Academic literature on the topic 'Exhaust nox decrease with urea'
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Journal articles on the topic "Exhaust nox decrease with urea"
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Venugopal, A., Kumar. J. Sathish, and Kumar. A. Satish. "Performance and Optimization of Nox Reduction by Urea Spray Formation in SI Engines." International Journal of Trend in Scientific Research and Development 2, no. 3 (2018): 1552–55. https://doi.org/10.5281/zenodo.3577795.
Full textAbstract:
Exhaust contains environmentally harmful pollutants such as oxides of nitrogen NOx and particulate matter PM .In order to control these exhaust pollutants engine after treatment technologies are being used in diesel engines. A urea selective catalytic reduction SCR is one of the promising after treatment devices for the abatement of exhaust emissions, particularly for NOx pollutants. The basic principal of emission reducing systems is to reduce the NOx pollutants by ammonia formed from urea. This project aims to analyse the NOx emissions from a petrol engine equipped with a Urea catalytic convertor using canister as a catalyst Venugopal A | Sathish Kumar. J | Satish Kumar. A "Performance and Optimization of Nox Reduction by Urea Spray Formation in SI Engines" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-3 , April 2018, URL: https://www.ijtsrd.com/papers/ijtsrd11423.pdf
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Sun, Ke, Gecheng Zhang, Zhengyong Wang, et al. "Thermal Management of Diesel Engine Aftertreatment System Based on Ultra-Low Nitrogen Oxides Emission." Applied Sciences 14, no. 1 (2023): 237. http://dx.doi.org/10.3390/app14010237.
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To achieve diesel engine ultra-low nitrogen oxide emission, light-off selective catalyst reduction (LO-SCR) has been suggested for better performance with lower exhaust temperature. An electric heater upstream of the exhaust aftertreatment system was applied to significantly decrease the NOx emission at a low exhaust temperature. With a 7.2 kW electric heater coupled with LO-SCR, the NOx emission during 200~500 s of the world harmonized transient cycle (WHTC) decreased from 282.6 ppm to 61.5 ppm, which is a decrease of 45%. Application of an upstream diesel oxidation catalyst (DOC) decreased the NOx emission by 63% at the same interval at the cost of worse cold-start performance. The urea input was also adjusted to avoid NOx emission during the latter part of the WHTC.
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Liu, Yingshuai, Jianwei Tan, Chenxing Liu, and Yunli He. "Research on real-world emission characteristics based on the Symmetry Solid SCR system." PLOS One 20, no. 4 (2025): e0320323. https://doi.org/10.1371/journal.pone.0320323.
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In the actual use process, especially under the low exhaust temperature in urban conditions, the actual NOx emission of diesel engines using the Urea SCR technology is higher than expected, which seriously affects the application of Urea SCR technology in urban diesel vehicles. To solve the defects of low-temperature freezing, urea crystallization in the exhaust pipeline at low exhaust temperature, and insufficient activity of the Urea SCR system at low exhaust temperature in the actual application process of the Urea SCR technology, this paper uses the Portable Emission Measurement System (PEMS) vehicle test system to run the real-world. A SAIC Hongyan Dump truck that meets the China VI emission standard is tested and studied, and the real-world emission characteristics of the Solid SCR system and the Urea SCR system are compared and studied. Among other things, solid-state SCR systems use solid ammonium as a precursor to ammonia, a change that reduces clogging problems due to icing and hydrolysis evaporation crystals at low temperatures compared to conventional aqueous urea solutions. This results in more reliable system operation in cold environments. Solid-state SCR technology offers a more efficient and reliable solution for diesel exhaust treatment through its unique ammonia supply method, system optimization and environmental adaptability, helping to reduce environmental pollution from diesel vehicles. The test results show that: Under real-world operation conditions, the NOx conversion efficiency of the Urea SCR system and the Solid SCR system with the same injection strategy is increased by 0.5% and the NOx emission is reduced by 8.9% when the window average temperature is 228.8°C and 231.3°C. For the PN emission, no matter whether the Urea SCR system or the Solid SCR system is selected, the results have little influence. Based on the Solid SCR system, CO, HC, NO, NOX, and other pollutant emission factors gradually decrease and tend to be relatively stable with the increase in vehicle speed. The Solid SCR technology is a promising NOx emission control technology for diesel engines.
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Thangapandian, P., S. Paulsingarayar, R. Chandraprakash, S. Seenivasan, I. Vimal Kannan, and S. A. Siddeshwar. "Development and experimental studies of a light vehicle diesel after treatment system with DOC, DPF and urea SCR." Journal of Physics: Conference Series 2925, no. 1 (2024): 012008. https://doi.org/10.1088/1742-6596/2925/1/012008.
