scholarly journals Comparison of four diesel engines with regard to blow-by aerosol properties as a basis for reduction strategies based on engine design and operation

2021 ◽  
Author(s):  
Kai-Michael Scheiber ◽  
Niclas Nowak ◽  
Magnus Lukas Lorenz ◽  
Jürgen Pfeil ◽  
Thomas Koch ◽  
...  
Keyword(s):  
Particle Size ◽  
Diesel Engines ◽  
Engine Speed ◽  
Total Concentration ◽  
Ventilation System ◽  
Sampling System ◽  
Brake Mean Effective Pressure ◽  
Engine Design ◽  
Aerosol Sources ◽  
Generation Mechanisms

AbstractUnderstanding how engine design and operation affect blow-by aerosol characteristics is key to reducing the emission of particulate matter (PM) via the crankcase ventilation system. To this end, representative aerosol data from four different diesel engines are compared on the basis of brake mean effective pressure (BMEP) and engine speed. The data were obtained from comparable sampling positions, using the same sampling system and optical particle counter. The discussion is based on the narrow particle size range of 0.4–1.3 µm, chosen for its significance with regard to blow-by aerosol sources, as well as for the challenges it poses for separation systems. Key findings include particle size distributions (PSD) of virtually identical shape, indicating that these engines share the same aerosol sources and underlying generation mechanisms. However, absolute concentrations differed by a factor of about six, presumably due to differences in engine design, which in turn affect key parameters such as temperature, pressure and flow rates. At BMEPs ≤ 10 bar all engines exhibited similarly low aerosol concentrations. With increasing BMEP the concentration rose exponentially. The engine with the smallest rise and the lowest total concentration featured an aluminum alloy piston, the smallest displacement, the lowest peak BMEP as well as the lowest maximum oil temperature. At maximum torque the aerosol concentration scaled fairly linearly with engine displacement. Increasing the engine speed had a minor impact on aerosol concentrations but affected blow-by flows, hence leading to a rise of aerosol mass flows. Within the limits of this comparative measurement studies, three generation mechanisms are provided for blow-by aerosols.

Metallic pollution in clogging materials of urban porous pavements

1995 ◽  
Vol 32 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Valérie Colandini ◽  
Michel Legret ◽  
Yves Brosseaud ◽  
Jean-Daniel Baladès
Keyword(s):  
Heavy Metal ◽  
Particle Size ◽  
Road Traffic ◽  
Total Concentration ◽  
Extraction Procedure ◽  
Interaction Strength ◽  
Metal Mobility ◽  
Residual Fraction ◽  
Metal Contents ◽  
Copper Zinc

Porous pavements infiltrated with stormwater are faced with clogging problems: runoff particles seep and clog the pervious surface layer of these structures. Clogging material samples (in the form of sludge) have been collected in cleaning operations on the pervious asphalt. This study aims at characterizing these materials, particle size distribution, heavy metal contents by particle size, and studying interactions between metals and particles. A sequential extraction procedure proposed by the experts of the Community Bureau of Reference (B.C.R.) was applied to provide information about heavy metal distribution on particles and to evaluate interaction strength, and consequently potential metal mobility when chemical variations occurred in the environment. Mainly made up of sand, the materials are polluted with lead, copper, zinc and cadmium. The concentrations appeared to be linked with road traffic intensity. The heavy metal contents by particle size showed that the finer are the particles, the higher are the heavy metal concentrations. Heavy metals were found potentially labile; metals contents in the residual fraction (mineral fraction) represented less than 20 % of the total concentration. Cadmium and zinc were apparently more labile than lead and copper.

scholarly journals Awareness of aerosol-related transmission of COVID-19 among the dentists of Nepal

BDJ Open ◽  
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Nashib Pandey ◽  
Buddha Bahadur Basnet ◽  
Sushmit Koju ◽  
Anju Khapung ◽  
Alka Gupta
Keyword(s):  
Social Sciences ◽  
Particle Size ◽  
High Efficiency ◽  
Emergency Services ◽  
Uv Light ◽  
Ventilation System ◽  
Age Groups ◽  
Air Filtration ◽  
Online Questionnaire ◽  
Dental Practitioners

Abstract Objective To access the awareness of dental practitioners of Nepal towards COVID-19 transmission through aerosols. Materials and methods The study involved 384 dentists from all over Nepal and was conducted for a period of 3 months. A self-reported online questionnaire was developed using Google forms and the link was shared. It emphasized the awareness related to the aerosol and ventilation system in their daily practices was prepared. The data were analyzed in Statistical Package for Social Sciences version 20.0 software. Results The majority of participants were female 52.9% (n = 203) and within the age groups of <30 years 57% (n = 219). Participants from Bagmati Province were 60.4% (n = 232), with least from Sudurpaschim Province 0.5% (n = 2). 60% of participants provided only emergency services during the COVID-19 pandemic and few (7%) provided consultations via telephone. The current ventilation system used was a well-ventilated room with open windows 65.4% (n = 251). However, 52.8% (n = 203) preferred specialized operatory incorporating high-efficiency particulate air (HEPA) filters and ultraviolet (UV) light. More than 60% of respondents were unaware of the particle size of the aerosol. Conclusions The obtained results signify the need for the proper ventilation system with appropriate air filtration systems in dental clinical setups.

