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SUMMARYThe chemical reaction networks (CRNs), which led to the transition on early Earth from geochemistry to biochemistry remain unknown. We show that under mild hydrothermal circumstances, a thermodynamic chemical reaction network including sulfite/sulfate coupled with anaerobic ammonium oxidation (Sammox), might have driven prebiotic peptides synthesis. Peptides comprise 14 proteinogenic amino acids, endowed Sammox-driven CRNs with autocatalysis. The peptides exhibit both forward and reverse catalysis, with the opposite catalytic impact in sulfite- and sulfate-fueled Sammox-driven CRNs, respectively, at both a variable temperature range and a fixed temperature, resulting in seesaw-like catalytic properties. The ratio of sulfite to sulfate switches the catalytic orientation of peptides, resulting in Sammox-driven CRNs that has both anabolic and catabolic reactions at all times. Furthermore, peptides produced from sulfite-fueled Sammox-driven CRNs could catalyze both sulfite-fueled Sammox and Anammox (nitrite reduction coupled with anaerobic ammonium oxidation) reactions. We propose that Sammox-driven CRNs were critical in the creation of life and that Anammox microorganisms that have both Sammox functions are direct descendants of Sammox-driven CRNs.

The increasing demand of cooling in internal combustion engine (ICE) may require the shift of heat removal method from traditional single phase liquid convection to subcooled flow boiling in order to fulfill the desired functional temperature. Thus, the characteristics of subcooled flow boiling heat transfer should be studied exclusively considering the practical conditions in ICEs. Accordingly, in this article, subcooled flow boiling experiments were conducted in a rectangular channel using 50/50 volume mixture of ethylene glycol and water coolant (EG/W) as working fluid. Aluminum and cast iron surfaces were selected as the heated surfaces to simulate the material of cylinder head in gasoline and diesel engines, respectively. Experimental results showed a trend that the aluminum surface had a better performance than the cast iron surface in terms of heat transfer coefficient in the boiling region. The difference between these two surfaces was concluded as results of different surface thermophysical properties. A modified wall heat flux model was proposed based on the power-type addition method. The proposed model modified the nucleation boiling contribution by introducing a new parameter which accounts for the influence of thermophysical properties of heated surface on the boiling process. Thus, one such modified model could be useful for practical engine cooling applications.

To further improve the thermal efficiency of diesel engines, a waste heat recovery system model utilizing organic Rankine cycle (ORC) is constructed and verified through system bench test and heat exchanger bench test. To recover waste heat from diesel engine exhaust, ethanol, cyclopentane, cyclohexane, R1233zd (E), and R245fa were selected for comparison. The quality of heat source, the quality of evaporator, the system output, and the system complicity were taken as variables for comparison. Analysis shows that for ORC systems without recuperator, ethanol system has the best system output of the five in a wide operation temper range, with the highest exergy efficiency of 24.1%, yet the exergy efficiency increase after the application of recuperator, 9.0%, is limited. For low temperature exhaust, cyclopentane system has the best performance with or without recuperator, and the cyclopentane system with recuperator has the best performance in terms of exergy efficiency, 27.6%, though complex heat exchangers are also required for high power output. The system output of the R1233zd system is better than the R245fa system, yet the advantage of low evaporate temperature can be better utilized for low quality waste heat recovery.

Thiosulfate reduction coupled with anaerobic ammonium oxidation (Sammox) has been recently reported as an ancient metabolic pathway. Therefore, the Sammox microbes are well worth discovering. In th...

We report the draft genome sequence of Thermomonas sp. strain XSG, isolated from a marine sediment. The genome is 3,047,478 bp long with a GC content of 68.5%., We report the draft genome sequence of Thermomonas sp. strain XSG, isolated from a marine sediment. The genome is 3,047,478 bp long with a GC content of 68.5%. Strain XSG was found to be closely related to strain NBRC 101115 of Thermomonas koreensis.

The antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) in Wastewater treatment plants (WWTPs) have attracted increasing attention. In this study, the abundance of ARB and resistance genes tet32 and defA1 were investigated using high-throughput sequencing and high-throughput qPCR in water samples collected from the inlet of the biological treatment pool and outlet of Beilun Yandong WWTP in Ningbo, China. The result shows there was a high level of ARGs in the water of both the inlets and outlets in 2017 and 2018, whereas no ARGs were detected after adding a new baffled bioreactor (BBR) water treatment process in 2019. The BBR process uses Bacillus subtilis, B. thuringiensis, B. megaterium, B. licheniformis and B. amyloliquefaciens to effectively eliminate the ARGs in wastewater. Notably, this process did not significantly change the bacterial community structure of outlet water samples. The findings demonstrate an effective new method for removing ARGs from sewage.

Sulfate-reducing bacteria (SRB) play an important role in sulfur, iron and carbon cycling. The majority of studies have illustrated the role of SRB in biogeochemical cycling in pure cultures. In this study, we established three SRB enrichment cultures (designated HL, NB and WC) from different paddy soils and conducted a transcriptomic analysis of their metabolic characteristics under sulfate and sulfate-free conditions. In the HL cultures, there was no sulfate consumption but ferrihydrite was reduced. This indicated that bacteria in the HL samples can reduce ferrihydrite and preferentially utilize ferrihydrite as the electron acceptor in the absence of both ferrihydrite and sulfate. Sulfate consumption was equal in the NB and the WC cultures, although more ferrihydrite was reduced in the NB cultures. Transcriptomics analysis showed that (i) upregulation of O-acetylserine sulfhydrylase gene expression indicating sulfate assimilation in the WC samples; (ii) the energy conservation trithionate pathway is commonly employed by SRB and (iii) sulfate not only enhanced iron reduction by its conversion to sulfide but also promoted enzymatic electron transfer via c-type cytochromes.

ObjectivesNo data were available about in-flight transmission of SARS-CoV-2. Here, we report an in-flight transmission cluster of COVID-19 and describe the clinical characteristics of these patients.MethodsAfter a flight, laboratory-confirmed COVID-19 was reported in 12 patients. Ten patients were admitted to the designated hospital. Data were collected from 25th January to 28th February 2020. Clinical information was retrospectively collected.ResultsAll patients are passengers without flight attendants. The median age was 33 years, and 70% were females. None was admitted to intensive care unit, and no patients succumbed through 28th February. The median incubation period was 3.0 days and from illness onset to hospital admission was 2 days. The most common symptom was fever. Two patients were asymptomatic and negative for chest CT scan throughout the disease courses. On admission, initial RT-PCR were positive in 9 patients, however initial chest CT were positive in only half patients. The median lung “total severity score” of chest CT was 6. Notably, “Crazy-Paving” pattern, pleural effusion, and ground-glass nodules were also seen.ConclusionIt is potential for COVID-19 transmission by airplane, but the symptoms are mild. Passengers and attendants must be protected during the flight.

The use of microorganisms in geochemical gold recycling was considered recently. To explore the feasibility of gold biomineralization in this study, bacteria GX-3 were isolated from a heavy metal c...

The control strategies of exhaust thermal management is experimental investigation to reduce Nitrogen oxides (NOx) emission under the world Harmonized transit cycle (WHTC) in this paper. The exhaust temperature of the 59.3% working conditions is lower than 200 °C under the cold start WHTC, and the average temperature of which is 196 °C, the urea injection system is in the state of stopping in most of time under cold start WHTC. The effects of intake throttle valve opening on NOx emission, fuel and urea consumption were studied in steady conditions with medium and low load. The 15–20% opening of intake throttle valve could increase the exhaust temperature to more than 200 °C when the torque is less than 250 N·m. The NOx emission weighted value of the WHTC is reduced by 41.5%, which could meet the requirements of the Europe V emission regulations for WHTC test cycle, but the fuel economy increase slightly. The Diesel Oxidation Catalyst (DOC) could increase the NO2/NOx ratio in the exhaust gas effectively, and increase the NOx conversion efficiency in the temperature range of 200–400 °C, which reduce the NOx emission weighted value of the diesel engine under WHTC by 8.7%.