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Abstract Strict adherence to pollution limits poses a risk to light-duty diesel engines due to challenges in post-treatment procedures, product limitations, and emission criteria. This paper aims to determine the underlying principles for the technological development of an after-treatment technique that incorporates a diesel oxidation catalyst (DOC), catalytic Diesel Particle Filter (DPF), urea injector, and catalytic urea selective reduction (SCR). Implementing this selective catalytic reduction (SCR) technique would greatly enhance the catalyst’s ability to convert NOx by regulating the evaporation of urea and avoiding a decrease in exhaust temperature and mixing efficiencies. Moreover, the uniformity of the NH3 concentration distribution over the catalyst surface is advantageous. This study explored the concept of an electrically evaporated urea-dosing device. The investigation revealed that heated urea had a beneficial effect on improving the elimination of NOx from both continuous and intermittent motor operations before its application to the gas exhaust. The cylindrical urea evaporative heating chamber was equipped with a venturi jet that directed urea vapour down the exhaust drain. The urea solution dosing technique, administered by spraying, was a customised method more advantageous than the conventional liquid dosage system.
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Mehdi, Ghazanfar, Song Zhou, Yuanqing Zhu, Ahmer Shah, and Kishore Chand. "Numerical Investigation of SCR Mixer Design Optimization for Improved Performance." Processes 7, no. 3 (2019): 168. http://dx.doi.org/10.3390/pr7030168.
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The continuous increase in the number of stringent exhaust emission legislations of marine Diesel engines had led to a decrease in NOx emissions at the required level. Selective catalyst reduction (SCR) is the most prominent and mature technology used to reduce NOx emissions. However, to obtain maximum NOx removal with minimum ammonia slip remains a challenge. Therefore, new mixers are designed in order to obtain the maximum SCR efficiency. This paper reports performance parameters such as uniformity of velocity, ammonia uniformity distribution, and temperature distribution. Also, a numerical model is developed to investigate the interaction of urea droplet with exhaust gas and its effects by using line (LM) and swirl (SM) type mixers alone and in combination (LSM). The urea droplet residence time and its interaction in straight pipe are also investigated. Model calculations proved the improvement in velocity uniformity, distribution of ammonia uniformity, and temperature distribution for LSM. Prominent enhancement in the evaporation rate was also achieved by using LSM, which may be due to the breaking of urea droplets into droplets of smaller diameter. Therefore, the SCR system accomplished higher urea conversion efficiency by using LSM. Lastly, the ISO 8178 standard engine test cycle E3 was used to verify the simulation results. It has been observed that the average weighted value of NOx emission obtained at SCR outlet using LSM was 2.44 g/kWh, which strongly meets International Maritime Organization (IMO) Tier III NOx (3.4 g/kWh) emission regulations.
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Qian, Feng, Dong Ma, Neng Zhu, Peng Li, and Xiaowei Xu. "Research on Optimization Design of SCR Nozzle for National VI Heavy Duty Diesel Engine." Catalysts 9, no. 5 (2019): 452. http://dx.doi.org/10.3390/catal9050452.
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For the National VI heavy-duty diesel vehicles, NOx emission regulations are becoming more and more stringent, and the selective catalytic reduction (SCR) system has become a necessary device. The design of the adblue nozzle in the SCR system is especially critical, directly affecting the NOx conversion efficiency and deposit formation. According to the structure of a National VI diesel engine exhaust pipe and SCR system, the nozzle is optimized by computational fluid dynamics (CFD) method to avoid the collision between the urea droplets and the exhaust pipe wall, to ensure that the exhaust gas and the urea droplets are as much as possible in full contact to ensure a sufficient urea pyrolysis. With the optimized nozzle, the NH3 distribution uniformity of the inlet face of the SCR catalyst can increase from 0.58 to 0.92. Additionally, test verifications are implemented based on the spray particle size test and the engine bench tests; the results show that the Sauter mean diameter of the optimized nozzle is more decreased than the initial nozzle and that the NOx conversion efficiency of the World Harmonized Transient Cycle (WHTC) and World Harmonized Stationary Cycle (WHSC) cycle improves by nearly 3%; additionally, it can also avoid deposit formation.
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Jo, Hyun, Ahyun Ko, Jinyoung Jang, and Ocktaeck Lim. "Study on Rates of NH3 Adsorption and Desorption in SCR on Various Engine Operation Conditions." Sustainability 15, no. 19 (2023): 14468. http://dx.doi.org/10.3390/su151914468.
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Aging diesel engines on the road require the development of an after-treatment system to meet current emission regulations, and a reduction in NOx (Nitrogen Oxide) is significant. The SCR (Selective Catalytic Reduction) system is the after-treatment system for removing NOx from exhaust gas in diesel engines using NH3 (Ammonia) gas. However, the mixing and conversion process between NH3 and NOx in SCR has not been entirely clarified. That process produces NH3 slip in the catalyst surface; the NH3 slip will make the after-treatment performance worse. This study informs how the UWS (Urea Water Solution) injection controlling method can minimize the NH3 slip in the after-treatment system. For this, the NH3 adsorption and desorption rates are important factors for determining the quantity of UWS injection in the system. The NH3 adsorption rate and desorption rate in the SCR are not significantly affected by engine speed, i.e., the exhaust gas flow rate. However, as the exhaust gas temperature increased, the adsorption rate and desorption rate of NH3 in the SCR increased. Through this, the exhaust gas temperature dramatically affects the NH3 adsorption rate and desorption rate in the SCR. Therefore, if the urea water is injected based on this knowledge that the NH3 adsorption amount in the SCR decreases as the exhaust gas flow rate increases, NH3 slip can be suppressed and a high NOx reduction rate can be achieved. Therefore, if the SCR adsorption and desorption mechanisms are analyzed according to the exhaust temperature and the exhaust flow rate in this paper, it can be used as a reference for selecting an appropriate SCR when retrofitting an old diesel engine car.
