Exhaust Pipe Research Articles

Investigation on formaldehyde generation characteristics and influencing factors of PODE/methanol dual-fuel combustion mode.

Polyoxymethylene dimethyl ether (PODE) and methanol are important low-carbon substitutable fuels for reducing carbon emissions in internal combustion engines. In the research, the impacts of methanol ratio, injection timing, and intake temperature on HCHO generation and emission were investigated using both engine tests and numerical simulations. Results suggest that an increase in methanol ratio suppresses auto-ignition tendency of PODE, leading to the increase of ignition delay period, pressure peak, and heat release rate peak inside the cylinder. The decrease in in-cylinder combustion temperature contributes to an increase in HCHO emission due to partial oxidation of methanol in the cylinder and exhaust pipe. While the injection timing is gradually postponed from -10 °CA ATDC to 2 °CA ATDC, in-cylinder high-temperature area decreases, the quantity of unburned methanol increases, but part of HCHO is converted to HCO due to H radical influence, resulting in 72% increased HCHO emission. With the increment of intake temperature, the oxidation and decomposition of in-cylinder methanol accelerate, leading to an improvement in combustion stability, more uniform temperature distribution, and a decrease in unburned methanol, which results in lower HCHO emission. When the intake temperature is rose from 30 to 60 °C, HCHO emission decreases by 11.2%.

Variation of Practice in Prophylactic Protocol to Reduce Prosthetic Joint Infection in Primary Hip and Knee Arthroplasty: A National Survey in the United Kingdom.

Prosthetic joint infection (PJI) has an enormous physiological and psychological burden on patients. Surgeons rightly wish to minimise this risk. It has been shown that a standardised, evidence-based approach to perioperative care leads to better patient outcomes. A review of current practice was conducted using a cross-sectional survey among surgeons at multiple centers nationwide. An 11-question electronic survey was circulated to hip and knee arthroplasty consultants nationally via the BOA (British Orthopaedic Association) e-newsletter. The respondents included 56 consultants working across 19 different trusts. Thirty-four (60.7%) screen patients for asymptomatic bacteriuria (ASB) preoperatively, with 19 (55.9%) would treating with antibiotics. Fifty-six (100%) screen for methicillin-resistant Staphylococcus aureus and treat if positive. Only 15 (26.8%) screen for methicillin-sensitive S. aureus (MSSA) or empirically eradicate. Zero (0%) routinely catheterise patients perioperatively. Forty-one (73.2%) would give intramuscular or intravenous gentamicin for a perioperative catheterisation. All surgeons use laminar flow theatres. Twenty-six (46.4%) use only an impervious gown, 6 (10.7%) exhaust pipes, and 24 (42.3%) surgical helmet system. Five different antimicrobial prophylaxis regimens are used 9 (16.1%) cefuroxime, 2 (3.6%) flucloxacillin, 19 (33.9%) flucloxacillin and gentamicin, 10 (17.9%) teicoplanin, 16 (28.6%) teicoplanin and gentamicin. Twenty-two (39.3%) routinely give further doses. ASB screening, treatment and intramuscular gentamicin for perioperative catheterisation is routinely practiced despite no supporting evidence base. MSSA screening and treatment is underutilised. Multiple antibiotic regimens exist despite little variation in organisms in PJI. Practice varies between surgeons and centers, we should all be practicing evidence-based medicine.

Detection of Urban Flood Inundation from Traffic Images Using Deep Learning Methods

Urban hydrological monitoring is essential for analyzing urban hydrology and controlling storm floods. However, runoff monitoring in urban areas, including flood inundation depth, is often inadequate. This inadequacy hampers the calibration of hydrological models and limits their capacity for early flood warning. To address this limitation, this study established a method for evaluating the depth of urban floods using image recognition and deep learning. This method utilizes the object recognition model YOLOv4 to identify submerged objects in images, such as the legs of pedestrians or the exhaust pipes of vehicles. In a dataset of 1,177 flood images, the mean average precision for water depth recognition reached 89.29%. The study also found that the accuracy of flood depth recognition by YOLOv4 is influenced by the type of reference object submerged by the flood; the use of a vehicle as the reference object yielded higher accuracy than using a person. Furthermore, image augmentation with Mosaic technology effectively enhanced the accuracy of recognition. The developed method extracts on-site, real-time, and continuous water depth data from images or video data provided by existing traffic cameras. This system eliminates the need for installing additional water gauges, offering a cost-effective and immediately deployable solution.

