In the diesel engine Exhaust Gas Recirculation (EGR) components, valve and connecting pipes are the critical components and often fail during new engine development. These components are important for meeting NOx emission norms. Thus design of these components should remain robust. The compact packaging of complete EGR components on the engine, however, is counted as a designing challenge in which the consequent vibration-related failure plays a major role. Normally in pneumatic EGR valve, shaft spring stiffness is considered important for shaft opening and closing. But during emission testing in this layout, shaft is self-opened without feedback signal from sensor; this is due to resonance where the problem is solved by increasing the spring stiffness. The next key components are the EGR pipes; the flexible bellows on these pipes are useful for thermal expansion during hot conditions. In this case the bellow crack failure is observed due to vibration. Therefore, design improvements due to proper design of bellow geometry and bracket support for these pipes facilitated prevention of EGR pipe failure. This paper also describes the methodology of conducting proper failure investigation to identify the root cause for vibration-related failures of EGR system during new product development.

This article investigates the effect of using three nanofluids as exhaust gas cooling fluid in an EGR cooler. Reducing the exhaust temperature of diesel engines can reduce environmental and thermal pollutants. In a conventional 3-liter engine in all kinds of vehicles, 20 to 40 kW of its 115 kW power is being wasted. The engine shell temperature rises to 600 degrees Celsius.  Exhaust gas recirculation can recover a part of it. Exhaust gas recirculation can recover thermal energy by exhaust gas recirculation method by charging a thermal energy storage tank to feed a diesel engine in cold start.Many researchers have simulated natural convection in the nanofluids. The innovation of the current research is the use of 61 tubes inside the small heat exchanger that is cooled by the discussed nanofluids in the exhaust gas recirculation system of the diesel engine that works with the paraffin phase changer and the exhaust gas recirculation rate is 60% to Reduce of environmental pollution and smoother operation of diesel engine. The inlet is steady state turbulent. The thickness of the inner tubes is considered close to zero. The shell is adiabatic. Both of them exit the heat exchanger under pressure. Three nanoparticles of diamond, silicon dioxide, and copper are considered. This numerical simulation has solved the continuity equations, energy, Navier-Stokes, the pressure drop along the pipe, flow, and rotation equation, kinetic energy disturbance, and energy loss rate equation. The results showed a higher pressure drop for the silicon dioxide-ethylene glycol nanofluid. Silicon dioxide-ethylene glycol nanofluid has a higher Nusselt number, slightly different from other nanofluids. Also, Copper ethylene glycol has a lower Velocity among nanofluids

Increase of environmental pollution and restricted emission legislations have forced companies to produce automobiles with lower air pollutants. In this respect, discharge of blowby gases into the environment has been prohibited and their recirculation into the combustion chamber is proposed as an alternative solution. In addition, using EGR technique to control and reduce nitrogen oxides in internal combustion engines has been quite effective. An important common feature of these two methods is the fact that improper EGR/blowby distribution leads to the increase in other pollutants and the significant engine power reduction. Therefore, the study of important factors in maldistribution of the injected gases is of great practical importance. Besides the injection position that has significant role on distribution of injected gases, it seems that other parameters such as engine speed, injection velocity and angle may affect the distribution of injected gases. In this numerical study, a new technique is used to determine the effect of these parameters on distribution of injected EGR or blowby gases into the EF7 intake manifold. Numerical calculations are performed for three injection velocities, five injection angles and three different engine speeds. It was found that recirculated gases distribution is slightly influenced by the injection angle and injection velocity, while the engine speed is the most influential factor.

Physical state of air-fuel mixture at inflammation instance is one of the factors which can strongly influence on performance and as well on the pollutants of an engine. In homogeneous mixture the amount of NO pollutant would be higher, because of improved combustion process and of high maximum cycle temperature. Effects of entrance location of the EGR fluid on reduction of detrimental effects of cold EGR and as well increasing its capability on further reduction of NO were studied on a 1600 cc carburetor type petrol engine which fits on paykan cars manufactured by Iran– Khodroo Co. Experimental results showed that when the EGR fluid introduced from two different points to air- fuel mixture, reduction on NO was 7% and increase on engine power was 3% higher in comparison with that where the same quantity of EGR was introduced to air- fuel mixture from a single point downstream to throttle valve.