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Guan, Wei, Vinícius B. Pedrozo, Hua Zhao, Zhibo Ban, and Tiejian Lin. "Miller cycle combined with exhaust gas recirculation and post–fuel injection for emissions and exhaust gas temperature control of a heavy-duty diesel engine." International Journal of Engine Research 21, no. 8 (2019): 1381–97. http://dx.doi.org/10.1177/1468087419830019.
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Miller cycle has been shown as a promising engine strategy to reduce in-cylinder nitrogen oxide (NOx) formation during the combustion process and facilitate its removal in the aftertreatment systems by increasing the exhaust gas temperature. However, the level of NOx reduction and the increase in exhaust gas temperature achieved by Miller cycle alone is limited. Therefore, research was carried out to investigate the combined use of Miller cycle with other advanced combustion control strategies in order to minimise the NOx emissions and the total cost of ownership. In this article, the effects of Miller cycle, exhaust gas recirculation, and post-injection were studied and analysed on the performance and exhaust emissions of a single cylinder heavy-duty diesel engine. A cost–benefit analysis was carried out using the corrected total fluid efficiency, which includes the estimated urea solution consumption in the NOx aftertreatment system as well as the fuel consumption. The experiments were performed at a low load of 6 bar net indicated mean effective pressure. The results showed that the application of a Miller cycle–only strategy with a retarded intake valve closing at −95 crank angle degree after top dead centre decreased NOx emissions by 21% to 6.0 g/kW h and increased exhaust gas temperature by 30% to 633 K when compared to the baseline engine operation. This was attributed to a reduction in compressed gas temperature by the lower effective compression ratio and the in-cylinder mass trapped due to the retarded intake valve closing. These improvements, however, were accompanied by a fuel-efficiency penalty of 1%. A further reduction in the level of NOx from 6.0 to 3.0 g/kW h was achieved through the addition of exhaust gas recirculation, but soot emissions were more than doubled to 0.022 g/kW h. The introduction of a post-injection was found to counteract this effect, resulting in simultaneous low NOx and soot emissions of 2.5 and 0.012 g/kW h, respectively. When taking into account the urea consumption, the combined use of Miller cycle, exhaust gas recirculation, and post-injection combustion control strategies were found to have relatively higher corrected total fluid efficiency than the baseline case. Thus, the combined ‘Miller cycle + exhaust gas recirculation + post-injection’ strategy was the most effective means of achieving simultaneous low exhaust emissions, high exhaust gas temperature, and increased corrected total fluid efficiency.
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Lee, Kyoungbok, Jongin Lee, Sangho Lee, Kwangchul Oh, and Sungwook Jang. "Fuel Consumption and Emission Reduction for Non-Road Diesel Engines with Electrically Heated Catalysts." Catalysts 13, no. 6 (2023): 950. http://dx.doi.org/10.3390/catal13060950.
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In this study, an exhaust system compliant with future regulations was developed for a non-road 110PS engine with a Tier-4f aftertreatment system, and the emission characteristics of the engine were investigated in the non-road transient mode (NRTC). For the system to comply with future exhaust regulations, a DPF was installed, and an electrical heated catalyst (EHC) device was installed to manage exhaust gas temperature. The emission characteristics of exhaust gas were examined according to the power and applied duration of EHC, and the effects of catalyst coating and the urea water solution (UWS) injection map on NOx reduction, NH3 slip, and N2O emissions in NRTC mode were investigated. The application of a 4 kW class EHC system enables the lowering of the injection starting temperature of the UWS, as reliable gas heating (heating duration control) is guaranteed. When the injection starting temperature (based on the SCR inlet temperature) was set to 150 °C, NSR map, (III) in conjunction with the operation of the EHC, effectively achieved significant NOx reduction in NRTC mode without deposit and wetting occurring in the mixer and exhaust pipe. Regarding changes in EHC power from 3 kW to 4 kW, it was observed that a NOx reduction of 0.05 g/kWh occurs in the cold NRTC mode, but in the hot NRTC mode, it was found that the relative decrease in the UWS is due to the increased NO2 conversion efficiency as a result of the oxidation catalyst, making 3 kW more advantageous. Furthermore, due to the increase in NO2 concentration caused by the oxidation catalyst and the increase in the low-temperature injected UWS, NH4NO3 was formed, which resulted in an increase in PM emissions and a significant increase in N2O emissions around an exhaust temperature of 250 °C. When the EHC power was set to 3 kW and the volume of oxidation catalyst and the amount of UWS injection were adjusted, applying EHC in the NRTC mode resulted in an additional NOx reduction of 58.6% and 88.4% in cold and hot modes, respectively, compared with not using EHC, with a fuel penalty of approximately 1.67%, while limiting the peak concentrations of N2O and NH3.