Low-Frequency Discontinuous Noise Diagnosis and Reduction of Air Conditioner Outdoor Unit

Abnormal discontinuous low-frequency noise occurs in the outdoor unit when the air conditioner is operating at 86~96 Hz. This noise has the characteristics of low frequency, strong penetration, long transmission distance, and poor sound quality, which can cause serious noise pollution. In order to reduce the low-frequency noise of the outdoor unit of the air conditioner, the discontinuous noise frequency is first located by testing the time-domain and frequency-domain maps of the noise. It is then compared with the frequency of fan rotation noise and structural radiation noise. It is found that the discontinuous noise is caused by the coupling of fan rotation noise and structural radiation noise. It is found that low-frequency noise improvement is significant when the frequency difference between two noise peaks is greater than 8 Hz or when a single noise peak is less than 25 dB(A) by studying the methods of frequency modulation and amplitude modulation of noise peaks. By adjusting the fan speed from 930 rpm to 940 rpm, the problem of 94 Hz noise is solved. Then, through testing the natural frequencies of the pipe and shell, it is found that the natural frequencies of the pipe are close to the excitation frequencies. The structural radiation noise is mainly caused by the pipe. Modal analysis is conducted on the pipe. When the normal boundary with the condenser and the normal boundary with the valve of the pipe is constrained by springs, the simulated values are closer to the measured values. Finally, structural optimization design is carried out on the pipe. When the U-tube of the exhaust pipe is shortened by 30 mm, a 30 g mass block is added to the cold inlet pipe, and a 97 g mass block is added to the lower part of the valve pipe of the suction pipe. The discontinuous noise of the optimized prototype is significantly improved.

Emission characteristics of diesel engines fuelled with B20 with different DPF, DOC and EGR arrangements

ABSTRACT In the present investigation, pre- and post-combustion techniques are adopted for diesel engines. This work focuses on optimisation of engine performance powered with biodiesel B20 blend by incorporating pre- and post-combustion techniques addressing emission from diesel engines within acceptable norms. In pre-combustion techniques, Karanja biodiesel with two proportions (B10 and B20) is injected along with diesel and exhaust gas recirculation with varied flow rates is used to address NOx emissions. A diesel particulate filter (DPF) and diesel oxidation catalyst (DOC) are fitted in the exhaust pipe of the engine. Initial test runs were conducted on engine using diesel with 0%, 5%, 10% and 20% EGR when DPF and DOC are positioned according to three arrangements. After optimising position of EGR, DPF and DOC, the engine was fuelled with B10 and B20 to study performance and emissions at different EGR rates with and without these devices. Results indicated changes in overall performance with injection of biodiesel; reduction in unburnt hydrocarbon by 43.9%, smoke by 71.15%, NOx by 22.6% for 20% biodiesel fuelled engine with 10% EGR, DPF and DOC. B20 can be fuelled into diesel engine with suitable modifications, least emissions can be achieved with 10% EGR, DPF and DOC.

The dispersion of various pollutants emitted from truck and passenger vehicles: a wind-tunnel study.

In recent years, investigation of the dispersion of exhaust gas from vehicles has received increasing attention in various studies using various approaches, including on-field measurements, experimental laboratory models, and software simulations. This study aimed to investigate the effects of changes in vehicle traffic conditions, fuel type used in an engine, and vehicle size on the emission and dispersion of gaseous pollutants from the exhaust pipe in a wind tunnel. The results showed that pollutant concentration decreases along the tailpipe centerline as the exhaust gas moves backward and the flow pattern changes significantly from 11.5 to 15 m/s. However, for the passenger car, the small recirculation region in the near-wake region at an inflow air velocity of 11.5 m/s carries away more particles compared to an incoming velocity of 15 m/s, resulting in lower gaseous concentrations in both longitudinal and transverse directions. The gaseous dispersion behind the truck and the car is wider for an inflow air velocity of 11 m/s, especially for NO, NO2, and SO2. The results also showed that the pollutant concentrations of the truck exhaust plume were higher than those of the passenger car in lower inflow air velocity in both longitudinal and transverse directions. The lower concentration of dispersed gaseous pollutants behind the passenger car model compared to the truck model may be attributed to the shape and height of the truck model, which can trap more particles behind the vehicle. Finally, the dispersion pattern of SO2 is almost identical to that of NO2, and the dispersion of the exhaust gas plume related to CO and NO pollutants is more prolonged than that of CO2 and NO2 particles along the tailpipe centerline. The findings of this study may help in estimating the concentration of pollutants along urban highways.