An Improved Rate of Heat Release Model for Modern High-Speed Diesel Engines

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Peter G. Dowell ◽  
Sam Akehurst ◽  
Richard D. Burke
Keyword(s):  
Heat Release ◽  
Diesel Engines ◽  
Engine Speed ◽  
Fuel Injection ◽  
Maximum Pressure ◽  
Injection Model ◽  
Wall Impingement ◽  
Small Set ◽  
Rate Of Heat Release ◽  
Engine System

To meet the increasingly stringent emissions standards, diesel engines need to include more active technologies with their associated control systems. Hardware-in-the-loop (HiL) approaches are becoming popular where the engine system is represented as a real-time capable model to allow development of the controller hardware and software without the need for the real engine system. This paper focusses on the engine model required in such approaches. A number of semi-physical, zero-dimensional combustion modeling techniques are enhanced and combined into a complete model, these include—ignition delay, premixed and diffusion combustion and wall impingement. In addition, a fuel injection model was used to provide fuel injection rate from solenoid energizing signals. The model was parameterized using a small set of experimental data from an engine dynamometer test facility and validated against a complete data set covering the full engine speed and torque range. The model was shown to characterize the rate of heat release (RoHR) well over the engine speed and load range. Critically, the wall impingement model improved R2 value for maximum RoHR from 0.89 to 0.96. This was reflected in the model's ability to match both pilot and main combustion phasing, and peak heat release rates derived from measured data. The model predicted indicated mean effective pressure and maximum pressure with R2 values of 0.99 across the engine map. The worst prediction was for the angle of maximum pressure which had an R2 of 0.74. The results demonstrate the predictive ability of the model, with only a small set of empirical data for training—this is a key advantage over conventional methods. The fuel injection model yielded good results for predicted injection quantity (R2 = 0.99) and enabled the use of the RoHR model without the need for measured rate of injection.

Matching and Optimisation of Turbochargers for Upgradation of High Horse Power Diesel Electric Locomotives for Indian Railways

2005 ◽  
Author(s):  
Anirudh Gautam ◽  
Avinash Kumar Agarwal
Keyword(s):  
Engine Speed ◽  
Thermal Loading ◽  
Fuel Efficiency ◽  
Operating Point ◽  
Inlet Temperature ◽  
Test Bed ◽  
Optimum Configuration ◽  
Air Inlet ◽  
First Case ◽  
Brake Mean Effective Pressure

As a part of the upgradation program of its fleet of 1940 kW diesel electric locomotives, Indian Railways undertook evaluation, matching and optimization of different turbochargers. The objective was to increase engine output, improve fuel efficiency and limit thermal loading. Trials with different makes of turbochargers using different combinations of diffuser, nozzle rings and compressors were carried out for identifying the optimum configuration for an uprated engine rating of 2310 kW. Test bed evaluations have been carried out on Research Design & Standards Organization (RDSO) test beds for four different designs of turbochargers with different configurations. Two types of surge tests were carried out at each operating point i.e. constant brake mean effective pressure (BMEP) and constant power. In the first case, BMEP was kept constant and engine speed varied and in the second case, power was kept constant and engine speed was varied. The tests consisted of recording the parameters at various combinations of engine speed and power. With different combinations, the highest operating point for a test was governed by peak firing pressures. Some of the parameters, which were monitored, were the compressor air inlet temperature, representative peak firing pressures, turbine inlet temperature, average cylinder head temperature, brake specific fuel consumption (BSFC) and air manifold temperature. This paper discusses the methods adopted in carrying out these evaluations and optimizations and the results obtained thereof along with the decision criteria for making final selections.

scholarly journals Optimization of the Performance of Marine Diesel Engines to Minimize the Formation of SOx Emissions

2020 ◽  
Vol 19 (3) ◽  
pp. 473-484
Author(s):  
Mina Tadros ◽  
Manuel Ventura ◽  
C. Guedes Soares
Keyword(s):  
Fuel Consumption ◽  
Diesel Engines ◽  
Engine Speed ◽  
Exhaust Emissions ◽  
Polynomial Equations ◽  
Marine Fuel ◽  
Marine Engines ◽  
Marine Diesel ◽  
Marine Applications ◽  
Generate Polynomial