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Sun, Xingyu, Mengjia Li, Jincheng Li, et al. "Nitrogen Oxides and Ammonia Removal Analysis Based on Three-Dimensional Ammonia-Diesel Dual Fuel Engine Coupled with One-Dimensional SCR Model." Energies 16, no. 2 (2023): 908. http://dx.doi.org/10.3390/en16020908.
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Ammonia, as an alternative fuel for internal combustion engines, can achieve nearly zero carbon emissions. Although the development of the pure ammonia engine is limited by its poor combustion characteristics, ammonia–hydrocarbon mixed combustion can effectively improve the combustion of ammonia fuel. With the increase in the ammonia fuel proportion in the fuel mixture, a large number of nitrogen oxides (NOX) and unburned ammonia may be discharged, which have a poor impact on the environment. In this study, the performance of selective catalytic reduction (SCR) aftertreatment technology in reducing NOX and ammonia emissions from ammonia–diesel dual-fuel engines was investigated using simulation. A good cross-dimensional model was established under the coupling effect, though the effect of a single-dimensional model could not be presented. The results show that when the exhaust gas in the engine cylinder is directly introduced into the SCR without additional reducing agents such as urea, unburned ammonia flowing into SCR model is in excess, and there will be only ammonia at the outlet; however, if the unburned ammonia fed into the SCR model is insufficient to reduce NO, the ammonia concentration at the outlet will be 0. NOX can be 100% effectively reduced to N2 under most engine conditions; thus, unburned ammonia in exhaust plays a role in reducing NOX emissions from ammonia–diesel dual-fuel engines. However, when the concentration of unburned ammonia in the exhaust gas of an ammonia–diesel dual-fuel engine is large, its ammonia emissions are still high even after the SCR. In addition, the concentrations of N2O after SCR do not decrease, but increase by 50.64 in some conditions, the main reason for which is that by the action of the SCR catalyst, NO2 is partially converted into N2O, resulting in an increase in its concentration at the SCR outlet. Adding excessive air or oxygen into the SCR aftertreatment model can not only significantly reduce the ammonia concentration at the outlet of the model without affecting the NOX conversion efficiency of SCR, but inhibit N2O production to some extent at the outlet, thus reducing the unburned ammonia and NOX emissions in the tail gas of ammonia–diesel dual-fuel engines at the same time without the urea injection. Therefore, this study can provide theoretical guidance for the design of ammonia and its mixed-fuel engine aftertreatment device, and provide technical support for reducing NOX emissions of ammonia and its mixed fuel engines.
Dissertations / Theses on the topic "Exhaust nox decrease with urea"
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Akbar, Mohammed Ishthiaq. "Selective catalytic reduction of NOx gases in diesel exhaust using aqueous urea." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415042.
Full textBooks on the topic "Exhaust nox decrease with urea"
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Hultermans, Ronald Johannes. Selective catalytic reduction of NOx form diesel engine exhaust using injection of urea. Technische Universiteit Delft, 1995.
Find full textBook chapters on the topic "Exhaust nox decrease with urea"
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Koebel, Manfred, Martin Elsener, and Thomas Marti. "NOx-Reduction in Diesel Exhaust Gas with Urea and Selective Catalytic Reduction." In Combustion Technology for a Clean Environment. CRC Press, 2024. http://dx.doi.org/10.1201/9781003578697-88.
Full textConference papers on the topic "Exhaust nox decrease with urea"
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Van Hemelryck, Johan, and Dirk Van Hemelryck. "Development of a New Aqueous Urea Solution Storage System Using Cathodic Protection." In CORROSION 2009. NACE International, 2009. https://doi.org/10.5006/c2009-09544.
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Abstract In order to reduce CO2 emissions of diesel engines in the EU the so called Euronorm 4 was introduced by the European Commission. By injecting a 32 % urea mixture, in the exhaust pipe of diesel engines, NOx emissions can be transformed into nitrogen and water. The urea-water mixture is stored nowadays in above ground temperature controlled FRP tanks or in SS 316 underground tanks. Recently, research made clear that the use of internally coated carbon steel tanks together with an impressed current cathodic protection (ICCP) system is a far better economic and technical solution. Unless different side effects of ureum storage the first try-outs of the system seemed very promising for the fuel retail industry.
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Yoshida, Fuka, Hideaki Takahashi, Yuya Kotani, Qiuyue Zu, Ratnak Sok, and Jin Kusaka. "Experimental and Numerical Investigations on the Effect of Urea Pulse Injection Strategies to Reduce NOx Emission in Urea-SCR Catalysts." In Energy & Propulsion Conference & Exhibition. SAE International, 2024. http://dx.doi.org/10.4271/2024-01-4304.