Exhaust Gas Recirculation (EGR) method has already shown its benefits on controlling NOx emissions in internal combustion engines. By using EGR, power reduction and increase of other pollutants may be appeared; therefore use of this method needs an accurate regulation system limiting EGR cylinder-to-cylinder misdistribution. On the other hand, emission law limitations make engine manufacturers to recycle back blowby gases into the cylinders. As the same reasons, mentioned above, homogeneous distribution of blowby gases shows better performance and more emission reduction. Geometrical parameters and injection location of EGR/blowby have substantial effects on homogenous cylinder-to-cylinder distribution of EGR/blowby gases. Therefore a numerical simulation of air flow with another species gas (for example CO2 injection inside intake manifold as EGR/blowby simulation gas) is needed to evaluate the misdistribution quantitatively. Although this method is practicable, it is time consuming because of various injection locations and long solution duration. In this study a new method based on particle tracking is proposed which decreases the time and effort needed to find appropriate injection locations. Furthermore, with the new method double injection analysis is available.

Introduction: Transcatheter mitral valve-in-valve (ViV) & valve-in-ring (ViR) are relatively novel therapeutic alternatives for patients with degenerated bioprostheses or failed annuloplasty rings whose reoperative risk is too high. The predominant procedural access for both procedures is transapical or transseptal. However, whether there are differences in outcomes of this procedure using transseptal versus transapical access has not yet been defined. Methods: We conducted a systematic review of all published articles from MEDLINE and EMBASE to explore the outcomes of these two procedural approaches. Results: A total of 55 studies including 183 patients (154 ViV and 29 ViR) were included. Patients that underwent ViV (101 transapical and 53 transseptal) using the transseptal approach required more iatrogenic atrial septal defect (ASD) closure (19% versus 0. 0 %; P < 0. 001) and hence had a lower device success rate (68% versus 89%; P = 0. 001). However, there was no significant difference between the two groups in procedural success and all-cause mortality at 30 days. Overall severe bleeding complications (major or life threatening) were not different the two groups (3. 7% versus 7. 9%; P = 0. 321). In the ViR group (19 transapical and 10 transseptal), no difference in procedural success, device success or 30-day outcomes were identified between transseptal and transapical groups, although sample size was small. Conclusion: In conclusion, mitral ViV and ViR using the two different procedural approaches appear to confer equal and reasonable 30-day outcomes.

Air pollution is one of the complexity and important problems of populous and industrial cities in the world. Physical state of air-fuel mixture at inflammation instant is one of the main factors which can strongly influence on the performance as well as on the engine pollutants. Cold EGR technique and it’s entrance location into air manifold that have been recently proposed for controlling NO pollutant, can be considered as an important parameter to improve the characteristic of the physic of mixture. Since, in order to, elimination the EGR particles, optimum utilization of different species of EGR fluid and increasing it’s efficiency for reducing the engine pollutants, especially, NO pollutants, the clean EGR (refined) was studied on carbureted 1600cc paykan engine made by Iran Khodro Company. Experimental data, based on 18 modes of European standard showed that when refined EGR is added to air-fuel mixture from two different locations, it is caused to prevent from closing the EGR circuit pipes, and also compared with base engine, the reduction rates of UHC, CO, NO and bsfc were 5.9, 12.6, 59 and 8.8 percent respectively. In addition, reduction of power in the same condition and quantity of EGR, based on 70020 DIN standard, under full-load and 2500 rpm conditions was 2.2 percent.

Vehicles are one of the major source of the environment pollution, particularly the air. The safety of the human being and all other creatures would be in serious danger if the amount of pollutants in air are not controlled. Exhaust gas recirculation is one of the common methods of reducing nitrogen oxides pollutants. In this experimental research work. in order to reduce the amount of NO pollutant further, and for reducing its negative effects on engine performance, cold EGR was investigated in a 1725cc spark ignited automotive engine of Iran khodro. The engine equipped with the EGR circuit went under comprehensive test of performance and pollutant evaluation. The results of the experiments showed that the power and torque losses for the experiments in which cold EGR was used were less than that of hot EGR. Moreover the amount of NO pollutant were reduced further for the cold EGR experiments. The optimum amount and temperature of EGR under test condition were 8% and 430K respectively.