The idle-up strategy of diesel particulate filter (DPF) regeneration during a drop to the idle (DTI) process was investigated in this study. This strategy could control the peak temperature and maximum temperature gradient of a cordierite ceramic filter. Experimental results showed that as the engine working condition dropped to idle speed during regeneration with a DPF soot load of 4 g/L, the peak temperature was reduced from 820 °C to 632 °C when the idle speed was increased to 1100 r/min, a decrease of 22.9%, while the maximum temperature gradient was reduced from 30 °C/cm to 10 °C/cm, a decrease of 66.7%. The peak temperature and temperature gradient of the DPF cordierite ceramic filterwith DTI during regeneration were effectively reduced. The idle speed range for the idle-up strategy to decrease the peak temperature and temperature gradient of a cordierite ceramic filter was discussed. The maximum idle speed of the idle-up strategy should not be higher than the speed of common engine working conditions in order to avoid DTI during a regeneration increase at current engine driving speed.

Biogeochemical interactions of iron and sulfur drive their cycles in many environments, which makes understanding the mechanism of sulfur redox cycling dependent abiotic iron(III) reduction by sulfate-reducing bacteria (SRB) particularly important. Here, we present a newly isolated Desulfitobacterium hafniense strain DH with the potential of reducing sulfate, sulfite, thiosulfate, and elemental sulfur from a paddy soil. Strain DH cannot enzymatically reduce ferrihydrite, but it can abiotically reduce ferrihydrite through extracellular electron transfer with biogenic sulfide or other sulfur compounds acting as electron shuttles. Sulfite, elemental sulfur, and thiosulfate, the oxidation products of sulfide, complete the sulfur cycle between ferrihydrite and strain DH. The presence of strain DH at the ferrihydrite surface results in mineral dissolution and secondary mineralization. Proteomic analysis revealed that the expression level of sulfur reduction functional protein DsrC and a thiosulfate reductase in...

Sulfate-reducing prokaryotes (SRP) represent a diverse group of heterotrophic and autotrophic microorganisms that are ubiquitous in anoxic habitats. In addition to their important role in both sulfur and carbon cycles, SRP are important biotic and abiotic regulators of a variety of sulfur-driven coupled biogeochemical cycling of elements, including: oxygen, nitrogen, chlorine, bromine, iodine and metal(loid)s. SRP gain energy form most of the coupling of element transformation. Once sulfate-reducing conditions are established, sulfide precipitation becomes the predominant abiotic mechanism of metal(loid)s transformation, followed by co-precipitation between metal(loid)s. Anthropogenic contamination, since the industrial revolution, has dramatically disturbed sulfur-driven biogeochemical cycling; making sulfur coupled elements transformation complicated and unpredictable. We hypothesise that sulfur might be detoxication agent for the organic and inorganic toxic compounds, through the metabolic activity of SRP. This review synthesizes the recent advances in the role of SRP in coupled biogeochemical cycling of diverse elements.

Ammonia (NH3), which has been considered as a threaten to human health, becomes increasingly concerned recently. In order to comply with the increasingly stringent emission standards, it is widely accepted that the technique combining stoichiometric operation with Three Way Catalyst (TWC) is a more efficient and cost-effective solution for emission control in natural gas engines. However, when equipped with TWC, part of the NOx emissions generated during the combustion process will be converted to NH3, making natural gas engines a significant contributor to NH3 emissions. With the promulgation of the Euro VI, the addition provision for the limitation of NH3 emissions further motivates the investigations on the NH3 emissions of natural gas engines equipped with TWC. In this paper, the effects of air/fuel ratio, engine speed and engine load on the NH3 emission characteristics of a natural gas engine operating at stoichiometric and equipped with TWC are first studied under steady-state conditions. Then the NH3 emissions are further evaluated and analyzed during both the WHSC steady-state test cycle and the WHTC transient test cycles. The results indicated that NH3 emissions have the highest values at air/fuel ratio of 0.96 and are lower when operating at stoichiometric conditions. With the increase of engine speed, NH3 emissions show a trend of first decrease and then increase while witness an increasing trend with the increase of engine load. During WHSC test cycle, NH3 emissions are depended on the trend of the raw NOx and raw CO emissions while during the WHTC test cycles, the effects of the oxygen induced during the motoring process should be taken into account. In summary, with the application of the combination of stoichiometric operation and TWC, NH3 emissions of the investigated natural gas engine could not meet the demand of the Euro VI emission standard, which means that the addition of an Ammonia Slip Catalyst(ASC) device is essential.