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<div class="section abstract"><div class="htmlview paragraph">A major challenge for auto industries is reducing NOx and other exhaust gas emissions to meet stringent Euro 7 emission regulations. A urea Selective Catalyst Reduction (SCR) after-treatment system (ATS) commonly uses upstream urea water injection to reduce NOx from the engine exhaust gas. The NOx emission conversion rate in ATSs is high for high exhaust gas temperatures but substantially low for temperatures below 200°C. This study aims to improve the NOx conversion rate using urea pulse injection in a mass-production 2.2 L diesel engine equipped with an SCR ATS operated under low exhaust gas temperature. The engine experimental results show that, under 200°C exhaust temperature and 3.73x10<sup>4</sup> h<sup>-1</sup> gross hourly space velocity (SV), the NOx conversion rate can be improved by 5% using 5-sec ON and 12-sec OFF (denoted as 5/12 s) urea pulse supply compared to the constant supply under time-averaged 1.0 urea equivalence ratio. It is experimentally observed that the urea pulse supply’s efficacy decreases under higher exhaust gas temperatures. The SCR model is developed with surface reactions, and the CFD results indicate that the urea pulse supply oscillates the surface reaction rates for NO and NO<sub>2</sub>, suggesting improved conversion rates. Further results on the urea pulse and constant supplies at high exhaust temperatures are reported. The NOx conversion improvement rates under various ON-OFF urea pulses are also discussed. The predicted dynamic fluctuation of the pulse supply and dithering SCR reaction is investigated.</div></div>
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Atkinson, William, Sam Barros, and Naag Piduru. "In Cylinder NOx Emissions Control via Water Injection." In ASME 2015 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icef2015-1122.
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Increasingly stringent emissions standards have accounted for continuing increases in the end-user cost of a modern diesel engine, most of which due to complex and expensive emissions after treatment devices such as selective catalytic reduction (SCR), which relies on urea to be injected into a catalyst bed to remove nitrogen oxide emissions from the engine exhaust. Prior to the current emissions standards the diesel industry had been able to meet NOx levels by reducing the combustion temperature in the engine via charge gas dilution, through cooled EGR. Although successful in reducing emissions, large levels of EGR have undesirable effects on oil quality, engine longevity, overall efficiency and warranty returns. There is also a limit to the efficacy of EGR in lowering NOx emissions such that at the current EPA mandated 0.2g/kWh, it is no longer sufficient. Another well-known NOx mitigating solution has been the introduction of water into the diesel engine combustion chamber. This has been known to decrease peak combustion temperatures and decrease NOx emissions but usage so far has been limited to stationary and marine applications due to the requirement of a separate water tank and thereby a two-tank system. Combustion of hydrocarbon fuels produces between 1.35 and 2.55 times their mass in water. As an enabler to water injection, this paper will also demonstrate a technique where the exhaust is first cooled via a heat exchanger, and then passed through a cyclonic separator to separate heavier liquid particles from the exhaust gas flow. Through vortex separation over 100% of the burned fuel mass can be recovered as liquid water from the exhaust. A prototype system was developed and installed on a VW TDI diesel engine. Tests were conducted with and without after-treatment and results have been discussed in subsequent sections. The water was then utilized in conjunction with EGR to control NOx emissions, allowing a reduction of over 97%, thus achieving the 0.2g/kWh standard with no after treatment.
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Aguilar, Jonathan, Leslie Bromberg, Alexander Sappok, Paul Ragaller, Jean Atehortua, and Xiaojin Liu. "Catalyst Ammonia Storage Measurements Using Radio Frequency Sensing." In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3572.
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Motivated by increasingly strict NOx limits, engine manufactures have adopted selective catalytic reduction (SCR) technology to reduce engine-out NOx below mandated levels. In the SCR process, nitrogen oxides (NOx) react with ammonia (NH3) to form nitrogen and water vapor. The reaction is influenced by several variables, including stored ammonia on the catalyst, exhaust gas composition, and catalyst temperature. Currently, measurements from NOx and/or NH3 sensors upstream and downstream of the SCR are used with predictive models to estimate ammonia storage levels on the catalyst and control urea dosing. This study investigated a radio frequency (RF) -based method to directly monitor the ammonia storage state of the SCR catalyst. This approach utilizes the SCR catalyst as a cavity resonator, in which an RF antenna excites electromagnetic waves within the cavity to monitor changes in the catalyst state. A mmonia storage causes changes in the dielectric properties of the catalyst, which directly impacts the RF signal. Changes in the RF signal relative to stored a mmonia (NH3) were evaluated over a wide frequency range as well as temperature and exhaust conditions. The RF response to NH3 storage, desorption, and oxidation on the SCR was observed to be well-correlated with changes in the catalyst state. Calibrated RF measurements demonstrate the ability to monitor the adsorption state of the SCR to within 10 % of the sensor full scale. The results indicate direct measurement of SCR ammonia storage levels, and resulting catalyst feedback control, via RF sensing to have significant potential for optimizing the SCR system to improve NOx conversion and decrease urea consumption.
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Larsson, Peter, Paul Ravenhill, Lars-Uno Larsson, and Per Tunestål. "SCR-Catalyst Utilisation and Mixing Comparison Using a Novel Biomimetic Flash-Boiling Injector." In ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9763.