Environmental assessment of several scenarios of active and passive radon control measures

In buildings, radon gas mainly enters through cracks in the floors and gaps around pipes and cables in contact with the soil, thereby increasing indoor radon levels. Like other building components or systems, the radon control measures have embodied and operational environmental impacts that have been neglected to a certain extent. While many actions have been taken recently to achieve carbon-neutral yet energy-efficient buildings, even radon control measures should be investigated not only for protecting human health since radon gas is the major source of ionising radiation for humans but also for the environment. This paper aims to undertake a comparative analysis of the embodied and operational impacts of variant radon-protective measures installed at the floor foundation level (both active and passive solutions) for new and existing buildings. In particular, this analysis includes four different measures based on radon venting from i) floor air gap created from plastic components, ii) flexible perforated pipes embedded in the gravel layer under the floor, iii) radon sump placed in the sub-floor layer, and iv) perforated tubes drilled horizontally into the subsoil under the house. In all cases, radon will be removed through a vertical exhaust pipe terminated above the roof or by a roof fan. The impacts are calculated for the life cycle assessment (LCA) stages A1-A3 (production phase) and B6 (operational energy) to determine whether future research should be focused on the reduction of environmental impacts on the production stages or the operational ones.

A novel adaptive-weight ensemble surrogate model base on distance and mixture error.

Surrogate models are commonly used as a substitute for the computation-intensive simulations in design optimization. However, building a high-accuracy surrogate model with limited samples remains a challenging task. In this paper, a novel adaptive-weight ensemble surrogate modeling method is proposed to address this challenge. Instead of using a single error metric, the proposed method takes into account the position of the prediction sample, the mixture error metric and the learning characteristics of the component surrogate models. The effectiveness of proposed ensemble models are tested on five highly nonlinear benchmark functions and a finite element model for the analysis of the frequency response of an automotive exhaust pipe. Comparative results demonstrate the effectiveness and promising potential of proposed method in achieving higher accuracy.

Heat Transfer Characteristics of Turbulent Flow in Double-90°-Bend Pipes

This study evaluates the heat dissipation and Nusselt number for an S-shaped double-bend pipe, for which an experimental evaluation is lacking. In terms of the velocity field, the mean velocity and turbulent kinetic energy were measured through particle image velocimetry. Heat transfer characteristics were evaluated in validated conjugate heat transfer simulations, and a k-ω SST turbulence model was used for flow simulation inside the pipe. Heat transfer enhancement was observed at the first bend, as observed in previous studies on single-bend and U-shaped bends, whereas no heat transfer enhancement was observed at the second bend. This result was due to higher turbulent heat flux at the first bend because of higher eddy diffusion on the outside of the bend, whereas eddy diffusion was lower on the outside of the second bend owing to the history of the first bend. The heat transfer characteristics of the S-shaped double-bend pipe elucidated in this study provide valuable insight for devising strategies to reduce heat loss in automotive exhaust pipes with multiple bends. Furthermore, the conjugate heat transfer simulation model used in this study provides a benchmark for heat transfer calculations for multi-bend pipes.

Analisis Penggunaan Knalpot Racing Slip-On Dan Knalpot Racing Full System Terhadap Performa Mesin Pada Motor 150 CC

One way to improve the performance of an engine without dismantling the original engine is to modify the exhaust pipe, which is commonly called the exhaust. Here we use 4 types of exhaust, namely factory standard exhaust, slip-on exhaust (standard header-modified muffler), slip-on (modified header-standard muffler), and full system exhaust that we take from the market. This study aims to test the performance of the motor which consists of torque, power, and exhaust emissions (CO and HC levels) from the four types of exhausts, using a dynamometer to determine torque and power, an emission gas analyzer to determine the level of exhaust emissions (CO and HC). Our experimental results show the data, the results are still below the standards set by the Indonesian government. The greatest torque of 15.02 N.m at 7500 rpm and the greatest power of 18.36 hp is achieved by a full-system modified exhaust compared to the standard exhaust with the highest torque of 14.62 N.m at 7000 rpm and the highest power of 16.67 hp at 9500 rpm. The best exhaust emission levels are achieved by standard exhaust with the largest CO content of 0.62% at 10000 rpm and the largest HC content of 107 ppm at 10000 rpm compared to full system exhaust with the largest CO content of 1.79% at 10000 rpm and 201 ppm HC levels at 10000 rpm, in other words the standard exhaust is still more environmentally friendly than the full system exhaust.

