion and particle emissions under different combustion modes on a heavy-duty diesel engine fueled by diesel/gasoline/diesel from direct coal liquefaction

In an effort to contribute in further reducing pollution and fuel consumption, the effects of various combustion modes on the combustion process and emissions were investigated on a modified single cylinder from a six-cylinder engine using diesel, gasoline, and diesel from direct coal liquefaction (DDCL). The engine was run at 1000 r/min with an indicated mean effective pressure (IMEP) of 0.7 MPa. Additionally, we experimentally evaluated the impact of exhaust gas recirculation (EGR) and did comparisons among the tested fuels. Gasoline was injected into the intake port to form a homogeneous mixture and compression ignition, which led to homogeneous charge compression ignition (HCCI). Diesel was injected near top dead center (TDC), which was dominated by diffused combustion depending on the mixing rate of diesel and air. DDCL was also injected near TDC. In comparison with diesel, DDCL has a longer ignition delay (ID) than diesel due to low cetane number and high volatility. It also had a heat release rate between that of gasoline and diesel. Among the tested fuels, gasoline displayed the highest gross indicated thermal efficiency, followed by DDCL, and then diesel. Moreover, emission test results showed that gasoline had the lowest NOx and soot emissions, but had the highest CO and HC emissions. Different particle modes were present under different EGR conditions. For instance, at an EGR ratio lower than 20%, the particles of the tested fuels were composed mainly of nucleation-mode particles. When the EGR ratio was higher than 20%, the particles of DDCL and diesel were of accumulation-mode, whereas those of gasoline were of small-diameter nucleation-mode.

Impact of exhaust gas recirculation on ignition delay times of gasoline fuel: An experimental and modeling study

The ignition delay times of a research grade gasoline, RON95E10, are measured in a rapid compression machine and in a shock tube. The experiments are carried out for fuel/O2/Ar/N2 mixtures with two equivalence ratios of 0.77 and 1.18 at pressures between 20 and 40 bar over the temperature range of 700–1250 K. In particular, data are reported for two exhaust gas recirculation (EGR) loadings of 0 and 25% to demonstrate the impact of EGR on gasoline ignition delay times. The presented data are, to the authors’ knowledge, the first set of ignition delay times of real gasoline with EGR and at engine relevant high pressures covering the entire intermediate temperature range. A published gasoline mechanism (Cai and Pitsch, 2015) is modified as part of this study following the latest kinetic knowledge and is further used to compute the ignition delay times at the conditions experimentally investigated. The simulations employ a four-component surrogate consisting of n-heptane, iso-octane, toluene, and ethanol. It is shown that the proposed model predicts the total ignition delay times of gasoline accurately under various conditions and reflects correctly the influences of pressure, EGR, and equivalence ratio on ignition delay times, while it fails to predict the first stage ignition delay times with very high accuracy due to the neglect of the olefin and naphthene content in the surrogate formulation. Furthermore, the influence of exhaust gas addition on ignition delay times is analyzed and discussed in more detail using results from numerical simulations. The chemical impact of EGR is minor but not negligible and varies at different conditions depending on the EGR composition.

Investigating the EGR rate and temperature impact on diesel engine combustion and emissions under various injection timings and loads by comprehensive two-zone modeling

The impact of exhaust gas recirculation (EGR) on combustion and emissions in direct injection (DI) diesel engine is examined in a predominately computational study, where the influence of EGR rate and temperature at various injection timings and loads is addressed using an in-house, comprehensive, two-zone model of diesel combustion, which divides the cylinder contents into a non-burning zone (air) and another in which fuel is supplied from the injector and burned with entrained air from the air zone. The validity of model computations is assessed favorably against pertinent experimental data, such as cylinder pressure and HRR diagrams, and NO and soot emissions, generated in this laboratory with tests on experimental, single-cylinder, ‘Hydra’ diesel engine, and also with relevant literature data. Various EGR rates and temperatures at different injection timings and loads were undertaken in the analysis. The numerical results provide insight into the local combustion and emissions formation mechanisms, and improve the understanding of important parameters dictating their behavior under various operating conditions. These results may be used for optimizing the NO – Smoke trade-off and efficiency, and pave the way for discussing the implications on the use of diesel fuels with diverse properties when fueling EGR-equipped diesel engines.

Impact of Exhaust Gas Recirculation on Performance and Emissions of Free-Piston Electrical Generator Fueled by DME

AbstractThis study presents a novel and interesting investigation regarding the use of exhaust gas recirculation (EGR) in free-piston engines by exploring EGR impact on both engine performance and ...

Experimental studies of impact of exhaust gas recirculation on the effective operation in heavy augmented diesel engine

This paper considers the problem of reducing the nitrogen oxides emissions in exhaust gases (EG) of diesel engine by exhaust gas recirculation (EGR). Based on the carried out study the influence of EGR on technical-and-economic and environmental performance of a diesel engine was found as well as main directions of improving a working process of diesel engines with EGR system were formulated.Keywords: diesel engine, warm-up mode, exhaust toxicity, exhaust gas recirculation, nitrogen oxides (NOx), heat exchanger of system exhaust gas recirculation

Oxidative Reactivity of Particles Emitted from a Diesel Engine Operating at Light Load with EGR

The impact of exhaust gas recirculation (including three levels: 0, 10%, and 30%) on engine combustion characteristics, gaseous emissions, and particulate properties (i.e., oxidative reactivity, carbonaceous compositions, size distribution, and nanostructure) was studied on a common rail diesel engine operating at low engine load. The results showed that the lack of oxygen with EGR prolongated ignition delay and the premixed portion of combustion started to rise significantly. Higher EC (accumulation mode) with larger particle size could be observed with increasing EGR from 0 to 30%, which is attributed to the promotion of soot formation with less available oxygen and the inhibition of soot oxidation with low in-cylinder temperature with increasing EGR. The soot nanostructure observation showed that soot changed from smooth surface under 0 EGR to rugose surface under 10% EGR. Moreover, the amorphous core turned larger with increasing EGR. With increasing EGR to 30%, the amorphous core appeared to include ...