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NOx pollution from Diesel engines causes over 10 000 premature deaths annually and the trend is increasing. In order to decrease this growing global problem, exhaust after-treatment systems for Diesel engines have to be improved. The most common SCR systems in the market place inject an aqueous Urea solution, DEF that evaporates prior the catalytic surface of the SCR-catalyst. Due to a catalytic reaction within the catalyst, NOx is converted nominally into Nitrogen and Water. Currently, the evaporative process is enhanced by aggressive mixer plates and long flow paths; these, negatively, create extra exhaust back pressure and cool the exhaust gases decreasing engine and catalyst efficiency. To achieve future emission legislation targets SCR efficiency has to be improved especially under low catalyst temperature conditions, plus Ammonia slip has to be avoided as it is now legislated against. Swedish Biomimetic’s novel μMist® platform technology, inspired by the Bombardier Beetle, injects a hot, effervescent, finely atomised, highly dispersed spray plume of DEF into the exhaust stream. This is achieved by raising the temperature of the DEF, in a closed volume, above its saturated vapour pressure. The DEF is then rapidly released creating effervescent atomisation. This study investigates a back to back study of the evaporating and mixing behaviour of the μMist® injector and a class leading DEF injector. The test conditions are with and without a mixer plate and the use of two different flow path designs. Spray distribution across the face of the catalyst is assessed by measuring NOx conversion whilst Ammonia slip is also measured post catalyst. This report describes how the novel μMist® injector significantly increases NOx conversion and catalyst surface usage whilst considerably reducing Ammonia slip.
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Tanaka, Kotaro, Ibuki Dobashi, Satoshi Sakaida, and Mitsuru Konno. "Experimental and Modeling Study of NH <sub>3</sub> -SCR on a Hydrocarbon-Poisoned Cu-CHA Catalyst." In Energy & Propulsion Conference & Exhibition. SAE International, 2023. http://dx.doi.org/10.4271/2023-01-1659.
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<div class="section abstract"><div class="htmlview paragraph">A urea-selective catalytic reduction (SCR) system is used for the reduction of NOx emitted from diesel engines. Although this SCR catalyst can reduce NOx over a wide temperature range, improvements in NOx conversion at relatively low temperatures, such as under cold-start or low-load engine conditions, are necessary. A close-coupled SCR (cc-SCR), which was set just after the engine exhaust manifold, was developed to address this issue. The temperature of the SCR catalyst increases rapidly owing to the higher exhaust temperatures, and NOx conversion is then enhanced under cold-start conditions. However, since the diesel oxidation catalyst is not installed before the SCR catalyst, hydrocarbon (HC) emissions pass directly through the SCR catalyst and poison it, leading to lower NOx conversion. Therefore, the mechanism of NOx conversion reduction on HC-poisoned SCR catalysts are required to be studied. In this study, the effects of HC poisoning on the NOx conversion of Cu-CHA catalysts experimentally investigated using propene, n-decane, and 1-methylnaphtalene. In addition, a kinetic model of NH<sub>3</sub>-SCR over the HC-poisoned Cu-CHA catalyst was constructed. When 500 ppm propene was passed through the SCR catalyst, the coke was found to be formed on the catalyst, which led the decrease of the NOx conversion (maximum 75% reduction at 210 °C). Conversely, when n-decane or 1-methylnaphthalene was used, no coke was formed at temperatures below 500 °C, and the NOx conversion was unaffected. Even when coke was formed, it decomposed above 350 °C, and the NOx conversion was equivalent to that of a fresh catalyst. Based on the experimental results, a model for NH<sub>3</sub>-SCR over an HC-poisoned Cu-CHA catalyst was constructed. The reactor model was the one channel model and one-dimensional mass, momentum, energy and species balances were solved in the channel gas phase, assuming a quasi-steady state. The model reproduced the experimental results reasonably well, including the recovery of the catalyst from poisoning at relatively high temperatures.</div></div>
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Kang, Lulu, Zhiguo Zhao, and Diming Lou. "Study on Energy Consumption and Emission Characteristics of EHC Coupled DOC+SDPF+SCR-ASC System under WLTC and RDE." In WCX SAE World Congress Experience. SAE International, 2025. https://doi.org/10.4271/2025-01-8498.