A new biogeochemical pathway has been suggested to be present in terrestrial ecosystems, linking the nitrogen and iron cycles via ferric iron reduction coupled to anaerobic ammonium oxidation. However, the underlying microbiological process has not been demonstrated to date. Here we report a stable consortium, HJ-4, composed of Anaerospora hongkongensis (85%) and facultative anaerobe, Comamonadaceae (15%), which can process ferrihydrite reduction coupled to anaerobic ammonium oxidation driven by sulfur redox cycling. In this process, A. hongkongensis reduces elemental sulfur, sulfite, and polysulfides to sulfide, which fuels ferrihydrite reduction. Sulfide, elemental sulfur, sulfite, and polysulfides serve as electron shuttles, completing the sulfur cycle between A. hongkongensis and ferrihydrite. In addition, Comamonadaceae shows ammonium oxidation potential under aerobic conditions, with nitrite as the main product. We inferred that Comamonadaceae mediates simultaneous nitrification-denitrification coupled to iron redox cycling through nitrate/nitrite-dependent ferrous oxidation under anaerobic conditions. Hence, we discovered a novel pathway for ferric iron reduction coupled to ammonium oxidation, highlighting the key role of electron shuttles and nitrate/nitrite-dependent ferrous oxidation in this process. The biogeochemical cycling of sulfur, iron, and nitrogen could be coupled in aquatic and terrestrial ecosystems.

The control strategies of exhaust thermal management are the premise of achieving the regeneration for Diesel Particulate Filter (DPF). In steady conditions with medium and low load, the effects of active control strategies on exhaust thermal management were studied at the test bench, which include intake throttle valve opening, injection advance angle, injection pressure and post injection. Compared with full opening of intake throttle valve, the 15–20% opening of intake throttle valve could increase the exhaust temperature by about 140 °C, decrease the NOx emission but deteriorated the Particulate matter (PM) emission and fuel consumption. The change of injection advance angle and injection pressure have little effect on the exhaust temperature, but have a great effect on the emissions of NOx, PM and the fuel consumption. Optimized matching of the injection advance angle and quantity of post injections improves the exhaust temperature by about 70 °C. The World Harmonized Transient Cycle (WHTC) was used to evaluate the effect of improving exhaust temperature. WHTC experimental results indicated clearly that the exhaust temperature was effectively increased within the whole 1800 s, especially in the idle and low load conditions.

The genus Bradyrhizobium is considered to be widespread and abundant group of symbiotic bacteria in many plant-soil ecosystems. However, the ecological versatility of this phylogenetic group remains highly understudied in man-made ecosystems, mainly due to the lack of pure cultures and genomic data. To further expand our understanding of this genus for human health, we analyzed the high quality draft genome of Bradyrhizobium strain BL, isolated from a municipal wastewater treatment plant in Ningbo, China. The Bradyrhizobium sp. BL draft genome has a total size of 7,718,431 bp with an overall G + C content of 46.43%. From a total of 7236 predicted sequences, 7176 and 60 are protein and RNA coding sequences, respectively. Moreover, 63.51% of the predicted genes were assigned into to Clusters of Orthologous Groups (COG) functional categories. The Bradyrhizobium sp. BL genome contains various defense mechanisms against antibiotics that up to predicted 60 antibiotic resistance coding genes. The Bradyrhizobium sp. BL genome contains 237 termed virulence factors coding genes which show its potential pathogenicity. This study provides important insights into the genomic diversity of the genus Bradyrhizobium and provides a foundation for future comparative genomic studies that will generate a better understanding of the antibiotic resistance process.