Identification of the most influential variables on the power generation of an automotive thermoelectric generator through a global sensitivity analysis

A methodology to determine the most influential independent input variables on the maximum power generation of an automotive thermoelectric generator is developed. A validated numerical model is used to predict the maximum power generation of a thermoelectric generator composed of several thermoelectric modules installed in the exhaust pipe of an internal combustion engine. The Morris sensitivity analysis and the least absolute shrinkage and selection operator feature selection approach are employed to identify the most influential variables. The amount of independent variables selected to carry out the analysis are 18 and they are embedded in different fields such as hydraulic, thermal, electrical, chemical, geometrical and design. Results show that the most influential variables are the inlet temperature of the hot fluid and the Seebeck coefficient and electric resistance of the thermoelectric modules. The thickness of the thermoelectric modules has the least influence on the maximum power generation. These findings could be useful to other researchers to develop simpler mathematical models without compromising the accuracy.

Optimized muffler design and its performance evaluation to environmental noise reduction on classrooms

Generators powered by diesel engines are widely used as a backup source of electrical energy. However, the generator produces very high noise, which is around 73–110 dBA. In this study, we designed a muffler and optimized to the highest possible noise reduction. We constructed and installed the designed muffler to evaluate the performance an absorptive muffler on the exhaust pipe of the simulated muffler with the installed one. We measured the sound pressure level (SPL) at the source of exhaust gas noise before the proposed muffler installed and after installation, including inside the surrounding classrooms. A survey was also conducted to determine the annoyance response of the teachers and the students. The results show that the presence of an absorptive muffler can reduce noise by 10 dBA and attenuate more at high frequencies (<500–16000 > 500–16000 Hz) at the source of the noise and also in the surrounding environment. The annoyance rating for generator exhaust noise is moderate to very disturbing for listeners who are outside the room and moderate for listeners positions in the room.

ЗНИЖЕННЯ ЗОВНІШНЬОГО ШУМУ БРОНЕАВТОМОБІЛЯ «НОВАТОР» ЗАСТОСУВАННЯМ ВИСОКОЕФЕКТИВНОГО ГЛУШНИКА ШУМУ

Armored vehicles are widely used for combat operations, for which it is extremely important to be as inconspicuous as possible. There are different types of masking, one of which is reducing the level of external noise. For the Novator armored car, a highly effective muffler of the exhaust gases of the internal combustion engine was devel-oped. The Novator armored car has a pickup-type body, a gross weight of 9,000 kg and a Ford F8 turbodiesel engine with a power of 300 hp. The uniqueness of the developed muffler is that it seeks to return all the sound waves that entered it back to the intake pipe. This effect is achieved due to the specific structure of the silencer housing. The case is an ellipsoid of rotation.At the same time, the section of the intake pipe (the pipe that goes into the muffler) is placed in the first focus of the ellipsoid of rotation, and the sound waves propagate to the inner wall of the elliptical body, reflect from it, con-verge at the second focus, and then continue to move to the opposite wall, reflect from it, converge in the first focus and spread further back into the intake pipe. In the intake pipe, there is partial interference of the reflected sound waves when they meet the incoming waves, and the final absorption by the sound-absorbing material. At the same time, exhaust gas-es, bouncing off the walls of the muffler, leave the latter through the exhaust pipe. At the same time, the exhaust pipe exits the ellipsoid of rotation coaxially with the intake pipe, which enters the pipe tel-escopically with a gap. Taking into account the directional diagram of sound energy radiation at the exit from the ex-haust pipe, a proposal was made to create a muffler not as a full ellipsoid of rotation, but in the form of a half ellipsoid of rotation. Such a solution will make the muffler significantly cheaper and much more compact, which is essential for a military vehicle. Keywords: armored car, “novator”, masking, camouflage, silencer, ellipsoid of rotation, directional diagram, acoustic efficiency, sound waves, sound absorbing material.