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<div class="section abstract"><div class="htmlview paragraph">With the tightening of emission regulations, Electrically Heated Catalyst (EHC) are an important technical solution for diesel vehicles to address the emission challenges of cold start and Real Driving Emission (RDE). This paper investigates the impact of EHC coupled exhaust aftertreatment system (Diesel Oxidation Catalyst (DOC) + Selective Catalytic Reduction Integrated into Diesel Particulate Filter (SDPF) + Selective Catalytic Reduction (SCR) - Ammonia Slip Catalyst (ASC)) on the energy consumption and emission characteristics of light-duty diesel vehicles based on the World Light Vehicle Test Cycle (WLTC) and RDE. The research results show that under WLTC conditions, compared to EHC off, the time for the SDPF inlet temperature to reach 180 °C when EHC on is 44 seconds earlier. The Carbon Monoxide (CO) emission of diesel vehicles is 63.5 mg/km, the Total Hydrocarbon (THC) emission value is 44.9 mg/km, the Non-Methane Hydrocarbon (NMHC) emission value is 39.5 mg/km, and the Nitrogen Oxide (NOx) emission value is 27.4 mg/km, which is far below the limit requirements of CHINA VI b and Euro 7. Among them, the average urea injection rate increased by 1.1 mg/s, and the overall NOx conversion efficiency increased by 7.1% compared to the EHC off, reaching over 94%. Fuel consumption increased by 1.64%. Under RDE conditions, compared to EHC off, the NOx emission during the urban operating phase when EHC on have decreased from 129.7 mg/km to 7.9 mg/km, the NOx conversion efficiency increased by 34.8%. The NOx emission throughout RDE have also decreased from 51.5 mg/km to 6 mg/km, the NOx conversion efficiency increased by 13.8%. This is an important technical solution to meet the requirements of the next phase of the CHINA VII emission regulations.</div></div>
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Krupakaran, R. L., Ratna Kamala Petla, Praveen Anchupogu, Vidyasagar Reddy Gangula, Jamuna Rani Ganipineni, and Raghurami Reddy Doddipalli. "“Experimental Investigations on NOx Reduction Using Antioxidant Additives in Conjunction with SCR in a Diesel Engine Powered by Ricinus Communis Biodiesel”." In International Conference on Advances in Design, Materials, Manufacturing and Surface Engineering for Mobility. SAE International, 2023. http://dx.doi.org/10.4271/2023-28-0059.
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<div class="section abstract"><div class="htmlview paragraph">The current study has concentrated on discovering and developing clean alternative energy sources like biodiesel and employing novel methods to reduce harmful emissions and enhance engine performance behavior. The consumption of biodiesel in diesel engines reduces the emissions from the tailpipe, but some researchers claim that it actually produces more NOx pollution than engines that run on regular diesel, which limits the use of biodiesel. In this study, Ricinus communis biodiesel was generated through transesterification process, and its fuel properties were assessed. The employ of biodiesel in diesel engines minimize exhaust emissions; however, multiple investigators claim that the consumption of biodiesel generates greater amounts of nitrogen oxide pollutants than diesel-fueled engines, which limits the possibility of biodiesel usage. In the present investigation, the combined influence of an antioxidant (tert-butyl hydroquinone (TBHQ)) additive introduced to the fuel alteration method and SCR (selective catalytic reduction) as an after-treatment approach on NOx diminution in a Ricinus communis biodiesel -fuelled CI engine was investigated.The antioxidant stabilizer together with the SCR approach substantially decreases the pollutant of NOx by 86%, with a small rise in HC and CO pollutant caused by the addition of antioxidant as additives to Ricinus communis biodiesel and aqueous urea solution introduced at the tailpipe gasses without a significant drop in BTE and BSFC.</div></div>
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Vernham, Bruce, Vaibhav Kadam, Mansour Masoudi, Sahm Noorfeshan, and Nick Poliakov. "Electrically Heated Mixer for Near-Zero Urea Deposit." In WCX SAE World Congress Experience. SAE International, 2024. http://dx.doi.org/10.4271/2024-01-2377.
Full textAbstract:
<div class="section abstract"><div class="htmlview paragraph">When used with injecting urea-water solution forming ammonia, Selective Catalytic Reduction (SCR) catalyst is a proven technology for greatly reducing tailpipe emission of nitrogen oxides (NOx) from Diesel engines. However, one major shortcoming of an SCR-based system is forming damaging urea deposits (crystals) in low temperature exhaust operations, especially exacerbated during lower exhaust temperature operations or higher injection rates. Deposits reduce SCR efficiency, damage exhaust components, and induce high concentration ammonia slips.</div><div class="htmlview paragraph">We describe here an Electrically Heated Mixer (EHM™) demonstrated on a Diesel engine markedly inhibiting deposit formation in urea SCR systems, both in low (near 200 °C) and higher exhaust temperature operations and for both low and high urea injection rates in various, realistic engine operations. Engine test runs were conducted in long durations, 10 to 20 hours each, for a total of nearly 100 hours. In nearly all operation modes, EHM maintained deposits below 1% of the total injected DEF mass; most were below 0.5%, practically non-existent, including when in higher injection rates. To further gain confidence in and validate the deposit-free outcome due to the EHM impact, CFD simulations of the same exhaust conditions were performed, which further confirmed EHM’s capability in substantially inhibiting urea deposits observed on the engine.</div><div class="htmlview paragraph">Along with prior publications, this work forms a trilogy demonstrating EHM enabling rapid heat-up making available several-fold lower tailpipe NOx, meeting ultra-stringent NOx regulations (e.g., Californian/EPA 2027 meeting 0.02 gr/bhp.hr), reducing tailpipe NOx in various regulatory and non-regulatory cycles [Frontier, 2022] while enabling highly efficient NOx conversion in low-load cycles and in fast transients [Topics in Catalysis, 2022, COMVEC, 2022].</div></div>
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Fadul, Fawaz, Amarnath Nelli, and Ahmad Fakheri. "Urea Mixing in Selective Catalytic Reduction Systems." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43393.