In this study, the novel trigeneration systems based on the atmospheric and pressurized SOFC are proposed and investigated. The proposed systems include the SOFC based top cycles and an innovative bottom cycle which combines a transcritical CO2 cycle, a transcritical organic Rankine cycle, and a LNG cold energy utilization system. The mathematical model is developed, and the energetic, exergetic and economic analysis is conducted accordingly. Then, the effects of key parameters, such as current density, operating temperature, steam-to-carbon ratio (STCR) on system performance are evaluated. Under design conditions, the results show that the electrical efficiencies, the overall system efficiencies, the exergy efficiencies, and the total cost rate of the integrated systems can reach 57.14%, 59.56%, 55.12%, 16.73 $/h for the atmospheric system and 68.1%, 68.8%, 65.7%, 19.84 $/h for the pressurized system, respectively. Parameter study shows that the thermodynamic performance of pressurized system is significantly better than that of the atmospheric system, but economic cost is much higher. SOFC inlet temperature has a positive effect on the pressurized system performance, while this positive effect is found when the inlet temperature is less than 510 °C for atmospheric system. Besides, the multi-objective optimization by using genetic algorithm (NSGA-II) for the novel trigeneration systems has been performed. And the technique for order preference by similarity to an ideal solution (TOPSIS) based on entropy weight is performed to choose the final optimum design point of the combined systems. The multi-objective optimization results demonstrate that the exergy efficiency and the total cost rate achieve the values of 56.1%, 16.82 $/h and 66.83%, 12.02 $/h for atmospheric and pressurized system, respectively, at the optimal balance point selected by the TOPSIS method.

// Naibin Yang 1 , Shanshan Li 2 , Guoxiang Li 1 , Shengguo Zhang 2 , Xinyue Tang 2 , Shunlan Ni 2 , Xiaomin Jian 3 , Cunlai Xu 4 , Jiayin Zhu 5 and Mingqin Lu 2 1 Department of Infection and Liver Diseases, Ningbo First Hospital, Ningbo, China 2 Department of Infection and Liver Diseases, The First Affiliated Hospital of Wenzhou Medical University, Institute of Liver Research, Wenzhou Medical University, Wenzhou, China 3 Department of The First Clinical Medical, Wenzhou Medical University, Wenzhou, China 4 Department of Respiration, Lishui People’s Hospital of Wenzhou Medical University, Lishui, China 5 Laboratory Animal Center, Wenzhou Medical University, Wenzhou, China Correspondence to: Mingqin Lu, email: // Keywords : extracellular vesicles, exosomes, miRNA, hepatocellular carcinoma, MSCs Received : April 28, 2016 Accepted : September 28, 2016 Published : October 04, 2016 Abstract Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide. As vectors for intercellular information exchange, the potential role of extracellular vesicles (EVs) in HCC formation, progression and therapy has been widely investigated. In this review, we explore the current status of the researches in this field. Altogether there is undeniable evidence that EVs play a crucial role in HCC development, metastasis. Moreover, EVs have shown great potential as drug delivery systems (DDSs) for the treatment of HCC. Exosomal miRNAs derived from HCC cells can enhance transformed cell growth in recipient cells by modulating the expression of transforming growth factor-β activated kinase-1(TAK1) and downstream signaling molecules. Furthermore, vacuolar protein sortin 4 homolog A(VPS4A) and insulin-like growth factor(IGF)-1 regulate exosome-mediated miRNAs transfer. Immune cells- derived EVs containing integrin αMβ2 or CD147 may facilitate HCC metastasis. In addition, EVs-mediated shuttle of long non-coding RNAs (lncRNAs), specifically linc- VLDLR and linc-ROR promote chemoresistance of malignant cells. Heat shock proteins (HSPs)-harboring exosomes derived from HCC tumor cells increase the antitumor effect of natural killer (NK) cells, thus enhancing HCC immunotherapy. Indeed, inhibition of HCC tumor growth has been associated with tumor cell-derived exosomes (TEX)-pulsed dentritic cells (DCs). Exosomes are also essential in liver metastasis during colorectal carcinoma (CRC) and pancreatic ductal adenocarcinomas (PDAC). Therefore, as nucleic acid and drug delivery vehicles, EVs show a tremendous potential for effective treatment against HCC.