Comprehensive Thermal Characteristic Investigations on Hemp- and Jute-Based Nature Fibre-Reinforced Composites for Engineering Applications through Coupled and Verified Engineering Approaches

Natural fibre-reinforced polymer composites (NFRPs) have gained increasing attention in recent years as an alternative to conventional materials such as steel and aluminum alloys due to their ecofriendly, renewable, and low-cost nature. This paper focuses on the thermal application of NFRPs, which have shown great potential due to their good thermal insulation properties. In this study, the fabrication of jute and hemp fibre-reinforced composites, experimental testing, comparison, validation by using computational method, and proposed hemp NFRPs insulated exhaust pipe in place of conventional steel pipe. However, challenges such as moisture absorption and limited thermal properties on high thermal load still need to be addressed to enable the full-scale commercialization of NFRPs in thermal applications. For these comprehensive investigations, coupled and verified engineering approaches have been imposed. Fluid-thermal coupling has been executed in ANSYS workbench associated with conventional test outcomes. Through this approach, the low weight and low cost-based thermal load resisting material has been proposed for various engineering applications.

STUDY OF THE PROGRAMMABLE ISOKINETIC SAMPLER EFFICIENCY FOR OF ECOLOGICAL DIAGNOSTICS SYSTEMS OF HEAT ENGINES AND BOILER PLANTS

The work is devoted to the solution of the actual scientific and practical task of creating a universal sampling device for systems of environmental diagnostics of heat engines and boiler plants of various purposes. Ensuring the isokinetic mode of sampling from the exhaust pipe (EP) of the engine is a more difficult task than carrying out a similar sampling process in the chimney of the boiler plant, since the exhaust gases of the engines are characterized by fluctuations of static pressures in the HT with an amplitude of up to ±500 Pa, which must be taken into account in the operation of the sampling equipment. In the course of research, based on the analysis of global and domestic experience in the production and use of equipment for environmental certification of internal combustion engines and boiler houses, a programmable isokinetic sampler (ICT) was created, which allows you to take a proportional part of the gas sample from the full flow of exhaust gases in the EP of the power plant with accuracy ±3%. Motorless and motorized test stands have been developed for modeling and research of gas-dynamic processes in the exhaust systems of engines and boiler plants, which provide the possibility of varying the parameters of gas flows - mass flow rate, speed, temperature, static pressure, velocity pressure in the ranges: 15 - 55 g/s; 5...30 m/s, 20...180 °С, 0...2.5 kPa, 10 - 550 Pa, respectively. On the basis of the created test stands, empirical dependences were established to determine the static pressure differences between the ICP and EP pipelines, in which the isokinetic mode of sampling is ensured, from the dynamic pressure of the gas flow in the EP. With the help of these dependencies, SMART control of the programmable ICP is carried out. An experimental development of the programmable ICP was carried out as part of the MT-1 minitunnel during environmental tests of the 1СН12/14 diesel engine in separate modes and according to the ESC cycle established by the UNECE Regulations R-49. The research results confirmed the compliance of the created sampling device with regulatory requirements for its design and the accuracy of determining the sampling coefficient.

Investigations of Weldment Joints of Exhaust Pipes Using Non-Destructive Testing (NDT)

Exhaust pipe components are especially vulnerable to accelerated degradation. Cracks are identified during the scheduled inspection and repaired by weld-filling procedure or by more invasive approaches like cutting and replacing sections. Such small defects can develop into fatigue or stress corrosion cracks in service, which can be extremely difficult to detect. The input parameter has a significant impact on weldment joint quality. Welds are checked to determine whether or not they meet specifications. The study was carried out to inspect and assess the quality of the weldment joints of exhaust pipes using non-destructive testing (NDT). An experimental approach methodology was adopted to achieve the aim of the study. Specimens of car exhaust pipes were welded and tested using some selected non-destructive testing techniques. Six (6) samples were selected for testing, with a serious fault or discontinuity in the artisan-made welded seam. The results showed that the principal fault signs were lack of fusion, surface porosity, crater fractures, linear indication, and undercuts, all of which were below the allowable standards of the AMSE B31.3 Stainless-Steel pipe code and therefore must be rejected.