Full textAbstract:
The tightening of emission standards mandates NOx and particulate emissions to be reduced by more than 90 percent by 2010 in Europe, United States, and Japan. Selective Catalyst Reduction (SCR) using Urea as the NOx reducing agent is fast becoming the preferred technology. This paper provides an overview of the state of art on the topic. It also examines the use of urea vapor instead of spraying an aqueous mixture and the impact of different spraying strategies on mixing. It is shown that by injecting urea vapor opposite to direction of the exhaust gas flow, better mixing with the exhaust and thus better conversion can be achieved as compared with injecting the urea vapor parallel to the gas. The increase in pressure drop does not appear significant.
Reports on the topic "Exhaust nox decrease with urea"
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Olsen. PR-179-07200-R01 Evaluation of NOx Sensors for Control of Aftertreatment Devices. Pipeline Research Council International, Inc. (PRCI), 2008. http://dx.doi.org/10.55274/r0010985.
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Emissions reduction through exhaust aftertreatment is becoming more common. It is likely to play an important role in meeting new emissions regulations in the future. Currently, the predominate aftertreatment technology for NOX reduction in lean burn natural gas engines appears to be selective catalytic reduction (SCR). In SCR, a reducing agent is injected into the exhaust upstream of a catalyst. Supplying the optimal quantity of reagent is critical to effective application of SCR. If too little reagent is supplied then the NOx reduction efficiency may be too low. If too much reagent is provided then the ammonia slip may be too high. Control of reagent injection is an area where improvements could be made. In many current SCR systems, the rate of reagent injection is determined by engine loading. The relationship between engine loading and engine out NOX emission is determined during SCR system commissioning, and assumed to remain constant. Ideally, NOX emissions would be measured and used as feedback to the SCR system. It may also be advantageous to employ transient reagent injection based on time dependent variations in NOX mass flow in the exhaust. This would be possible with a fast response NOx sensor. Close loop engine control is an area of increasing importance. As regulatory emissions levels are reduced, compliance margins generally decrease. Precise control of air/fuel ratio and ignition timing become more critical. Cylinder-to-cylinder control of air/fuel ratio, ignition timing, and IMEP are also important. Advanced sensors are an enabling technology for more precise engine control. Ion sensing is an example of a technology that potentially can improve cylinder balancing and ignition timing. Cylinder-to-cylinder air/fuel ratio can be accomplished in several different ways. One approach would be to install individual sensors in the exhaust manifold, one for each cylinder. Ceramic based sensors (O2 and NOx) may be reliable enough at exhaust port temperatures. They are typically used in the exhaust of 4-stroke cycle engines, which have higher exhaust temperatures than 2-stroke cycle engines. Ceramic based NOx sensors have been under development for use, primarily, in Lean NOx Traps (LNTs). This technology is expected to be used on over-the-road Diesel truck engines in 2010. Therefore, the research effort has momentum. This provides an opportunity to capitalize on the efforts of another industry. In this project a NOx sensor will be evaluated using the SCR slipstream system on the GMV-4TF. The basic tasks are: 1. Identify commercial NOx sensors and procure most promising sensor 2. Design and modification of SCR slipstream system to accept sensors 3. Installation of sensors, sensor electronics, and data logging hardware and software 4. Sensor evaluation during SCR slipstream testing.
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Kudin, Roman, Prabhat Chand, and Anura Bakmeedeniya. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive. Unitec ePress, 2020. http://dx.doi.org/10.34074/rsrp.083.
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This research has been commissioned by Eco Fuel Global Limited, a New Zealand-based company, to further evaluate the effects of their fuel-additive product on the tailpipe exhaust emissions of petrol cars. At the time this research was conducted (end of 2018), the product was still in development and had not been released to the market. Prior to the testing in this research, an initial pilot test was done for the same product on a single car (Nissan Pulsar 1998), which showed favourable results, with a reduction in hydrocarbons and oxides of nitrogen at the tailpipe by more than 70%. The current research included five test cars, all running on RON 95 fuel, with the years of manufacture ranging between 1994 and 2006, and the odometer readings between 112,004 km and 264,001 km. The effects of the fuel-additive product were assessed by comparing the emissions from a car running on standard fuel with the emissions from the same car after it completed a road run (250±20 km) on the additive-treated fuel. The exhaust emissions were measured using the AVL series 4000 Emission Tester, which analyses five components: carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOX), hydrocarbons (HC) and oxygen (O2). The most noticeable outcome of using the fuel-additive product was the reduction in the concentration of oxides of nitrogen in the tailpipe exhaust (by up to 27.7%), when compared with the same cars running on standard fuel. In addition, the results showed a decrease in residual oxygen concentration, which normally indicates more complete utilisation of O2 as an oxidising agent. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive Dr Roman Kudin, Prabhat Chand and Anura Bakmeedeniya 2 The changes for other emission parameters were either relatively small (below 1%) or were not statistically significant. The application of such fuel-additive products could be beneficial for mitigating nitrogen oxides exhaust emissions from petrol vehicles in countries with ageing car fleets. These include New Zealand, which has a relatively high proportion of old cars in use, with no government-run scrappage scheme, and without a mandatory objective emissions testing.