In this paper, the effects of the injection timing, the injection pressure and the engine load on the combustion noise of a pilot-ignited direct-injection natural-gas engine were explored by analysing the separate components of the in-cylinder pressure. The results suggested that retarding the injection timing and reducing the injection pressure are effective ways of controlling the combustion noise. This can be attributed to the promoted burning rate at advanced injection timings and to the increased injection pressure. However, the effect of the engine load seems to be less obvious, although the resonance pressure level appears to increase with increasing engine load; the estimated combustion noise shows a decreasing tendency.

Sewage in WWTPs is one of main way to spread antibiotic resistant microbes (ARMs), and beach bay water is in direct contact with human skin. It is necessary to pay attention to remove the ARMs in WWTP sewage and bay water. Our results showed that ARMs and total microbes (TMs) can be effectively removed by S2O82-/Fe2+ in the effluent stage of WWTPs and bay water. Quenching experiments using tert-butyl alcohol, dimethyl sulfoxide and Al2O3 as scavengers confirmed that the primary reactive oxidants responsible for microbes removal during the Fe(II)-activated persulfate oxidation process might be SO4•- and Fe(IV), rather than •OH. The bacterial community shifted and the alpha diversity significantly reduced after treatment. In WWTP group, relative abundance of Firmicutes increased to 8.56%, and potential pathogens such as genus Vibrio decreased to 0.03% in bay water after treatment. The ecological toxicity to the environment of S2O82-/Fe2+ further illustrated that the mortality of indicator species Oryzias latipes did not increase after treatment, and the dosage of 60/30 μM can be potentially ideal dosage of S2O82-/Fe2+. This study revealed Fe(II)-activated persulfate oxidation as an eco-friendly and economical method could reduce TMs and ARMs in WWTP sewage and bay water.

A three-dimensional multi-phase non-isothermal model of proton exchange membrane fuel cell (PEMFC) is developed based on a modified Bruggeman equation. The developed model is validated with experimental results and it shows the modified model can more accurately simulate actual working conditions of PEMFC at medium and high current density. The influences of different cooling patterns on the performances of PEMFC are explored. Results reveal that different gas flow patterns have roughly the same effect on the temperature distribution of the membrane in the case of the cooling water counter-current flowing. Under the counter-current gas flow pattern, pattern 3 is the best cooling pattern, that is to keep the cooling water flow direction consistent with the cathode gas flow direction. Under the co-current gas flow pattern, pattern 6 is the best cooling pattern, that is to keep the cooling water flow direction consistent with the gas flow direction. Meanwhile, the temperature distribution of the cathode and the anode is basically symmetrical at the interface of the cathode gas diffusion layer and the cathode catalyst layer. Additionally, the optimal cooling patterns need to ensure the cooling water co-current flowing, and it has obvious advantages of system integration and cost reduction.

Two new approximate formulations to joint chance-constrained optimization problems are proposed in this paper. The relationships of CVaR (conditional-value-at-risk), chance constrains and robust optimization are reviewed. Firstly, two new upper bounds on E((·) + ) are proposed, where E stands for the expectation and x + = max(0, x ), based on which two approximate formulations for individual chance-constrained problems are derived. The approximations are proved to be the robust optimization with the corresponding uncertain sets. Then the approximations are extrapolated to joint chance-constrained problem. Finally numerical studies are performed to compare the solutions of individual and joint chance constraints approximations and the results demonstrate the validity of our method.