Monitoring of electricity generation from exhaust waste heat and wireless data recording from a mobile phone in real driving conditions of a vehicle.

In this study, a system is designed to generate electrical energy from the exhaust waste heat of vehicles using a thermoelectric generator. Electronic hardware that can communicate wirelessly, firmware, and mobile software specific to the system have been developed to control and monitor this system. The system comprises hexagonal aluminum components, thermoelectric generators, a cooler, sensors, software, and electronic hardware. The easily removable hexagonal modular aluminum component is designed to transmit heat from the exhaust pipe to thermoelectric generators. It used a thermoelectric generator (TEG-SP1848) on each edge of this hexagonal component and a heatsink to cool the generator. The voltage and current values of the electrical energy produced in the observations made under real driving conditions are recorded on the SD card on the system. In addition, system-specific mobile software has been developed by the work team. With this software, the system can be controlled, as well as visualizing the instantaneous parameters of the system. According to the results obtained from the test drives, electrical energy was obtained at a maximum voltage of 9.8 V and a current of 0.32 A. This electrical energy from the exhaust waste heat can be stored in the vehicle's existing battery. In this way, since the alternator used for the vehicle's electricity generation will be activated less, fuel savings will be achieved in the engine, and harmful exhaust emissions will be reduced. In addition, the electrical energy obtained by this method can be stored in an external battery independent of the vehicle battery and used for various purposes. In contrast, the vehicle is stationary or has a portable battery.

Study on PM diffusion and distribution of trackless rubber-tyred vehicle under different driving conditions in underground coal mining environment.

Particulate matter (PM) is one of the most harmful exhaust pollutants to human health. In this study, the PM diffusion and distribution emitted by trackless rubber-tyred vehicle under different driving conditions in coal mine were analyzed with numerical simulations and field measurements. The results show that when the vehicle velocity was constant, the PM concentration of the trackless rubber-tyred vehicle decreased with increasing distance from the exhaust pipe orifice. In addition, the proportion of PM with a concentration below 10mg/m3 was the highest owing to the influences of diffusion and airflow dilution. However, when the diffusion distance is less than 3m, the PM concentration far exceeds the occupational exposure limit (10mg/m3). In this case, underground personnel should stay away from the area near and along the exhaust pipe as far as possible. With increasing vehicle velocity, the PM concentration gradient at a diffusion distance of 0-6m showed the most significant slope. Besides, the concentration fluctuation of PM was the largest and relatively high when the diffusion distance was 5-15m. Therefore, the area 15m from the exhaust gas pipe opening of the trackless rubber-tyred vehicle should be controlled. In addition, the relative errors between the measured and numerical simulation results were mostly less than 10%, which proved that the numerical simulation results were reliable.

The effect of chicken eggshell (Gallus gallus domesticus) particle size as filler to polyester composite as motorcycle’s exhaust pipe cover material

This research was done to know the effect of chicken eggshell (Gallus gallus domesticus) powder particle size on unsaturated polyester resin mechanical properties. The eggshell was mashed and sifted to get the 50 mesh, 70 mesh, 90 mesh, 110 mesh, 130 mesh, 150 mesh, and 170 mesh particle size by using a ball mill. Then, the eggshell was mixed with an unsaturated polyester resin matrix with the ratio of 70:30 and methyl ethyl ketone peroxide (MEKP) catalyst as much as 1 % of the matrix mass. After that, it was pressed by using compression molding. The composite formed was characterized by Scanning Electron Microscopy Energy Dispersive X-ray (SEM EDX), Fourier Transform Infra-Red (FTIR), and X-Ray Diffraction (XRD). The physical properties of the composite were analyzed and the mechanical properties were tested. The SEM EDX result showed that the eggshell and composite were made up of Ca, C, and O, and the polyester was made up of C, O, and Si. The composite highest tensile strength and impact strength were at 150 mesh particle size of chicken eggshell powder which is 45.153 MPa and 9. 04 J/m2.

Effect of Temperature on Morphologies and Microstructures of Soot Particles in the Diesel Exhaust Pipe

Effect of Temperature on Morphologies and Microstructures of Soot Particles in the Diesel Exhaust Pipe