Exhaust gas recirculation – Zero dimensional modelling and characterization for transient diesel combustion control

The application of exhaust gas recirculation (EGR) during transient engine operation is a challenging task since small fluctuations in EGR may cause larger than acceptable spikes in NOx/soot emissions or deterioration in the combustion efficiency. Moreover, the intake charge dilution at any EGR ratio is a function of engine load and intake pressure, and typically changes during transient events. Therefore, the management of EGR during transient engine operation or advanced combustion cycles (that are inherently less stable) requires a fundamental understanding of the transient EGR behaviour and its impact on the intake charge development.In this work, a zero-dimensional EGR model is described to estimate the transient (cycle-by-cycle) progression of EGR and the time (engine cycles) required for its stabilization. The model response is tuned to a multi-cylinder engine by using an overall engine system time-constant and shown to effectively track the transient EGR changes. The impact of EGR on the actual air–fuel ratio of the cylinder charge is quantified by defining an in-cylinder excess-air ratio that accounts for the oxygen in the recycled exhaust gas. Furthermore, a twin lambda sensor (TLS) technique is implemented for tracking the intake dilution and in-cylinder excess-air ratio in real-time. The modelling and analysis results are validated against a wide range of engine operations, including transient and steady-state low temperature combustion tests.

Performance comparison of 2-methylfuran and gasoline on a spark-ignition engine with cooled exhaust gas recirculation

In the present study, the impact of exhaust gas recirculation (EGR) rates, from 0% to 15%, and compression ratio (CR) of 8, 9, and 10 on the combustion characteristics and emission performance of 2-methylfuran (MF) and gasoline were studied. Experiments were carried out on a Ricardo E6 single-cylinder spark-ignition (SI) research engine, under stoichiometric conditions, MF could produce higher cylinder pressure, knocking intensity, combustion temperature, and nitrogen oxides (NOx) emissions than gasoline at higher CRs. However, an appropriate level of cool EGR improved the combustion and emissions, particularly through knock suppression and reduced NOx emissions. When the cooled EGR rate reached 15%, the NOx emissions from the gasoline at a compression ratio of 10 was reduced by about 20.6g/kWh (>72.5%) compared with 0% EGR. With a low EGR rate, there was only a slight improvement in the indicated thermal efficiency; however, when the EGR reaches 15%, the MF results in 31.2% higher indicated thermal efficiency when compared to gasoline with a CR of 10. This work further advances the knowledge of how to improve the overall performance of MF as an alternative fuel for internal combustion engines.

Impact of exhaust gas recirculation (EGR) on soot reactivity from a diesel engine operating at high load

Past work demonstrated that the exhaust gas recirculation (EGR) enhanced the soot reactivity from a diesel engine operating at low load. In this paper, reactivity of diesel soot generated from a common rail diesel engine at high load (75% load, 336 N m) under 0, 10% and 30% EGR was studied. Combustion properties of the diesel engine with the diffusion-dominated heat release patters under the high temperature and low-fuel ratio condition resulted in the combustion duration increased 39.8% as EGR rate increases from 0 to 30%. Correspondingly, noticeable changes in nanostructure, carbonaceous components and oxidative reactivity with the increase of EGR have been observed. The soot with highly soot-EC content, highly ordered graphitic structure and low organic carbon (OC) fraction in the particle sample presents at high EGR level, which is the consequence of the longer combustion duration and the decrease of air-fuel ratio. Both of highly ordered graphitic structure and low OC fraction in the particle sample are responsible for the observed decrease of soot reactivity with the increase of EGR at high load.

Evaluation of natural gas combined cycle power plant for post-combustion CO2 capture integration

Over the coming decade, gas-fired power plants are projected to account for a substantial share of global output. CO2 capture would be required to mitigate the associated emissions. Thus, high fidelity models of a 440MW natural gas combined cycle power plant, a CO2 capture plant and a CO2 compression train were built and integrated for 90% capture level. Power output is observed to fall by 15%, while cooling water demand increases by 33%. A 40% exhaust gas recirculation (EGR) causes a 10MW power recovery, but increases cooling water demand further. It is shown that higher exhaust gas CO2 concentration enhances mass transfer in the capture plant, which reduces its steam requirement. Supplementary firing (SF) of the exhaust gas is observed to generally improve the plant output. Economic analysis, performed via a bottom-up approach, reveals integrated plant overnight cost to be 58% higher than the power plant cost, discouraging deployment of CO2 capture. The impact of EGR is marginal, while SF implementation almost doubles the overnight cost. Cost of electricity increases by 30% for the integrated plant, but only by 26% with EGR, and 24% with SF. However, the price of gas remains the largest contributor to cost of electricity.