Abstract Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines. This study discusses the procedures to optimize the performance of any marine engine implemented in a 0D/1D numerical model in order to achieve lower values of exhaust emissions. From that point, an extension of previous simulation researches is presented to calculate the amount of SOx emissions from two marine diesel engines along their load diagrams based on the percentage of sulfur in the marine fuel used. The variations of SOx emissions are computed in g/kW·h and in parts per million (ppm) as functions of the optimized parameters: brake specific fuel consumption and the amount of air-fuel ratio respectively. Then, a surrogate model-based response surface methodology is used to generate polynomial equations to estimate the amount of SOx emissions as functions of engine speed and load. These developed non-dimensional equations can be further used directly to assess the value of SOx emissions for different percentages of sulfur of the selected or similar engines to be used in different marine applications.

scholarly journals A Comprehensive Study of Particle Size Distributions with the Use of PostInjection Strategies in DI Diesel Engines

2011 ◽  
Vol 45 (10) ◽  
pp. 1161-1175 ◽  
Author(s):  
José María Desantes ◽  
Vicente Bermúdez ◽  
Antonio García ◽  
Waldemar G. Linares
Keyword(s):  
Particle Size ◽  
Diesel Engines ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Comprehensive Study

Piston Temperatures in a Sleeve Valve Oil Engine

1937 ◽  
Vol 135 (1) ◽  
pp. 35-71 ◽  
Author(s):  
H. Wright Baker
Keyword(s):  
Cast Iron ◽  
Engine Speed ◽  
Effective Pressure ◽  
Final Temperature ◽  
Piston Head ◽  
Brake Mean Effective Pressure ◽  
Head Section ◽  
Normal Water ◽  
Time Required ◽  
Valve Engine

The paper describes tests on a Mirrlees-Ricardo sleeve valve engine of inches bore, running at speeds up to 1,400 r.p.m. The pistons used were: (1) a simple piston of cast iron; (2) a piston with tapered head section, cast in “L8” alloy; and (3) a heavily ribbed and strutted piston of “Y” alloy. A robust form of thermocouple gear which has been devised is described in the paper, and the probable errors are discussed. The temperatures attained by a number of points in each piston are shown for various conditions. The effect of the sleeve is much less than might be expected. The rates of heat reception by the central and outer portions of the piston head differ considerably owing to the vortex type of combustion chamber used. Values of these rates have been estimated for different loads and speeds. The alloy pistons become warm in about half the time required by the cast iron piston. Piston temperature appears to be a linear function of engine speed, the alloy pistons showing an increase of 42 deg. C. at the centre when the speed was increased from 800 to 1,400 r.p.m. at constant brake mean effective pressure. The temperatures of the lower edges of ribs of moderate depth were only 10–18 deg. C. cooler than the under surface of an unribbed piston. Distortion of the pin seatings due to the expansion of the struts must be very slight. With normal water circulation and a constant temperature of water supply, piston temperatures in this engine are almost independent of the final temperature of the water.

scholarly journals Particle Size-Selective Assessment of Protection of European Standard FFP Respirators and Surgical Masks against Particles-Tested with Human Subjects

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Shu-An Lee ◽  
Dong-Chir Hwang ◽  
He-Yi Li ◽  
Chieh-Fu Tsai ◽  
Chun-Wan Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Human Subjects ◽  
Strong Association ◽  
European Standard ◽  
Sampling System ◽  
Protection Level ◽  
British Standard ◽  
Surgical Masks ◽  
Significant Difference ◽  
Personal Sampling

This study was conducted to investigate the protection of disposable filtering half-facepiece respirators of different grades against particles between 0.093 and 1.61 μm. A personal sampling system was used to particle size-selectively assess the protection of respirators. The results show that about 10.9% of FFP2 respirators and 28.2% of FFP3 respirators demonstrate assigned protection factors (APFs) below 10 and 20, which are the levels assigned for these respirators by the British Standard. On average, the protection factors of FFP respirators were 11.5 to 15.9 times greater than those of surgical masks. The minimum protection factors (PFs) were observed for particles between 0.263 and 0.384 μm. No significant difference in PF results was found among FFP respirator categories and particle size. A strong association between fit factors and protection factors was found. The study indicates that FFP respirators may not achieve the expected protection level and the APFs may need to be revised for these classes of respirators.

Paper 13: Developments in Starter Motor Application to Diesel Engines

1969 ◽  
Vol 184 (1) ◽  
pp. 97-102 ◽  
Author(s):  
K. F. Hutcheon ◽  
R. L. Marks
Keyword(s):  
Diesel Engines ◽  
Starter Motor ◽  
Engine Design ◽  
Recent Trends ◽  
Design And Application

The greater precision required today, for technical and economic reasons, in the application of starter motors to diesel engines has prompted a closer examination of the factors involved in effective cranking. The results, when taken in conjunction with recent trends in engine design, suggest that some detailed changes may become necessary in the design and application of starter motors.

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