This paper simulated a six-cylinder diesel engine with 3d model, and optimized combustion and emission through modify project distance of injector and nozzle angle. Simulation result shows that appropriate project distance will enhance entraining power of vortices and reduce soot generation without increasing NOx generation; yet inappropriate nozzle angle will deteriorate combustion in either clearance volume or combustion chamber bowl. Variation in either project distance or nozzle angle has greater influence on soot generation than NOx generation, and both can be optimized to reduce soot emission without affect NOx emission significantly.

In this paper, we propose a new data hiding scheme based on prediction difference. The difference between prediction value and the real value in the corresponding position of the cover image is calculated, and the secret bits are embedded into the difference. That is changing or staying the original pixel of corresponding position in the original image to embed secret bits. Experimental results indicated that our scheme provides higher PSNR value with the same payload.

With consideration of asperity contact, the minimum oil film thickness and friction power loss are calculated by simultaneous solution of the dynamics, blow-by and lubrication of piston ring pack. Take the piston ring pack in the first cylinder from the free end of a six-cylinder diesel engine for example, results show that the asperity contact takes place at all of the compression rings and oil ring; the minimum oil film thickness is 1.04μm at the top ring; the total friction loss power is 0.94kW, the top ring accounts for 37.2%, the second ring accounts for 33.0%, the oil ring accounts for 29.8%.

Based on the structure analysis of a hybrid truck, design a single-axle parallel hybrid powertrain test platform. Modular design method is used to realize this platform and this platform is divided into four modules. Function design, software design and realization of the four modules are respectively discussed. Finally, a cycle run test was taken and the test result indicates that effectiveness and accurateness of the test platform are realized well.

Avoiding the urea deposition in the exhaust stream is one of the basic requirements for SCR system normal application. Unreasonable structure design, machining and installation position all could lead to urea crystallization on the wall of exhaust pipe and the front end surface of the catalyst, in addition, unreasonable control strategy also could deteriorate this phenomenon. The components of the urea depositions are the urea and cyanuric acid analyzed by thermogravimetry - FTIR technology. The integrated injector mounting is designed to alleviate the urea crystallization based on analysis results. The engine test and the vehicle road test are all shown that the optimal structural design and calibration strategies could avoid crystallization and sedimentation effectively in the exhaust system.

Based on the Woschni correlation, a three dimensional in-cylinder heat transfer model is proposed, which develops Woschni correlation from zero dimension to three dimension. Characteristic parameters are proposed as transient flow and heat transfer parameters from in-cylinder CFD simulation, with further consideration of the influence of thermal conductivity, viscosity and Prandtl number. According to test data, the new correlation can be regressed. The new model costs little more calculation time, and it can satisfy the engineering demand.

In this paper, the thermo-hydraulic performance of an opposed piston opposed cylinder (OPOC) cylinder water jacket with helical fins on the annulus side was studied experimentally and numerically. Three dimensional computational fluid dynamics (CFD) software FLUENT has been adopted to explore fluid flow characteristics, pressure drop and cylinder wall temperature under different configurations. Four different cases of helical fin pitch (154 mm, 170 mm, 184 mm and 205 mm) were analyzed under same flow rate, of which the values of Reynolds number are all in turbulent region. The numerical model was first validated by comparison with Particle Image Velocity (PIV) experiment result. Then heat transfer validation was conducted using a double-pipe heat exchanger with longitudinal fins and the results were compared with empirical correlation. The validated model was used to calculate the thermo-hydraulic performance of OPOC cylinder water jacket of four different cases. The results showed that compared with cylinder water jacket without helical fins, configurations with helical fins increased heat transfer performance obviously and the pressure drop went up in the same time. A comprehensive thermal performance factor which takes into account both heat transfer and pressure drop was defined to analyze different cases, and the case with fin pitch of 187 mm performed optimal thermal performance.